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Gymnotus cylindricus LaMonte, 1935. Round Knifefish; Pez Cuchillo, Pez Cuchillo Redondo, Pez Navaja, Pez Machete, Anguila, Anguila Falsa, Madre de Barbudo. Distribution: Global: Middle America; from central Guatemala to eastern Costa Rica, Atlantic and Pacific drainages; Costa Rica: LN, RF, SJ, SC, Sa, To, Pa, Ma and Si (Atlantic), 1��� 50 m.a.s.l., Pri, Pot. Occurrence and conservation status: Nat, LC. References: Bussing (1966: 221; brief description and information on distribution), Bussing (1987: 98; 1998: 130; brief description, including illustrations and an identification key, information on distribution, with a map, and ecology) and Angulo et al. (2013: 994; listed, including taxonomic information and distributional data)., Published as part of Angulo, Arturo, 2021, New records and range extensions to the Costa Rican freshwater fish fauna, with an updated checklist, pp. 1-72 in Zootaxa 5083 (1) on page 28, DOI: 10.11646/zootaxa.5083.1.1, http://zenodo.org/record/5800630

The capture of live bait for sport fishing is an important activity for fishing communities. The main species used for this purpose are members of the genus Gymnotus, which comprises numerous species of cryptic nature that are difficult to identify based on external morphology. The aims of this work were to identify through partial sequences of the COI gene Gymnotus species fished in the Jacaré-Guaçu River, SP, and to develop a molecular diagnostic approach using PCR-RFLP to identify these species. Partial COI sequences were compared to those of other species deposited in GenBank. The sequences were assessed in the NEBCutter program to determine restriction sites in the sequence and the enzymes to be tested. Phenetic analysis performed by Neighbor-Joining method showed that the specimens sampled belong to two species preliminary identified here as G. cf. sylvius and G. cf. cuia, with G. cf. sylvius accounting for 95.2% of the individuals sampled. The enzymes NlaIII and SacI generated fragments that allowed distinguishing the Gymnotus species using PCR-RFLP. This analysis can be used to accurately identify these species, which is fundamental for monitoring Gymnotus fishing and assessing the conservation of this genetic resource. RESUMO A captura de iscas-vivas para a pesca esportiva constitui uma atividade importante em comunidades de pescadores. As principais espécies utilizadas para este propósito pertencem ao gênero Gymnotus, o qual compreende inúmeras espécies de natureza críptica que dificulta a identificação baseada na morfologia externa. Os objetivos deste trabalho foram identificar através de sequências parciais do gene COI, espécies de Gymnotus capturadas no Rio Jacaré-Guaçu, Ibitinga, SP, e desenvolver um diagnóstico molecular por meio de PCR-RFLP. Sequências parciais de COI foram comparadas com outras espécies depositadas no GenBank. As sequências foram analisadas no Programa NebCutter para determinar os sítios de restrição e definir as enzimas a serem testadas. A análise fenética pelo método de Neighbor-Joining mostrou que os espécimes pertencem a duas espécies identificadas preliminarmente aqui como G. cf. sylvius e G. cf. cuia, sendo que G. cf. sylvius representou 95,2% dos indivíduos amostrados. As enzimas NlaIII e SacI geraram fragmentos que permitiram discriminar as espécies por meio de PCR-RFLP. Esta análise pode ser usada na identificação precisa destas espécies, fundamental na proposição de monitoramento da pesca de Gymnotus na região e para medidas adequadas de conservação.

Gymnotus carapo Linnaeus, 1758 FIRST RECORD FOR THE MITARAKA. ��� This study. OCCURENCES. ��� S4, S5, S9, S10, S11, S12, S13, S14. SPECIMENS IN COLLECTION. ��� 10 MNHN (MNHN-IC-2018-0503, MNHN-IC-2018-0504, MNHN-IC-2018-0505, MNHN- IC-2018 -0506, MNHN-IC-2018-0507, MNHN-IC-2018-0508, MNHN-IC-2018-0509, MNHN-IC-2018-0510, MNHN- IC-2018 -0511, MNHN-IC-2018-0512); 10 Hydreco. DISTRIBUTION IN FRENCH GUIANA. ��� Widespread. ECOLOGY. ��� Observed in both Alama mainstream and tributaries. This nocturnal species hides during the day in submersed tree roots and undercut banks. Captured using rotenone., Published as part of S��bastien Brosse, Fr��deric Melki & R��gis Vigouroux, 2019, Fishes of the Mitaraka Mountains (French Guiana), pp. 131-151 in Zoosystema 41 (8) on page 146, DOI: 10.5252/zoosystema2019v41a8, http://zenodo.org/record/2639414, {"references":["FISCH- MULLER S., MOL J. H. & COVAIN R. 2018. - An integrative framework to reevaluate the Neotropical catfish genus Guyanancistrus (Siluriformes: Loricariidae) with particular emphasis on the Guyanancistrus brevispinis complex. PLoS ONE 13: e 0189789. https: // doi. org / 10.1371 / journal. pone. 0189789"]}

Gymnotus carapo Linnaeus, 1758 FIRST RECORD FOR THE MITARAKA. — This study. OCCURENCES. — S4, S5, S9, S10, S11, S12, S13, S14. SPECIMENS IN COLLECTION. — 10 MNHN (MNHN-IC-2018-0503, MNHN-IC-2018-0504, MNHN-IC-2018-0505, MNHN- IC-2018 -0506, MNHN-IC-2018-0507, MNHN-IC-2018-0508, MNHN-IC-2018-0509, MNHN-IC-2018-0510, MNHN- IC-2018 -0511, MNHN-IC-2018-0512); 10 Hydreco. DISTRIBUTION IN FRENCH GUIANA. — Widespread. ECOLOGY. — Observed in both Alama mainstream and tributaries. This nocturnal species hides during the day in submersed tree roots and undercut banks. Captured using rotenone.

Gymnotus coropinae Hoedeman, 1962 FIRST RECORD FOR THE MITARAKA. ��� This study. OCCURENCES. ��� S2. SPECIMEN IN COLLECTION. ��� None. DISTRIBUTION IN FRENCH GUIANA. ��� Widespread. ECOLOGY. ��� Observed in a single small and shallow stream. This nocturnal species hides during the day in submersed tree roots and undercut banks. Captured using rotenone., Published as part of S��bastien Brosse, Fr��deric Melki & R��gis Vigouroux, 2019, Fishes of the Mitaraka Mountains (French Guiana), pp. 131-151 in Zoosystema 41 (8) on page 146, DOI: 10.5252/zoosystema2019v41a8, http://zenodo.org/record/2639414

Gymnotus coropinae Hoedeman, 1962 FIRST RECORD FOR THE MITARAKA. — This study. OCCURENCES. — S2. SPECIMEN IN COLLECTION. — None. DISTRIBUTION IN FRENCH GUIANA. — Widespread. ECOLOGY. — Observed in a single small and shallow stream. This nocturnal species hides during the day in submersed tree roots and undercut banks. Captured using rotenone.

Gymnotus paraguensis Albert, Crampton, 2003 Fig. 16 Body elongated and compressed; greatest depth contained 9.7 to 10.2 times in TL; head length 7.5 to 8.2, anal-fin base length 1.2 in LEA; snout length 2.8 to 3.0, horizontal orbital diameter 13.9 to 15.4 and least interorbital width 2.4 to 3.2 in HL. Mouth superior, dentary prognathous. Pectoral fin with 17-21 rays and anal fin with 260-270 rays; transverse series above lateral line with 11 or 12 scale rows. Ground color dark-brown; body with 23-26 light-beige oblique stripes, with well-defined margins; two to seven inverted Y-shaped stripes, or sometimes X-shaped, or sometimes interrupted on porterior half of body. Hyaline fins or light-beige, with scattered dark-brown spots (Graça, Pavanelli, 2007). Maximum total length. 280.0 mm (Graça, Pavanelli, 2007). Distribution. Paraná-Paraguay system. Remarks. Gymnotus paraguensis is a non-native species from the upper rio Paraná, and its occurrence in the region can be associated with its introduction as a live bait by anglers, or with the filling of the Itaipu Reservoir and the consequent inundation of the Sete Quedas Falls., Published as part of Ota, Renata Rúbia, Deprá, Gabriel de Carvalho, Graça, Weferson Júnio da & Pavanelli, Carla Simone, 2018, Peixes da planície de inundação do alto rio Paraná e áreas adjacentes: revised, annotated and updated, pp. 1-111 in Neotropical Ichthyology 16 (2) on page 57, DOI: 10.1590/1982-0224-20170094, http://zenodo.org/record/3678395, {"references":["Pavanelli CS, Graca WJ, Zawadzki CH, Britski HA, Vidotti AP, Avelino GS, Verissimo S. Fishes from the Corumba Reservoir, Paranaiba River drainage, upper rio Parana basin, State of Goias, Brazil. Check List. 2007; 3 (1): 58 - 64."]}

Gymnotus sylvius Albert, Fernandes-Matioli, 1999 Fig. 16 Body elongated and compressed; greatest depth contained 7.0 to 9.3 times in TL; head length 7.1 to 8.2, anal-fin base length 1.2 in LEA; snout length 3.0 to 3.3, horizontal orbital diameter 12,8 to 14.0 and least interorbital width 2.6 to 2.7 in HL. Mouth superior, dentary prognathous. Pectoral fin with 15 or 16 rays and anal fin with 220-228 rays; transverse series above lateral line with 8 or 9 scale rows (Albert et al., 1999). Ground color pale brown; body with light-beige transverse bars alternating with dark-brown transverse bars; light-beige bars wider than dark-brown bars. Anal fin with posterior portion light-beige (Graça, Pavanelli, 2007). Maximum total length. 360.0 mm (Graça, Pavanelli, 2007). Distribution. Rio Ribeira de Iguape, rio Paraíba do Sul and rio Pardo basins., Published as part of Ota, Renata Rúbia, Deprá, Gabriel de Carvalho, Graça, Weferson Júnio da & Pavanelli, Carla Simone, 2018, Peixes da planície de inundação do alto rio Paraná e áreas adjacentes: revised, annotated and updated, pp. 1-111 in Neotropical Ichthyology 16 (2) on page 57, DOI: 10.1590/1982-0224-20170094, http://zenodo.org/record/3678395, {"references":["Albert JS, Fernandes-Matioli FMC, Almeida-Toledo LF. New species of Gymnotus (Gymnotiformes, Teleostei) from southeastern Brazil: toward the deconstruction of Gymnotus carapo. Copeia. 1999; (2): 410 - 21.","Pavanelli CS, Graca WJ, Zawadzki CH, Britski HA, Vidotti AP, Avelino GS, Verissimo S. Fishes from the Corumba Reservoir, Paranaiba River drainage, upper rio Parana basin, State of Goias, Brazil. Check List. 2007; 3 (1): 58 - 64."]}

Gymnotus pantanal Fernandes, Albert, Daniel-Silva, Lopes, Crampton, Almeida-Toledo, 2005 Fig. 16 Body elongated and compressed; greatest depth contained 10.5 to 12.5 times in TL; head length 9.9 to 11.1, anal-fin base length 1.2 to 1.3 in LEA; snout length 2.7 to 2.9, horizontal orbital diameter 14.3 to 15.0 and least interorbital width 2.2 to 3.0 in HL. Mouth superior, dentary prognathous. Pectoral fin with 16-18 rays and anal fin with 256-270 rays; transverse series above lateral line with 7 or 8 scale rows. Ground color brown; body with seven to 25 light-beige transverse stripes, spaced apart. Hyaline fins or light-beige, with scattered dark-brown spots (Graça, Pavanelli, 2007). Maximum total length. 200.0 mm (Graça, Pavanelli, 2007). Distribution. Paraná-Paraguay system, in Brazil and Paraguay, and río Capare-Mamoré, in Bolívia (Eschmeyer et al., 2017). Remarks. Gymnotus pantanal is a non-native species from the upper rio Paraná, and its occurrence in the region can be associated with its introduction as a live bait by anglers, or with the filling of the Itaipu Reservoir and the consequent inundation of the Sete Quedas Falls., Published as part of Ota, Renata Rúbia, Deprá, Gabriel de Carvalho, Graça, Weferson Júnio da & Pavanelli, Carla Simone, 2018, Peixes da planície de inundação do alto rio Paraná e áreas adjacentes: revised, annotated and updated, pp. 1-111 in Neotropical Ichthyology 16 (2) on page 57, DOI: 10.1590/1982-0224-20170094, http://zenodo.org/record/3678395, {"references":["Pavanelli CS, Graca WJ, Zawadzki CH, Britski HA, Vidotti AP, Avelino GS, Verissimo S. Fishes from the Corumba Reservoir, Paranaiba River drainage, upper rio Parana basin, State of Goias, Brazil. Check List. 2007; 3 (1): 58 - 64.","Eschmeyer WN, Fricke R, van der Laan R, editors. Catalog of fishes: genera, species, references [Internet]. San Francisco: California Academy of Science; 2017 [updated 2017 Jan 31; cited 2017 Feb 24]. Available from: http: // researcharchive. calacademy. org / research / ichthyology / catalog / fishcatmain. asp"]}

Gymnotus 1. Body elongated (subcilindrical); light-beige transverse bars narrow and distant from each other along the side of the body.............................................................. G. pantanal 1’. Body deep (knife-shaped); light-beige transverse bars narrow and close to each other along the side of the body............................................................................................. 2 2. Transversal series above lateral line with 11 or 12 scale rows (to the mid dorsum); two to seven light-beige transverse bars along the side of the body, some of them forming an inverted Y.................................. G. paraguensis 2’. Transversal series above lateral line with 6 to 9 scale rows (to the mid dorsum); light-beige transverse bars along the side of the body not forming Y........................... 3 3. Head lenght contained 8.3 to 11.1 times in total length; interorbital contained 2.3 to 2.4 times in head length.......................................................................... G. inaequilabiatus 3’. Head lenght contained 7.1 to 8.2 times in total length; interorbital contained 2.6 to 2.7 times in head length........................................................................................ G. sylvius, Published as part of Ota, Renata Rúbia, Deprá, Gabriel de Carvalho, Graça, Weferson Júnio da & Pavanelli, Carla Simone, 2018, Peixes da planície de inundação do alto rio Paraná e áreas adjacentes: revised, annotated and updated, pp. 1-111 in Neotropical Ichthyology 16 (2) on page 56, DOI: 10.1590/1982-0224-20170094, http://zenodo.org/record/3678395

Gymnotus chaviro Maxime & Albert, 2009 Figure 6B, Table 1 Diagnosis: Gymnotus chaviro differs from all sympatric members of the G. carapo clade on a color pattern consisting of 17���29 (mode 20, n=100) dark gray bands with irregular, wavy margins approximately as wide as pale interbands, 2���3 of the anteriormost five pale interbands with both margins crescent-shaped vs. margins of anteriormost interbands straight or curved in parallel in the G. carapo clade of the Upper Madeira. Description: Sexually monomorphic. Size up to 275 mm TL with adult body proportions attained at about 120 mm TL. Adult body shape subcylindrical with a mean ratio of body width to depth of 77%. Head length moderate, 8.8���11.7% total length. Snout length moderate, 31.4���39.8% head length. Mouth width intermediate, 35.5���57.8% head length. Preanal distance long, 67.8���99.4% head length. Anal-fin long, 76.5���84.3% total length. Cycloid or ovoid scales present on entire post-cranial portion of body from nape to caudal appendage. Scales above lateral line intermediate, five to nine, mode eight. Scales over anal-fin pterygiophores large, with 12���13, mode 12 rows. Gape small, never extending beyond posterior nares. Mouth position superior, lower jaw longer than upper, rictus decurved. Chin round in lateral, dorsal profiles, fleshy and bulbous with mental electroreceptive organ overlying lower jaw. Anterior narial pore partially or entirely included within gape, in small narial fold, pipe shaped. Anterior nares small, its diameter four to five times less than that of eye. Eye below horizontal with mouth. Circumorbital series ovoid. Premaxilla with 14 teeth in two rows, and curved median margin. Curved median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, narrow distally with a straight ventral margin, length equal to roughly width of seven to nine dentary teeth. Dentary with 14 arrowhead-shaped teeth anteriorly in outer row and 10 in an anterior inner tooth patch. Posterodorsal and posteroventral dentary processes abut at midlength. Dentary posteroventral process shorter than posterodorsal, narrow distally. Dentary ventral margin lamella wide, depth greater than posterior process. Dentary anteroventral margin rounded in lateral view, without a hook. Mandible long, extended, length greater than twice depth. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Anguloarticular process long, extending beyond ventral margin of dentary. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base shorter than length, curved, tip simple. Hyomandibular trigeminal canals connected. Dorsal region of hyomandibula with four lateral foramenae, supraorbital and infraorbital nerves divided. Posterior lateral line fenestra contacting posterodorsal margin of hyomandibula. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf large, more than half width of symplectic. Interopercle dorsal margin ascending process broad. Subopercle dorsal margin concave. Opercle dorsal margin straight to slightly convex, its posterior margin smooth. Opercular posterior margin entirely smooth. Cranial fontanels closed in juveniles and adults. Frontal shape broad, width at fourth infraorbital greater than that of parietal, anterior margin of straight, continuous with margins of adjacent roofing bones, postorbital process narrow, less than two times width of supraorbital canal. Lateral ethmoid unossified. Parietal rectangular, length less than width. Parasphenoid anteroventral portion robust, extending ventral to lateral margin of parasphenoid, posterior processes narrow. Prootic foramen Vp separate from V2-3 +VII. Adductor mandibula undivided at insertion, intermusculars absent. All basibranchials unossified. Gill rakers not contacting gill bar. Cleithrum narrow, ventral margin straight, anterior limb long, more than one-point-eight times ascending limb, deeply incised on its anteroventral margin, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle shaped. Body cavity of moderate length, with 35���38 precaudal vertebrae, mode=37, n=4. Rib 5 robust along its entire extent, less than three times width of rib 6. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Pectoral fin large, with 16���19 rays, mode 19. Anal fin long, with 212���280 rays, mode 270. Lateral-line variable, seven to 23 ventral rami, mode eight. Lateral-line dorsal rami absent in adults. Single hypaxial electric organ, extending along entire ventral margin of body with four rows of electroplates near caudal insertion of anal fin. Color in Alcohol: Body ground color dark, chocolate brown. Bands variable in number among individuals and in shape and arrangement within individuals, uncorrelated with sex. Adults (TL> 90 mm TL) with 17���29 (mode 20, n=100) oblique pigment gray bands with irregular, wavy margins on lateral surface extending from nape and pectoral-fin base to tip of caudal appendage, oriented vertically to obliquely in an antero-ventral to postero-dorsal diagonal. Dark bands approximately as wide as pale interbands, thinner anteriorly. Majority of dark bands paired with pale intraband. Most bands poorly divided with no sharp contrast; intraband formed by less density of pigments at the middle of the band. Greatest pigment density at band margins, sharper caudally. Three to four dark bands meet at ventral midline anterior to anal-fin origin. Two to three of the anteriormost five pale interbands crescent-shaped. Bands above lateral line continuous on anterior half of body, not visible against ground color at dorsal midline. More regularly-arrayed pigment bands, sharper contrast in juveniles. Head never banded, characterized by dense speckling dorsally fading to pale yellow ventrally. Pectoral and anal fins with uniform light gray rays and interradial membranes. Anal fin with pale zone caudally. Materials Examined: Peru, Madre de Dios: MUSM 1406, 127 mm TL, Parque Nacional Man��, Quebrada Pakitza, Aguajal; MUSM 1759 (2), 142���150 mm TL, Puerto Maldonado, river near Tambopata, Cochachica; MUSM 21405, 138 mm TL; MUSM 22731 (10), 143���210 mm TL, Madre de Dios drainage; MUSM 16662, 325 mm TL, Tambopata, Madre de Dios drainage, Lago Copamanu. Peru, Ucayali: MUSM 33715 (holotype), 233 mm TL, Alto Yuru��, Quebrada Dos y medio, small terra firme stream ~two km NW of Breu (09��31���10.50���S, 072��45���45.30���W); MUSM 33714 (40, paratypes), 95���275 mm TL, same locality as MUSM 33715; FMNH 118274 (10, paratypes), 134���179 mm TL, same locality as MUSM 33715; CAS 227893 (10, paratypes), 123���150 mm TL, same locality as MUSM 33715; MCZ 168419 (10, paratypes), 115���160 mm TL, same locality as MUSM 33715; MCP 43880 (10, paratypes), 116���164 mm TL, same locality as MUSM 33715; MZUSP 103035 (10, paratypes), 130���217 mm TL, same locality as MUSM 33715; AMNH 248884 (10, paratypes), 104���180 mm TL, same locality as MUSM 33715., Published as part of Craig, Jack M., Correa-Rold��n, Vanessa, Ortega, Hern��n, Crampton, William G. R. & Albert, James S., 2018, Revision of Gymnotus (Gymnotiformes: Gymnotidae) from the Upper Madeira Basin of Bolivia and Peru, with descriptions of two new species, pp. 111-132 in Zootaxa 4413 (1) on pages 118-119, DOI: 10.11646/zootaxa.4413.1.3, http://zenodo.org/record/1221950

Key to the Gymnotus of the Upper Madeira based on external morphology 1a. Single laterosensory pore in the posterior corner of the preopercle, cylindrical body profile................. G. coropinae. 1b. Two laterosensory pores in the posterior corner of the preopercle, laterally-compressed body profile................... 2. 2a. Two to three of the anteriormost five pale interbands with both margins crescent-shaped..................... G. chaviro. 2b. Margins of all pale interbands straight or curved in parallel.................................................... 3. 3a. Long, shallow head; pale interbands greater than two-thirds width of dark bands....................... G. c. madeirensis. 3b. hort, deep head; pale bands less than two-thirds width of dark bands............................................ 4. 4a. Laterally compressed body......................................................................... G. eyra. 4b. Sub-cylindrical body.......................................................................... G. riberalta.

Gymnotus carapo madeirensis Craig, Crampton and Albert, 2017:428 Figure 6A, Table 1 Description: Gymnotus carapo madeirensis differs from all sympatric members of the G. carapo clade on the following characters: one, large maximum adult body size (up to 360 mm TL vs. 237���275 mm TL in the G. carapo clade of the Upper Madeira; two, a color pattern consisting of 16���25, mode 24 obliquely-oriented dark bands with wavy, irregular margins from nape and to tip of caudal appendage vs. dark bands greater than twice width of pale bands in G. eyra and G. riberalta and anteriormost two to three pale interbands crescent-shaped in G. chaviro. Sexually monomorphic. Size up to 360 mm TL with adult body proportions attained at about 130 mm TL. Adult body shape subcylindrical with a mean ratio of body width to depth of 67%. Head length moderate, 17.8���27.5% total length. Snout length moderate, 32.3���34.9% head length. Mouth width narrow, 38.6���49.0% head length. Preanal distance long, 65.2���84.0% head length. Anal-fin long, 74.9���83.8% total length. Cycloid or ovoid scales present on entire post-cranial portion of body from nape to caudal appendage. Scales above lateral line intermediate, five to seven, mode seven. Scales over anal-fin pterygiophores large, with eight rows. Gape large, extending to or beyond posterior nares. Mouth position superior, lower jaw longer than upper, rictus decurved. Chin round in lateral, dorsal profiles, fleshy and bulbous with mental electroreceptive organ overlying lower jaw. Anterior narial pore partially or entirely included within gape, in small narial fold. Anterior nares large subequal to eye diameter. Eye below horizontal with mouth. Circumorbital series ovoid. Premaxilla with 11���16 (mode 14, n=10) teeth disposed in single row along outer margin, arrowhead shaped anteriorly, conical posteriorly. Curved median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, narrow distally with a straight ventral margin, length equal to roughly width of four to six dentary teeth. Dentary with one row of 16���19 (mode 17, n=4) teeth, two to four arrowhead shaped anteriorly, all others conical posteriorly. Posterodorsal and posteroventral dentary processes abut at midlength. Dentary posteroventral process nearly as long as posterodorsal, narrow distally. Dentary ventral margin lamella narrow, depth less than posterior process. Dentary anteroventral margin rounded in lateral view, without a hook. Mandible long, extended, length greater than twice depth. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Anguloarticular process long, extending beyond ventral margin of dentary. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base shorter than length, curved, tip simple. Hyomandibular trigeminal canals connected. Dorsal region of hyomandibula with four lateral foramenae, supraorbital and infraorbital nerves divided. Posterior lateral line fenestra contacting posterodorsal margin of hyomandibula. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf large, more than half width of symplectic. Interopercle dorsal margin ascending process broad. Opercle dorsal margin straight to slightly convex, its posterior margin smooth. Opercular posterior margin entirely smooth. Subopercle dorsal margin concave. Cranial fontanels closed in juveniles and adults. Frontal shape narrow, width at fourth infraorbital less than that of parietal, anterior margin of straight, continuous with margins of adjacent roofing bones, postorbital process broad, more than two times width of supraorbital canal. Lateral ethmoid unossified. Parietal rectangular, length less than width. Parasphenoid anteroventral portion robust, extending ventral to lateral margin of parasphenoid, posterior processes narrow. Prootic foramen Vp separate from V2-3 +VII. Adductor mandibula undivided at insertion, intermuscular bones absent. All basibranchials unossified. Gill rakers not contacting gill bar. Cleithrum narrow, ventral margin straight, anterior limb long, more than one-point-eight times ascending limb, deeply incised on its anteroventral margin, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle shaped. Body cavity of moderate length, with 32���36 precaudal vertebrae, mode 33, n=41. Rib 5 robust along its entire extent, less than three times width of rib 6. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Pectoral fin intermediate, with 13���16 rays, mode 13. Anal fin of moderate length, with 210���268 rays, median 228. Single hypaxial electric organ, extending along entire ventral margin of body with three to four rows of electroplates near caudal insertion of anal fin. Color in Alcohol: Body ground color tan ventrally grading to darker brown dorsally in adults, pale yellow throughout in smaller specimens. Bands variable in number among individuals and in shape and arrangement within individuals, uncorrelated with sex. Adults (TL> 200 mm TL) with 16���25 (mode 24, n=8) obliquelyoriented, chocolate-colored bands with wavy, irregular margins on lateral surface from nape and to tip of caudal appendage, occurring singly or as band-pairs (increasingly divided and irregular with size). Band-interband contrast increases ventrally and caudally, fades with growth (juveniles> 150 mm TL with distinct margins, specimens 200���300 mm TL faintly banded, and some specimens over 250 mm TL unbanded except very faintly in posterior one third of body). Band-interband contrast increases ventrally and caudally, fades with growth (juveniles with distinct margins, adults faintly banded, some specimens over 250 mm TL unbanded except very faintly in posterior one third of body). Bands may be divided dorsally or ventrally to form X - or inverted Y -shaped patterns. Pale inter-bands roughly one third width of dark bands at mid-body. Head never banded, characterized by dense speckling dorsally fading to pale yellow ventrally. Numerous chromatophores speckled over branchiostegal membranes and ventral surface of head. Pectoral-fin rays brown, interradial membranes hyaline. Anterior 80% of anal fin membrane dark brown, gray or black, posterior 20% translucent. Materials Examined: Bolivia: UF 82191, 187 mm, Santa Cruz, R��o Guapor��, R��o San Pablo, R��o San Diablo, Velasco, 71 km N. San Jos�� de Chiquitos (17��18���S, 60��35���W); UF 82211 (2), 196���205 mm, same locality as UF 82191; UF 82345 (3) 111���360 mm, Santa Cruz, R��o Jorge, W. of Warnes, R��o Piray (17��34���12���S, 63��12���36���W); UF 82470 (2), 170���218 mm, Beni, R��o Mamor��, R��o Ibar��, Cercado, Arroyo San Javier (14��38���S, 64��53���W); UF 82485, 360 mm, Beni, R��o Mamor��, R��o Ibar��, Cercado, 20 km N San Javier (14��28���S, 64��56���W); UF 82510, 241 mm, Beni, R��o Mamor��, R��o Ibar��, Cercado, 25 km N San Javier (14��24���S, 64��56���W); UMMZ 66433 (2), 215���331 mm, Beni, R��o Beni, Lago Rogoagua (13��57���S, 66��58���W); UMSS 0 6962, 108 mm, Beni, R��o Madeira, Arroyo Tres Cuchillas (10��49���23.02���S, 66��4���50.300��� W); UMSS 0 6963, 121 mm, same locality as UMSS 06962; UMSS 0 6964, 174 mm, same locality as UMSS 06962; UMSS 0 6964, 177 mm, Beni, R��o Madeira, Arroyo Tres Cuchillas (10��49���23.02���S, 66��4���50.30���W); UMSS 0 6965, 145 mm, same locality as UMSS 06962; UMSS 0 6966, 179 mm, same locality as UMSS 06962; UMSS 0 6969, 302 mm, same locality as UMSS 06962; UMSS 0 6970, 119 mm, same locality as UMSS 06962; UMSS 0 6977, 202 mm, R��o Beni aff. R��o Madeira (11��01���41.20���S, 66��5���58.80���W). Peru: MUSM 60285 (holotype), 227 mm TL, Puno, Sandia, R��o Candamo (13��31���S, 069��41���W); MUSM 60286 (2; paratypes), 101���121 mm TL, same locality as MUSM 60285., Published as part of Craig, Jack M., Correa-Rold��n, Vanessa, Ortega, Hern��n, Crampton, William G. R. & Albert, James S., 2018, Revision of Gymnotus (Gymnotiformes: Gymnotidae) from the Upper Madeira Basin of Bolivia and Peru, with descriptions of two new species, pp. 111-132 in Zootaxa 4413 (1) on pages 116-117, DOI: 10.11646/zootaxa.4413.1.3, http://zenodo.org/record/1221950, {"references":["Craig, J. M., Crampton, W. G. R. & Albert, J. S. (2017) Revision of the polytypic electric fish Gymnotus carapo (Gymnotiformes, Teleostei), with descriptions of seven subspecies. Zootaxa, 4318 (3), 401 - 438. https: // doi. org / 10.11646 / zootaxa. 4318.3.1"]}

Key to the Gymnotus of the Upper Madeira based on external morphology 1a. Single laterosensory pore in the posterior corner of the preopercle, cylindrical body profile................. G. coropinae. 1b. Two laterosensory pores in the posterior corner of the preopercle, laterally-compressed body profile................... 2. 2a. Two to three of the anteriormost five pale interbands with both margins crescent-shaped..................... G. chaviro. 2b. Margins of all pale interbands straight or curved in parallel.................................................... 3. 3a. Long, shallow head; pale interbands greater than two-thirds width of dark bands....................... G. c. madeirensis. 3b. hort, deep head; pale bands less than two-thirds width of dark bands............................................ 4. 4a. Laterally compressed body......................................................................... G. eyra. 4b. Sub-cylindrical body.......................................................................... G. riberalta., Published as part of Craig, Jack M., Correa-Rold��n, Vanessa, Ortega, Hern��n, Crampton, William G. R. & Albert, James S., 2018, Revision of Gymnotus (Gymnotiformes: Gymnotidae) from the Upper Madeira Basin of Bolivia and Peru, with descriptions of two new species, pp. 111-132 in Zootaxa 4413 (1) on page 128, DOI: 10.11646/zootaxa.4413.1.3, http://zenodo.org/record/1221950

Gymnotus eyra n. sp. Figure 6D, Table 2 Holotype: MUSM 60276, 122, Peru, Madre de Dios, Manu, Cuenca R��o Los Amigos, Aguajal cicra Pozo Pedro (12��33.611���S, 070��06.593���W), coll. By Max Hidalgo, 05/07/2002. Paratypes: MUSM 21404 (5), 51���119, same date and locality as MUSM 60276. Nontypes: Bolivia, Beni: AUM 23644, 152 mm TL, Rio Beni, Rio Madeira drainage, 26 km SSW of Riberalta (11��07���00���S, 066��11���00���W); INHS 37119 (5), 94���176 mm TL, Rio Beni, Rio Madeira drainage, Cuneta (borrow pit) 3 km E Estac. (14��47���32.28���S, 066��12���59.69���W). Peru, Madre de Dios: MUSM 14021, 185 mm TL, Manu, Rio Madre de Dios, Quebrada Pachija (11��57���S, 071��17���W); MUSM 19993 (2), 132���148 mm TL, Manu, Rio Madre de Dios, Los Amigos, Aguajal (12��33���00���S, 070��00���36���W); MUSM 2 1388 (6), 67���132 mm TL, Cuenca Rio Los Amigos, cerca Aguajal, Pozo Pedro (12��33���00���S, 070��06���00���W); MUSM 21778, 147 mm TL, Madre de Dios, Tambopata, Cuenca R��o Madre de Dios, Aguajal, Aguas Negras, Pozo Santa Elena. Peru, Cusco: MUSM 36141 (2), 199���254 mm TL, La Convenci��n, Echarate, Rio Urubamba Basin, Rio Parotori, Quebrada Piriabindeni (11��46���59.88���S, 073��05���60.00���W). Diagnosis: Gymnotus eyra is morphologically similar to G. mamiraua, but differs on the following characters: one, fewer pectoral-fin rays (P1R 10���13, mode 11 vs. 12���16, mode 15 in G. mamiraua); two, fewer ventral lateralline rami (VLR 10���15, mode 13 vs. 16���18, median 17 in G. mamiraua). Gymnotus eyra further differs from other members of the G. carapo clade from the Upper Madeira (G. c. madeirensis, G. chaviro and G. riberalta) on the following characters: one, a color pattern (shared with G. mamiraua) consisting of pale bands narrow, less than one third width of dark bands, sharp band margins, and pale bands extending to dorsal mid-line; two, few, larger scales over the anal-fin pterygiophores (APS six to eight, mode seven vs. eight to 13, mode 12 in other G. carapo clade from the Upper Madeira); three, few pored lateral-line scales before the first ventral lateral-line ramus (PLR 30���41, median 39 vs. 40���61, median 50 in other G. carapo clade from the Upper Madeira). Gymnotus eyra further differs from other members of the G. carapo clade throughout the Neotropics in possessing a color pattern (similar to G. mamiraua) consisting of pale bands less than one fifth width of dark bands, sharp band margins, and pale bands extending to dorsal mid-line vs. bands interrupted into patches anterodorsally, with silver, blue or green metallic countershading on dorsum of adults of G. arapaima, dark bands lost in large adults (> 250 mm TL) of G. ardilai, small, rounded dark spots over entire body except posterior 20% of some specimens of G. bahianus, bands faint or absent in all specimens of G. chimarrao, one to three inverted Y -shaped dark bands posteriorly and pale bands not reaching above lateral line in anterior two thirds of body of G. choco, bands faint or absent from 80% of dorsum in all specimens, and narrow pale bands (less than one fifth width of dark bands) which never extend above lateral line on anterior half of body in G. pantanal, pale bands wider than dark bands in G. sylvius, narrow pale interbands (less than one third width of dark bands) extending above lateral line and often to dorsal midline in G. ucamara. Description: Sexually monomorphic. Size up to 185 mm TL with adult body proportions attained at about 110 mm TL. Adult body shape subcylindrical with a mean ratio of body width to depth of 55%. Body profile slender, body depth 85.4���114.5% total length. Head length moderate, 9.6���12.3% total length. Snout length moderate, 32.0��� 40.0% head length. Mouth width narrow, 30.9���43.9% head length. Preanal distance long, 61.3���84.5% head length. Anal-fin long, 78.5���84.4% total length. Cycloid or ovoid scales present on entire post-cranial portion of body from nape to caudal appendage. Scales above lateral line intermediate, four to six, mode 5. Scales over anal-fin pterygiophores large, with six to eight, mode seven rows. Gape large, extending to or beyond posterior nares. Mouth position superior, lower jaw longer than upper, rictus decurved. Chin round in lateral, dorsal profiles, fleshy and bulbous with mental electroreceptive organ overlying lower jaw. Anterior narial pore partially or entirely included within gape, in small narial fold. Anterior nares small, its diameter less than that of eye. Eye below horizontal with mouth. Circumorbital series ovoid. Premaxilla with 16 teeth disposed in single row along outer margin. Curved median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, narrow distally with a straight ventral margin, length equal to roughly width of 4���6 dentary teeth. Dentary with one row of 15 teeth, four to five arrowhead shaped anteriorly. Dentary posteroventral process nearly as long as posterodorsal, narrow distally. Dentary ventral margin lamella narrow, depth less than posterior process. Dentary anteroventral margin rounded in lateral view, without a hook. Mandible long, extended, length greater than twice depth. Anguloarticular process long, extending beyond ventral margin of dentary. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base shorter than length, curved, tip complex. Hyomandibular trigeminal canals connected. Dorsal region of hyomandibula with four lateral foramenae, supraorbital and infraorbital nerves divided. Posterior lateral line fenestra contacting posterodorsal margin of hyomandibula. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf large, more than half width of symplectic. Interopercle dorsal margin ascending process broad. Opercle dorsal margin straight to slightly convex, its posterior margin smooth. Opercular posterior margin entirely smooth. Subopercle dorsal margin concave. Cranial fontanels closed in juveniles and adults. Frontal shape broad, width at fourth infraorbital less than that of parietal, anterior margin of straight, continuous with margins of adjacent roofing bones, postorbital process broad, more than two times width of supraorbital canal. Lateral ethmoid unossified. Parietal rectangular, length less than width. Parasphenoid anteroventral portion robust, extending ventral to lateral margin of parasphenoid, posterior processes narrow. Prootic foramen Vp separate from V2-3 +VII. Adductor mandibula undivided at insertion, intermusculars absent. All basibranchials unossified. Gill rakers not contacting gill bar. Cleithrum narrow, ventral margin straight, anterior limb short, less than one-point-eight times ascending limb, deeply incised on its anteroventral margin, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle-shaped. Body cavity of moderate length, with 34 precaudal vertebrae (n=1). Rib 5 robust along its entire extent, less than three times width of rib 6. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Pectoral fin narrow, with 10���13 rays, mode 11. Anal fin of moderate length, with 167���227 rays, median 193. Lateral-line variable, with 10���15 ventral rami, median 12. Lateral-line dorsal rami absent in adults. Single hypaxial electric organ, extending along entire ventral margin of body with three rows of electroplates near caudal insertion of anal fin. Color in alcohol: Body ground color dark, chocolate brown. Bands variable in number among individuals and in shape and arrangement within individuals, uncorrelated with sex. Adults (TL> 110 mm TL) with 16���23 (mode 20, n=16) obliquely-oriented, thin cream-colored bands located between tail tip and pectoral-fin base on lateral surface and onto dorsum, more regular in juveniles. Pale bands regular, sinuous and undivided, with sharp contrast between margins and ground color. Dark bands chocolate-brown in color, three times as wide as pale anteriorly, similar in width dorsoventrally, and wider caudally. Head chocolate-brown dorsally and on operculum, grading to lighter brown ventrally and on snout. Posteroventrally-oriented band at nape connected to anteriormost anteroventral pale band of body in many specimens. Pectoral and anal fins with dark rays and inter-radial membranes. Anal fin with pale zone caudally. Etymology: Specific epithet derived from to the jaguarundi (Herpailurus yagouaroundi), the red form of which is locally known as the ��� eyra ���. The convention of naming Gymnotus for felids, which are often similarly nocturnal, predatory, banded or spotted, is shared with G. pantherinus, G. tigre and G. onca. Noun in apposition. Habitats: Gymnotus eyra usually inhabits slowly-moving channels (ca��os) on forested floodplains, aguajales of the palm Mauritia flexuosa, and seasonally flooded savannahs, and is less commonly found in small, upland (non-floodplain) forest streams (quebradas)., Published as part of Craig, Jack M., Correa-Rold��n, Vanessa, Ortega, Hern��n, Crampton, William G. R. & Albert, James S., 2018, Revision of Gymnotus (Gymnotiformes: Gymnotidae) from the Upper Madeira Basin of Bolivia and Peru, with descriptions of two new species, pp. 111-132 in Zootaxa 4413 (1) on pages 122-125, DOI: 10.11646/zootaxa.4413.1.3, http://zenodo.org/record/1221950

Gymnotus riberalta n. sp. Figure 6E, Table 3 Holotype: CBF 10248, 199 mm TL, Bolivia, Beni, Riberalta, Rio Beni, Rio Madeira drainage, Rio Amazonas drainage, Arroyo near Lago de San Jose (10°54’47”S, 065°59’49”W), coll. William Crampton, 06/27/2008. Paratypes: CBF 10243, 193 mm TL, same date and locality as CBF 10248; CBF 10244, 135 mm TL, same locality as CBF 10248; CBF 10245, 220 mm TL, same locality as CBF 10248; CBF 10246, 142 mm TL, same locality as CBF 10248; CBF 10247, 196 mm TL, same locality as CBF 10248; CBF 10249, 173 mm TL, same locality as CBF 10248; UMSS 7008, 138 mm TL, same locality as CBF 10248; UMSS 7009, 153 mm TL, same locality as CBF 10248; UMSS 7010, 200 mm TL, same locality as CBF 10248; UMSS 7011, 152 mm TL, same locality as CBF 10248; UMSS 7012, 237 mm TL, same locality as CBF 10248; UMSS 7013, 209 mm TL, same locality as CBF 10248; UMSS 7014, 247 mm TL, same locality as CBF 10248. Nontypes: UMMZ 82146, 153 mm TL, Bolivia, Santa Cruz, Ñuflo de Chaves, Río Blanco near Concepción (~ 16°07’55”S, 062°01’34”W); UMSS 0 7015, 194 mm TL, Brazil, Amazonas, Rio Beni, Rio Madeira drainage, stream near Porto Hamburgo (10°54’7.75”S, 065°59’8.18”W); UMSS 0 7016, 216 mm TL, same locality as UMSS 07015; UMSS 0 7017 170 mm TL, same locality as UMSS 07015; UF 180238 (3), 187–267 mm TL, Bolivia, Beni, Riberalta, Rio Beni, Rio Madeira drainage, Rio Amazonas drainage, Small Stream near Puerto Hamburgo, Riberalta (11°01’52”S, 066°05’39”W, 147 m). Diagnosis: Gymnotus riberalta is morphologically similar to G. pantanal, but differs on the following characters: one, a narrow maximum body width (BW 53.3–72.0% TL, mean 61.2% TL vs. 71.5–76.7% TL, mean 73.7 TL in G. pantanal); two, a narrow mouth (MW 32.7–45.7% HL, mean 41.2% vs. 42.0–50.7% HL, mean 46.0% in G. pantanal); three, a narrower pectoral fin, possessing fewer rays (P1R 10–13, mode 13 vs. 14–18, mode 15 in G. pantanal); four, more anal-fin pterygiophore scales (APS 10–11, mode 10 vs. seven to eight, mode seven in G. pantanal). Gymnotus riberalta further differs from other members of the G. carapo clade throughout the Neotropics in possessing a color pattern (similar to G. pantanal) consisting of narrow pale bands less than one quarter width of dark bands, wavy band margins, pale bands exclusively on ventral portion of body anteriorly vs. bands interrupted into patches anterodorsally, with silver, blue or green metallic countershading on dorsum of adults of G. arapaima, dark bands lost in large adults (> 250 mm TL) of G. ardilai, small, rounded dark spots over entire body except posterior 20% of some specimens of G. bahianus, bands faint or absent in all specimens of G. chimarrao, one to three inverted Y-shaped dark bands posteriorly and pale bands not reaching above lateral line in anterior two thirds of body of G. choco, bands broken into speckles throughout in G. diamantinensis, narrow pale bands (less than one fifth width of dark bands) with sharp margins, and pale bands extending fully to dorsal midline in G. mamiraua, pale bands wider than dark bands in G. sylvius, narrow pale interbands (less than one third width of dark bands) extending above lateral line and often to dorsal midline in G. ucamara. Description: Sexually monomorphic. Size up to 302 mm TL with adult body proportions attained at about 150 mm TL. Adult body shape subcylindrical with a mean ratio of body width to depth of 65%. Body profile slender, body depth 81.1–102.1% total length. Head length moderate, 7.3–10.3% total length. Snout length moderate, 31.1– 37.3% head length. Mouth width narrow, 32.7–45.7% head length. Preanal distance long, 71.9–97.9% head length. Anal-fin long, 79.7–97.4% total length. Cycloid or ovoid scales present on entire post-cranial portion of body from nape to caudal appendage. Scales above lateral line intermediate, six to eight, mode six. Scales over anal-fin pterygiophores large, with 10–11, mode 10 rows. Gape large, extending to or beyond posterior nares. Mouth position superior, lower jaw longer than upper, rictus decurved. Chin round in lateral, dorsal profiles, fleshy and bulbous with mental electroreceptive organ overlying lower jaw. Anterior narial pore partially or entirely included within gape, in small narial fold. Anterior nares small, its diameter less than that of eye. Eye below horizontal with mouth. Circumorbital series ovoid. Premaxilla with 20 teeth disposed in two rows along outer margin, arrowhead shaped anteriorly, conical posteriorly. Curved median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, narrow distally with a straight ventral margin, length equal to roughly width of four to six dentary teeth. Dentary with one row of 18 teeth, four arrowhead shaped anteriorly, all others conical posteriorly. Posterodorsal and posteroventral dentary processes abut at midlength. Dentary posteroventral process nearly as long as posterodorsal, narrow distally. Dentary ventral margin lamella narrow, depth less than posterior process. Dentary anteroventral margin rounded in lateral view, with a hook. Mandible long, extended, length greater than twice depth. Anguloarticular process long, extending beyond ventral margin of dentary. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base shorter than length, curved, tip simple. Interopercle dorsal margin ascending process broad. Hyomandibular trigeminal canals connected. Dorsal region of hyomandibula with four lateral foramenae, supraorbital and infraorbital nerves connected. Posterodorsal laterosensory ramus of preopercle with single superficial pore. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf large, more than half width of symplectic. Opercle dorsal margin straight to slightly convex, its posterior margin smooth. Opercular posterior margin entirely smooth. Subopercle dorsal margin concave. Cranial fontanels closed in juveniles and adults. Frontal shape narrow, width at fourth infraorbital less than that of parietal, anterior margin straight, continuous with margins of adjacent roofing bones, postorbital process broad, more than two times width of supraorbital canal. Lateral ethmoid unossified. Parietal rectangular, length less than width. Parasphenoid anteroventral portion reduced, extending ventral to lateral margin of parasphenoid, posterior processes robust. Prootic foramen Vp combined with V2-3 +VII. Adductor mandibula undivided at insertion, intermusculars absent. All basibranchials unossified. Gill rakers not contacting gill bar. Cleithrum narrow, ventral margin straight, anterior limb long, more than 1.8 times ascending limb, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle-shaped. Body cavity of moderate length, with 35 precaudal vertebrae, mode=35, n=2. Rib 5 robust along its entire extent, less than three times width of rib 6. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Pectoral fin narrow, with 10–13 rays, mode 13 rays. Anal fin of moderate length, with 169–239 rays, median 202. Lateral-line variable, with 10–16 ventral rami, mode 13. Lateral-line dorsal rami absent in adults. Single hypaxial electric organ, extending along entire ventral margin of body with three rows of electroplates near caudal insertion of anal fin. Color in alcohol: Body ground color dark, chocolate brown. Bands variable in number among individuals and in shape and arrangement within individuals, uncorrelated with sex. Juveniles (TL 150 mm TL) with 22–27 (mode 24, n=9) obliquely-oriented, thin cream-colored bands with wavy, irregular margins ventrolaterally located between tail tip and pectoral-fin base. Pale bands infrequently branched, and very rarely extend above lateral line on anterior half of body. Dark bands chocolate-brown in color, four times as wide as pale anteriorly and forming inverted Y-shapes posteriorly. Interband contrast greatest in juveniles and ventrally to caudally in adults. Anterior 80% of dorsum with very faint or absent banding in specimens of all sizes. Head ground color chocolate brown dorsally grading to lighter brown ventrally. Ventral surface of head and branchiostegal membranes speckled. Pectoral fin with brown or gray rays, hyaline inter-radial membranes. Analfin membrane uniformly light brown or gray. Ecology: All specimens were captured in small terra firme rainforest streams with sandy beds and dense emergent aquatic vegetation. Water chemistry parameters were as follows: conductivity 6.8–8.2, pH 5.2–5.5, temperature 22.2–25.0 °C, Dissolved Oxygen 3.4–4.2 mg ̇l -1. Electric Organ Discharge: The EOD waveforms of G. riberalta were previously described by Crampton et al. (2013) as “ Gymnotus n. sp. ALT ”. The head-to-tail EOD waveform (sensu Waddell et al. (2016)) of this species is tetraphasic with a dominant P1–P2 phase flanked by a lower voltage negative P0 phase (Figure 7), following the nomenclature of Crampton et al. (2011). A positive P3 phase after P0 is invariably absent. This EOD waveform conforms to the ht-EOD category “2” of Crampton et al. (2013). The peak power frequency (PPF) of the EOD ranged from 0.946–1.597 kHz, mean=1.158, standard deviation (SD)=0.151 kHz, with no significant disparity between males (0.946–1.597 kHz, mean=1.148 kHz, SD=0.152 kHz, n=13 recorded specimens) and females (0.976–1.292 kHz, mean=1.12 kHz, SD=0.110 kHz, n=7) (two-tailed t-Test p=0.81). Resting (daytime) pulse rates (1 minute averages) are reported for G. riberalta in the range 33.9–51.9 Hz, mean 41.9 Hz, SD=5.5 (n= 18 specimens) and active (nighttime) pulse rates in the range 44.7–77.1 Hz, mean 3.2 Hz, SD=7.8 (n=19) (two-tailed t-Test night> day, p=7.2 x 10-11). No sex disparity was observed in the mean resting pulse rates (females=40.7 Hz, n=8; males=42.8 Hz, n=10; two-tailed t-Test, p=0.45) and mean active pulse rates (females=62.0 Hz, n=7; males=63.8 Hz, n=12; two-tailed t-Test, p=0.62). Etymology: Specific epithet derived from the city of Riberalta in the Beni Department of Bolivia, where the type series was collected. Noun in apposition. Habitats: Gymnotus riberalta inhabits slowly-moving channels (caños) on forested floodplains and aquatic vegetation at the margins of oxbow lakes on seasonally flooded savannahs.

Gymnotus coropinae Hoedeman, 1962 Figure 6C, Table 1 G. anguillaris in part: Nijssen and Isbr��cker, 1968 Diagnosis: Gymnotus coropinae is the only representative of the G. coatesi clade sensu Tagliacollo et al. (2016) present in the Upper Madeira, and can be easily differentiated from members of the G. carapo clade on the following characters: one, small maximum adult body size up to 135 mm TL in the G. coropinae of the Upper Madeira, vs. large (237���360 mm TL) in the G. carapo clade of the Upper Madeira; two, single laterosensory pore in the posterior corner of the preopercle vs. two in the G. carapo clade of the Upper Madeira; three, teeth all small and needle shaped teeth, vs. two to seven arrowhead-shaped in the G. carapo clade of the Upper Madeira; four, cylindrical body profile, vs. laterally-compressed in the G. carapo clade of the Upper Madeira. Description: Sexually monomorphic. Size up to 162 mm TL with adult body proportions attained at 90���120 mm TL. Adult body shape subcylindrical with a mean ratio of body width to depth of 75%. Head length moderate, 7.9���11.6% total length. Snout length moderate, 29.3���34.5% head length. Mouth width intermediate, 33.2���46.1% head length. Preanal distance long, 88.4���120.3% head length. Anal-fin intermediate, 70.6���84.2% total length. Cycloid or ovoid scales present on entire post-cranial portion of body from nape to caudal appendage. Scales above lateral line intermediate, seven to eight, mode seven. Gape moderate, extending three quarters distance from anterior tip of snout to posterior nares. Mouth position superior, lower jaw longer than upper, rictus decurved. Chin round in lateral, dorsal profiles, fleshy and bulbous with mental electroreceptive organ overlying lower jaw. Anterior narial pore partially or entirely included within gape, pipe-shaped. Anterior nares large, half diameter of eye. Eye below horizontal with mouth. Circumorbital series ovoid. Anterior margin of ethmoid region rounded. Premaxilla with 11���12 (mode 12, n=2) teeth disposed in single row along outer margin, and four to five (mode five, n=2) in inner row. Outer row teeth large and needle shaped, inner teeth short and needle shaped, no arrowhead shaped teeth present. Curved median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, broad distally with a straight ventral margin, length equal to roughly width of four to six dentary teeth. Dentary with outer row of 19���21 (mode 21, n=2) teeth, and inner row of 10���12 (mode 11, n=2), none arrowhead shaped. Outer row with one to 10 slender recurved needle-shaped teeth anteriorly, those posteriorly larger and less slender. Inner tooth row extending about two-thirds along the tooth-bearing portion of dentary bone. Teeth longer, more needle-shaped and closer-spaced anteriorly. Posterodorsal and posteroventral dentary processes abut at midlength. Dentary posteroventral process nearly as long as posterodorsal, narrow distally. Dentary ventral margin lamella wide, depth greater than posterior process. Dentary anteroventral margin rounded in lateral view, without a hook. Mandible long, extended, length greater than twice depth. Anguloarticular process long, extending beyond ventral margin of dentary. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base shorter than length, curved, tip complex. Posterior lateral line fenestra contacting posterodorsal margin of hyomandibula. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf small, less than half width of symplectic. Interopercle dorsal margin ascending process broad. Opercle dorsal margin straight to slightly convex, its posterior margin smooth. Opercular posterior margin entirely smooth. Subopercle dorsal margin concave. Cranial fontanels closed in juveniles and adults. Frontal shape broad, width at fourth infraorbital greater than that of parietal, anterior margin of straight, continuous with margins of adjacent roofing bones, postorbital process narrow, less than two times width of supraorbital canal. Adductor mandibula undivided at insertion, intermusculars absent. All basibranchials unossified. Gill rakers not contacting gill bar. Cleithrum very narrow, ventral margin straight, anterior limb long, more than one-point-eight times ascending limb, deeply incised on its anteroventral margin, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle shaped. Rib 5 robust along its entire extent, less than three times width of rib 6. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Pectoral fin intermediate, with 13���14 rays, mode 13. Anal fin of moderate length, with 210���230 rays, mode 230. Single hypaxial electric organ, extending along entire ventral margin of body with 3 rows of electroplates near caudal insertion of anal fin. Color in alcohol: Ground color dark brown in adults and juveniles. four to 20 (median 17, n =6) white or cream bands on lateral surface. In anterior one to two thirds of body of adults, bands absent, restricted to the ventral part of the lateral surface such that the dark interbands fuse into a uniform dark coloration anteriorly, or highly reduced in width. More anterior bands may extend onto dorsal part of lateral surface, but never meet bands from the other side of body. Pale bands with high-contrast margins, dark ground color, extending to mid-dorsum along posterior one quarter of body. Two to three pale bands posterior to last anal-fin ray. Pale bands never completely divided, but fainter coloration in middle of posterior-most three to six bands. Pale bands oriented vertically or obliquely in anterior-inferior to posterior-superior orientation. Pale bands irregular in shape, width, arrangement, both on and among individuals. Pale bands narrow and shorten anteriorly, only rarely extending to midline anteriorly. No pale bands meet on ventral midline, between anus and anal-fin origin. Area between pale bands infrequently marked by cream colored patch near ventral margin of anal-fin pterygiophores, especially posteriorly. Pale bands of juveniles resemble adults, sometimes extend further dorsally in anterior portion of body. Head never banded, characterized by dense speckling dorsally fading to pale yellow ventrally. Pectoral-fin rays dark brown, inter-radial membranes hyaline. Anal-fin membrane charcoal gray anteriorly, black posteriorly. No unpigmented patch at the caudal end. Material Examined: Peru, Madre de Dios: MUSM 17596 (3), 90���112 mm TL, R��o Madre de Dios (12��36���S, 069��11���W); MUSM 20146, 76 mm TL, R��o Madre de Dios, R��o Los Amigos, Parque Nacional Manu (12��34���36���S, 070��04���14"W); MUSM 20264 (8), 50���118, Rio Los Amigos, CRA, Quebrada Moro Blanco, abajo Aguajal; MUSM 20272, 140 mm TL, Tambopata, Tambopata National Reserve, nr. Explorer���s Inn (12��50���12.01���S, 069��17���38.12���W); MUSM 3013, 105 mm TL, R��o Tambopata, Cochachica (~ 12��44���S, 069��11���W); MUSM 4176, 81 mm TL, same locality as MUSM 3013; MUSM 4503 (2), 66���70 mm TL, R��o Tambopata, cuenca del R��o Heath, Quebrada San Antonio (~ 12��44���S, 69��11���W); MUSM 535 (13), 79���136 mm TL; MUSM 7594, 76 mm TL; USNM 264102 (2), 112���114 mm TL, R��o Tambopata, nr. Cochachica (~ 12��50���30���S, 069��17���31���W); USNM 264108 (2), 117���121 mm TL, R��o Tambopata, nr. R��o la Torre (~ 12��49���40���S, 069��18���00���W); USNM 366207 (3), 86���142 mm TL, R��o Tambopata, nr. Cochachica (~ 12��49���45���S, 069��16���15���W); USNM 366208, 97 mm TL, R��o Tambopata, nr. R��o la Torre (12��50���S, 069��18���W)., Published as part of Craig, Jack M., Correa-Rold��n, Vanessa, Ortega, Hern��n, Crampton, William G. R. & Albert, James S., 2018, Revision of Gymnotus (Gymnotiformes: Gymnotidae) from the Upper Madeira Basin of Bolivia and Peru, with descriptions of two new species, pp. 111-132 in Zootaxa 4413 (1) on pages 119-120, DOI: 10.11646/zootaxa.4413.1.3, http://zenodo.org/record/1221950, {"references":["Hoedeman, J. J. (1962) Notes on the ichthyology of Surinam and other Guianas. 9. New records of gymnotid fishes. Bulletin of Aquatic Biology, 3, 53 - 60."]}

Gymnotus eyra n. sp. Figure 6D, Table 2 Holotype: MUSM 60276, 122, Peru, Madre de Dios, Manu, Cuenca Río Los Amigos, Aguajal cicra Pozo Pedro (12°33.611’S, 070°06.593’W), coll. By Max Hidalgo, 05/07/2002. Paratypes: MUSM 21404 (5), 51–119, same date and locality as MUSM 60276. Nontypes: Bolivia, Beni: AUM 23644, 152 mm TL, Rio Beni, Rio Madeira drainage, 26 km SSW of Riberalta (11°07’00”S, 066°11’00”W); INHS 37119 (5), 94–176 mm TL, Rio Beni, Rio Madeira drainage, Cuneta (borrow pit) 3 km E Estac. (14°47’32.28”S, 066°12’59.69”W). Peru, Madre de Dios: MUSM 14021, 185 mm TL, Manu, Rio Madre de Dios, Quebrada Pachija (11°57’S, 071°17’W); MUSM 19993 (2), 132–148 mm TL, Manu, Rio Madre de Dios, Los Amigos, Aguajal (12°33’00”S, 070°00’36”W); MUSM 2 1388 (6), 67–132 mm TL, Cuenca Rio Los Amigos, cerca Aguajal, Pozo Pedro (12°33’00”S, 070°06’00”W); MUSM 21778, 147 mm TL, Madre de Dios, Tambopata, Cuenca Río Madre de Dios, Aguajal, Aguas Negras, Pozo Santa Elena. Peru, Cusco: MUSM 36141 (2), 199–254 mm TL, La Convención, Echarate, Rio Urubamba Basin, Rio Parotori, Quebrada Piriabindeni (11°46’59.88”S, 073°05’60.00”W). Diagnosis: Gymnotus eyra is morphologically similar to G. mamiraua, but differs on the following characters: one, fewer pectoral-fin rays (P1R 10–13, mode 11 vs. 12–16, mode 15 in G. mamiraua); two, fewer ventral lateralline rami (VLR 10–15, mode 13 vs. 16–18, median 17 in G. mamiraua). Gymnotus eyra further differs from other members of the G. carapo clade from the Upper Madeira (G. c. madeirensis, G. chaviro and G. riberalta) on the following characters: one, a color pattern (shared with G. mamiraua) consisting of pale bands narrow, less than one third width of dark bands, sharp band margins, and pale bands extending to dorsal mid-line; two, few, larger scales over the anal-fin pterygiophores (APS six to eight, mode seven vs. eight to 13, mode 12 in other G. carapo clade from the Upper Madeira); three, few pored lateral-line scales before the first ventral lateral-line ramus (PLR 30–41, median 39 vs. 40–61, median 50 in other G. carapo clade from the Upper Madeira). Gymnotus eyra further differs from other members of the G. carapo clade throughout the Neotropics in possessing a color pattern (similar to G. mamiraua) consisting of pale bands less than one fifth width of dark bands, sharp band margins, and pale bands extending to dorsal mid-line vs. bands interrupted into patches anterodorsally, with silver, blue or green metallic countershading on dorsum of adults of G. arapaima, dark bands lost in large adults (> 250 mm TL) of G. ardilai, small, rounded dark spots over entire body except posterior 20% of some specimens of G. bahianus, bands faint or absent in all specimens of G. chimarrao, one to three inverted Y -shaped dark bands posteriorly and pale bands not reaching above lateral line in anterior two thirds of body of G. choco, bands faint or absent from 80% of dorsum in all specimens, and narrow pale bands (less than one fifth width of dark bands) which never extend above lateral line on anterior half of body in G. pantanal, pale bands wider than dark bands in G. sylvius, narrow pale interbands (less than one third width of dark bands) extending above lateral line and often to dorsal midline in G. ucamara. Description: Sexually monomorphic. Size up to 185 mm TL with adult body proportions attained at about 110 mm TL. Adult body shape subcylindrical with a mean ratio of body width to depth of 55%. Body profile slender, body depth 85.4–114.5% total length. Head length moderate, 9.6–12.3% total length. Snout length moderate, 32.0– 40.0% head length. Mouth width narrow, 30.9–43.9% head length. Preanal distance long, 61.3–84.5% head length. Anal-fin long, 78.5–84.4% total length. Cycloid or ovoid scales present on entire post-cranial portion of body from nape to caudal appendage. Scales above lateral line intermediate, four to six, mode 5. Scales over anal-fin pterygiophores large, with six to eight, mode seven rows. Gape large, extending to or beyond posterior nares. Mouth position superior, lower jaw longer than upper, rictus decurved. Chin round in lateral, dorsal profiles, fleshy and bulbous with mental electroreceptive organ overlying lower jaw. Anterior narial pore partially or entirely included within gape, in small narial fold. Anterior nares small, its diameter less than that of eye. Eye below horizontal with mouth. Circumorbital series ovoid. Premaxilla with 16 teeth disposed in single row along outer margin. Curved median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, narrow distally with a straight ventral margin, length equal to roughly width of 4–6 dentary teeth. Dentary with one row of 15 teeth, four to five arrowhead shaped anteriorly. Dentary posteroventral process nearly as long as posterodorsal, narrow distally. Dentary ventral margin lamella narrow, depth less than posterior process. Dentary anteroventral margin rounded in lateral view, without a hook. Mandible long, extended, length greater than twice depth. Anguloarticular process long, extending beyond ventral margin of dentary. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base shorter than length, curved, tip complex. Hyomandibular trigeminal canals connected. Dorsal region of hyomandibula with four lateral foramenae, supraorbital and infraorbital nerves divided. Posterior lateral line fenestra contacting posterodorsal margin of hyomandibula. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf large, more than half width of symplectic. Interopercle dorsal margin ascending process broad. Opercle dorsal margin straight to slightly convex, its posterior margin smooth. Opercular posterior margin entirely smooth. Subopercle dorsal margin concave. Cranial fontanels closed in juveniles and adults. Frontal shape broad, width at fourth infraorbital less than that of parietal, anterior margin of straight, continuous with margins of adjacent roofing bones, postorbital process broad, more than two times width of supraorbital canal. Lateral ethmoid unossified. Parietal rectangular, length less than width. Parasphenoid anteroventral portion robust, extending ventral to lateral margin of parasphenoid, posterior processes narrow. Prootic foramen Vp separate from V2-3 +VII. Adductor mandibula undivided at insertion, intermusculars absent. All basibranchials unossified. Gill rakers not contacting gill bar. Cleithrum narrow, ventral margin straight, anterior limb short, less than one-point-eight times ascending limb, deeply incised on its anteroventral margin, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle-shaped. Body cavity of moderate length, with 34 precaudal vertebrae (n=1). Rib 5 robust along its entire extent, less than three times width of rib 6. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Pectoral fin narrow, with 10–13 rays, mode 11. Anal fin of moderate length, with 167–227 rays, median 193. Lateral-line variable, with 10–15 ventral rami, median 12. Lateral-line dorsal rami absent in adults. Single hypaxial electric organ, extending along entire ventral margin of body with three rows of electroplates near caudal insertion of anal fin. Color in alcohol: Body ground color dark, chocolate brown. Bands variable in number among individuals and in shape and arrangement within individuals, uncorrelated with sex. Adults (TL> 110 mm TL) with 16–23 (mode 20, n=16) obliquely-oriented, thin cream-colored bands located between tail tip and pectoral-fin base on lateral surface and onto dorsum, more regular in juveniles. Pale bands regular, sinuous and undivided, with sharp contrast between margins and ground color. Dark bands chocolate-brown in color, three times as wide as pale anteriorly, similar in width dorsoventrally, and wider caudally. Head chocolate-brown dorsally and on operculum, grading to lighter brown ventrally and on snout. Posteroventrally-oriented band at nape connected to anteriormost anteroventral pale band of body in many specimens. Pectoral and anal fins with dark rays and inter-radial membranes. Anal fin with pale zone caudally. Etymology: Specific epithet derived from to the jaguarundi (Herpailurus yagouaroundi), the red form of which is locally known as the “ eyra ”. The convention of naming Gymnotus for felids, which are often similarly nocturnal, predatory, banded or spotted, is shared with G. pantherinus, G. tigre and G. onca. Noun in apposition. Habitats: Gymnotus eyra usually inhabits slowly-moving channels (caños) on forested floodplains, aguajales of the palm Mauritia flexuosa, and seasonally flooded savannahs, and is less commonly found in small, upland (non-floodplain) forest streams (quebradas).

Gymnotus riberalta n. sp. Figure 6E, Table 3 Holotype: CBF 10248, 199 mm TL, Bolivia, Beni, Riberalta, Rio Beni, Rio Madeira drainage, Rio Amazonas drainage, Arroyo near Lago de San Jose (10��54���47���S, 065��59���49���W), coll. William Crampton, 06/27/2008. Paratypes: CBF 10243, 193 mm TL, same date and locality as CBF 10248; CBF 10244, 135 mm TL, same locality as CBF 10248; CBF 10245, 220 mm TL, same locality as CBF 10248; CBF 10246, 142 mm TL, same locality as CBF 10248; CBF 10247, 196 mm TL, same locality as CBF 10248; CBF 10249, 173 mm TL, same locality as CBF 10248; UMSS 7008, 138 mm TL, same locality as CBF 10248; UMSS 7009, 153 mm TL, same locality as CBF 10248; UMSS 7010, 200 mm TL, same locality as CBF 10248; UMSS 7011, 152 mm TL, same locality as CBF 10248; UMSS 7012, 237 mm TL, same locality as CBF 10248; UMSS 7013, 209 mm TL, same locality as CBF 10248; UMSS 7014, 247 mm TL, same locality as CBF 10248. Nontypes: UMMZ 82146, 153 mm TL, Bolivia, Santa Cruz, ��uflo de Chaves, R��o Blanco near Concepci��n (~ 16��07���55���S, 062��01���34���W); UMSS 0 7015, 194 mm TL, Brazil, Amazonas, Rio Beni, Rio Madeira drainage, stream near Porto Hamburgo (10��54���7.75���S, 065��59���8.18���W); UMSS 0 7016, 216 mm TL, same locality as UMSS 07015; UMSS 0 7017 170 mm TL, same locality as UMSS 07015; UF 180238 (3), 187���267 mm TL, Bolivia, Beni, Riberalta, Rio Beni, Rio Madeira drainage, Rio Amazonas drainage, Small Stream near Puerto Hamburgo, Riberalta (11��01���52���S, 066��05���39���W, 147 m). Diagnosis: Gymnotus riberalta is morphologically similar to G. pantanal, but differs on the following characters: one, a narrow maximum body width (BW 53.3���72.0% TL, mean 61.2% TL vs. 71.5���76.7% TL, mean 73.7 TL in G. pantanal); two, a narrow mouth (MW 32.7���45.7% HL, mean 41.2% vs. 42.0���50.7% HL, mean 46.0% in G. pantanal); three, a narrower pectoral fin, possessing fewer rays (P1R 10���13, mode 13 vs. 14���18, mode 15 in G. pantanal); four, more anal-fin pterygiophore scales (APS 10���11, mode 10 vs. seven to eight, mode seven in G. pantanal). Gymnotus riberalta further differs from other members of the G. carapo clade throughout the Neotropics in possessing a color pattern (similar to G. pantanal) consisting of narrow pale bands less than one quarter width of dark bands, wavy band margins, pale bands exclusively on ventral portion of body anteriorly vs. bands interrupted into patches anterodorsally, with silver, blue or green metallic countershading on dorsum of adults of G. arapaima, dark bands lost in large adults (> 250 mm TL) of G. ardilai, small, rounded dark spots over entire body except posterior 20% of some specimens of G. bahianus, bands faint or absent in all specimens of G. chimarrao, one to three inverted Y-shaped dark bands posteriorly and pale bands not reaching above lateral line in anterior two thirds of body of G. choco, bands broken into speckles throughout in G. diamantinensis, narrow pale bands (less than one fifth width of dark bands) with sharp margins, and pale bands extending fully to dorsal midline in G. mamiraua, pale bands wider than dark bands in G. sylvius, narrow pale interbands (less than one third width of dark bands) extending above lateral line and often to dorsal midline in G. ucamara. Description: Sexually monomorphic. Size up to 302 mm TL with adult body proportions attained at about 150 mm TL. Adult body shape subcylindrical with a mean ratio of body width to depth of 65%. Body profile slender, body depth 81.1���102.1% total length. Head length moderate, 7.3���10.3% total length. Snout length moderate, 31.1��� 37.3% head length. Mouth width narrow, 32.7���45.7% head length. Preanal distance long, 71.9���97.9% head length. Anal-fin long, 79.7���97.4% total length. Cycloid or ovoid scales present on entire post-cranial portion of body from nape to caudal appendage. Scales above lateral line intermediate, six to eight, mode six. Scales over anal-fin pterygiophores large, with 10���11, mode 10 rows. Gape large, extending to or beyond posterior nares. Mouth position superior, lower jaw longer than upper, rictus decurved. Chin round in lateral, dorsal profiles, fleshy and bulbous with mental electroreceptive organ overlying lower jaw. Anterior narial pore partially or entirely included within gape, in small narial fold. Anterior nares small, its diameter less than that of eye. Eye below horizontal with mouth. Circumorbital series ovoid. Premaxilla with 20 teeth disposed in two rows along outer margin, arrowhead shaped anteriorly, conical posteriorly. Curved median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, narrow distally with a straight ventral margin, length equal to roughly width of four to six dentary teeth. Dentary with one row of 18 teeth, four arrowhead shaped anteriorly, all others conical posteriorly. Posterodorsal and posteroventral dentary processes abut at midlength. Dentary posteroventral process nearly as long as posterodorsal, narrow distally. Dentary ventral margin lamella narrow, depth less than posterior process. Dentary anteroventral margin rounded in lateral view, with a hook. Mandible long, extended, length greater than twice depth. Anguloarticular process long, extending beyond ventral margin of dentary. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base shorter than length, curved, tip simple. Interopercle dorsal margin ascending process broad. Hyomandibular trigeminal canals connected. Dorsal region of hyomandibula with four lateral foramenae, supraorbital and infraorbital nerves connected. Posterodorsal laterosensory ramus of preopercle with single superficial pore. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf large, more than half width of symplectic. Opercle dorsal margin straight to slightly convex, its posterior margin smooth. Opercular posterior margin entirely smooth. Subopercle dorsal margin concave. Cranial fontanels closed in juveniles and adults. Frontal shape narrow, width at fourth infraorbital less than that of parietal, anterior margin straight, continuous with margins of adjacent roofing bones, postorbital process broad, more than two times width of supraorbital canal. Lateral ethmoid unossified. Parietal rectangular, length less than width. Parasphenoid anteroventral portion reduced, extending ventral to lateral margin of parasphenoid, posterior processes robust. Prootic foramen Vp combined with V2-3 +VII. Adductor mandibula undivided at insertion, intermusculars absent. All basibranchials unossified. Gill rakers not contacting gill bar. Cleithrum narrow, ventral margin straight, anterior limb long, more than 1.8 times ascending limb, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle-shaped. Body cavity of moderate length, with 35 precaudal vertebrae, mode=35, n=2. Rib 5 robust along its entire extent, less than three times width of rib 6. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Pectoral fin narrow, with 10���13 rays, mode 13 rays. Anal fin of moderate length, with 169���239 rays, median 202. Lateral-line variable, with 10���16 ventral rami, mode 13. Lateral-line dorsal rami absent in adults. Single hypaxial electric organ, extending along entire ventral margin of body with three rows of electroplates near caudal insertion of anal fin. Color in alcohol: Body ground color dark, chocolate brown. Bands variable in number among individuals and in shape and arrangement within individuals, uncorrelated with sex. Juveniles (TL 150 mm TL) with 22���27 (mode 24, n=9) obliquely-oriented, thin cream-colored bands with wavy, irregular margins ventrolaterally located between tail tip and pectoral-fin base. Pale bands infrequently branched, and very rarely extend above lateral line on anterior half of body. Dark bands chocolate-brown in color, four times as wide as pale anteriorly and forming inverted Y-shapes posteriorly. Interband contrast greatest in juveniles and ventrally to caudally in adults. Anterior 80% of dorsum with very faint or absent banding in specimens of all sizes. Head ground color chocolate brown dorsally grading to lighter brown ventrally. Ventral surface of head and branchiostegal membranes speckled. Pectoral fin with brown or gray rays, hyaline inter-radial membranes. Analfin membrane uniformly light brown or gray. Ecology: All specimens were captured in small terra firme rainforest streams with sandy beds and dense emergent aquatic vegetation. Water chemistry parameters were as follows: conductivity 6.8���8.2, pH 5.2���5.5, temperature 22.2���25.0 ��C, Dissolved Oxygen 3.4���4.2 mg ��l -1. Electric Organ Discharge: The EOD waveforms of G. riberalta were previously described by Crampton et al. (2013) as ��� Gymnotus n. sp. ALT ���. The head-to-tail EOD waveform (sensu Waddell et al. (2016)) of this species is tetraphasic with a dominant P1���P2 phase flanked by a lower voltage negative P0 phase (Figure 7), following the nomenclature of Crampton et al. (2011). A positive P3 phase after P0 is invariably absent. This EOD waveform conforms to the ht-EOD category ���2��� of Crampton et al. (2013). The peak power frequency (PPF) of the EOD ranged from 0.946���1.597 kHz, mean=1.158, standard deviation (SD)=0.151 kHz, with no significant disparity between males (0.946���1.597 kHz, mean=1.148 kHz, SD=0.152 kHz, n=13 recorded specimens) and females (0.976���1.292 kHz, mean=1.12 kHz, SD=0.110 kHz, n=7) (two-tailed t-Test p=0.81). Resting (daytime) pulse rates (1 minute averages) are reported for G. riberalta in the range 33.9���51.9 Hz, mean 41.9 Hz, SD=5.5 (n= 18 specimens) and active (nighttime) pulse rates in the range 44.7���77.1 Hz, mean 3.2 Hz, SD=7.8 (n=19) (two-tailed t-Test night> day, p=7.2 x 10-11). No sex disparity was observed in the mean resting pulse rates (females=40.7 Hz, n=8; males=42.8 Hz, n=10; two-tailed t-Test, p=0.45) and mean active pulse rates (females=62.0 Hz, n=7; males=63.8 Hz, n=12; two-tailed t-Test, p=0.62). Etymology: Specific epithet derived from the city of Riberalta in the Beni Department of Bolivia, where the type series was collected. Noun in apposition. Habitats: Gymnotus riberalta inhabits slowly-moving channels (ca��os) on forested floodplains and aquatic vegetation at the margins of oxbow lakes on seasonally flooded savannahs., Published as part of Craig, Jack M., Correa-Rold��n, Vanessa, Ortega, Hern��n, Crampton, William G. R. & Albert, James S., 2018, Revision of Gymnotus (Gymnotiformes: Gymnotidae) from the Upper Madeira Basin of Bolivia and Peru, with descriptions of two new species, pp. 111-132 in Zootaxa 4413 (1) on pages 125-127, DOI: 10.11646/zootaxa.4413.1.3, http://zenodo.org/record/1221950, {"references":["Crampton, W. G. R., Rodriguez-Cattaneo, A., Lovejoy, N. R. & Caputi, A. A. (2013) Proximate and ultimate causes of signal diversity in the electric fish Gymnotus. The Journal of Experimental Biology, 216, 2523 - 2541. https: // doi. org / 10.1242 / jeb. 083261","Crampton, W. G. R., Lovejoy, N. R. & Waddell, J. C. (2011) Reproductive character displacement and signal ontogeny in a sympatric assemblage of electric fish. Evolution, 65, 1650 - 1666. https: // doi. org / 10.1111 / j. 1558 - 5646.2011.01245. x"]}

Gymnotus cuia n. sp. Figure 7, Table 1 Synonyms: G. aff. carapo ���(Bertaco et al. 2016; Cognato et al. 2007a; b; Cognato & Fialho 2006; Malabarba et al. 2013; Serra et al. 2014). Holotype: UFRGS 23700, 193 mm, Brazil, Rio Grande do Sul, Viam��o, Lagoa Verde, Itapu�� State Park, Rio Grande, do Sul (30��22���52���S, 051��01���25���W). Paratypes: UFRGS 6854 (5), 104���169 mm, same locality as UFRGS 23700; UFRGS 6855 (3), 164���279 mm, same locality as UFRGS 23700; UFRGS 6857 (4), 152���236 mm, same locality as UFRGS 23700; UFRGS 6858 (2), 168���223 mm, same locality as UFRGS 23700; UFRGS 6859, 266 mm, same locality as UFRGS 23700; UFRGS 8655, 130 mm, same locality as UFRGS 23700; UFRGS 9103 (2), 216���237 mm, same locality as UFRGS 23700; UFRGS 9104, 153 mm, same locality as UFRGS 23700; UFRGS 9105 (2), 125���131 mm, same locality as UFRGS 23700; UFRGS 9106 (2), 152���187 mm, same locality as UFRGS 23700; UFRGS 9115, 166 mm, same locality as UFRGS 23700; UFRGS 9790 (4), 188���261 mm, same locality as UFRGS 23700; UFRGS 9794 (4), 171���217 mm, same locality as UFRGS 23700. Non-Types (Type locality was restricted to Lagoa Verde, Viam��o, Itapu�� State Park, Rio Grande, do Sul, Brazil): Argentina: MLP 110805 (3), 183���221 mm, Corrientes, R��o Paran�� (~ 27��27���28.41���S, 058��47���54.13���W); UF 125973 (4), 197���238 mm, Formosa, R��o Bermejo drainage, ponds near R��o Bermejo (~ 26��13���39���S, 058��09���60���W). Brazil, Mato Grosso do Sul: MZUSP 59316, 198 mm, Corumb��, Rio Vermelho drainage. Brazil, Rio Grande do Sul: MCP 19550 (2), 185���270 mm, S��o Gabriel, bridge over Banhado do Inhatium (30��15���43���S, 054��31���33���W); MCP 19999 (2), 265���305 mm, Sapiranga, Arroio Feitoria (29��34���00���S, 051��00���00���W); MCP 41952 (4), 140���205 mm, Rio Cacequi drainage, stream alongside RS640 to Cacequi (29��55���23���S, 054��49���52���W); MCP 42587, 208 mm, Viam��o, Lagoa Negra, Itapu�� State Park (30��21���35���S, 050��58���34���W); UFRGS 10066, Porto Alegre (30��07���32.57���S, 051��11���22.21���W); UFRGS 16370, 206 mm, Viam��o, Area de Preserva����o Ambiental Banhado dos Pachecos (30��07���44.63���S, 050��50���17.67���W); UFRGS 5618 (2), 261���264 mm, Viam��o, Lagoa Negra, Itapu�� State Park (30��21���35���S, 050��58���34���W); UFRGS 5738, 162 mm, Santa Rosa, Lageado do Pessegueiro; UFRGS 6536, 208 mm, same locality as UFRGS 5618; UFRGS 6537, 233 mm, same locality as UFRGS 5618; UFRGS 6538, 195 mm, same locality as UFRGS 5618; UFRGS 6539, 195 mm, same locality as UFRGS 5618; UFRGS 6540, 130 mm, same locality as UFRGS 5618; UFRGS 6541, 140 mm, Sanga do Jacar��, 82 km from Alegrete (30�� 12���42���S, 055��03���17���W); UFRGS 6544 (c&s), same locality as UFRGS 6541; UFRGS 6542, 152 mm, same locality as UFRGS 6541; UFRGS 6543, 198 mm, same locality as UFRGS 6541; UFRGS 6548, 241 mm, Terra de Areia, Rio Tr��s Forquilhas (29��33���22���S, 050��04���19���W); UFRGS 6549, 203 mm, same locality as UFRGS 6548; UFRGS 6550, 116 mm, Eldorado do Sul, Arroio Passo dos Carros (30��05���54���S, 051��23���18���W); UFRGS 6551, 115 mm, same locality as UFRGS 6550; UFRGS 6553, 172 mm, Eldorado do Sul, Arroio Passo dos Carros (30��02���55���S, 051��23���34���W); UFRGS 6554, 135 mm, same locality as UFRGS 6553; UFRGS 6555, 128 mm, same locality as UFRGS 6550; UFRGS 6556, 166 mm, S��o Gabriel, Rio Uruguai drainage, Arroio Pira�� (30��18���56���S, 054��24���22���W); UFRGS 6557, 143 mm, same locality as UFRGS 6556; UFRGS 6558, 191 mm, same locality as UFRGS 6556; UFRGS 6559, (c&s), same locality as UFRGS 6556; UFRGS 6560, 145 mm, same locality as UFRGS 6556; UFRGS 6561, 197 mm, same locality as UFRGS 6556; UFRGS 6573, 217 mm, Terra de Areia, streams in the Reserva Biol��gica da Mata Paludosa (29��30���41���S, 050��06���27���W); UFRGS 6581, Agudo, Arroio Corup�� along the road from Agudo to UHE Dona Francisca (29��33���54���S, 053��17���09���W); UFRGS 6587 (2), 159���170 mm, same locality as UFRGS 6581; UFRGS 6589, 268 mm, same locality as UFRGS 6587; UFRGS 8265 (2), 212���245 mm, Charqueadas (29��57���31���S, 051��33���10���W). Brazil, S��o Paulo: MZUSP 79348, 222 mm, Reservat��rio de Barra Bonita, Rio Tiet�� (22�� 31���56���S, 048��31���05���W); MZUSP 83409, 195 mm, Bariri, Rio Tiet�� a near UHE Bariri road; MZUSP 83421 (2), 20���181 mm, Rio Tiet�� drainage, Bariri, Queixada stream (22��08���00���S, 048��44���33���W); MZUSP 83427 (5), 90.6���146 mm, Rio Tiet�� drainage, Bariri, Catingueiro stream (22��07���00���S, 048��45���05���W). Paraguay: MNHNP 189, PTE Hayes, General Bruguez, lake on the premises of the General Jos�� M. Brugues military base (24��44���33���S, 058��50���10���W); MNHNP 1064, Alto Paran��, R��o Aray, dry stream below the dam; MNHNP 1070 (3), PTE Hayes, "La Golondrina" Hotel, small puddle (~24��31���00���S, 058��40���10���W); MNHNP 1620, Cordillera, Piribebuy, Saltos de Pirareta, 500 m below the falls (25��30���24���S, 056��55���32���W); MNHNP 1734 (2); MNHNP 3389 (2), Alto Paraguay, Tajamar, Madrejon, 50 m from the administration building (20��37���34���S, 059��52���47���W). Uruguay: UFRGS 7990 (2), 144��� 206 mm, Artigas, R��o Uruguay, Arroyo Guaviy�� (30��37���51���S, 057��41���18���W). Diagnosis. Gymnotus cuia is most similar to the sympatric G. c. australis, from which it differs on the following characters: 1, a shorter head (HL 9.8%���12.2% TL, mean 10.9% TL, vs. 11.7%���14.0% TL, mean 12.9% TL); 2, a deeper body (BD 85.4%���133.3% HL, mean 110.6% HL vs. 67.0%���98.8% HL, mean 87.9% HL); 3, a deeper head (HD 61.9%���80.2% HL, mean 68.5% HL vs. 51.2%���64.6% HL, mean 59.7% HL) (Figure 8). Gymnotus cuia is also morphologically similar to the sympatric G. omarorum, from which it differs on by the following characters: 1, more anal-fin pterygiophore scales (APS 6���10, mode 8 vs. 5���6, mode 6); 2, more pored lateral-line scales anterior to the first ventral lateral-line ramus (PLR 32���47, mode 37 vs. 23���30, mode 27); 3, fewer ventral lateral-line rami (VLR 14���28, mode 22 vs. 28���30, mode 29). Gymnotus cuia further differs from all other members of the G. carapo clade in possessing a color patter comprised of 21���29 (mode 28) obliquelyoriented, chocolate-colored bands with wavy, irregular margins and pale interbands less than one-third width of dark bands at mid-body vs. bands interrupted into patches anterodorsally, with silver, blue or green metallic countershading on dorsum of adults of G. arapaima, dark bands lost in large adults (> 250 mm) of G. ardilai, small, rounded dark spots over entire body except posterior 20% of some specimens of G. bahianus, bands faint or absent in all specimens of G. chimarrao, one to three inverted Y -shaped dark bands posteriorly and pale bands not reaching above lateral line in anterior two thirds of body of G. choco, bands broken into speckles throughout in G. diamantinensis, narrow pale bands (G. mamiraua, bands faint or absent from 80% of dorsum in all specimens, and narrow pale bands (G. pantanal, pale bands wider than dark bands in G. sylvius, narrow pale interbands (G. ucamara. Gymnotus cuia further differs from all members of the G. varzea clade (G. chaviro, G. curupira G. mamiraua, G. obscurus, and G. varzea) the following characters: 1, relatively more arrowhead-shaped dentary teeth (6 vs. 2���4 in the G. varzea clade except in G. chaviro, G. curupira and G. mamiraua,, with 4���7); 2, anterior 80% of anal fin membrane pigmented, posterior 20% translucent (vs. wholly clear or evenly pigmented in the G. varzea clade); 3, large adult total length (305 mm TL vs. 215 mm ��� 275 mm TL in the G. varzea clade). Description: Morphometric and meristic data in Table 1. Sexually monomorphic, including in breeding condition. Total length to 305 mm. Morphological maturity at roughly 110 mm. Scales rounded to slightly ovoid, present on entire postcranial portion of body. Gape large in mature specimens, to or beyond posterior nares. Mouth superior with lower jaw longer than upper, rictus decurved. Chin fleshy and protuberant with fleshy pad of electrosensitive organs overlying tip of snout and oral jaws. Anterior narial pore partially to entirely included within gape in narial fold. Anterior nares large, subequal to eye diameter. Circumorbital series ovoid. Ethmoid region broad between anterior nares, with rounded anterior margin. Eye position lateral, lower margin of eye dorsal or horizontal to rictus. Premaxilla with 13���14 (mode 13) teeth disposed in single row along outer margin, arrowhead shaped anteriorly, conical posteriorly. Curved median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, narrow distally with a straight ventral margin, length equal to roughly width of four���six dentary teeth. Dentary with one row of 26���27 (mode 26) teeth, 6 arrow-head shaped anteriorly, all others conical posteriorly. Posterodorsal and posteroventral dentary processes abut at midlength. Dentary posteroventral process shorter than posterodorsal, narrow distally. Dentary ventral margin lamella narrow, depth less than posterior process. Opercle dorsal margin straight to slightly convex. Dorsal opercular process lamellar or rugose, crest absent or small, posterior margin entirely smooth, without spines or processes. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf large, more than one-half width of symplectic. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base shorter than length, curved, tip simple. Interopercle dorsal margin ascending process broad. Subopercle dorsal margin concave. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Anguloarticular process long, extending beyond ventral margin of dentary. Mandible short, extended, length less than twice depth. Trigeminal nerve canals divided within the hyomandibula. Posterior lateral line fenestra contacting posterodorsal margin of hyomandibula. Cranial fontanels closed in juveniles and adults. Frontal shape narrow, width at fourth infraorbital less than that of parietal, anterior margin of straight, continuous with margins of adjacent roofing bones, postorbital process broad, more than two times width of supraorbital canal. Lateral ethmoid absent. Parietal rectangular, length less than width. Parasphenoid anteroventral portion gracile, extending ventral to lateral margin of parasphenoid, posterior processes narrow. Prootic foraminae separate for cranial nerves Vp and V2���3 +VII. Adductor mandibula muscle undivided at insertion, intermuscular bones absent. All basibranchials unossified. Gill rakers not contacting gill bar. Pectoral with 11���16 (mode 14) rays, medial radial large. Mesocoracoid elongate, length more than four times width. Cleithrum broad, ventral margin curved, anterior limb long, more than 1.8 times ascending limb, deeply incised on its anteroventral margin, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle shaped. Body cavity of moderate length, with 31���34 (mode 33) precaudal vertebrae. Rib five robust along its entire extent, less than three times width of rib six. Hemal spines present. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Anal fin with 141���259 (median 192) rays. Lateral line ventral rami 14���28 (median 22). Caudal appendage short, less one-half length of pectoral fin. Single hypaxial electric organ along entire ventral margin of body. Three rows of electroplates near caudal insertion of anal fin. Color in Alcohol: Bands irregular in shape, width and color, on specimens and among individuals. Ground color tan ventrally grading to darker brown or olive green dorsally in adults, pale yellow throughout in smaller specimens. Many obliquely-oriented, chocolate-colored bands with wavy, irregular margins on lateral surface from nape and to tip of caudal appendage, occurring singly or as band-pairs, increasingly divided and irregular with size (21���29 mode 28). Pale interbands less than one-third width of dark bands at mid-body. Bands rarely divided dorsally or ventrally to form X- or inverted Y -shaped patterns. Band-interband contrast increases ventrally and caudally, fades with growth (juveniles> 150 mm with distinct margins, specimens 200���300 mm more faintly banded). Head never banded, spotted, or blotched, dark brown grading to lighter brown dorsally to ventrally. Numerous chromophores speckled over branchiostegal membranes and ventral surface of head. Pectoral-fin rays brown, interradial membranes hyaline. Anterior 80% of anal fin membrane dark brown, gray or black, posterior 20% translucent. Etymology: The specific epithet is derived from the species��� especially deep body and head, evoking the short, rounded cuia gourd used to drink the traditional mate popular throughout its range. The convention of honoring this practice in gymnotiform taxonomy is shared with G. chimarrao (chimarr��o =the mate itself) and Brachyhypopomus bombilla (bombilla =the metal straw used for drinking mate). The common name ��� bombilla ��� is often used to describe gymnotiform fish throughout the southern Neotropics as well. Ecology: Gymnotus cuia inhabits lakes and small streams, associated to densely vegetated areas. The species is abundant in the type locality (Figure 9), a shallow lake (less than 1 m deep) with dense emergent vegetation, including Ludwigia peploides (Onagraceae), Utricularia spp. (Lenticulariaceae), Nymphoides indica (Menyanthaceae), Pontederia lanceolata (Pontederiaceae), Azolla sp. (Azollaceae), Eleocharis sp. (Cyperaceae), Cabomba australis (Cabombaceae), Echinodorus sp. (Alismataceae), Lemna valdiviana (Lemnaceae), Scirpus sp. (Sciperaceae) and abundant grass in the shores (Cognato & Fialho 2006). Throughout its distribution it is usually abundant in the roots of dense beds of floating water hyacinths (Eichornia crassipes). Reproductive cycle extends from November to March (Cognato & Fialho 2006). Electric Organ Discharge: The EOD waveforms of G. cuia were previously described by Crampton et al. (2013) as ��� Gymnotus n. sp. ITU���. The head-to-tail EOD waveform sensu Waddell et al. (2016) of G. cuia is tetraphasic with a dominant P1-P2 phase flanked by a lower voltage negative P0 phase and very low and variably present positive P3 phase (Figure 10). A positive P-1 phase preceding P0 is invariably absent. This EOD waveform conforms to the ht-EOD category 2 of Crampton et al. (2013). The (red) waveforms in Figure 10 refer to specimens of G. cuia collected from the Lagoa dos Patos and Rio Uruguai drainages of Rio Grande do Sul, Brazil. The peak power frequency of the EODs for G. cuia depicted in Figure 10 range from 0.832���1.484 kHz, mean 1.029, standard deviation 0.135 kHz (n=23 recorded specimens). We reported resting pulse rates (1 minute averages) for G. cuia in the range 31���52 Hz, mean 44 Hz (n= 15 specimens). In Rio Uruguai drainages of Rio Grande do Sul G. cuia (red EODs in Figure 10, UFRGS 6556-6561) occurs in sympatry and syntopy with G. carapo australis (black EODs in Figure 10, UFRGS 6763). This species was reported in Crampton et al. (2013), Figure 2, as ��� G. sylvius ���. The pentaphasic EOD waveform of G. carapo australis conforms to the ht-EOD category ���3��� of Crampton et al. (2013) and is readily distinguishable by the invariable presence of both a P-1 and P3 phase. The EOD of G. carapo australis is also shorter, throughout all phases, than that of G. cuia, with a consequent higher peak power frequency, which ranges from 1.289���1.676 kHz, mean 1.476, standard deviation 0.19 (n=3 recorded specimens). We reported resting pulse rates (1 minute averages) for G. carapo australis in the range 46���51 Hz, mean 49 Hz, n = 3 specimens)., Published as part of Craig, Jack M., Malabarba, Luiz R., Crampton, William G. R. & Albert, James S., 2018, Revision of Banded Knifefishes of the Gymnotus carapo and G. tigre clades (Gymnotidae Gymnotiformes) from the Southern Neotropics, pp. 47-73 in Zootaxa 4379 (1) on pages 55-59, DOI: 10.11646/zootaxa.4379.1.3, http://zenodo.org/record/1172318, {"references":["Bertaco, V. A., Ferrer, J., Carvalho, F. R. & Malabarba, L. R. (2016) Inventory of the freshwater fishes from a densely collected area in South America - a case study of the current knowledge of Neotropical fish diversity. Zootaxa, 4138 (3), 401 - 440. https: // doi. org / 10.11646 / zootaxa. 4138.3.1","Cognato, D., Giora, J. & Fialho, C. B. (2007 a) Analise da ocorrencia de lesoes corporais em tres especies de peixe eletrico (Pisces: Gymnotiformes) do sul do Brasil. Pan-American Journal of Aquatic Sciences, 2, 242 - 246.","Cognato, D., Richer-de-Forges, M. M., Albert, J. S. & Crampton, W. G. R. (2007 b) Gymnotus chimarrao, a new species of electric fish (Gymnotiformes: Gymnotidae) from Southern Brazil. Ichthyological Exploration of Freshwaters, 18, 375 - 382.","Cognato, D. D. P. & Fialho, C. B. (2006) Reproductive biology of a population of Gymnotus aff. carapo (Teleostei: Gymnotidae) from southern Brazil. Neotropical Ichthyology, 4, 339 - 348. https: // doi. org / 10.1590 / S 1679 - 62252006000300005","Malabarba, L. R., Neto, P. C., Bertaco, V. A., Carvalho, T. P., Santos, J. F. & Artioli, L. G. S. (2013) Via Sapiens Guia de identificacao dos peixes da bacia do Rio Tramandai. Via Sapiens, Porto Alegre, Brazil, 140 pp.","Serra, S., Bessonart, J., de Mello, F. T., Duarte, A., Malabarba, L. & Loureiro, M. (2014) Peces del Rio Negro. 1 st Edition. Ministerio de Ganaderia, Agricultura y Pesca, Montevideo, pp. 1 - 208.","Crampton, W. G. R., Rodriguez-Cattaneo, A., Lovejoy, N. R. & Caputi, A. A. (2013) Proximate and ultimate causes of signal diversity in the electric fish Gymnotus. The Journal of experimental biology, 216, 2523 - 41. https: // doi. org / 10.1242 / jeb. 083261","Waddell, J. C., Rodriguez-Cattaneo, A., Caputi, A. A. & Crampton, W. G. R. (2016) Electric organ discharges and near-field spatiotemporal patterns of the electromotive force in a sympatric assemblage of Neotropical electric knifefish. Journal of Physiology Paris, 110, 164 - 181. https: // doi. org / 10.1016 / j. jphysparis. 2016.10.004"]}

Gymnotus omarorum Richer-de-Forges, Crampton and Albert, 2009 Figure 12, Table 1 Material examined: Uruguay, Artigas: ZVC-P 16, 185 mm, R��o Uruguay drainage, R��o Cuareim, del Yucutuja, Rancho El Ombu (31��40���12���S, 057��10���12���W); ZVC-P 404 (2), 160���190 mm, R��o Uruguay drainage, R��o Cuareim, Picada Tareira (34��25���12���S, 056��25���12���W); ZVC-P 2273, 278 mm, Canal de Riego; ZVC-P 2906 (3), 95���205 mm, R��o Uruguay drainage, R��o Cuareim, Rancho Pereira Reverbell (30��11���24���S, 057��09���36���W); ZVC-P 3407b (3), 195���240 mm, R��o Uruguay drainage, Catal��n Chico, Rancho Martine; ZVC-P 3634, 286 mm, Salto, R��o Uruguay drainage, Salto City. Uruguay, Florida: ZVC-P 105 (2), 100���170 mm, R��o Uruguay drainage, Laguna en Ca��ada Invernada (31��00���36���S, 056��00���36���W); ZVC-P 303 (2), 173���215 mm, R��o Uruguay drainage, R��o Santa Lucia (34��26���24���S, 056��23���60���W); ZVC-P 3423, 146 mm, R��o Uruguay drainage, Ca��ada Milano; ZVC-P 5502, 227 mm, R��o Uruguay drainage, R��o Santa Lucia, Ca��ada Casupa. Uruguay, Lavalleja: ZVC-P 950 (2), 123���158 mm, Rio Cebollat��, Laguna Mer��n, Rancho Sosa Diaz, Canada Mariscala (33��26���24���S, 054��23���60���W); ZVC-P 1917, 82 mm, Laguna Mer��n drainage, Villa Serrana, Ca��ada los Chanchos (34��19���12���S, 054��57���36���W). Uruguay, Maldonado: ZVC-P 6480 (holotype), 250 mm, R��o Cisne drainage, Laguna del Sauce (34��50���20���S, 055��06���52���W); AMNH 239656 (16) (paratypes), 32���222 mm, same locality as ZVC-P 6480; MCP 41266 (3) (paratypes), 150���190 mm, same locality as ZVC-P 6480; ZVC-P 6481 (33) (paratypes), 23���201 mm, same locality as ZVC-P 6480. Uruguay, Rivera: ZVC-P 1351, 245 mm, R��o Negro, Ca��ada Cu��apir�� (31��11���60���S, 055��36���00���W). Uruguay, Treinta y Tres: ZVC-P 7429 (3), 227���269 mm, Laguna El Tigre. Uruguay, Tacuaremb��: ZVC-P 7430, 222 mm, Laguna Lavalle. Diagnosis. Gymnotus omarorum differs from all sympatric members of the G. carapo clade on the following characters: 1, few anal-fin pterygiophore scales (APS 2���6, mode 6 vs. 6���13, mode 8); 2, few pored lateral-line scales anterior to the first ventral lateral-line ramus (PLR 23���30, median 27 vs. 30���50, median 38); 3, many ventral lateral-line rami (VLR 28���30, median 29 vs. 13���28, median 22). Description: Morphometric and meristic data in Table 1. Sexually monomorphic, including in breeding condition. Total length to 262 mm. Morphological maturity at roughly 110 mm. Scales rounded to slightly ovoid, present on entire postcranial portion of body. Gape large in mature specimens, to or beyond posterior nares. Mouth superior with lower jaw longer than upper, rictus decurved. Chin fleshy and protuberant with fleshy pad of electrosensitive organs overlying tip of snout and oral jaws. Anterior narial pore partially to entirely included within gape in narial fold. Anterior nares large, subequal to eye diameter. Circumorbital series ovoid. Ethmoid region broad between anterior nares, with rounded anterior margin. Eye position lateral, lower margin of eye dorsal or horizontal to rictus. Premaxilla with 13 teeth disposed in single row along outer margin, arrow-head shaped anteriorly, conical posteriorly. Curved median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, narrow distally with a straight ventral margin, length equal to roughly width of 4���6 dentary teeth. Dentary with one row of 20 teeth, 3 arrow-head shaped anteriorly, all others conical posteriorly. Posterodorsal and posteroventral dentary processes abut at midlength. Dentary posteroventral process shorter than posterodorsal, narrow distally. Dentary ventral margin lamella narrow, depth less than posterior process. Opercle dorsal margin straight to slightly convex. Dorsal opercular process lamellar or rugose, crest absent or small, posterior margin entirely smooth, without spines or processes. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf large, more than one-half width of symplectic. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base shorter than length, curved, tip simple. Interopercle dorsal margin ascending process broad. Subopercle dorsal margin concave. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Anguloarticular process long, extending beyond ventral margin of dentary. Mandible short, compressed, length less than twice depth. Trigeminal nerve canals divided within the hyomandibula. Posterior lateral line fenestra contacting posterodorsal margin of hyomandibula. Cranial fontanels closed in juveniles and adults. Frontal shape narrow, width at fourth infraorbital less than that of parietal, anterior margin of straight, continuous with margins of adjacent roofing bones, postorbital process broad, more than two times width of supraorbital canal. Lateral ethmoid absent. Parietal rectangular, length less than width. Parasphenoid anteroventral portion gracile, extending ventral to lateral margin of parasphenoid, posterior processes narrow. Prootic foraminae separate for cranial nerves Vp and V2���3 +VII. Adductor mandibula muscle undivided at insertion, intermuscular bones absent. All basibranchials unossified. Gill rakers not contacting gill bar. Pectoral with 13���14 (mode 13) rays, medial radial large. Mesocoracoid elongate, length more than four times width. Cleithrum broad, ventral margin curved, anterior limb long, more than 1.8 times ascending limb, deeply incised on its anteroventral margin, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle shaped. Body cavity of moderate length, with 34 precaudal vertebrae. Rib five robust along its entire extent, less than three times width of rib six. Hemal spines present. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Anal fin with 130���184 (median 166) rays. Lateral line ventral rami 28���30 (median 29). Caudal appendage short, less one-half length of pectoral fin. Single hypaxial electric organ along entire ventral margin of body. Three rows of electroplates near caudal insertion of anal fin. Color in Alcohol: Bands irregular in shape, width and color, on specimens and among individuals. Ground color light grey or tan ventrally grading to darker grey or brown dorsally in adults. As in G. cuia, many obliquelyoriented, chocolate-colored bands with wavy, irregular margins on lateral surface from nape and to tip of caudal appendage, occurring singly or as band-pairs, increasingly divided and irregular with size and broken into spots anterodorsally in large specimens (24���29 mode 29). Pale interbands less than one-third width of dark bands at midbody. Bands rarely divided dorsally or ventrally to form X - or inverted Y -shaped patterns. Band-interband contrast increases ventrally and caudally, fades with growth (juveniles> 150 mm with distinct margins, specimens 200���300 mm more faintly banded). Head never banded, spotted, or blotched, dark grey dorsally grading to lighter grey ventrally. Numerous chromophores speckled over branchiostegal membranes and ventral surface of head. Pectoralfin rays brown, interradial membranes hyaline. Pectoral-fin rays brown, interradial membranes hyaline. Anterior 80% of anal fin membrane dark brown, gray or black, posterior 20% translucent., Published as part of Craig, Jack M., Malabarba, Luiz R., Crampton, William G. R. & Albert, James S., 2018, Revision of Banded Knifefishes of the Gymnotus carapo and G. tigre clades (Gymnotidae Gymnotiformes) from the Southern Neotropics, pp. 47-73 in Zootaxa 4379 (1) on pages 61-63, DOI: 10.11646/zootaxa.4379.1.3, http://zenodo.org/record/1172318, {"references":["Richer-de-Forges, M. M., Crampton, W. G. R. & Albert, J. S. (2009) A New Species of Gymnotus (Gymnotiformes, Gymnotidae) from Uruguay: Description of a Model Species in Neurophysiological Research. Copeia, 2009, 538 - 544. https: // doi. org / 10.1643 / CI- 07 - 103"]}

Gymnotus pantanal Fernandes, Albert, Daniel-Silva, Lopes, Crampton and de Almeida-Toledo, 2005 Figure 13, Table 1 Material examined: Argentina: MACN-ict 9655 (19), 154���257 mm, Corrientes, R��o Paran�� drainage, Esteros del Riachuelo (27��34���39���S, 058��15���23���W). Brazil, Mato Grosso do Sul: MZUSP 67874 (holotype), 196 mm, R��o Miranda, near Miranda (20��11���78���S, 056��30���13���W); MZUSP 67875 (paratype), 189 mm, Rio Paraguar�� (18��59���81���S, 057��39���24���W); MZUSP 67875, 192 mm, same locality as MZUSP 67875; MZUSP 67876, 251 mm, same locality as MZUSP 67875; NUP 4554 (5), 195���235 mm, upper Rio Paran�� drainage, marginal lagoons of Rio Paran�� (24��05���33���S, 054��15���17���W); NUP 6044 (2), 152���204 mm, ��gua Que��aba stream; NUP 7934, 152 mm, upper Rio Paran�� drainage, Rio Paraca�� (23��39���30���S, 053��55���10���W); NUP 9290 (17), 139���260 mm, same locality as NUP 9311; NUP 9311 (5), 168���210 mm, upper Rio Paran�� drainage, Rio Marreco, Jacutinga stream (24��42���56���S, 053��46���21���W); NUP 9312 (11), 113���248 mm, upper Rio Paran�� drainage, Rio Toledo, Pinheirinho stream (24��44���05���S, 053��42���55���W); UFRGS 11910, Corumb��, Rio Paraguai drainage, Rio Miranda or Aquidauna between Corumb�� and Aquidauna (23��22���47���S, 052��30���07���W). Paraguay: NRM 42830, 240 mm, Caaguazu, R��o Paran�� drainage, arroyo crossing Rt. 2 West of J. E. Estringarriba (25��22���40���S, 055��42���32���W���); UMMZ 206080 (21), 82���260 mm, Paraguar��, R��o Paraguay drainage, Arroyo in Parque Nacional Ybycui (26��58���00���S, 057��19���60���W). Diagnosis. Gymnotus pantanal differs from all sympatric members of the G. carapo clade on the following characters: 1, a short head (HL 7.4%���11.7%, mean 8.9% TL vs. 9.7%���14.1%, mean 11.7% TL); 2, a wide head (HW 62.2���76.8% HL, mean 69.8% HL vs. 46.2%���71.9% HL, mean 61.5% HL); 3, many precaudal vertebrae (PCV 37���38, mode 37 vs. 31���34, mode 32); 4, many pored lateral-line scales anterior to the first ventral lateral-line ramus (PLR 45���50, median 47 vs. 23���47, median 37). Gymnotus pantanal also differs from other Gymnotus on its color pattern, characterized by 21���24, mode 22 dark bands, four times as wide as pale anteriorly and forming inverted Y -shapes posteriorly, with pale bands never extending above lateral line on anterior half of body, and anterior 80% of dorsum with very faint or absent banding. Description: Morphometric and meristic data in Table 1. Sexually monomorphic, including in breeding condition. Total length to 251 mm. Morphological maturity at roughly 110 mm. Scales rounded to slightly ovoid, present on entire postcranial portion of body. Gape large in mature specimens, to or beyond posterior nares. Mouth superior with lower jaw longer than upper, rictus decurved. Chin fleshy and protuberant with fleshy pad of electrosensitive organs overlying tip of snout and oral jaws. Anterior narial pore partially to entirely included within gape in narial fold. Anterior nares large, subequal to eye diameter. Circumorbital series ovoid. Ethmoid region broad between anterior nares, with rounded anterior margin. Eye position lateral, lower margin of eye dorsal or horizontal to rictus. Premaxilla with 13���16 (mode 15) teeth disposed in two rows along outer margin, arrowhead shaped anteriorly, conical posteriorly. Curved median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, narrow distally with a straight ventral margin, length equal to roughly width of 4���6 dentary teeth. Dentary with one row of 26���28 (mode 28) teeth, 7 arrow-head shaped anteriorly, all others conical posteriorly. Posterodorsal and posteroventral dentary processes abut at midlength. Dentary posteroventral process shorter than posterodorsal, narrow distally. Dentary ventral margin lamella narrow, depth less than posterior process. Opercle dorsal margin straight to slightly convex. Dorsal opercular process lamellar or rugose, crest absent or small, posterior margin entirely smooth, without spines or processes. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf large, more than one-half width of symplectic. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base equal in length, curved, tip simple. Interopercle dorsal margin ascending process broad. Subopercle dorsal margin concave. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Anguloarticular process long, extending beyond ventral margin of dentary. Mandible long, extended, length greater than twice depth. Trigeminal nerve canals connected within the hyomandibula. Posterior lateral line fenestra contacting posterodorsal margin of hyomandibula. Cranial fontanels closed in juveniles and adults. Frontal shape broad, width at fourth infraorbital greater than that of parietal, anterior margin of straight, continuous with margins of adjacent roofing bones, postorbital process broad, more than two times width of supraorbital canal. Lateral ethmoid absent. Parietal rectangular, length less than width. Parasphenoid anteroventral portion reduced, extending dorsal to lateral margin of parasphenoid, posterior processes narrow. Prootic foraminae combined for cranial nerves Vp and V2���3 +VII. Adductor mandibula muscle undivided at insertion, intermuscular bones absent. All basibranchials unossified. Gill rakers not contacting gill bar. Pectoral with 14���18 (mode 15) rays, medial radial large. Mesocoracoid broad, length more than four times width. Cleithrum narrow, ventral margin curved, anterior limb long, more than 1.8 times ascending limb, deeply incised on its anteroventral margin, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle shaped. Body cavity of moderate length, with 37���38 (mode 37) precaudal vertebrae. Rib five robust along its entire extent, less than three times width of rib six. Hemal spines present. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Anal fin with 131���280 (median 184) rays. Lateral line ventral rami 19���23 (median 20). Caudal appendage short, less one-half length of pectoral fin. Single hypaxial electric organ along entire ventral margin of body. Three rows of electroplates near caudal insertion of anal fin. Color in Alcohol: Bands irregular in shape, width and color, on specimens and among individuals. Ground color dark, chocolate brown. Anterior 80% of dorsum with very faint or absent banding in specimens of all sizes. Juveniles (TL Y -shapes posteriorly. Pale bands infrequently branched, and never extend above lateral line on anterior half of body. Interband contrast greatest in juveniles and ventrally to caudally in adults. Head never banded, spotted, or blotched, dark grey dorsally grading to lighter grey ventrally. Numerous chromophores speckled over branchiostegal membranes and ventral surface of head. Pectoral-fin rays brown, interradial membranes hyaline. Anterior 80% of anal fin membrane dark brown, gray or black, posterior 20% translucent., Published as part of Craig, Jack M., Malabarba, Luiz R., Crampton, William G. R. & Albert, James S., 2018, Revision of Banded Knifefishes of the Gymnotus carapo and G. tigre clades (Gymnotidae Gymnotiformes) from the Southern Neotropics, pp. 47-73 in Zootaxa 4379 (1) on pages 63-64, DOI: 10.11646/zootaxa.4379.1.3, http://zenodo.org/record/1172318, {"references":["Fernandes, F. M., Albert, J. S., Daniel-Silva, M. F. Z., Lopes, C. E., Crampton, W. G. R. & Almeida-Toledo, L. F. (2005) A new Gymnotus (Teleostei: Gymnotiformes: Gymnotidae) from the Pantanal Matogrossense of Brazil and adjacent drainages: continued documentation of a cryptic fauna. Zootaxa, 933 (1), 1 - 14. https: // doi. org / 10.11646 / zootaxa. 933.1.1"]}

Gymnotus carapo Linnaeus Figure 6; Table 1 Gymnotus carapo australis Craig, Crampton and Albert, 2017:427, Published as part of Craig, Jack M., Malabarba, Luiz R., Crampton, William G. R. & Albert, James S., 2018, Revision of Banded Knifefishes of the Gymnotus carapo and G. tigre clades (Gymnotidae Gymnotiformes) from the Southern Neotropics, pp. 47-73 in Zootaxa 4379 (1) on page 52, DOI: 10.11646/zootaxa.4379.1.3, http://zenodo.org/record/1172318, {"references":["Craig, J. M., Crampton, W. G. R. & Albert, J. S. (2017) Revision of the polytypic electric fish Gymnotus carapo (Gymnotiformes, Teleostei), with descriptions of seven subspecies. Zootaxa, 4318 (3), 401 - 438. https: // doi. org / 10.11646 / zootaxa. 4318.3.1"]}

Gymnotus chimarrao Cognato, Richer-de-Forges, Crampton and Albert, 2007b Figure 11, Table 1 Material examined: Brazil, Rio Grande do Sul: UFRGS 6774 (holotype), 185 mm, Rio Taquari Drainage, Arroio do Meio, Arroio Grande (29��21���09���S, 051��57���28���W); UFRGS 6770 (paratype), 190 mm, same locality as UFRGS 6774; UFRGS 6771 (paratype), 243 mm, same locality as UFRGS 6774; UFRGS 6772 (paratype), 177 mm, same locality as UFRGS 6774; UFRGS 6773 (paratype), 206 mm, same locality as UFRGS 6774; UFRGS 6776 (paratype), 124 mm, same locality as UFRGS 6774; UFRGS 11952, 223 mm, Nova Roma do Sul (28��57���18���S, 051��22���32���W); UFRGS 17607 (2), 111���222 mm, Canudos do Vale (29��24���22���S, 052��03���19���W). Diagnosis. Gymnotus chimarrao differs from all sympatric congeners in possessing a color pattern characterized by singly-occurring dark pigment bands in juveniles (29���45, mode 32) and faint or absent bands in mature specimens (vs. distinct dark bands and pale interbands in all sympatric congeners except G. inaequilabiatus, which possesses bands as a juvenile, and irregular spots when mature). Description: Morphometric and meristic data in Table 1. Sexually monomorphic, including in breeding condition. Total length to 243 mm. Morphological maturity at roughly 110 mm. Scales rounded to slightly ovoid, present on entire postcranial portion of body. Gape large in mature specimens, to or beyond posterior nares. Mouth superior with lower jaw longer than upper, rictus decurved. Chin fleshy and protuberant with fleshy pad of electrosensitive organs overlying tip of snout and oral jaws. Anterior narial pore partially to entirely included within gape in narial fold. Anterior nares large, subequal to eye diameter. Circumorbital series ovoid. Ethmoid region broad between anterior nares, with rounded anterior margin. Eye position lateral, lower margin of eye dorsal or horizontal to rictus. Premaxilla with 11���13 teeth disposed in single row along outer margin, arrow-head shaped anteriorly, conical posteriorly. Curved median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, narrow distally with a straight ventral margin, length equal to roughly width of 4���6 dentary teeth. Dentary with one row of 12���17 teeth, 2���4 arrow-head shaped anteriorly, all others conical posteriorly. Posterodorsal and posteroventral dentary processes abut at midlength. Dentary posteroventral process shorter than posterodorsal, narrow distally. Dentary ventral margin lamella narrow, depth less than posterior process. Opercle dorsal margin straight to slightly convex. Dorsal opercular process lamellar or rugose, crest absent or small, posterior margin entirely smooth, without spines or processes. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf large, more than one-half width of symplectic. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base shorter than length, curved, tip simple. Interopercle dorsal margin ascending process broad. Subopercle dorsal margin concave. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Anguloarticular process long, extending beyond ventral margin of dentary. Mandible short, compressed, length greater than twice depth. Trigeminal nerve canals divided within the hyomandibula. Posterior lateral line fenestra contacting posterodorsal margin of hyomandibula. Cranial fontanels closed in juveniles and adults. Frontal shape narrow, width at fourth infraorbital less than that of parietal, anterior margin of straight, continuous with margins of adjacent roofing bones, postorbital process broad, more than two times width of supraorbital canal. Lateral ethmoid absent. Parietal rectangular, length less than width. Parasphenoid anteroventral portion gracile, extending ventral to lateral margin of parasphenoid, posterior processes narrow. Prootic foraminae separate for cranial nerves Vp and V2���3 +VII. Adductor mandibula muscle undivided at insertion, intermuscular bones absent. All basibranchials unossified. Gill rakers not contacting gill bar. Pectoral with 14���17 (mode 15) rays, medial radial large. Mesocoracoid elongate, length more than four times width. Cleithrum broad, ventral margin curved, anterior limb long, more than 1.8 times ascending limb, deeply incised on its anteroventral margin, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle shaped. Body cavity of moderate length, with 29���32 (mode 30) precaudal vertebrae. Rib five robust along its entire extent, less than three times width of rib six. Hemal spines present. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Anal fin with 191���250 (median 210) rays. Lateral line ventral rami 13���24 (median 23). Caudal appendage short, less one-half length of pectoral fin. Single hypaxial electric organ along entire ventral margin of body. Three rows of electroplates near caudal insertion of anal fin. Color in Alcohol: Bands barely visible in all specimens. Ground color olive green to yellow ventrally grading to darker brown dorsally in all specimens. Obliquely-oriented, darker brown bands narrow anteriorly, wider posteriorly, typically occurring singly (29���45 mode 32). Band-interband contrast increases ventrally and caudally, fades with growth (juveniles> 150 mm with distinct margins, specimens 150���200 mm faintly banded, and some specimens over 250 mm unbanded except very faintly in posterior one-third of body). Head never banded, spotted, or blotched, dark grey dorsally grading to lighter grey ventrally. Numerous chromophores speckled over branchiostegal membranes and ventral surface of head. Pectoral-fin rays dark brown, interradial membranes hyaline. Anterior 80% of anal fin membrane dark brown, gray or black, posterior 20% translucent., Published as part of Craig, Jack M., Malabarba, Luiz R., Crampton, William G. R. & Albert, James S., 2018, Revision of Banded Knifefishes of the Gymnotus carapo and G. tigre clades (Gymnotidae Gymnotiformes) from the Southern Neotropics, pp. 47-73 in Zootaxa 4379 (1) on page 60, DOI: 10.11646/zootaxa.4379.1.3, http://zenodo.org/record/1172318, {"references":["Cognato, D., Richer-de-Forges, M. M., Albert, J. S. & Crampton, W. G. R. (2007 b) Gymnotus chimarrao, a new species of electric fish (Gymnotiformes: Gymnotidae) from Southern Brazil. Ichthyological Exploration of Freshwaters, 18, 375 - 382."]}

Gymnotus inaequilabiatus Valenciennes, 1847 Figure 15, Table 2 Material examined: Argentina: MACN 5979, 250 mm, Rosario, R��o La Plata (~ 32��56���S, 060��38���W); MLP 3353, 250 mm, Misiones, R��o Paran�� (~ 26��49���S, 055��00���W); MNHN 4615 (neotype), 920 mm (600 mm according to the original description, 850 mm according to the label), Argentina, Buenos Aires, Rio de La Plata (~30��40���S, 058��30���W according to MNHN database or ~34��37���S, 058��23���W). Brazil, Mato Grosso: LBP 12616, ~ 650 mm, Corumb��, Rio Paraguai drainage, Rio Cuiab�� (~ 18��09���S, 057��33���W). Brazil, Mato Grosso do Sul: MCP 15818, 535 mm, Rio Paraguai near C��ceres; USNM 1643, 791 mm, Rio Paraguai drainage (~ 17��53���S, 057��29���W). Brazil, Rio Grande do Sul: MCP 6059 (3), 173���355 mm, Ira��, Rio Uruguai drainage, Sanga das ��guas Frias, 100 m from Rio Uruguai (27��12���00���S, 053��16���60���W); MCP 6956, 602 mm, Rio Uruguai at Santana Velha, near Uruguaiana (~ 29��45���S, 057��50���W); MCP 19552 (3), 145���336 mm, Ros��rio do Sul, pool next to Olaria in the floodplain along Rio Santa Maria, North side of BR290 (30��14���16���, 054��53���33���W); MCP 31177, 560 mm, Roque Gonzales, Rio Uruguai drainage, Rio Iju�� near small hydroelectric power station (PCH) Pirap�� (~ 28��30���S, 055��10���W); MCP 39375, 550 mm, same locality as MCP 31177; UFRGS 14457, 498 mm, (~27��11���S, 053��06���W). Brazil, Santa Catarina: MCP 19044, 440 mm, It��, Rio Uruguai, Rio do Engano, road between It�� and Seara (27��08���60���S, 52��13���00���W); MCP 20683, 410 mm, Itapiranga, Rio Uruguai, near Fortaleza (27��11���42���S, 053��38���34���W). Brazil, S��o Paulo: MZUSP 22246 (3), 130���282 mm, Represa do Boa, Corumbata��, Rio Paran�� drainage, Rio Tiet�� (~ 21��46���S, 048��58���W); MZUSP 22862, 238 mm, Corumbata��, Rio Paran�� drainage, Rio Tiet��, Lagoa Ponte Seca (~ 21��46���S, 048��58���W); MZUSP 46001, 998 mm, Rio Paran�� drainage, Porto Primavera (~ 22��31���S, 053��10���W). Diagnosis. Gymnotus inaequilabiatus differs from all sympatric members of the Gymnotus tigre clade (G. paraguensis) on the following characters: 1, more precaudal vertebrae (45 in all specimens vs. 32���35, median 34); 2, fewer ventral lateral-line rami (VLR 23���38, median 32 vs. 49���55, median 50). Gymnotus inaequilabiatus further differs from sympatric Gymnotus species on the following characters: 1, total length (max. 998 mm vs. max. 419 mm in G. c. australis and max. 305 mm in G. cuia the next two largest species); 2, a color pattern characterized by 21���29, mode 22 obliquely-oriented, chocolate-colored bands in juveniles (Description: Morphometric and meristic data in Table 1. Sexually monomorphic, including in breeding condition. Total length to 1 m. Morphological maturity at roughly 130 mm. Scales rounded to slightly ovoid on anterior two thirds of body, ovoid on posterior one third. Gape large in mature specimens, to or beyond posterior nares. Mouth superior with lower jaw longer than upper, rictus decurved. Chin especially fleshy and protuberant with fleshy pad of electrosensitive organs overlying tip of snout and oral jaws. Anterior narial pore partially to entirely included within gape in narial fold. Anterior nares large, subequal to eye diameter. Circumorbital series ovoid. Ethmoid region broad between anterior nares, with rounded anterior margin. Eye position lateral, lower margin of eye dorsal or horizontal to rictus. Premaxilla with 11 teeth disposed in single row along outer margin, arrow-head shaped anteriorly, conical posteriorly. Straight median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, narrow distally with a straight ventral margin, length equal to roughly width of 4���6 dentary teeth. Dentary with one row of 12���15 teeth, none arrow-head shaped anteriorly. Posterodorsal and posteroventral dentary processes abut at midlength. Dentary posteroventral process shorter than posterodorsal, narrow distally. Dentary ventral margin lamella narrow, depth less than posterior process. Opercle dorsal margin straight to slightly convex. Dorsal opercular process lamellar or rugose, crest absent or small, posterior margin entirely smooth, without spines or processes. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf large, more than one-half width of symplectic. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base shorter than length, curved, tip simple. Interopercle dorsal margin ascending process broad. Subopercle dorsal margin concave. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Anguloarticular process short, extending beyond ventral margin of dentary. Mandible long, extended, length greater than twice depth. Trigeminal nerve canals divided within the hyomandibula. Posterior lateral line fenestra not contacting posterodorsal margin of hyomandibula. Cranial fontanels closed in juveniles and adults. Frontal shape broad, width at fourth infraorbital greater than that of parietal, anterior margin of straight, continuous with margins of adjacent roofing bones, postorbital process broad, more than two times width of supraorbital canal. Lateral ethmoid absent. Parietal rectangular, length less than width. Parasphenoid anteroventral portion robust, extending ventral to lateral margin of parasphenoid, posterior processes narrow. Prootic foraminae separate for cranial nerves Vp and V2���3 +VII. Adductor mandibula muscle undivided at insertion, intermuscular bones absent. All basibranchials unossified. Gill rakers not contacting gill bar. Pectoral with 13���21 (mode 19) rays, medial radial large. Mesocoracoid elongate, length more than four times width. Cleithrum broad, ventral margin curved, anterior limb long, more than 1.8 times ascending limb, deeply incised on its anteroventral margin, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle shaped. Body cavity of long, with 45 precaudal vertebrae. Rib five robust along its entire extent, less than three times width of rib six. Hemal spines present. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Anal fin with 214���390 (median 370) rays. Lateral line ventral rami 23���38 (median 32). Caudal appendage short, less one-half length of pectoral fin. Single hypaxial electric organ along entire ventral margin of body. Four rows of electroplates near caudal insertion of anal fin. Color in Alcohol: Bands, spots and blotches irregular in shape, width and color, on specimens and among individuals. Ground color tan to yellow. In juveniles (250���400 mm), obliquely-oriented, chocolate-colored bands with wavy, irregular margins on lateral surface from nape and to tip of caudal appendage, occurring singly or as band-pairs, increasingly divided and irregular with size (21���29 mode 22). In adults, bands replaced by spots and blotches. Head never banded, spotted, or blotched, dark grey dorsally grading to lighter grey ventrally. Numerous chromophores speckled over branchiostegal membranes and ventral surface of head. Pectoral-fin rays brown, interradial membranes hyaline. Anal-fin membrane with irregular broken horizontal stripes on posterior 20%., Published as part of Craig, Jack M., Malabarba, Luiz R., Crampton, William G. R. & Albert, James S., 2018, Revision of Banded Knifefishes of the Gymnotus carapo and G. tigre clades (Gymnotidae Gymnotiformes) from the Southern Neotropics, pp. 47-73 in Zootaxa 4379 (1) on pages 67-69, DOI: 10.11646/zootaxa.4379.1.3, http://zenodo.org/record/1172318, {"references":["Valenciennes, A. (1847) Poissons. Catalogue des principales especes de poissons, rapportees de l'Amerique meridionale. In: D'Orbigny, A. (Ed.), Voyage dans l'Amerique meridionale. Chez Pitois-Levrault, Paris, pp. 1 - 11."]}

Gymnotus omarorum Richer-de-Forges, Crampton and Albert, 2009 Figure 12, Table 1 Material examined: Uruguay, Artigas: ZVC-P 16, 185 mm, Río Uruguay drainage, Río Cuareim, del Yucutuja, Rancho El Ombu (31°40’12”S, 057°10’12”W); ZVC-P 404 (2), 160–190 mm, Río Uruguay drainage, Río Cuareim, Picada Tareira (34°25’12”S, 056°25’12”W); ZVC-P 2273, 278 mm, Canal de Riego; ZVC-P 2906 (3), 95–205 mm, Río Uruguay drainage, Río Cuareim, Rancho Pereira Reverbell (30°11’24”S, 057°09’36”W); ZVC-P 3407b (3), 195–240 mm, Río Uruguay drainage, Catalán Chico, Rancho Martine; ZVC-P 3634, 286 mm, Salto, Río Uruguay drainage, Salto City. Uruguay, Florida: ZVC-P 105 (2), 100–170 mm, Río Uruguay drainage, Laguna en Cañada Invernada (31°00’36”S, 056°00’36”W); ZVC-P 303 (2), 173–215 mm, Río Uruguay drainage, Río Santa Lucia (34°26’24”S, 056°23’60”W); ZVC-P 3423, 146 mm, Río Uruguay drainage, Cañada Milano; ZVC-P 5502, 227 mm, Río Uruguay drainage, Río Santa Lucia, Cañada Casupa. Uruguay, Lavalleja: ZVC-P 950 (2), 123–158 mm, Rio Cebollatí, Laguna Merín, Rancho Sosa Diaz, Canada Mariscala (33°26’24”S, 054°23’60”W); ZVC-P 1917, 82 mm, Laguna Merín drainage, Villa Serrana, Cañada los Chanchos (34°19’12”S, 054°57’36”W). Uruguay, Maldonado: ZVC-P 6480 (holotype), 250 mm, Río Cisne drainage, Laguna del Sauce (34°50’20”S, 055°06’52”W); AMNH 239656 (16) (paratypes), 32–222 mm, same locality as ZVC-P 6480; MCP 41266 (3) (paratypes), 150–190 mm, same locality as ZVC-P 6480; ZVC-P 6481 (33) (paratypes), 23–201 mm, same locality as ZVC-P 6480. Uruguay, Rivera: ZVC-P 1351, 245 mm, Río Negro, Cañada Cuñapirú (31°11’60”S, 055°36’00”W). Uruguay, Treinta y Tres: ZVC-P 7429 (3), 227–269 mm, Laguna El Tigre. Uruguay, Tacuarembó: ZVC-P 7430, 222 mm, Laguna Lavalle. Diagnosis. Gymnotus omarorum differs from all sympatric members of the G. carapo clade on the following characters: 1, few anal-fin pterygiophore scales (APS 2–6, mode 6 vs. 6–13, mode 8); 2, few pored lateral-line scales anterior to the first ventral lateral-line ramus (PLR 23–30, median 27 vs. 30–50, median 38); 3, many ventral lateral-line rami (VLR 28–30, median 29 vs. 13–28, median 22). Description: Morphometric and meristic data in Table 1. Sexually monomorphic, including in breeding condition. Total length to 262 mm. Morphological maturity at roughly 110 mm. Scales rounded to slightly ovoid, present on entire postcranial portion of body. Gape large in mature specimens, to or beyond posterior nares. Mouth superior with lower jaw longer than upper, rictus decurved. Chin fleshy and protuberant with fleshy pad of electrosensitive organs overlying tip of snout and oral jaws. Anterior narial pore partially to entirely included within gape in narial fold. Anterior nares large, subequal to eye diameter. Circumorbital series ovoid. Ethmoid region broad between anterior nares, with rounded anterior margin. Eye position lateral, lower margin of eye dorsal or horizontal to rictus. Premaxilla with 13 teeth disposed in single row along outer margin, arrow-head shaped anteriorly, conical posteriorly. Curved median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, narrow distally with a straight ventral margin, length equal to roughly width of 4–6 dentary teeth. Dentary with one row of 20 teeth, 3 arrow-head shaped anteriorly, all others conical posteriorly. Posterodorsal and posteroventral dentary processes abut at midlength. Dentary posteroventral process shorter than posterodorsal, narrow distally. Dentary ventral margin lamella narrow, depth less than posterior process. Opercle dorsal margin straight to slightly convex. Dorsal opercular process lamellar or rugose, crest absent or small, posterior margin entirely smooth, without spines or processes. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf large, more than one-half width of symplectic. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base shorter than length, curved, tip simple. Interopercle dorsal margin ascending process broad. Subopercle dorsal margin concave. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Anguloarticular process long, extending beyond ventral margin of dentary. Mandible short, compressed, length less than twice depth. Trigeminal nerve canals divided within the hyomandibula. Posterior lateral line fenestra contacting posterodorsal margin of hyomandibula. Cranial fontanels closed in juveniles and adults. Frontal shape narrow, width at fourth infraorbital less than that of parietal, anterior margin of straight, continuous with margins of adjacent roofing bones, postorbital process broad, more than two times width of supraorbital canal. Lateral ethmoid absent. Parietal rectangular, length less than width. Parasphenoid anteroventral portion gracile, extending ventral to lateral margin of parasphenoid, posterior processes narrow. Prootic foraminae separate for cranial nerves Vp and V2–3 +VII. Adductor mandibula muscle undivided at insertion, intermuscular bones absent. All basibranchials unossified. Gill rakers not contacting gill bar. Pectoral with 13–14 (mode 13) rays, medial radial large. Mesocoracoid elongate, length more than four times width. Cleithrum broad, ventral margin curved, anterior limb long, more than 1.8 times ascending limb, deeply incised on its anteroventral margin, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle shaped. Body cavity of moderate length, with 34 precaudal vertebrae. Rib five robust along its entire extent, less than three times width of rib six. Hemal spines present. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Anal fin with 130–184 (median 166) rays. Lateral line ventral rami 28–30 (median 29). Caudal appendage short, less one-half length of pectoral fin. Single hypaxial electric organ along entire ventral margin of body. Three rows of electroplates near caudal insertion of anal fin. Color in Alcohol: Bands irregular in shape, width and color, on specimens and among individuals. Ground color light grey or tan ventrally grading to darker grey or brown dorsally in adults. As in G. cuia, many obliquelyoriented, chocolate-colored bands with wavy, irregular margins on lateral surface from nape and to tip of caudal appendage, occurring singly or as band-pairs, increasingly divided and irregular with size and broken into spots anterodorsally in large specimens (24–29 mode 29). Pale interbands less than one-third width of dark bands at midbody. Bands rarely divided dorsally or ventrally to form X - or inverted Y -shaped patterns. Band-interband contrast increases ventrally and caudally, fades with growth (juveniles> 150 mm with distinct margins, specimens 200–300 mm more faintly banded). Head never banded, spotted, or blotched, dark grey dorsally grading to lighter grey ventrally. Numerous chromophores speckled over branchiostegal membranes and ventral surface of head. Pectoralfin rays brown, interradial membranes hyaline. Pectoral-fin rays brown, interradial membranes hyaline. Anterior 80% of anal fin membrane dark brown, gray or black, posterior 20% translucent.

Gymnotus sylvius Albert, de Campos Fernandes-Matioli and de Almeida-Toledo, 1999 Figure 14, Table 1 Material examined: Brazil, Paran��: MCP 47810, 81 mm, Cascavel, Igua��u drainage, Rio do Oeste, between Rio do Salto and Castelo Branco (25��09���19���S, 053��19���41���W). Brazil, S��o Paulo: LGP88 (P2336), 180 mm, Jacare��, Rio Para��ba do Sul; LGP 93, 160 mm, same locality as LGP88; LGP94 (P2333), 230 mm, same locality as LGP88; LGP95 (P2352), 130 mm, same locality as LGP88; LGP 0 925.1 (holotype), 259 mm, Rio Ribeira de Iguape, near Miracatu (24��32���50���S, 047��26���13���W); LGP 0 925.2 (2) (paratypes), 251���307 mm, same locality as LGP 0925.1; LGP 0 931 (paratype), 157 mm, Rio Pardo drainage, S��o Sim��o, Rio Tamandu�� (21��30���00���S, 047��31���11���W); UMMZ 234347 (2) (paratypes), 255���271 mm, same locality as LGP 0931; LGP96 (P2338), 170 mm, same locality as LGP88; LGP91 (P2353), 170 mm, Paraibuna, Rio Para��ba do Sul; LGP 92, 280 mm, Paraibuna, Rio Para��ba do Sul; LGP98 (P2330), 160 mm, same locality as LGP92; UFRGS 14743 (4), 87���168 mm, Pindamonhangaba, downstream of the Bosque da Princesa, near Chacrinha (22��55���05���S, 045��27���45���W). Diagnosis. Gymnotus sylvius differs from all other Gymnotus on its color pattern, characterized by 25���28, mode 25 chocolate-colored bands with wavy, irregular margins and pale interbands wider than dark bands. Description: Morphometric and meristic data in Table 1. Sexually monomorphic, including in breeding condition. Total length to 291 mm. Morphological maturity at roughly 110 mm. Scales rounded to slightly ovoid, present on entire postcranial portion of body. Gape large in mature specimens, to or beyond posterior nares. Mouth superior with lower jaw longer than upper, rictus decurved. Chin fleshy and protuberant with fleshy pad of electrosensitive organs overlying tip of snout and oral jaws. Anterior narial pore partially to entirely included within gape in narial fold. Anterior nares large, subequal to eye diameter. Circumorbital series ovoid. Ethmoid region broad between anterior nares, with rounded anterior margin. Eye position lateral, lower margin of eye dorsal or horizontal to rictus. Premaxilla with 16 teeth disposed in single row along outer margin, arrow-head shaped anteriorly, conical posteriorly. Curved median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, narrow distally with a straight ventral margin, length equal to roughly width of 4���6 dentary teeth. Dentary with one row of 28���30 (median 29) teeth, 5���6 arrow-head shaped anteriorly, all others conical posteriorly. Posterodorsal and posteroventral dentary processes abut at midlength. Dentary posteroventral process shorter than posterodorsal, narrow distally. Dentary ventral margin lamella narrow, depth less than posterior process. Opercle dorsal margin straight to slightly convex. Dorsal opercular process lamellar or rugose, crest absent or small, posterior margin entirely smooth, without spines or processes. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf large, more than one-half width of symplectic. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base shorter than length, curved, tip simple. Interopercle dorsal margin ascending process broad. Subopercle dorsal margin concave. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Anguloarticular process long, extending beyond ventral margin of dentary. Mandible short, compressed, length greater than twice depth. Trigeminal nerve canals divided within the hyomandibula. Posterior lateral line fenestra contacting posterodorsal margin of hyomandibula. Cranial fontanels closed in juveniles and adults. Frontal shape narrow, width at fourth infraorbital less than that of parietal, anterior margin of straight, continuous with margins of adjacent roofing bones, postorbital process broad, more than two times width of supraorbital canal. Lateral ethmoid absent. Parietal rectangular, length less than width. Parasphenoid anteroventral portion gracile, extending ventral to lateral margin of parasphenoid, posterior processes narrow. Prootic foraminae separate for cranial nerves Vp and V2���3 +VII. Adductor mandibula muscle undivided at insertion, intermuscular bones absent. All basibranchials unossified. Gill rakers not contacting gill bar. Pectoral with 15���16 (mode 16) rays, medial radial large. Mesocoracoid elongate, length more than four times width. Cleithrum broad, ventral margin curved, anterior limb long, more than 1.8 times ascending limb, deeply incised on its anteroventral margin, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle shaped. Body cavity of moderate length, with 32���35 precaudal vertebrae. Rib five robust along its entire extent, less than three times width of rib six. Hemal spines present. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Anal fin with 165���189 (median 175) rays. Lateral line ventral rami 19���25 (median 22). Caudal appendage short, less one-half length of pectoral fin. Single hypaxial electric organ along entire ventral margin of body. Rows of electroplates 3���4 (mode 3) near caudal insertion of anal fin. Color in Alcohol: Bands irregular in shape, width and color, on specimens and among individuals. Ground color tan ventrally grading to darker brown dorsally in adults, pale yellow throughout in smaller specimens. As in G. c. australis, obliquely-oriented, chocolate-colored bands with wavy, irregular margins on lateral surface from nape and to tip of caudal appendage, occurring singly or as band-pairs, increasingly divided and irregular with size (25���28 mode 25). Uniquely, pale interbands wider than dark bands. Bands often divided dorsally or ventrally to form X - or inverted Y -shaped patterns. Band-interband contrast increases ventrally and caudally, fades with growth (juveniles> 150 mm with distinct margins, specimens 200��� 200 mm faintly banded, and some specimens over 250 mm unbanded except very faintly in posterior one-third of body). Head never banded, spotted, or blotched, dark brown grading to lighter brown dorsally to ventrally. Numerous chromophores speckled over branchiostegal membranes and ventral surface of head. Pectoral-fin rays brown, interradial membranes hyaline. Anterior 80% of anal fin membrane dark brown, gray or black, posterior 20% translucent. ......continued on the next page, Published as part of Craig, Jack M., Malabarba, Luiz R., Crampton, William G. R. & Albert, James S., 2018, Revision of Banded Knifefishes of the Gymnotus carapo and G. tigre clades (Gymnotidae Gymnotiformes) from the Southern Neotropics, pp. 47-73 in Zootaxa 4379 (1) on pages 65-66, DOI: 10.11646/zootaxa.4379.1.3, http://zenodo.org/record/1172318

Gymnotus paraguensis Albert and Crampton, 2003:34 Figure 16, Table 2 Material examined: Brazil: FMNH 108546, 164 mm, Mato Grosso do Sul, Aquiduana, Brejo do Santa Sofia, Rio Novo (19��35���89���S, 056��20���47���W); MCP 13415, Santa Catarina, Rio Uruguai drainage, Rio Uruguai / It�� (27��17���60���S, 052��19���60���W). Paraguay: NRM 42380, 240 mm, Canindey��, Saltos da Guaira, Mulle Ytaip��, R��o Paran�� drainage (24��03���44���S, 054��18���W); NRM 42397, 171 mm, Central Province, R��o Paraguay drainage, swamp close to Lago Ypacarai; MNHNP 4169, Department of Paraguay, Itapua, Capitan Meza R��o de La Plata drainage, R��o Paran��, Capitan Meza, Club de Caza y Pesca de Capitan Meza (26��57���44���S, 055��10���57���W); UMMZ 206155 (holotype), 222 mm, Department of Paraguay, Itapua, R��o Paran�� drainage, Arroyo Tembey, 7.4 km SW of San Rafael de Paran�� (26��35���S, 055��34���W); UMMZ 240700 (paratype), 193 mm, same locality as UMMZ 206155. Uruguay: ANSP uncat., R��o Negro, Nuevo Berl��n, R��o de La Plata drainage, R��o Uruguay, along shore near municipal pier (32��58���46���S, 058��3���48���W). Diagnosis. Gymnotus paraguensis differs from all sympatric members of the Gymnotus tigre clade (G. inaequilabiatus) on the following characters: 1, more precaudal vertebrae (PCV 32���35, median 34 vs. 45 in all specimens of G. inaequilabiatus); 2, more ventral lateral-line rami (VLR 49055, median 50 vs. 23���38, median 32). Description: Morphometric and meristic data in Table 1. Sexually monomorphic, including in breeding condition. Total length to 240 mm. Morphological maturity at roughly 110 mm. Scales rounded to slightly ovoid on anterior two thirds of body, ovoid on posterior one third. Gape large in mature specimens, to or beyond posterior nares. Mouth superior with lower jaw longer than upper, rictus decurved. Chin especially fleshy and protuberant with fleshy pad of electrosensitive organs overlying tip of snout and oral jaws. Anterior narial pore partially to entirely included within gape in narial fold. Anterior nares large, subequal to eye diameter. Circumorbital series ovoid. Ethmoid region broad between anterior nares, with rounded anterior margin. Eye position lateral, lower margin of eye dorsal or horizontal to rictus. Premaxilla with 12���13 teeth disposed in single row along outer margin, arrow-head shaped anteriorly, conical posteriorly. Straight median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, narrow distally with a straight ventral margin, length equal to roughly width of 4���6 dentary teeth. Dentary with one row of 16���18 (median 17) teeth, none arrow-head shaped anteriorly. Posterodorsal and posteroventral dentary processes abut at midlength. Dentary posteroventral process shorter than posterodorsal, narrow distally. Dentary ventral margin lamella narrow, depth less than posterior process. Opercle dorsal margin straight to slightly convex. Dorsal opercular process lamellar or rugose, crest absent or small, posterior margin entirely smooth, without spines or processes. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf large, more than one-half width of symplectic. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base shorter than length, curved, tip simple. Interopercle dorsal margin ascending process broad. Subopercle dorsal margin concave. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Anguloarticular process short, extending beyond ventral margin of dentary. Mandible long, extended, length greater than twice depth. Trigeminal nerve canals divided within the hyomandibula. Posterior lateral line fenestra not contacting posterodorsal margin of hyomandibula. Cranial fontanels closed in juveniles and adults. Frontal shape broad, width at fourth infraorbital greater than that of parietal, anterior margin of straight, continuous with margins of adjacent roofing bones, postorbital process broad, more than two times width of supraorbital canal. Lateral ethmoid absent. Parietal rectangular, length less than width. Parasphenoid anteroventral portion robust, extending ventral to lateral margin of parasphenoid, posterior processes narrow. Prootic foraminae separate for cranial nerves Vp and V2���3 +VII. Adductor mandibula muscle undivided at insertion, intermuscular bones absent. All basibranchials unossified. Gill rakers not contacting gill bar. Pectoral with 17���21 (mode 19) rays, medial radial large. Mesocoracoid elongate, length more than four times width. Cleithrum broad, ventral margin curved, anterior limb long, more than 1.8 times ascending limb, deeply incised on its anteroventral margin, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle shaped. Body cavity of long, with 32���35 (mode 34) precaudal vertebrae. Rib five robust along its entire extent, less than three times width of rib six. Hemal spines present. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Anal fin with 214���390 (median 370) rays. Lateral line ventral rami 49���55 (median 50). Caudal appendage short, less one-half length of pectoral fin. Single hypaxial electric organ along entire ventral margin of body. Four rows of electroplates near caudal insertion of anal fin. Color in Alcohol: Bands irregular in shape, width and color, on specimens and among individuals. Ground color tan to yellow. Obliquely-oriented, evenly-pigmented, chocolate-colored bands sharp margins on lateral surface from nape and to tip of caudal appendage (23���26 mode 24). Uniquely, three dark bands from either side meet at ventral midline between anus and anal-fin origin. Pale interband contrast similar along entire body axis. Head never banded, spotted, or blotched, dark grey dorsally grading to lighter grey ventrally. Numerous chromophores speckled over branchiostegal membranes and ventral surface of head. Pectoral-fin rays brown, interradial membranes hyaline. Anterior 40% of anal-fin brown, mid 40% black, posterior 20% translucent., Published as part of Craig, Jack M., Malabarba, Luiz R., Crampton, William G. R. & Albert, James S., 2018, Revision of Banded Knifefishes of the Gymnotus carapo and G. tigre clades (Gymnotidae Gymnotiformes) from the Southern Neotropics, pp. 47-73 in Zootaxa 4379 (1) on pages 70-72, DOI: 10.11646/zootaxa.4379.1.3, http://zenodo.org/record/1172318

Banded Knifefishes (Gymnotus, Gymnotidae) comprise the most species-rich, ecologically tolerant (eurytopic), and geographically widespread genus of Neotropical electric fishes (Gymnotiformes), with 40 valid species occupying most habitats and regions throughout the humid Neotropics. Despite substantial alpha-taxonomic work in recent years, parts of the genus remain characterized by taxonomic confusion. Here we describe and delimit species of the G. carapo and G. tigre clades from the southern Neotropics, using body proportions (caliper-based morphometrics), fin-ray, scale and laterosensory-pore counts (meristics), quantitative shape differences (geometric morphometrics), osteology, color patterns and electric organ discharges. We report these data from 174 Gymnotus specimens collected from 100 localities throughout the southern Neotropics, and delimit species boundaries in a multivariate statistical framework. We find six species of the G. carapo clade (G. carapo australis, G. cuia n. sp., G. chimarrao, G. omarorum, G. pantanal, and G. sylvius), and two species of the G. tigre clade (G. inaequilabiatus and G. paraguensis) in the southern Neotropics. The new species G. cuia is readily distinguished from the morphologically similar and broadly sympatric G. c. australis by a shorter head and deeper head and body, and from the morphologically similar and sympatric G. omarorum by fewer lateral-line ventral rami and fewer pored lateral-line scales anterior to the first ventral ramus. We also review the geographic distributions of all eight species of the G. carapo and G. tigre clades in the southern Neotropics, showing that G. cuia is the most widespread species in the region. These results affirm the importance of understanding the structure of variation within and between species, both geographic and ontogenetic, in delimiting species boundaries.

Gymnotus cuia n. sp. Figure 7, Table 1 Synonyms: G. aff. carapo —(Bertaco et al. 2016; Cognato et al. 2007a; b; Cognato & Fialho 2006; Malabarba et al. 2013; Serra et al. 2014). Holotype: UFRGS 23700, 193 mm, Brazil, Rio Grande do Sul, Viamão, Lagoa Verde, Itapuã State Park, Rio Grande, do Sul (30°22’52”S, 051°01’25”W). Paratypes: UFRGS 6854 (5), 104–169 mm, same locality as UFRGS 23700; UFRGS 6855 (3), 164–279 mm, same locality as UFRGS 23700; UFRGS 6857 (4), 152–236 mm, same locality as UFRGS 23700; UFRGS 6858 (2), 168–223 mm, same locality as UFRGS 23700; UFRGS 6859, 266 mm, same locality as UFRGS 23700; UFRGS 8655, 130 mm, same locality as UFRGS 23700; UFRGS 9103 (2), 216–237 mm, same locality as UFRGS 23700; UFRGS 9104, 153 mm, same locality as UFRGS 23700; UFRGS 9105 (2), 125–131 mm, same locality as UFRGS 23700; UFRGS 9106 (2), 152–187 mm, same locality as UFRGS 23700; UFRGS 9115, 166 mm, same locality as UFRGS 23700; UFRGS 9790 (4), 188–261 mm, same locality as UFRGS 23700; UFRGS 9794 (4), 171–217 mm, same locality as UFRGS 23700. Non-Types (Type locality was restricted to Lagoa Verde, Viamão, Itapuã State Park, Rio Grande, do Sul, Brazil): Argentina: MLP 110805 (3), 183–221 mm, Corrientes, Río Paraná (~ 27°27’28.41”S, 058°47’54.13”W); UF 125973 (4), 197–238 mm, Formosa, Río Bermejo drainage, ponds near Río Bermejo (~ 26°13’39”S, 058°09’60”W). Brazil, Mato Grosso do Sul: MZUSP 59316, 198 mm, Corumbá, Rio Vermelho drainage. Brazil, Rio Grande do Sul: MCP 19550 (2), 185–270 mm, São Gabriel, bridge over Banhado do Inhatium (30°15’43”S, 054°31’33”W); MCP 19999 (2), 265–305 mm, Sapiranga, Arroio Feitoria (29°34’00”S, 051°00’00”W); MCP 41952 (4), 140–205 mm, Rio Cacequi drainage, stream alongside RS640 to Cacequi (29°55’23”S, 054°49’52”W); MCP 42587, 208 mm, Viamão, Lagoa Negra, Itapuã State Park (30°21’35”S, 050°58’34”W); UFRGS 10066, Porto Alegre (30°07’32.57”S, 051°11’22.21”W); UFRGS 16370, 206 mm, Viamão, Area de Preservação Ambiental Banhado dos Pachecos (30°07’44.63”S, 050°50’17.67”W); UFRGS 5618 (2), 261–264 mm, Viamão, Lagoa Negra, Itapuã State Park (30°21’35”S, 050°58’34”W); UFRGS 5738, 162 mm, Santa Rosa, Lageado do Pessegueiro; UFRGS 6536, 208 mm, same locality as UFRGS 5618; UFRGS 6537, 233 mm, same locality as UFRGS 5618; UFRGS 6538, 195 mm, same locality as UFRGS 5618; UFRGS 6539, 195 mm, same locality as UFRGS 5618; UFRGS 6540, 130 mm, same locality as UFRGS 5618; UFRGS 6541, 140 mm, Sanga do Jacaré, 82 km from Alegrete (30° 12’42”S, 055°03’17”W); UFRGS 6544 (c&s), same locality as UFRGS 6541; UFRGS 6542, 152 mm, same locality as UFRGS 6541; UFRGS 6543, 198 mm, same locality as UFRGS 6541; UFRGS 6548, 241 mm, Terra de Areia, Rio Três Forquilhas (29°33’22”S, 050°04’19”W); UFRGS 6549, 203 mm, same locality as UFRGS 6548; UFRGS 6550, 116 mm, Eldorado do Sul, Arroio Passo dos Carros (30°05’54”S, 051°23’18”W); UFRGS 6551, 115 mm, same locality as UFRGS 6550; UFRGS 6553, 172 mm, Eldorado do Sul, Arroio Passo dos Carros (30°02’55”S, 051°23’34”W); UFRGS 6554, 135 mm, same locality as UFRGS 6553; UFRGS 6555, 128 mm, same locality as UFRGS 6550; UFRGS 6556, 166 mm, São Gabriel, Rio Uruguai drainage, Arroio Piraí (30°18’56”S, 054°24’22”W); UFRGS 6557, 143 mm, same locality as UFRGS 6556; UFRGS 6558, 191 mm, same locality as UFRGS 6556; UFRGS 6559, (c&s), same locality as UFRGS 6556; UFRGS 6560, 145 mm, same locality as UFRGS 6556; UFRGS 6561, 197 mm, same locality as UFRGS 6556; UFRGS 6573, 217 mm, Terra de Areia, streams in the Reserva Biológica da Mata Paludosa (29°30’41”S, 050°06’27”W); UFRGS 6581, Agudo, Arroio Corupá along the road from Agudo to UHE Dona Francisca (29°33’54”S, 053°17’09”W); UFRGS 6587 (2), 159–170 mm, same locality as UFRGS 6581; UFRGS 6589, 268 mm, same locality as UFRGS 6587; UFRGS 8265 (2), 212–245 mm, Charqueadas (29°57’31”S, 051°33’10”W). Brazil, São Paulo: MZUSP 79348, 222 mm, Reservatório de Barra Bonita, Rio Tietê (22° 31’56”S, 048°31’05”W); MZUSP 83409, 195 mm, Bariri, Rio Tietê a near UHE Bariri road; MZUSP 83421 (2), 20–181 mm, Rio Tietê drainage, Bariri, Queixada stream (22°08’00”S, 048°44’33”W); MZUSP 83427 (5), 90.6–146 mm, Rio Tietê drainage, Bariri, Catingueiro stream (22°07’00”S, 048°45’05”W). Paraguay: MNHNP 189, PTE Hayes, General Bruguez, lake on the premises of the General José M. Brugues military base (24°44’33”S, 058°50’10”W); MNHNP 1064, Alto Paraná, Río Aray, dry stream below the dam; MNHNP 1070 (3), PTE Hayes, "La Golondrina" Hotel, small puddle (~24°31’00”S, 058°40”10”W); MNHNP 1620, Cordillera, Piribebuy, Saltos de Pirareta, 500 m below the falls (25°30’24”S, 056°55’32”W); MNHNP 1734 (2); MNHNP 3389 (2), Alto Paraguay, Tajamar, Madrejon, 50 m from the administration building (20°37’34”S, 059°52’47”W). Uruguay: UFRGS 7990 (2), 144– 206 mm, Artigas, Río Uruguay, Arroyo Guaviyú (30°37’51”S, 057°41’18”W). Diagnosis. Gymnotus cuia is most similar to the sympatric G. c. australis, from which it differs on the following characters: 1, a shorter head (HL 9.8%–12.2% TL, mean 10.9% TL, vs. 11.7%–14.0% TL, mean 12.9% TL); 2, a deeper body (BD 85.4%–133.3% HL, mean 110.6% HL vs. 67.0%–98.8% HL, mean 87.9% HL); 3, a deeper head (HD 61.9%–80.2% HL, mean 68.5% HL vs. 51.2%–64.6% HL, mean 59.7% HL) (Figure 8). Gymnotus cuia is also morphologically similar to the sympatric G. omarorum, from which it differs on by the following characters: 1, more anal-fin pterygiophore scales (APS 6–10, mode 8 vs. 5–6, mode 6); 2, more pored lateral-line scales anterior to the first ventral lateral-line ramus (PLR 32–47, mode 37 vs. 23–30, mode 27); 3, fewer ventral lateral-line rami (VLR 14–28, mode 22 vs. 28–30, mode 29). Gymnotus cuia further differs from all other members of the G. carapo clade in possessing a color patter comprised of 21–29 (mode 28) obliquelyoriented, chocolate-colored bands with wavy, irregular margins and pale interbands less than one-third width of dark bands at mid-body vs. bands interrupted into patches anterodorsally, with silver, blue or green metallic countershading on dorsum of adults of G. arapaima, dark bands lost in large adults (> 250 mm) of G. ardilai, small, rounded dark spots over entire body except posterior 20% of some specimens of G. bahianus, bands faint or absent in all specimens of G. chimarrao, one to three inverted Y -shaped dark bands posteriorly and pale bands not reaching above lateral line in anterior two thirds of body of G. choco, bands broken into speckles throughout in G. diamantinensis, narrow pale bands (G. mamiraua, bands faint or absent from 80% of dorsum in all specimens, and narrow pale bands (G. pantanal, pale bands wider than dark bands in G. sylvius, narrow pale interbands (G. ucamara. Gymnotus cuia further differs from all members of the G. varzea clade (G. chaviro, G. curupira G. mamiraua, G. obscurus, and G. varzea) the following characters: 1, relatively more arrowhead-shaped dentary teeth (6 vs. 2–4 in the G. varzea clade except in G. chaviro, G. curupira and G. mamiraua,, with 4–7); 2, anterior 80% of anal fin membrane pigmented, posterior 20% translucent (vs. wholly clear or evenly pigmented in the G. varzea clade); 3, large adult total length (305 mm TL vs. 215 mm – 275 mm TL in the G. varzea clade). Description: Morphometric and meristic data in Table 1. Sexually monomorphic, including in breeding condition. Total length to 305 mm. Morphological maturity at roughly 110 mm. Scales rounded to slightly ovoid, present on entire postcranial portion of body. Gape large in mature specimens, to or beyond posterior nares. Mouth superior with lower jaw longer than upper, rictus decurved. Chin fleshy and protuberant with fleshy pad of electrosensitive organs overlying tip of snout and oral jaws. Anterior narial pore partially to entirely included within gape in narial fold. Anterior nares large, subequal to eye diameter. Circumorbital series ovoid. Ethmoid region broad between anterior nares, with rounded anterior margin. Eye position lateral, lower margin of eye dorsal or horizontal to rictus. Premaxilla with 13–14 (mode 13) teeth disposed in single row along outer margin, arrowhead shaped anteriorly, conical posteriorly. Curved median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, narrow distally with a straight ventral margin, length equal to roughly width of four–six dentary teeth. Dentary with one row of 26–27 (mode 26) teeth, 6 arrow-head shaped anteriorly, all others conical posteriorly. Posterodorsal and posteroventral dentary processes abut at midlength. Dentary posteroventral process shorter than posterodorsal, narrow distally. Dentary ventral margin lamella narrow, depth less than posterior process. Opercle dorsal margin straight to slightly convex. Dorsal opercular process lamellar or rugose, crest absent or small, posterior margin entirely smooth, without spines or processes. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf large, more than one-half width of symplectic. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base shorter than length, curved, tip simple. Interopercle dorsal margin ascending process broad. Subopercle dorsal margin concave. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Anguloarticular process long, extending beyond ventral margin of dentary. Mandible short, extended, length less than twice depth. Trigeminal nerve canals divided within the hyomandibula. Posterior lateral line fenestra contacting posterodorsal margin of hyomandibula. Cranial fontanels closed in juveniles and adults. Frontal shape narrow, width at fourth infraorbital less than that of parietal, anterior margin of straight, continuous with margins of adjacent roofing bones, postorbital process broad, more than two times width of supraorbital canal. Lateral ethmoid absent. Parietal rectangular, length less than width. Parasphenoid anteroventral portion gracile, extending ventral to lateral margin of parasphenoid, posterior processes narrow. Prootic foraminae separate for cranial nerves Vp and V2–3 +VII. Adductor mandibula muscle undivided at insertion, intermuscular bones absent. All basibranchials unossified. Gill rakers not contacting gill bar. Pectoral with 11–16 (mode 14) rays, medial radial large. Mesocoracoid elongate, length more than four times width. Cleithrum broad, ventral margin curved, anterior limb long, more than 1.8 times ascending limb, deeply incised on its anteroventral margin, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle shaped. Body cavity of moderate length, with 31–34 (mode 33) precaudal vertebrae. Rib five robust along its entire extent, less than three times width of rib six. Hemal spines present. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Anal fin with 141–259 (median 192) rays. Lateral line ventral rami 14–28 (median 22). Caudal appendage short, less one-half length of pectoral fin. Single hypaxial electric organ along entire ventral margin of body. Three rows of electroplates near caudal insertion of anal fin. Color in Alcohol: Bands irregular in shape, width and color, on specimens and among individuals. Ground color tan ventrally grading to darker brown or olive green dorsally in adults, pale yellow throughout in smaller specimens. Many obliquely-oriented, chocolate-colored bands with wavy, irregular margins on lateral surface from nape and to tip of caudal appendage, occurring singly or as band-pairs, increasingly divided and irregular with size (21–29 mode 28). Pale interbands less than one-third width of dark bands at mid-body. Bands rarely divided dorsally or ventrally to form X- or inverted Y -shaped patterns. Band-interband contrast increases ventrally and caudally, fades with growth (juveniles> 150 mm with distinct margins, specimens 200–300 mm more faintly banded). Head never banded, spotted, or blotched, dark brown grading to lighter brown dorsally to ventrally. Numerous chromophores speckled over branchiostegal membranes and ventral surface of head. Pectoral-fin rays brown, interradial membranes hyaline. Anterior 80% of anal fin membrane dark brown, gray or black, posterior 20% translucent. Etymology: The specific epithet is derived from the species’ especially deep body and head, evoking the short, rounded cuia gourd used to drink the traditional mate popular throughout its range. The convention of honoring this practice in gymnotiform taxonomy is shared with G. chimarrao (chimarrão =the mate itself) and Brachyhypopomus bombilla (bombilla =the metal straw used for drinking mate). The common name “ bombilla ” is often used to describe gymnotiform fish throughout the southern Neotropics as well. Ecology: Gymnotus cuia inhabits lakes and small streams, associated to densely vegetated areas. The species is abundant in the type locality (Figure 9), a shallow lake (less than 1 m deep) with dense emergent vegetation, including Ludwigia peploides (Onagraceae), Utricularia spp. (Lenticulariaceae), Nymphoides indica (Menyanthaceae), Pontederia lanceolata (Pontederiaceae), Azolla sp. (Azollaceae), Eleocharis sp. (Cyperaceae), Cabomba australis (Cabombaceae), Echinodorus sp. (Alismataceae), Lemna valdiviana (Lemnaceae), Scirpus sp. (Sciperaceae) and abundant grass in the shores (Cognato & Fialho 2006). Throughout its distribution it is usually abundant in the roots of dense beds of floating water hyacinths (Eichornia crassipes). Reproductive cycle extends from November to March (Cognato & Fialho 2006). Electric Organ Discharge: The EOD waveforms of G. cuia were previously described by Crampton et al. (2013) as “ Gymnotus n. sp. ITU”. The head-to-tail EOD waveform sensu Waddell et al. (2016) of G. cuia is tetraphasic with a dominant P1-P2 phase flanked by a lower voltage negative P0 phase and very low and variably present positive P3 phase (Figure 10). A positive P-1 phase preceding P0 is invariably absent. This EOD waveform conforms to the ht-EOD category 2 of Crampton et al. (2013). The (red) waveforms in Figure 10 refer to specimens of G. cuia collected from the Lagoa dos Patos and Rio Uruguai drainages of Rio Grande do Sul, Brazil. The peak power frequency of the EODs for G. cuia depicted in Figure 10 range from 0.832–1.484 kHz, mean 1.029, standard deviation 0.135 kHz (n=23 recorded specimens). We reported resting pulse rates (1 minute averages) for G. cuia in the range 31–52 Hz, mean 44 Hz (n= 15 specimens). In Rio Uruguai drainages of Rio Grande do Sul G. cuia (red EODs in Figure 10, UFRGS 6556-6561) occurs in sympatry and syntopy with G. carapo australis (black EODs in Figure 10, UFRGS 6763). This species was reported in Crampton et al. (2013), Figure 2, as “ G. sylvius ”. The pentaphasic EOD waveform of G. carapo australis conforms to the ht-EOD category “3” of Crampton et al. (2013) and is readily distinguishable by the invariable presence of both a P-1 and P3 phase. The EOD of G. carapo australis is also shorter, throughout all phases, than that of G. cuia, with a consequent higher peak power frequency, which ranges from 1.289–1.676 kHz, mean 1.476, standard deviation 0.19 (n=3 recorded specimens). We reported resting pulse rates (1 minute averages) for G. carapo australis in the range 46–51 Hz, mean 49 Hz, n = 3 specimens).

Gymnotus carapo septentrionalis New Subspecies Figure 3 G, Tables 3 and 4 Holotype: UF 80734, 220 mm, Venezuela, Apure, R��o Apure, E. dike in UNELLEZ module (09��55���7.26���N, 068��17���56.82���W). Paratypes: UF 80734 (46), 165���262 mm, Venezuela, Apure, R��o Apure, E. dike in UNELLEZ module (09��55���7.26���N, 068��17���56.82���W). Non-Types: NRM 27717 (1), 235 mm, Colombia, Meta, R��o Meta, R��o Ocoa, Laguna Santa Clara, ca. 5 km S Villavicencio (04��09���N, 073��39���W). UF 26178 (39), 134���239 mm, Colombia, Meta, R��o Guatiquia-Meta, Ca��os Negros, ca. 9 km Villavicencio on road to Puerto Porfia (04��09���N, 073��39���W). UF 33245 (1), 200 mm, Colombia, Meta, R��o Meta, R��o Guamal, 7 km E. R��o Guayuriba, just N. Guamal (03��52���N, 073��45���W). UF 35402 (3), 148��� 178 mm, Venezuela, Guarico, R��o Apure, ca. 50 km N San Fernando de Apure (07��54���N, 067��28���W). UF 37030 (20), 101���176 mm, Venezuela, Apure, R��o Apure, R��o Guaritico, Hato El Fr��o (09��03���N, 068��20���W). UF 77334 (1), 173 mm, Venezuela Apure, R��o Apure, Cano Caicara, ca. 30 km SW La Ye (07��40���N, 072��22���W). UF 78069 (3), 151���190 mm, Venezuela, Apure, R��o Apure, 2. 3 km N San Fernando de Apure (07��54���N, 067��28���W). UMMZ 169080 (5), 46���71 mm, Trinidad & Tobago, Mayaro, Gunupia, Mt. Plaisance Village (10��16���N, 061��00���W). Description: Specimens of G. carapo from the R��o Orinoco Basin in the northern Neotropics overlap substantially in morphometric and meristic PC-space with specimens from other localities (Figures 4, 5, and 12). Gymnotus carapo septentrionalis is characterized by the following combination of statistically significant (p Distribution: Known from the Orinoco basin of Colombia and Venezuela, and the island of Trinidad (Figure 2 B). Etymology: Subspecific epithet derived from the Latin word ��� septentrionalis ���, meaning ���of the North���., Published as part of Albert, James S., 2017, Revision of the polytypic electric fish Gymnotus carapo (Gymnotiformes, Teleostei), with descriptions of seven subspecies, pp. 401-438 in Zootaxa 4318 (3) on page 432, DOI: 10.11646/zootaxa.4318.3.1, http://zenodo.org/record/887692

Gymnotus carapo australis New Subspecies Figure 3 A, Tables 3 and 4 Holotype: MLP 11221 (1), 341 mm, Argentina, Misiones province, R��o Iguaz�� basin, Arroyo Verde (25��40���15���S, 053��56���00.8���W). Paratype: MLP 11222 (6), 262���321 mm, same locality as MLP 11221. Non-Types: MLP 11223 (4), 216���272 mm, Arroyo Deseado Chico (25��47���19,7���S, 054��01���45.0���W), cuenca R��o Iguaz��, Misiones. Col.: J. Casciotta, et al. II/2002. MLP 11223 (7), 110���330 mm, Arroyo Deseado Chico (25��47���19.7���S, 054��01���45.0���W), cuenca R��o Iguaz��, Misiones. Col.: J. Casciotta, et al. II/2002. MLP 11225 (3), 221���318 mm, Arroyo Lobo (25��42���32���S, 054��05���36���W), cuenca R��o Iguaz��, Misiones. Col.: J. Casciotta, et al. II/ 2002. MLP 11226 (3), 268���274 mm, Arroyo Tateto (25��47���12.8���S, 053��58���12.9���W), cuenca R��o Iguaz��, Misiones. Col.: J. Casciotta, et al. II/2002. MCP 19552 (3), 145���336 mm. MCP 6059 (3), 173���355 mm. Description: Specimens of G. carapo from the southern fauna overlap substantially in morphometric and meristic PC-space with specimens from other localities (Figures 4, 5, and 12). Gymnotus carapo australis is characterized by the following combination of statistically significant (p Distribution: Occurs in the southern humid Neotropics, including the greater La Plata (Paran��-Paraguay), Uruguay, and Jacu�� basins (Figure 2 B). Etymology: Subspecific epithet derived from the Latin ���australis��� meaning ���of the South���., Published as part of Albert, James S., 2017, Revision of the polytypic electric fish Gymnotus carapo (Gymnotiformes, Teleostei), with descriptions of seven subspecies, pp. 401-438 in Zootaxa 4318 (3) on page 427, DOI: 10.11646/zootaxa.4318.3.1, http://zenodo.org/record/887692

Gymnotus carapo carapo New Subspecies Figure 3 C, Tables 3 and 4 Syntypes: NRM 64 (1), 262 mm; NRM 8224 (1), 331 mm; UUZM Linn. coll. 56 (1), 293 mm. Collected in the first half of the 18th Century near Paramaribo, Suriname (L��nnberg 1896:23; Fernholm & Wheeler 1983:216���217; Wheeler 1991:162���163, fig. 6). Non-Types: MCZ 31219 (1), 262 mm, Suriname (exact locality unknown). UMMZ 190414, 260 mm, Suriname, Brokopondo, Suriname River, Tapeoeripa creek near Brokopondo village (05��04���N, 054��58���W). UMMZ 190414 (5), 71���214 mm, Suriname, Brokopondo, Suriname River, Tapeoeripa creek near. Brokopondo village (05��04���N, 054��58���W). USNM 225274 (8), 81���318 mm, Suriname, Nickerie, Lucie River, upstream of Amotopo-Camp Geologie Rd. (03��36���N, 57��37���W). USNM 225275 (11), 81���270 mm, Suriname, Nickerie, Corantijn River, 350 m downstream from Wilhelm II falls (03��34���N, 057��15���W). USNM 225276 (16), 75���148 mm, Suriname, Nickerie, Corantijn River, Dalbana Creek, ca. 3 km upstream from Amotopo���Camp Geologie Rd. (04��20���N, 057��37���W). USNM 225284 (10), 54���143 mm, Suriname, Nickerie, Corantijn River, Lana Creek, ca. 4 km from intersection with W. Corantijn River (05��28���N, 057��15���W). USNM 225285 (12), 85���257 mm, Suriname, Nickerie, Corantijn River, creek south of Matapi, approx. 2 km downstream of Cow Falls (04��59���N, 057��38���W). USNM 225286 (15), 80���319 mm, Suriname, Nickerie, Corantijn River, Koekwie creek (05��31���N, 057��10���W). USNM 225290 (19), 14���157 mm, Suriname, Nickerie, Corantijn River, Dalibane Creek, Camp Dacclemmen (05��34���N, 057��11���W). USNM 225297 (14), 53���137 mm, Suriname, Nickerie, Corantijn River, stream on S. side Lucie River (03��35���N, 057��39���W). UF 180165 (6), 185���337 mm, Suriname, Para, Kola Kreek aff. Para River (05��27���8.820���N, 055��14���42.060���W). UF 180169 (5), 182���340 mm, Suriname, Brokopondo, Marshall Kreek, aff. Suriname River (05��14���24.9���N, 055��05���58.6���W). UF 180173 (11), 34���72 mm; UF 180175 (2), 65���219 mm, Suriname, Marowijne, Cottica Rivier, aff. Commewijne River (05��35.21���N, 054��17.11���W). Description: Specimens of G. carapo from Suriname overlap substantially in morphometric and meristic PCspace with specimens from other localities (Figures 4, 5, and 12). Gymnotus carapo carapo is characterized by the following combination of statistically significant (p Distribution: Known from Atlantic coastal drainages of Suriname and French Guiana, including the Brokopondo, Nickerie, and Suriname districts of Suriname in the Lucie, Suriname, and Corantijn rivers, and all departments of French Guiana (Figure 2 B). Etymology: Subspecific epithet derived from the specific epithet., Published as part of Albert, James S., 2017, Revision of the polytypic electric fish Gymnotus carapo (Gymnotiformes, Teleostei), with descriptions of seven subspecies, pp. 401-438 in Zootaxa 4318 (3) on pages 427-428, DOI: 10.11646/zootaxa.4318.3.1, http://zenodo.org/record/887692, {"references":["Fernholm, B. & Wheeler, A. (1983) Linnaean fish specimens in the Swedish Museum of Natural History, Stockholm. Zoological Journal of the Linnean Society, 78, 199 - 286. https: // doi. org / 10.1111 / j. 1096 - 3642.1983. tb 00867. x","Wheeler, A. (1991) The Linnaean fish collection in the Zoological Museum of the University of Uppsala. Zoological Journal of the Linnean Society, 103, 145 - 195. https: // doi. org / 10.1111 / j. 1096 - 3642.1991. tb 00901. x"]}

Gymnotus carapo madeirensis New Subspecies Figure 3 D, Tables 3 and 4 Holotype: MUSM 12949, 227 mm, Peru, Puno, Sandia, R��o Candamo (13��31���S, 069��41���W). Paratypes: MUSM 12949 (2), 101���121 mm, Peru, Puno, Sandia, R��o Candamo (13��31���S, 069��41���W). Non-Types: MUSM 12949 b (4), 101���227mm, Peru, Puno, Sandia, R��o Candamo, (13��25���S, 070��01���W). UF 82191 (1), 187 mm, Bolivia, Santa Cruz, R��o Guapor��, R��o San Pablo, R��o San Diablo, Velasco, 71 km N. San Jos�� de Chiquitos (17��18���S, 060��35���W). UF 82211 (2), 196���205 mm, Bolivia, Santa Cruz, R��o Guapor��, R��o San Pablo, Chiquitos, Comunidad La Esperanza, ca. 40 km N. San Jos�� de Chiquitos (17��25���S, 060��47���W). UF 82345 (3) 111��� 360 mm, Bolivia, Santa Cruz, R��o Jorge, W. Warnes, R��o Piray (17��34���12.0���S, 063��12���36.0���W). UF 82470 (2), 170���218 mm, Bolivia, Beni, R��o Mamor��, R��o Ibar��, Cercado, Arroyo San Javier (14��38���S, 064��53���W). UF 82485 (1), 360 mm, Bolivia, Beni, R��o Mamor��, R��o Ibar��, Cercado, 20 km N San Javier (14��28���S, 064��56���W). UMSS 0 6969 (1), 302 mm, Bolivia, Beni, R��o Madeira, Arroyo Tres Cuchillas (10��49���23.016���N, 066��04���50.30���W). UF 82510 (1), 241 mm, Bolivia, Beni, R��o Mamor��, R��o Ibar��, Cercado, 25 km N San Javier (14��24���S, 064��56���W). UMMZ 66433 (2), 215���331 mm, Bolivia, Beni, R��o Beni, Lago Rogoagua (13��57���S, 066��58���W). UMSS 0 6962 (1), 108 mm, Bolivia, Beni, R��o Madeira, Arroyo Tres Cuchillas (10��49���23.016���N, 066��04���50.3���W). UMSS 0 6963 (1), 121 mm, Bolivia, Beni, R��o Madeira, Arroyo Tres Cuchillas (10��49���23.016���N, 066��04���50.3���W). UMSS 0 6964 (1), 174 mm, Bolivia, Beni, R��o Madeira, Arroyo Tres Cuchillas (10��49���23.016���N, 066��04���50.3���W). UMSS 0 6964 (1), 177 mm, Bolivia, Beni, R��o Madeira, Arroyo Tres Cuchillas (10��49���23.016���N, 066��04���50.30���W). UMSS 0 6965 (1), 145 mm, Bolivia, Beni, R��o Madeira, Arroyo Tres Cuchillas (10��49���23.016���N, 066��04���50.3���W). UMSS 0 6966 (1), 179 mm, Bolivia, Beni, R��o Madeira, Arroyo Tres Cuchillas (10��49���23.016���N, 066��04���50.3���W). UMSS 0 6970 (1), 119 mm, Bolivia, Beni, R��o Madeira, Arroyo Tres Cuchillas (10��49���23.016���N, 066��04���50.3���W). UMSS 0 6977 (1), 202 mm, Brazil, Amazonas, R��o Beni aff. R��o Madeira (11��01���41.2���S, 066��05���58.801���W). Description: Specimens of G. carapo from the R��o Madeira basin overlap substantially in morphometric and meristic PC-space with specimens from other localities (Figures 4, 5, and 12). Gymnotus carapo madeirensis is characterized by the following combination of statistically significant (p Distribution: Known from the R��o Madre de Dios in the Madre de Dios Department of Peru, the R��o Candamo in Sandia province Peru, and the R��o Guapor�� in the Santa Cruz department and the R��o Mamor�� and R��o Madeira and R��o Beni in the Beni department of Bolivia (Figure 2 B). Etymology: Subspecific epithet derived from the R��o Madeira., Published as part of Albert, James S., 2017, Revision of the polytypic electric fish Gymnotus carapo (Gymnotiformes, Teleostei), with descriptions of seven subspecies, pp. 401-438 in Zootaxa 4318 (3) on pages 428-429, DOI: 10.11646/zootaxa.4318.3.1, http://zenodo.org/record/887692

Gymnotus carapo orientalis New Subspecies Figure 3 F, Tables 3 and 4 Holotype: MZUSP 30025 237 mm, Brazil Par��, R��o Tocantins, R��o Itacaiuna, Serra Norte, Serra dos Caraj��s (05��05���S, 050��22���W). Paratypes: MZUSP 30025 (6), 165���235 mm, Brazil Par��, R��o Tocantins, R��o Itacaiuna, Serra Norte, Serra dos Caraj��s (05��05���S, 050��22���W). Non-Types: MCZ 45189 (19), 133���210 mm, Brazil Par��, Parauapebas, Ilha de Maraj��, R��o Tocantins, R��o Arari, Cachoeira do Arari (01��01���S, 048��58���W). MZUSP 30008 (8), 173���253 mm, Brazil Par��, R��o Trombetas, R��o Itacaiunas, Caldeir��o, Igarap�� do Pojuca (approx. 00��45���S, 056��13���W). MZUSP 30025 (7), 165���237 mm, Brazil, Par��, R��o Tocantins, R��o Itacaiuna, Serra Norte, Serra dos Caraj��s (05��05���S, 050��22���W). Description: Specimens of G. carapo from the eastern Amazon overlap substantially in morphometric and meristic PC-space with specimens from other localities (Figures 4, 5, and 12). Gymnotus carapo orientalis is characterized by the following combination of statistically significant (p Distribution: Known from the eastern Amazon basin in the Brazilian Par�� state of Par��, in Amazon river near Bel��m and Santar��m, and the Tocantins and Trombetas basins (Figure 2 B). Etymology: Subspecific epithet derived from the Latin ��� orientalis ��� meaning ���of the East���. G. carapo G. carapo G. carapo G. carapo G. carapo G. carapo G. carapo Character australis caatingaensis carapo madeirensis occidentalis orientalis septentrionalis MLP 11222 AUM 20624 UMMZ 190414 MUSM 12949 UMMZ 230734 MZUSP 30025 UF 80734 Morphom. 341 225.0 260.0 227.0 210.0 237.0 220.0 45.0 27.1 31.5 25.9 27.8 31.7 26.0 % 13.2 12.0 12.1 11.4 13.2 13.4 11.8 % 34.4 37.6 36.1 37.8 33.1 35.0 34.3 % 41.1 43.9 42.8 39.0 36.0 43.7 35.5 % 56.9 65.7 61.9 60.6 61.2 60.9 63.7 % 37.6 37.6 41.7 39.8 36.0 35.6 38.4 % 88.9 84.5 96.9 90.0 86.3 74.1 93.2 % 67.1 64.2 68.8 64.1 61.2 54.3 70.3 /BD 82.7 76.0 71.0 71.2 70.8 73.2 75.4 % 57.8 58.3 61.8 57.1 57.9 52.1 62.9 % 66.2 61.3 63.0 59.5 61.9 53.3 61.3 % 28.7 33.2 32.0 37.9 34.5 36.5 38.8 % 63.6 83.8 88.0 74.9 82.7 89.0 80.0 % 40.0 46.9 12.7 43.4 40.3 44.2 45.2 % 82.7 75.6 86.0 74.9 81.0 79.3 81.8 Meristics 23 23 21 16 21 23 21 269 220 235 220 170 220 245 R 15 16 16 13 16 13 17 10 6 6 6 7 6 7 3 4 4 4 4 3 4 8 8 8 8 9 8 8 36 45 40 49 46 46 53 88 76 95 92 88 75 112 10 19 24 18 20 21 23, Published as part of Albert, James S., 2017, Revision of the polytypic electric fish Gymnotus carapo (Gymnotiformes, Teleostei), with descriptions of seven subspecies, pp. 401-438 in Zootaxa 4318 (3) on pages 430-431, DOI: 10.11646/zootaxa.4318.3.1, http://zenodo.org/record/887692

Gymnotus carapo occidentalis New Subspecies Figure 3 E, Tables 3 and 4 Holotype: UF 126181, 272 mm, Peru, Loreto, R��o Pacaya, Cocha Zapote (05��20���02���S, 074��29���05���W). Paratypes: UF 126181, 245 mm, Peru, Loreto, R��o Pacaya, Cocha Zapote (05��20���02���S, 074��29���05���W). Non-Types: ANSP 203173 (20) 105���263 mm, Peru, Loreto, Cocha Santo Tom��s aff. R��o Nanay near Iquitos. INHS 55038 (1) 323 mm, Peru, Loreto, R��o Napo aff. Amazon. INPA 6390 (1) 450 mm, Brazil, Mato Grosso, Aripuan��, R��o Aripuan��, Igarap�� Castanhal. MUSM 11590 (5), 193���211 mm, Cuenca Ebehuabaeji, Sandia. MUSM 58770 (20) 86���275 mm, Peru, Loreto, Cocha Santo Tom��s aff. R��o Nanay near Iquitos (03��47���59.92���S, 073��20���14.48���W). MZUSP 76061 (1), 260 mm, Brazil, Amazonas, R��o Tef��, Lago Tef��, Cabe��eira do Lago Tef�� (03��34���35���S, 064��59���19���W). MZUSP 76063 (1), 298 mm, Brazil, Amazonas, MSDR, Ressaca da Vila Alencar (03��07���42���S, 064��48���02���W). MZUSP 76064 (1), 253 mm, Brazil, Amazonas, MSDR, Cano do Lago Mamirau�� (03��04���26���S, 064��48���39���W). NRM 27650 (1), 305 mm, Peru, Loreto, R��o Samiria, Maynas, right bank stream tributary between Ca��o Pastos and Hamburgo (05��2���S, 075��08���W). NRM 27650 (1), 305 mm, Peru, Loreto, R��o Samiria, Maynas, right bank stream tributary between Ca��o Pastos and Hamburgo (05��12���S, 075��08���W). NRM 40772 (1), 91 mm, Peru, Loreto, R��o Maniti, Maynas, 50 km NE of Iquitos (03��29���S, 072��44���W). NRM 40772 (1), 91 mm, Peru, Loreto, R��o Maniti, Maynas, 50 km NE of Iquitos (03��29���S, 072��44���W). UF 116573 (2), 189���279 mm, Peru, Loreto, R��o Amazonas, Maynas, R��o Nanay. UF 116665 (1), 298 mm, Peru, Loreto, R��o Nanay, Maynas, 3 km upstream Mishana, Reserva Allpahuayo-Mishana (03��52���05���S, 073��29���03���W). UF 116665 (1), 298 mm, Peru, Loreto, R��o Nanay, Maynas, 3 km upstream Mishana, Reserva Allpahuayo-Mishana (03��52���05���S, 073��29���03���W). UF 122820 (1), 275 mm, Peru, Loreto, R��o Amazonas, Maynas, R��o Nanay. UF 122821 (1), 331 mm, Peru, Loreto, acquired from fishermen 28 May, 2002, R��o Amazonas near Iquitos, Loreto Department, Peru (03��46���S, 073��15���W). UF 122822 (1), 330 mm, Peru, Loreto, R��o Amazonas, Maynas, R��o Nanay. UF 122822 (1), 334 mm, Peru, Loreto, acquired from fishermen 28 May, 2002, R��o Amazonas near Iquitos, Loreto Department, Peru (03��46���S, 073��15���W). UF 122825 (1), 158 mm, Peru, Loreto, R��o Amazonas, Maynas, R��o Nanay. UF 122825 (1), 158 mm, Peru, Loreto, R��o Amazonas, Maynas, R��o Nanay. UF 122847 (1), 188 mm, Peru, Loreto, R��o Amazonas, Maynas, R��o Nanay. UF 122847 (1), 188 mm, Peru, Loreto, R��o Amazonas, Maynas, R��o Nanay. UF 122848 (1), 112 mm, Peru, Loreto, R��o Amazonas, Maynas, R��o Nanay. UF 122849 (1), 132 mm, Peru, Loreto, R��o Amazonas, Maynas, R��o Nanay. UF 122849 (1), 132 mm, Peru, Loreto, R��o Amazonas, Maynas, R��o Nanay. UF 122852 (1), 92 mm, Peru, Loreto, R��o Amazonas, Maynas, R��o Nanay. UF 128991 (1) 291���307 mm, Peru, Loreto, Ucayali, (05��18���7.3���N, 074��03���36.03���W). UF 131129 (1) 172 mm, Peru, Loreto, R��o Amazonas, Maynas, R��o Nanay (03��45���S, 073��15���W). UF 131129 (1), 172 mm, Peru, Loreto, R��o Amazonas, Maynas, R��o Nanay, near Iquitos. UFRGS 22695 (23) 104���266 mm, Peru, Loreto, Cocha Santo Tom��s aff. R��o Nanay near Iquitos. UMMZ 228999 (1), 162 mm, Peru, Loreto, R��o Tahuayo (04��10���S, 073��12���W). UMMZ 230733 (1), 251 mm, Peru, Loreto, R��o Yavari, Buen Suceso, Quebrada Carana (04��08���S, 070��26���W). UMMZ 230733 (1), 251 mm, Peru, Loreto, R��o Yavari, Buen Suceso, Quebrada Carana (approx. 04��08���S, 070��26���W). UMMZ 230734 (2), 190���210 mm, Brazil, Santa Cruz, Benjamin Constante, R��o Nanay R��o Nanay, R��o Cayari (04��22���S, 070��02���W). ROM 83885 (1) 233 mm, Guyana, Essequibo, Cuyuni-Mazaruni. ROM 83886 (1) 238 mm, Guyana, Essequibo, Cuyuni-Mazaruni. ROM 83887 (1) 210 mm, Guyana, Essequibo, Cuyuni-Mazaruni. ROM 89520 (1) 189 mm, Guyana, Essequibo, Cuyuni-Mazaruni. ROM 89583 (1) 278 mm, Guyana, Essequibo, Cuyuni-Mazaruni. ROM 89660 (1) 176 mm, Guyana, Essequibo, Cuyuni-Mazaruni. ROM 89661 (1) 158 mm, Guyana, Essequibo, Cuyuni-Mazaruni. ROM 89662 (1) 132 mm, Guyana, Essequibo, Cuyuni-Mazaruni. ROM 93388 (1) 246 mm, Guyana, Essequibo, Cuyuni- Mazaruni. ROM 93389 (1) 238 mm, Guyana, Essequibo, Cuyuni-Mazaruni. ROM 93407 (1) 248 mm, Guyana, Essequibo, Cuyuni-Mazaruni. ROM 93424 (1) 245 mm, Guyana, Essequibo, Cuyuni-Mazaruni. ROM 93425 (1) 205 mm, Guyana, Essequibo, Cuyuni-Mazaruni. ROM 93426 (1) 186 mm, Guyana, Essequibo, Cuyuni-Mazaruni. Description: Specimens of G. carapo from the western Amazon overlap substantially in morphometric and meristic PC-space with specimens from other localities (Figures 4, 5, and 12). Gymnotus carapo occidentalis is characterized by the following combination of statistically significant (p Distribution: Known from the western Amazon basin including Department of Loreto, Peru, the R��o Aripuan�� in the state of Mato Grosso, Brazil and the Amazon at Tef�� in Brazil. Also known from the Cuyuni-Mazaruni in Essequibo basin of Guyana and the Napo basin in Ecuador (Figure 2 B). Etymology: Subspecific epithet derived from the Latin ��� occidentalis ��� meaning ���of the West���., Published as part of Albert, James S., 2017, Revision of the polytypic electric fish Gymnotus carapo (Gymnotiformes, Teleostei), with descriptions of seven subspecies, pp. 401-438 in Zootaxa 4318 (3) on pages 429-430, DOI: 10.11646/zootaxa.4318.3.1, http://zenodo.org/record/887692

Gymnotus carapo caatingaensis New Subspecies Figure 3 B, Tables 3 and 4 Holotype: AUM 20624, 225 mm. Brazil, Piau��, R��o Gurgueia aff. R��o Parna��ba (08��32���24���S, 044��25���48���W). Paratype: AUM 20624, 210 mm. Brazil, Piau��, R��o Gurgueia aff. R��o Parna��ba (08��32���24���S, 044��25���48���W). Non-Types: AUM 20689 (2), 95���138 mm, Brazil, Piau��, R��o Gurgueia, 25 km SW Urucui. AUM 2079 (4), 156���192 mm, Piau��, Parna��ba, between Santa Filomena and Jurumenha. AUM 20793 (4), 111���195 mm, Brazil, Piau��, Parna��ba, between Santa Filomenha and Jurumenha. Description: Specimens of G. carapo from the Caatinga ecoregion in the Brazilian state of Piau�� overlap substantially in morphometric and meristic PC-space with specimens from other localities (Figures 4, 5, and 12). Gymnotus carapo caatingaensis is characterized by the following combination of statistically significant (p Distribution: Known from R��o Parna��ba basin in the Brazilian Piau�� state of Piau�� (Figure 2 B). Etymology: Subspecific epithet derived from the Caatinga ecoregion of northeastern Brazil, home to a characteristic arid scrubland and thorny scrub forest., Published as part of Albert, James S., 2017, Revision of the polytypic electric fish Gymnotus carapo (Gymnotiformes, Teleostei), with descriptions of seven subspecies, pp. 401-438 in Zootaxa 4318 (3) on page 427, DOI: 10.11646/zootaxa.4318.3.1, http://zenodo.org/record/887692

Gymnotus refugio, new species (Fig. 1) Gymnotus aff. pantherinus (non Steindachner, 1908). Malabarba et al. 2013: 95 (photo, brief description, distribution map in the rio Tramanda�� drainage). Gymnotus pantherinus (non Steindachner, 1908). Decreto Estadual No 51.797, 9 September 2014 (EN���Endangered species in the list of threatened species of Rio Grande do Sul State, Brazil). Correa et al. 2015: listed for the arroio Chasqueiro). Holotype. UFRGS 8752, 1 (171.53 mm TL), Brazil, Rio Grande do Sul State, Amaral Ferrador, creek in the former Ferraria farm, laguna dos Patos drainage (30 �� 50 ' 54 "S 52 �� 23 ' 19 "W), November 2006, J. Anza & R. Hirano. Paratypes. Brazil, Rio Grande do Sul State. Laguna dos Patos drainage: MCP 20197, 2 (203.06���213.73 mm TL), Viam��o, puddle in the swampy forest located at Ref��gio da Vida Silvestre Banhado dos Pachecos (30 ��05' 44 "S 50 �� 50 ' 59 "W), 22 December 2011, J. P. Miranda, B. Calegari, R. Fonseca & C. Alff. MZUSP 8749, 2 (124.87���156.72 mm TL), collected with the holotype. UFRGS 8749, 2 (136.66mm C&S, and 148.55 mm TL), collected with the holotype. UFRGS 13603, 1 (193.93mm TL), UFRGS 13618, 3 (126.42���160.10 mm TL), Amaral Ferrador, creek in the former Ferraria farm (30 �� 50 ' 46 "S 52 �� 23 ' 17 "W), 3 November 2010, J. Giora, J. Wingert, J. Ferrer & E. Oliveira. UFRGS 13296, 1 (84.14 mm TL), Turu��u, Corrientes creek (31 �� 29 ' 48 "S 52 �� 17 ' 42 "W), 17 March 2008, L. E. K. Lanes, A. C. Gon��alves & M. V. Volcan. UFRGS 13328, 1 (68.99), UFRGS 20196, 2 (116.15���167.83 mm TL), Pelotas, Carmelitas creek (31 �� 44 ' 53 "S 52 �� 13 ' 27 "W), 16 May 2006, A. C. Gon��alves, M. V. Volcan & L. E. K. Lanes. UFRGS 13607, 3 (130.02���187.87 mm TL), Pelotas, Laranjal beach, Carmelitas creek near its mouth in laguna dos Patos (31 �� 44 ' 52 "S 52 �� 13 ' 22 "W), 3 November 2010, J. Giora, J. Wingert, J. Ferrer & E. Oliveira. UFRGS 13813, 3 (81.48-161.13 mm TL), Viam��o, puddle in the swampy forest at Ref��gio da Vida Silvestre Banhado dos Pachecos (30 ��05' 43 "S 50 �� 50 ' 59 "W), 9 November 2010, G. Frainer, S. Leonardi, J. Giora & L. R. Malabarba. UFRGS 16371, 3 (151.19���186.49), Viam��o, puddle in the swampy forest located at Ref��gio da Vida Silvestre Banhado dos Pachecos (30 ��05' 44 "S 50 �� 50 ' 59 "W), 13 September 2011, C. Mesquita & V. Caorsi. UFRGS 20197, 2 (190.30���213.73 mm TL), Viam��o, puddle in the swampy forest located at Ref��gio da Vida Silvestre Banhado dos Pachecos (30 ��05' 44 "S 50 �� 50 ' 59 "W), 22 December 2011, J. P. Miranda, B. Calegari, R. Fonseca & C. Alff. UFRGS 20198, 2 (227.54���229.70 mm TL), Viam��o, puddle in the swampy forest located at Ref��gio da Vida Silvestre Banhado dos Pachecos (30 ��05' 44 "S 50 �� 50 ' 59 "W), 17 August 2011, J. P. Miranda, F. A. S. Santos, C. V. Machado & S. Costa. UFRGS 20199, 2 (202.66���207.21 mm TL), Viam��o, puddle in the swampy forest located at Ref��gio da Vida Silvestre Banhado dos Pachecos (30 ��05' 44 "S 50 �� 50 ' 59 "W), 15 July 2011, J. P. Miranda, F. A. S. Santos, E. Senna, C. V. Machado & C. S. Prauchner. Rio Tramanda�� drainage: MNRJ 9439, 2 (101.20���116.84 mm TL), Torres, Parque Estadual de Itapeva (29 �� 21 ' 23 "S 49 �� 45 ' 57 "W), 13 September 2005, F. Mello, R. Setubal & M. de Luz. UFRGS 9439, 2 (80.37���116.84 mm TL), Torres, Parque Estadual de Itapeva (29 �� 21 ' 23 "S 49 �� 45 ' 57 "W), 13 September 2005, F. Mello, R. Setubal & M. de Luz. UFRGS 19595, 3 (101.85��� 216.44 mm TL), Maquin��, Barra do Ouro, road to Garapi�� waterfall (29 �� 32 ' 14 "S 50 �� 14 ' 45 "W), 19 September 2014, L. R. Malabarba, P. C. Silva, U. Santo & A. Langoni. Brazil, Santa Catarina State. Rio Mampituba drainage: UFRGS 10829, 2 (68.47���107.66 mm TL), Praia Grande, creek tributary of the rio Mampituba (29 �� 10 ' 36 "S 49 �� 58 ' 14 "W), 12 September 2008, A. Thomaz, G. Neves, J. Ferrer & J. Wingert. UFRGS 10873, 1 (128.28 mm TL), Praia Grande, flooded area near rio Mampituba (29 �� 15 ' 10 "S 50 ��07'00"W), 14 September 2008, A. Thomaz, G. Neves, J. Ferrer & J. Wingert. Diagnosis. Gymnotus refugio differs from other members of the G. pantherinus species-group (except G. capitimaculatus and G. pantherinus) in possessing a color pattern in life or in alcohol composed of yellow to dark brown ground with thick and/or vermiculated spots near anal-fin base up until the lateral line, some specimens showing very few or absent spots ventral to lateral line, versus body with color pattern composed of light and dark pigments bands (G. anguillaris, G. capitimaculatus, G. cataniapo, G. coatesi, G. coropinae, G. javari, G. jonasi, G. melanopleura, G. panamensis, G. pantanal, G. pedanopterus, G. stenoleucus) or broad irregular dark pigment blotches (G. onca). The new species further differs from G. pantherinus in possessing a deeper head (55.6���68.1 vs. 48.1���55.05 % HL), shorter caudal filament (0.7���3.2 vs. 2.7���5.4 % TL) (Fig. 6) and wider mouth gape (31.8���43.9 vs. 27.1���36.1 % HL) (Fig. 7) and from G. capitimaculatus in possessing shorter interorbital distance (28.3���38.5 vs. 39.8���43.4 % HL), wider mouth gape (31.8���43.9 vs. 26.0��� 28.3 % HL), shorter caudal filament (0.7���3.2 vs. 3.2���5.5 % TL), higher number of pectoral-fin rays (16���18 vs. 15), and higher number of pored lateral line scales (80���105 vs. 56���74). Description. Morphometric and meristic data presented in Table 1. Lateral head profile conical; dorsal portion flattened towards tip of snout. Mouth superior, lower jaw longer than upper. Mouth large, extending nearly posterior naris. Eyes small and lateral; mean interorbital distance 32.2 % of HL. Anterior narial pore within mouth gape in large narial fold. Body slender, slightly compressed laterally, and relatively deep. Dorsal profile slightly convex from snout to supraoccipital, nearly straight posteriorly to caudal filament. Ventral profile gently convex from lower jaw to caudal filament. Highest body depth posterior to anal-fin origin. Body depth increasing smoothly from head to body region near 20 th anal-fin ray, nearly same depth to 2 / 3 of TL, and gradually decreasing from that point to caudal filament. Caudal filament short, slender, and laterally compressed. Moderate cycloid scales covering all trunk. Scales smaller on anterior third portion of body; posterior scales at dorsal and medial body regions nearly two to three times larger in diameter than anterior ones; smallest scales covering region of anal-fin pterygiophores. First anterior perforated scale of lateral line above pectoral fin origin; lateral line extending to caudal filament tip with an intermittent distribution. Absence of urogenital papilla. Pectoral fins rounded with perpendicular insertion; pectoral-fin rays i���ii + 14���17 (16���18 total pectoral-fin rays, n = 36, mode = 17). Anal fin long with iii���vi + 205���244 rays (210���247 total anal-fin rays, n = 27, mode = 229). Anal-fin origin posterior to distal tip of pectoral fin. Precaudal vertebrae 45���47 (n = 2). n Min Max Mean SD Total length (mm) 10 176.8 246.5 212.2 - Percents of total length Head length 10 9.9 11.0 10.5 0.4 Body width 9 5.0 6.7 5.6 0.5 Body depth 10 6.9 10.2 8.3 1.1 Pre-anal distance 9 8.9 10.6 9.8 0.5 Snout to anal aperture 10 7.7 9.8 9.0 0.6 Snout to anal-fin origin 10 17.8 20.3 19.0 0.7 Pre-pectoral distance 10 9.5 10.6 10.1 0.4 Anal-fin length 10 72.8 78.3 77.0 1.6 Caudal filament length 9 2.7 5.4 4.0 0.8 Percents of head length Posorbital length 13 57.7 63.3 61.5 1.7 Preorbital length 13 23.9 32.7 29.9 2.3 Orbital diameter 13 5.8 7.4 6.4 0.5 Nasal aperture distance 13 13.5 18.8 16.8 1.6 Posterior narine to eye 13 9.8 12.5 11.1 0.9 Head depth 13 48.1 55.0 52.2 1.8 Head width at eye 13 39.2 49.1 44.7 2.7 Interorbital distance 13 28.5 35.8 31.2 2.3 Branchial opening 13 30.2 37.3 33.0 2.3 Head width at operculum 13 50.2 63.9 58.3 4.0 Gape width 13 27.1 36.1 32.6 2.5 Pectoral-fin length 11 32.6 40.6 36.4 2.58 Color in life. Ground color solid dark brown dorsal to lateral line. Ground color light brown to yellowish ventral to lateral line; presence of thick and/or vermiculated dark brown spots, between anal-fin base and lateral line is variable, some specimens showing very few or absent brown spots ventral to lateral line (Fig. 2). Specimens with both color patterns can be found in same lot, and this variation in coloration is not related to sexual dimorphism or ontogeny. Anal and pectoral-fin rays dark brown, with pale hyaline inter-radial membranes. Color in alcohol. The same pattern described for color in life, except that the specimen may appears more opaque due to the fixation of the mucus covering head and body. Distribution. Gymnotus refugio is known from coastal rivers of laguna dos Patos, rio Tramanda��, rio Maquin��, and rio Mampituba drainages, occurring from southern Rio Grande do Sul to the southern border of Santa Catarina States, Brazil (Fig. 3). Habitat. Gymnotus refugio inhabits streams, small tributaries, and puddles with shallow and lentic waters, muddy bottom and dense riparian vegetation. It is specially associated to riparian vegetation known as Mata Paludosa (= swampy forest), living under aquatic vegetation roots or in flooded vegetated margins (Fig. 4). At collecting sites throughout Rio Grande do Sul State, the only gymnotiform species occasionally collected along with G. refugio was Brachypopomus draco Giora, Malabarba & Crampton 2008. Gymnotus refugio is usually a rare fish where it has been collected (Correa et al. 2015 and personal observation), except in conservation areas of the Rio Grande do Sul State where it seems to be abundant associated with preserved dense riparian vegetation. Conservation Status. Gymnotus refugio was recently evaluated as EN (Endangered) according to the IUCN criteria in the list of threatened species of fauna of Rio Grande do Sul State, Brazil, but it is named therein as Gymnotus pantherinus (Decreto Estadual No 51.797, 9 setembro de 2014). The classification was based on the low and drastically fragmented distribution of the species associated with its high habitat specificity, and the high susceptibility of this habitat to anthropic alteration. Etymology. The name ��� refugio ���, from the Portuguese meaning ���sanctuary���, is in reference to the distribution of the species that was found abundant only in two conservation areas of the Rio Grande do Sul State: ��� Ref��gio da Vida Silvestre Banhado dos Pachecos (where it was collected monthly for ecological studies)��� and ���Parque Estadual de Itapeva���., Published as part of Giora, Julia & Malabarba, Luiz Roberto, 2016, Gymnotus refugio, a new and endangered species of electric fish of the Gymnotus pantherinus species-group from southern Brazil (Gymnotiformes: Gymnotidae), pp. 581-590 in Zootaxa 4066 (5) on pages 583-587, DOI: 10.11646/zootaxa.4066.5.6, http://zenodo.org/record/263709, {"references":["Steindachner, F. (1908) Uber eine wahrend der brasilianischen Expedition entdeckte Brachyplatystoma - Art aus dem Rio Parnahyba und uber eine dicht gefleckte und gestrichelte Varietat von Giton fasciatus aus den Gewassern von Santos (Staat Sao Paulo). Anzeiger der Akademie der Wissenschaften in Wien, 45 (9), 126 - 130.","Malabarba, L. R., Neto, P. C., Bertaco, V. A., Carvalho, T. P., Santos, J. F. & Artioli, L. G. S. (2013) Guia de identificacao dos peixes da bacia do rio Tramandai. Via Sapiens, Porto Alegre, 140 pp.","Correa, F., Oliveira, E. F., Tuchtenhagen, T., Pouey, J. & Piedras, S. (2015) Ichthyofauna of the hydrographic basin of the Chasqueiro Stream (Mirim Lagoon system, southern Brazil): generating subsidies for conservation and management. Biota Neotropica, 15 (4), e 0006. http: // dx. doi. org / 10.1590 / 1676 - 0611 - bn- 2015 - 0006","Giora, J., Malabarba, L. R. & Crampton, W. G. R. (2008) Brachyhypopomus draco, a new sexually dimorphic species of Neotropical electric fish from southern South America (Gymnotiformes: Hypopomidae). Neotropical Ichthyology, 6 (2), 159 - 168. http: // dx. doi. org / 10.1590 / S 1679 - 62252008000200002"]}

Four species of the genus Gymnotus are present in Argentina: G. inaequilabiatus, G. omarorum, G. pantanal, and G. sylvius, the last three species being recorded for the first time in freshwater courses. Gymnotus omarorum, G. pantanal, and G. sylvius together with others of the genus Brachyhypopomus are the group of fishes that bear the greatest impact in the trade as live bait for sport fishing in the northeastern region of Argentina. Within this large area, only the provinces of Chaco, Corrientes, and Formosa have regulations for the catch, trade, and sale of species as live bait. Unfortunately, the species covered by legal regulations are Gymnotus carapo and Brachyhypopomus brevirostris, neither of which occurs in freshwater habitats of Argentina. Comments are included as to how this bad taxonomy affects the regulations and conservation status of these species. Fil: Casciotta, Jorge Rafael. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico Zoología Vertebrados; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina Fil: Almirón, Adriana Edith. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico Zoología Vertebrados; Argentina Fil: Sánchez, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias. Instituto de Ictiología del Nordeste; Argentina Fil: Iwaszkiw, Juan Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina Fil: Bruno, María Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Centro Regional de Estudios Genómicos; Argentina

Gymnotus chaviro, new species Figs. 1- 2 Holotype. MUSM 33715, 233 mm. Peru, Dept. Ucayali, Quebrada Dos y medio, a small terra firme stream ca. 2 km NW the town of Breu, on the Alto Yuruá River, 09°31.175S 72°45.755W, 271 m elevation, 20 Jul, 2008, J. S. Albert, R. Quispe & I. Corahua. Paratypes. Peru, all collected with holotype: MUSM 33714, 40, 4 c&s, 95-275 mm; FMNH 118274, 10, 134- 179 mm; CAS 227893, 10, 123- 150 mm; MCZ 168419, 10, 115- 160 mm; MCP 43880, 10, 116- 164 mm; MZUSP 103035, 10, 130- 217 mm; AMNH 248884, 10, 104- 180 mm. Nontype specimens. All from Peru. MUSM 1406, 1, 127 mm, Madre de Dios, Parque Nacional Manú, Quebrada Pabitza, Aguajal. MUSM 1759, 2, 142- 150 mm, Madre de Dios, Puerto Maldonado, river near Tambopata, Cochachica. MUSM 21405, 1, 138 mm, Madre de Dios. MUSM 22731, 10, 2 c&s, 143-210 mm, Madre de Dios drainage. MUSM 16662, 1, 325 mm, Madre de Dios, Tambopata, Madre de Dios drainage, lago Copamanu. Diagnosis. Gymnotus chaviro is unique among members of the G. carapo group (sensu Albert et al., 2004) in having a color pattern composed of oblique, dark, unbroken pigment bands along the length of the body, dark band-pairs with wavy, irregular margins, mainly unbranched or incompletely separated, pale inter-bands rarely reaching to the dorsal midline on the anterior half of the body and crescent-shaped in abdominal area. Gymnotus chaviro can further be distinguished from all congeners by the following unique combination of morphometric and meristic traits: 1, 17-22 oblique bands (vs. 24-26 in G. chimarrao); 2, clear (unpigmented) patch of membrane at the caudal end of the anal-fin in specimens (vs. even pigmentation in G. cylindricus and G. pantherinus groups, or striped in G. tigre group); 3, anal fin pale gray (vs. black in G. carapo, G. arapaima, G. ucamara); 4, several (4-5) arrow-head shaped teeth at anterior end of the dentary (vs. all conical in G. cylindricus and G. pantherinus groups, or five or more in most members of G. carapo group); 5, body depth 6.3-10.2% TL (vs. 10.3-13.1% in G. sylvius); 6, mouth width 35.5-52.5% HL (vs. 26.9-28.1 in G. diamantinensis); 7, interorbital distance 37.9-49.2% HL (vs. 28.6-36.5% in G. arapaima and in G. choco); 8, head depth 61.8-89.0% HL (vs. 54.4-61.8% in G. choco and G. sylvius); 9, head width 58.5- 74.7% HL (vs. 51.1-51.3% in G. diamantinensis); 10, pectoral fin length 45.8-66.8% HL (vs. 36.3-41.1 in G. diamantinensis); 11, pectoral-fin rays 18-19 (vs. 13-17 in G. carapo, G. ucamara, G. sylvius, G. mamiraua, G. diamantinensis, G. choco, G. bahianus, G. arapaima, G. omarorum, G. chimarrao, vs. 20-22 in G. obscurus); 12, pored lateral-line scales to first ventral ramus 48-52 (vs. 32-39 in G. mamiraua, 40-41 in G. bahianus, 40 in G. chimarrao, and 24-35 in G. omarorum); 13, head length 8.9-12.0% TL (vs. 12.2-15.8% in G. arapaima and G. ucamara); 14, number of ventral lateral-line rami 7-12 (vs. 16-37 in G. chimarrao and G. omarorum); 15, anal-fin rays 228-280 (vs. 180-213 in G. chimarrao and G. tigre); 16, caudal rows of electroplates 4 (vs. 3 in G. diamantinensis and G. choco); and 17, number of scales above the lateral line 7-9 (vs. 6 in G. ucamara). Gymnotus chaviro is most similar in external appearance to G. curupira from the western Amazon, from which it may be distinguished by the presence of two (rarely one) pores in the dorsoposterior corner of preopercle (vs. always one pore), fewer total pored lateral-line scales 86-100 (vs. 104-140), fewer pored lateral-line scales to the first ventral ramus (48-52 vs. 59-62), more pectoral-fin rays (18-19 vs. 16-17), and more electrocyte tubes (4 rows vs. 3) in the caudal region. Gymnotus chaviro is also similar in external appearance to G. varzea from the western Amazon from which it may be distinguished by more teeth on the dentary (16 vs. 11-12) and more teeth on the premaxilla (10 vs. 6-7). Gymnotus chaviro is also similar in external appearance to G. pantanal from Paraguay from which it may be distinguished by an incomplete separation of the dark pigment bands (vs. no separation), white interbands about as broad as dark bands (vs. no larger than one third), fewer dark bands (17-22 vs. 22-26), more scales over anal-fin pterygiophores (12-13 vs. 10-11), and fewer ventral lateralline rami (7-12 vs. 14-23). Description. Morphometric and meristic data (Table 2) were pooled from 89 specimens of type-series. Size up to 275 mm. No secondary sexual dimorphism observed in body shape or anatomy. Scales cycloid, ovoid, present on entire post-cranial portion of body from nape to tip of caudal appendage, large above lateral line small, over anal fin pterygiophores. Mouth superior, lower jaw extending beyond upper one, rictus decurved. Chin fleshy and bulbous with thick support tissues overlying tip of snout and oral jaws. Eyes below horizontal midline.Anterior narial pore pipe-shaped, located within gape. Anterior nares small, approximately 4-5 times smaller than diameter of eye. Gape never extended beyond posterior nares even in largest specimens. Posterior narial pore flush with head surface, circumorbital series ovoid. Maxilla and palatine near tip of mesopterygoid. Maxilla oriented vertically, rod-shaped, narrow distally with a length of dentary portion bearing 7-9 tooth sockets. Premaxilla with two rows of teeth with few of them in outer row (less than 10), and curved median margin. Mandible short, dentary teeth flattened anteroposteriorly along long axis of oral margin of dentary grading to conical posteriorly, with 14 arrowheadshaped teeth in outer row and 10 in an anterior inner tooth patch. Ventroposterior hook-like process at mental symphysis. Opercular dorsal margin convex, its posterior margin smooth. Two closely-positioned laterosensory pores (rarely one) in dorsoposterior corner of preopercle, associated cutaneous laterosensory pores well separated. Ascending mesopterygoid process contacting orbitosphenoid, arched mediolateraly. Dorsal region of hyomandibula with four lateral foramenae, supraorbital and infraorbital nerves divided. Hyomandibular posterior lateral-line foramen contacting posterior margin. Neurocranium with approximately triangular aspect in dorsal view, with narrow ethmoid region. Cranial fontanels closed. Mesethmoid anterior margin with paired anterolateral processes. Four tubes (rows) of electroplates at one HL distance from tip of caudal appendage. 37-38 precaudal vertebrae (including those of Weberian apparatus). Coloration. Ground color yellowish. 17 to 22 (mode 20) oblique and non broken (or incompletely broken in largest specimen) pigment bands (gray) with irregular wavy margins on lateral surface extending from nape and pectoral-fin base to tip of caudal appendage and oriented either vertically or obliquely in an antero-ventral to postero-dorsal diagonal. Anterior most 2 to 3 pale interbands crescent-shaped. Majority of dark bands paired with pale middle region (intraband), dark bands approximately as wide as pale interbands. Dark bands above lateral line continuous on anterior half of body, not visible against dark ground color on dorsal midline. Pigment density greater at band margins than in middle. Band-interband contrast sharper caudally and bands thinner anteriorly. Most bands are not well divided, intraband formed by less density of pigments at the middle of the band, no sharp band-intraband contrast. Three to four dark bands meet irregularly at ventral midline in region anterior to anal-fin origin. Juveniles possess more regularly arrayed alternating pigment bands with sharper band-interband contrast. Head never banded, spotted or blotched, strongly countershaded with dense speckling dorsally fading to pale yellow ventrally. No rosy hue visible to operculum from underlying gills in juveniles. Pectoral-fin rays and interradial membranes uniform light gray. Anal fin membrane never blotched, spotted or marked. Anal fin membrane lightly and evenly pigmented with scattered chromophores along most of its length, fading to an absence of chromophores caudally. Preservational artifacts. After capture specimens were either fixed immediately in 10% unbuffered formalin, or transported live to a field base in buckets for processing (i. e., photography and tissue sampling) before fixation. Some differences in coloration and superficial appearance were observed among specimens subjected to these different preservational treatments. Specimens fixed immediately after capture exhibit the following traits: 1, pigments bands with high contrast dark brown ground color and yellow interbands (vs. low contrast); 2, body surface (skin of head and scales) lighter and more reflective due to a thicker mucous layer, scale margins less visible; 3, head orientation straight (vs. recurved or arched); 5, laterosensory pores small, their margins flush with surrounding body surface (vs. large with bulging margins); 6, lens black (vs. hyaline), Specimens subjected to different preservational treatments did not differ in morphometric, meristic or osteological traits, or in the diagnostic aspects of coloration. Geographic distribution. The type series of Gymnotus chaviro is known from the upper Yuruá basin, Department Ucayali, Peru (Fig. 3) and the Manu and Tampobata rivers of the Madre de Dios basin, Department Madre de Dios, Peru. Ecological notes. Gymnotus chaviro inhabit pools and runs of small terra firme streams as they enter the floodplain, and the vegetated margins of flooplain lakes, with substrates of leaf litter and organic rich mud. Specimens are most dense in submerged stems and roots of aquatic grasses (e. g., Oryza spp.) and floating macrophytes (e. g., Eichornia crassipes). At the period of low water (August) when collections were made, specimens were very abundant, aggregated closely together, and were not distributed into discrete territories. The holotype was collected in a small terra firme stream (1.2 m deep, 2.5 m wide, 25°C) with a muddy bottom and deeply undercut banks, about 1 km from the edge of the floodplain. Local Name. Anguilla, Spanish for eel. Etymology. From the common name for Gymnotus in the language of the Asheninka indigenous people (Arawak/ Maipurean language family). A noun in apposition. Remarks. Types specimens were restricted to localities in the Yuruá basin. Specimens from the Manu and Tampobata basins are excluded from the type series. Comparative examined material. Materials examined are listed in Campos-da-Paz & Costa (1996), Albert (2001), Albert & Crampton (2001, 2003), Campos-da-Paz (2002), Crampton et al. (2003, 2005), Maldonado-Ocampo & Albert (2003), Fernandes et al. (2005), Cognato et al. (2007), and Richer-de- Forges et al. (2009)., Published as part of Maxime, Emmanuel L. & Albert, James S., 2009, A new species of Gymnotus (Gymnotiformes: Gymnotidae) from the Fitzcarrald Arch of southeastern Peru, pp. 579-585 in Neotropical Ichthyology 7 (4) on pages 580-584, DOI: 10.1590/S1679-62252009000400004, http://zenodo.org/record/4567225, {"references":["Albert, J. S., W. G. R. Crampton, D. H. Thorsen & N. R. Lovejoy. 2004. Phylogenetic systematics and historical biogeography of the Neotropical electric fish Gymnotus (Teleostei: Gymnotiformes). Systematic and Biodiversity, 2: 375 - 417.","Albert, J. S. & W. G. R. Crampton. 2005. Diversity and phylogeny of Neotropical electric fishes (Gymnotiformes). Pp. 360 - 409. In: Bullock, T. H., C. D. Hopkins, A. N. Popper & R. R. Fay (Eds.). Electroreception. Vol. 21. New York, Springer Handbook of Auditory Research, 485 p.","Campos-da-Paz, R. 2002. Gymnotus diamantinensis, a new species of electric knifefish from upper rio Arinos basin, Brazil (Ostariophysi: Gymnotidae). Ichthyological Exploration of Freshwaters, 13: 185 - 192.","Albert, J. S. & W. G. R. Crampton. 2003. Seven new species of the Neotropical electric fish Gymnotus (Teleostei, Gymnotiformes) with a redescription of G. carapo (Linnaeus). Zootaxa, 287: 1 - 54.","Albert, J. S. 2001. Species diversity and phylogenetic systematics of American knifefishes (Gymnotiformes, Teleostei). Miscellaneous Publications, Museum of Zoology, University of Michigan, 190: 1 - 129.","Maldonado-Ocampo, J. A. & J. S. Albert. 2003. Species diversity of gymnotiform fishes in Colombia. Biota Colombiana, 4: 147 - 165.","Fernandes, F. M. C., J. S. Albert, M. D. Z. Daniel-Silva, C. E. Lopes, W. G. R. Crampton & L. F. Almeida-Toledo. 2005. A new Gymnotus (Teleostei: Gymnotiformes: Gymnotidae) from the Pantanal Matogrossense of Brazil and adjacent drainages: continued documentation of a cryptic fauna. Zootaxa, 933: 1 - 14.","Cognato, D., M. Richer-de-Forges, J. S. Albert & W. G. R. Crampton. 2007. Gymnotus chimarrao: a new species of electric fish (Gymnotiformes: Gymnotidae) from Southern Brazil. Ichthyological Exploration of Freshwaters, 18 (4): 375 - 382."]}

Gymnotus refugio, new species, is described from coastal rivers of Rio Grande do Sul and Santa Catarina states, Brazil. It is diagnosed from most species of the Gymnotus pantherinus species-group by the coloration pattern, further differing from G. pantherinus and G. capitimaculatus on the basis of morphometric and meristic characters. The new species represents the most meridional record of the G. pantherinus species-group.

[[Gymnotus (L.)]] Introduction Gymnotus (L.) is a monophyletic group of gymnotiform fishes that is readily recognizable by the presence of a superior mouth with a prognathous lower jaw, a fleshy pad of electroreceptor organs and support tissues over the tip of the snout and mandible, a pair of dorsally oriented pipe-shaped anterior nares partially or entirely included within the gape, a ventrally curved rictus, the lateral position of the eyes on the head (at a horizontal with the gape), numerous long rami of the posterior lateral line extending ventrally on the caudal portion of the body, and a very long body cavity with 31-48 precaudal vertebrae (Albert 2001; Albert et al. 2005). Most Gymnotus species possess obliquely oriented bands of dark and light pigments along the length of the body from which they derive the English common name “banded knife-fish.” Gymnotus species extend from the Pampas of Argentina (36 °S) to Chiapas, Mexico (18 °N) and are known from the continental waters of all South and Middle American countries except Chile and Belize (Albert 2001). Many species of Gymnotus exhibit sizable variation in body shape and color patterns within and between populations (MagoLeccia1994; Albert & Miller 1995; Albert et al. 1999). Since these features are also used to recognize Gymnotus species, much of the diversity in the group remains undocumented and many undescribed species exist in museum collections and in the wild (Nelson, 1994, Albert et al. 1999; Albert 2001). There are currently 31 species of Gymnotus recognized (Albert et al. 2005). As for many Neotropical freshwater fishes, species diversity of this group is greatest in the Amazon basin where 15 species are known, 10 of which inhabit vrzea Whitewater floodplains (Albert & Crampton 2001, Crampton et al. 2003). Fewer data are available on species diversity, distributions and population structure of this group in other Neotropical basins (Fernandes-Matioli et al. 2000). In central and southeastern Brazil many specimens are ascribed to G. carapo L., the type locality of which is in Surinam (Albert 2001). Three other Gymnotus species have been recognized from central and southeastern Brazil: G. pantherinus (Steindachner) from the coastal drainages of southeastern, Brazil, G. inaequilabiatus (Valenciennes) from the Parana-Paraguay basin and some coastal drainages of Uruguay and southeastern Brazil, and G. sylvius (Albert et al. 1999) from coastal drainages of São Paulo State and the Rio Paraná basin. Here we describe a new species discovered by one of us (FMCF) as part of a survey of population structure and genealogical/coalescent analysis of Gymnotus from the Pantanal Matogrossense, Brazil.

Gymnotus cf. anguillaris. - Brazil: INPA 11553 (1), 111 mm, Mato Grosso, Ig. do aeroporto. Cidade de Humboldt. Rio Aripuana, 1976.XI.09.INPA 11556 (1), 185 mm, Mato Grosso, Ig. do aeroporto. Cidade de Humboldt. Rio Aripuana, 1976.XI.09.INPA 6388b (1) 348 mm, Mato Grosso, Rio Aripuana. Regiao do Castanhal, 1976.VIII.22.INPA 6407b (4) 160-190 mm, Mato Grosso, Ig. do aeroporto. Cidade de Humboldt, Rio Aripuana, 1976.XI.09.INPA 6408b (9) 96-223 mm, Mato Grosso, Ig. acima da cachoeira, Rio Aripuana, 1976.XI.14., Published as part of Flora M. C. Fernandes, James S. Albert, Maria de Fatima Z. Daniel-Silva, Carlos E. Lopes, William G. R. Crampton & Lurdes F. Almeida-Toledo, 2005, A new Gymnotus (Teleostei: Gymnotiformes: Gymnotidae) from the Pantanal Matogrossense of Brazil and adjacent drainages: continued documentation of a cryptic fauna., pp. 1-14 in Zootaxa 933 on page 12

Gymnotus inaequilabeatus. - Brazil: MCP 7155 (1), 254 mm, Rio Maquine, Osorio, 1984.IX.26.MZUSP 46001 (1), 998 mm, Porto Primavera, Rio Parana, S��o Paulo, 1993.VIII.MZUSP 51667 (1), Paraibo do Sul, Jacarei, S��o Paulo, 1993.I.24.MZUSP 51268 (1), c. 370 mm, Rio Capivara, affluent do Rio Paranapanema, S��o Paulo, 1994.III.USNM 1643 (1), 791 mm, Rio Paraguay., Published as part of Flora M. C. Fernandes, James S. Albert, Maria de Fatima Z. Daniel-Silva, Carlos E. Lopes, William G. R. Crampton & Lurdes F. Almeida-Toledo, 2005, A new Gymnotus (Teleostei: Gymnotiformes: Gymnotidae) from the Pantanal Matogrossense of Brazil and adjacent drainages: continued documentation of a cryptic fauna., pp. 1-14 in Zootaxa 933 on page 12

[[Gymnotus (L.)]] Introduction Gymnotus (L.) is a monophyletic group of gymnotiform fishes that is readily recognizable by the presence of a superior mouth with a prognathous lower jaw, a fleshy pad of electroreceptor organs and support tissues over the tip of the snout and mandible, a pair of dorsally oriented pipe-shaped anterior nares partially or entirely included within the gape, a ventrally curved rictus, the lateral position of the eyes on the head (at a horizontal with the gape), numerous long rami of the posterior lateral line extending ventrally on the caudal portion of the body, and a very long body cavity with 31-48 precaudal vertebrae (Albert 2001; Albert et al. 2005). Most Gymnotus species possess obliquely oriented bands of dark and light pigments along the length of the body from which they derive the English common name ���banded knife-fish.��� Gymnotus species extend from the Pampas of Argentina (36 ��S) to Chiapas, Mexico (18 ��N) and are known from the continental waters of all South and Middle American countries except Chile and Belize (Albert 2001). Many species of Gymnotus exhibit sizable variation in body shape and color patterns within and between populations (MagoLeccia1994; Albert & Miller 1995; Albert et al. 1999). Since these features are also used to recognize Gymnotus species, much of the diversity in the group remains undocumented and many undescribed species exist in museum collections and in the wild (Nelson, 1994, Albert et al. 1999; Albert 2001). There are currently 31 species of Gymnotus recognized (Albert et al. 2005). As for many Neotropical freshwater fishes, species diversity of this group is greatest in the Amazon basin where 15 species are known, 10 of which inhabit vrzea Whitewater floodplains (Albert & Crampton 2001, Crampton et al. 2003). Fewer data are available on species diversity, distributions and population structure of this group in other Neotropical basins (Fernandes-Matioli et al. 2000). In central and southeastern Brazil many specimens are ascribed to G. carapo L., the type locality of which is in Surinam (Albert 2001). Three other Gymnotus species have been recognized from central and southeastern Brazil: G. pantherinus (Steindachner) from the coastal drainages of southeastern, Brazil, G. inaequilabiatus (Valenciennes) from the Parana-Paraguay basin and some coastal drainages of Uruguay and southeastern Brazil, and G. sylvius (Albert et al. 1999) from coastal drainages of S��o Paulo State and the Rio Paran�� basin. Here we describe a new species discovered by one of us (FMCF) as part of a survey of population structure and genealogical/coalescent analysis of Gymnotus from the Pantanal Matogrossense, Brazil., Published as part of Flora M. C. Fernandes, James S. Albert, Maria de Fatima Z. Daniel-Silva, Carlos E. Lopes, William G. R. Crampton & Lurdes F. Almeida-Toledo, 2005, A new Gymnotus (Teleostei: Gymnotiformes: Gymnotidae) from the Pantanal Matogrossense of Brazil and adjacent drainages: continued documentation of a cryptic fauna., pp. 1-14 in Zootaxa 933 on pages 2-3

Gymnotus pantanal new species (Fig. 1) Holotype: MZUSP 67874, female, Brazil, Mato Grosso do Sul State, Rio Miranda, 196 mm, 20 July 2000, near Miranda, 20��11' 78" S, 56��30' 13" W, F. M. C. Fernandes. Paratypes: 2 spec. MZUSP 67875, 189 mm, and MZUSP 67876, 264 mm, Brazil, Mato Grosso do Sul State, Rio Paraguay, 22 July 2000, Corumb., 18��59' 81" S, 57��39' 24" W, F. M. C. Fernandes. Nontypes: Bolivia: UF 82146 (1), Santa Cruz, near Concepcion, Rio Blanco, 153 mm, 1990.06.16.Brazil: MZUSP 67876 (1), Mato Grosso do Sul, Rio Paraguay, 18��59'81"S, 57��39'24"W, 251 mm, 22 July 2000.MZUSP 67875 (1), Mato Grosso do Sul, Rio Paraguay, 18��59'81"S, 57��39'24"W, 192 mm, 22 July 2000.Paraguay: NRM 42830 (1), Rio Parana, 240 mm, 1998.03.15.NRM 42397 (1), Rio Paraguay, 171 mm, 1998.03.25.UF 38173 (1), Dept Cochabamba, Province Chapare, Rio Espiritu, Chapare-Mamore drainage, brook at Villa Tunari, elevation 350 m., 192 mm, 1982.XII.12.UMMZ 206080 (21), Arroyo in Parque Nacional Ybycui, Rio Paraguay, 82-260 mm, 1979.VI.20. Diagnosis: Gymnotus pantanal differs from other members of the G. pantherinus species-group (except G. anguillaris) in possessing a color pattern composed of thin obliquely oriented pale pigment bands (about one third the width of the dark bands) with wavy margins restricted to the ventral portion of the body (rarely extending above the lateral line) on the anterior half of the body. Gymnotus pantanal further differs from other members of the G. pantherinus species-group in possessing a wider head (72-77 vs. 52-69% head length). Gymnotus pantanal further differs from G. anguillaris in possessing more narrowly set eyes (37-41 vs. 43-56% head length), a deeper head (66-74 vs. 60-65% head length), larger branchial openings (38-43 vs. 29-36% head length), longer pectoral fins (51-56 vs. 42-50% head length), more pectoral-fin rays (mode 17 vs. 16), and fewer pored posterior lateral-line scales (to first ventral ramus: 47-58 vs. 58-62; total: 102-114 vs. 124-130). Description: Fig. 1 illustrates body shape and pigment patterns. Morphometric and meristic data for specimens in type series and additional lots in Table 1. Size up to 251 mm. No known sexual dimorphism. Adult body proportions attained at about 120 mm total length. Size at sexual maturity unknown. Adult body shape subcylindrical, ratio body width/depth 0.70-0.81. Body profile slender, body depth 8.0-9.5% total length. Head length moderate, 8.6-9.3% total length. Snout length moderate, 34-37% head length. Mouth width moderate, 44-48% head length. Preanal distance moderate, 82-93% head length. Anal-fin long, 78-82% total length. Scales present on entire post-cranial portion of body from nape to caudal appendage. Scales above lateral line large, (7-8, mode 8). Scales cycloid, ovoid. Scales over anal-fin pterygiophores large, (mode) 5-6 rows. Gape size in mature specimens large, extending to or beyond posterior nares. Mouth position superior, rictus decurved. Eye position below horizontal with front of mouth. Anterior narial pore partially or entirely included within gape. Circumorbial series ovoid. Maxilla orientation vertical. Maxilla rod- or paddle-shaped with straight ventral margin. Dorsoposterior laterosensory ramus of preopercle with single superficial pore. Cranial fontanels closed in juveniles and adults. Anterior margin of frontal straight, continuous with margins of adjacent roofing bones. Frontal postorbital process narrow, less than two times width of supraorbital canal. Frontal broad, its width at the posterior articulation of the infraorbital series subequal to that of parietal. Pectoral fin broad, with 15-19 (mode 17) rays. Anterior limb of cleithrum long, more than 1.8 times ascending limb. Cleithrum anterior notch absent. Cleithrum without large facet for insertion of muscle from supracleithrum. Body cavity long, with 35-38 (mode 37) precaudal vertebrae. Rib 5 broad, with a large medial triangular shelf. Hemal spines present. Displaced hemal spines absent. Anal fin of moderate length, with 217-260 rays. Multiple anal-fin ray branching posterior to rays 10-17. Lateral-line ventral rami 7-12. Lateral-line dorsal rami absent in adults. Length anal-fin pterygiophores equal to or longer than hemal spines. Caudal appendage long, more than 0.5 time pectoral-fin length in undamaged and unregenerated specimens. Single hypaxial electric organ, extending along entire ventral margin of body. Two to three (mode 3) rows of electroplates near caudal insertion of anal fin. Electric organ discharge not known. Color in alcohol: Ground color of body dark brown. All juveniles and some adults (TL more than 160 mm) with 21 to 26 obliquely oriented, thin pale-yellow bands with wavy irregular margins on ventrolateral surface, extending from tip of tail to pectoral-fin base. Some subadults and most adults with fewer pale bands. Band appearance variable in shape, width, arrangement, and number, both on and among individuals. Band-interband margins irregular and wavy. Dark bands evenly pigmented, or partially divided ventrally (inverted Y-shaped) at middle to posterior portions of body. Dark bands four times as broad as pale bands on anterior half of body. In adults pale bands rarely branched, and never extending above lateral line on anterior half of body. Interband contrast increases ventrally and caudally; more pronounced in smaller specimens. Anterior 80% of dorsum (anterior to anal-fin clear patch) without banding. Three bands from either side meet on ventral midline, between the anus and anal-fin origin. One band lies posterior to last analfin ray. Head not banded or blotched; ground color dark brown dorsally grading to lighter brown ventrally, without freckles and with numerous speckles distributed over branchiostegal membranes and ventral surface of head. Pectoral-fin rays brown or gray, interradial membranes hyaline. Anal-fin membrane uniformly light brown to dusky gray. Comparisons with other species. In terms of salient features of color pattern and general body proportions, G. pantanal most closely resembles G. anguillaris from which it differs by character states provided in the Diagnosis. Gymnotus anguillaris and G. pantanal can be differentiated from other members of the G. pantherinus species-group by the following unique combination of characters: no pale band at nape, pale bands not extending above lateral line on anterior half of body, adult body size greater than 200 mm total length, fewer ventral lateral-line rami (7-18 vs. 19-30), fewer anterior anal-fin rays without multiple branching (10-17 vs. 18-26), and a single row (vs. two rows) of conical teeth along outer margin of dentary. On morphometric grounds, G. pantanal can be separated from sympatric congeners (i.e., G. carapo, G. inaequilabiatus, and G. sylvius) of similar size (130-250 mm TL) by a shorter head (head length 8.6-10.1% vs. 10.5-14.0 total length) and a more slender body (BD 9.0-9.5 vs. 10.0-13.0% total length. Among species of Gymnotus, G. pantanal most closely resembles G. anguillaris from Surinam, in terms of morphometric, meristic, and color variables. Gymnotus pantanal shares several meristic counts with other species from southern Brazil, including the number of the pectoral-fin rays (16-18) and number of scales above the lateral line at midbody (7-8). Juvenile specimens of G. pantanal also share 21-26 oblique bands (or band pairs) with sympatric congeners and G. anguillaris from Surinam. Karyological features: Diploid number of 2n=40 chromosomes, arranged in seven pairs of metacentric/submetacentric and 13 pairs of subtelocentric/acrocentric chromosomes. Chromosome pair 19 with a secondary constriction on the short arms, at the site of active NORs (evidenced after silver staining). A third active NOR is also present in one of the homologues of the larger pair of metacentric/ submetacentric on the terminal region of the long arm. The C-bands evidence the constitutive heterochromatin distribution in the pericentromeric region of all chromosome pairs. The karyological features observed in the holotype (MZUSP 67874) are illustrated in Fig. 2 and summarized in Table 2. According to data available in the literature, G. pantanal shares the diploid number of 2n=40 chromosomes with G. sylvius. However, the chromosome morphology differs greatly between these two species. Gymnotus pantanal possesses seven pairs of metacentric/submetacentric and 13 pairs of subtelocentric/acrocentric chromosomes, whereas G. sylvius possesses 14 pairs of metacentric, 5 pairs of submetacentric and 1 pair of subtelocentric/acrocentric chromosomes. The occurrence of constitutive heterochromatin in the pericentromeric region of the chromosomes is shared with the other species from southern Brazil (see Fernandes-Matioli et al. 1998). G. pantanal also possesses a unique cytological characteristic among the species chromosomally characterized; the presence of 3 active NORs in the metaphase plates (only two active NORs is observed in the other species). Molecular characterization: Amplification of the microsatellite marker micro11 (Fernandes-Matioli et al. 2000) using the SPAR-PCR technique resulted in a unique pattern of two amplified bands (fragments) of relatively high molecular weight, 800 base pairs (bp) and 1,370 bp. This pattern was observed in ten individuals analyzed (Table 2, Fig. 3). The molecular marker micro11 exhibits species-specific patterns among members of the Gymnotidae (Fernandes-Matioli et al. 2000). The micro11 pattern observed in all G. pantanal individuals analyzed, with two bands of relatively high molecular size (800 bp and 1,370 bp, Table 2), differs conspicuously from its congeners (Fig. 3). Amplified fragments with high molecular weight, albeit with different size, are also observed in G. carapo (one of two bands with 1,476 bp), in G. inaequilabiatus (one of four bands with 1,968 bp) and in G. pantherinus (one of four bands with 1,150 bp). The molecular micro11 pattern observed in G. pantanal is unique among congeners in southern Brazil. Distribution: Known from the Parana-Paraguay system of Brazil and Paraguay, and the Rio Chapare-Mamor�� of Bolivia. Etymology: The specific epithet pantanal from the Pantanal Matogrossense of Brazil, the hydrological region of the type locality. A noun in apposition. Discussion Among congeners, G. pantanal most closely resembles G. anguillaris from the area of the type locality in Surinam in aspects of coloration, and also in several morphometric and meristic features associated with a highly elongate body (i.e., body slender, body cavity long, and relative head length short). In combination, these particular features are known to have diagnostic value for differentiating other Gymnotus species living in sympatry, under conditions when species-identities are well established from additional electric signal, chromosomal, or molecular data (Albert et al. 1999; Albert & Crampton, 2001). Gymnotus pantanal also differs from G. anguillaris in several features known to have diagnostic value at the species level within Gymnotus: i.e., interorbital distance, size of the branchial opening, pectoral-fin length, number of fin pectoral-fin rays, and lateral-line scale counts. At present it is not possible to determine whether phenotypic intergrades occur between G. pantanal and G. anguillaris. Specimens of the G. anguillaris species-complex are absent from collections from the central and eastern Amazon (Crampton, 1998; Albert & Crampton, 2001), including from the extensive INPA collections of these areas (JSA and WGRC, pers. obs.). Undescribed populations resembling G. anguillaris are known from tributaries of the Napo and Madeira rivers in the Amazon basin (Fig. 4), each possessing distinct phenotypes. The morphological, cytogenetic, and molecular data reported here indicate that the populations described here as G. pantanal represent a distinct species (i.e., a separately evolving evolutionary lineage) rather than a geographic variant of G. anguillaris. This hypothesis will be tested with future collections of the G. pantherinus species-group from across its range, and by comparisons of molecular sequence data., Published as part of Flora M. C. Fernandes, James S. Albert, Maria de Fatima Z. Daniel-Silva, Carlos E. Lopes, William G. R. Crampton & Lurdes F. Almeida-Toledo, 2005, A new Gymnotus (Teleostei: Gymnotiformes: Gymnotidae) from the Pantanal Matogrossense of Brazil and adjacent drainages: continued documentation of a cryptic fauna., pp. 1-14 in Zootaxa 933 on pages 4-11

Gymnotus pantanal new species (Fig. 1) Holotype: MZUSP 67874, female, Brazil, Mato Grosso do Sul State, Rio Miranda, 196 mm, 20 July 2000, near Miranda, 20°11' 78" S, 56°30' 13" W, F. M. C. Fernandes. Paratypes: 2 spec. MZUSP 67875, 189 mm, and MZUSP 67876, 264 mm, Brazil, Mato Grosso do Sul State, Rio Paraguay, 22 July 2000, Corumb., 18°59' 81" S, 57°39' 24" W, F. M. C. Fernandes. Nontypes: Bolivia: UF 82146 (1), Santa Cruz, near Concepcion, Rio Blanco, 153 mm, 1990.06.16.Brazil: MZUSP 67876 (1), Mato Grosso do Sul, Rio Paraguay, 18°59'81"S, 57°39'24"W, 251 mm, 22 July 2000.MZUSP 67875 (1), Mato Grosso do Sul, Rio Paraguay, 18°59'81"S, 57°39'24"W, 192 mm, 22 July 2000.Paraguay: NRM 42830 (1), Rio Parana, 240 mm, 1998.03.15.NRM 42397 (1), Rio Paraguay, 171 mm, 1998.03.25.UF 38173 (1), Dept Cochabamba, Province Chapare, Rio Espiritu, Chapare-Mamore drainage, brook at Villa Tunari, elevation 350 m., 192 mm, 1982.XII.12.UMMZ 206080 (21), Arroyo in Parque Nacional Ybycui, Rio Paraguay, 82-260 mm, 1979.VI.20. Diagnosis: Gymnotus pantanal differs from other members of the G. pantherinus species-group (except G. anguillaris) in possessing a color pattern composed of thin obliquely oriented pale pigment bands (about one third the width of the dark bands) with wavy margins restricted to the ventral portion of the body (rarely extending above the lateral line) on the anterior half of the body. Gymnotus pantanal further differs from other members of the G. pantherinus species-group in possessing a wider head (72-77 vs. 52-69% head length). Gymnotus pantanal further differs from G. anguillaris in possessing more narrowly set eyes (37-41 vs. 43-56% head length), a deeper head (66-74 vs. 60-65% head length), larger branchial openings (38-43 vs. 29-36% head length), longer pectoral fins (51-56 vs. 42-50% head length), more pectoral-fin rays (mode 17 vs. 16), and fewer pored posterior lateral-line scales (to first ventral ramus: 47-58 vs. 58-62; total: 102-114 vs. 124-130). Description: Fig. 1 illustrates body shape and pigment patterns. Morphometric and meristic data for specimens in type series and additional lots in Table 1. Size up to 251 mm. No known sexual dimorphism. Adult body proportions attained at about 120 mm total length. Size at sexual maturity unknown. Adult body shape subcylindrical, ratio body width/depth 0.70-0.81. Body profile slender, body depth 8.0-9.5% total length. Head length moderate, 8.6-9.3% total length. Snout length moderate, 34-37% head length. Mouth width moderate, 44-48% head length. Preanal distance moderate, 82-93% head length. Anal-fin long, 78-82% total length. Scales present on entire post-cranial portion of body from nape to caudal appendage. Scales above lateral line large, (7-8, mode 8). Scales cycloid, ovoid. Scales over anal-fin pterygiophores large, (mode) 5-6 rows. Gape size in mature specimens large, extending to or beyond posterior nares. Mouth position superior, rictus decurved. Eye position below horizontal with front of mouth. Anterior narial pore partially or entirely included within gape. Circumorbial series ovoid. Maxilla orientation vertical. Maxilla rod- or paddle-shaped with straight ventral margin. Dorsoposterior laterosensory ramus of preopercle with single superficial pore. Cranial fontanels closed in juveniles and adults. Anterior margin of frontal straight, continuous with margins of adjacent roofing bones. Frontal postorbital process narrow, less than two times width of supraorbital canal. Frontal broad, its width at the posterior articulation of the infraorbital series subequal to that of parietal. Pectoral fin broad, with 15-19 (mode 17) rays. Anterior limb of cleithrum long, more than 1.8 times ascending limb. Cleithrum anterior notch absent. Cleithrum without large facet for insertion of muscle from supracleithrum. Body cavity long, with 35-38 (mode 37) precaudal vertebrae. Rib 5 broad, with a large medial triangular shelf. Hemal spines present. Displaced hemal spines absent. Anal fin of moderate length, with 217-260 rays. Multiple anal-fin ray branching posterior to rays 10-17. Lateral-line ventral rami 7-12. Lateral-line dorsal rami absent in adults. Length anal-fin pterygiophores equal to or longer than hemal spines. Caudal appendage long, more than 0.5 time pectoral-fin length in undamaged and unregenerated specimens. Single hypaxial electric organ, extending along entire ventral margin of body. Two to three (mode 3) rows of electroplates near caudal insertion of anal fin. Electric organ discharge not known. Color in alcohol: Ground color of body dark brown. All juveniles and some adults (TL more than 160 mm) with 21 to 26 obliquely oriented, thin pale-yellow bands with wavy irregular margins on ventrolateral surface, extending from tip of tail to pectoral-fin base. Some subadults and most adults with fewer pale bands. Band appearance variable in shape, width, arrangement, and number, both on and among individuals. Band-interband margins irregular and wavy. Dark bands evenly pigmented, or partially divided ventrally (inverted Y-shaped) at middle to posterior portions of body. Dark bands four times as broad as pale bands on anterior half of body. In adults pale bands rarely branched, and never extending above lateral line on anterior half of body. Interband contrast increases ventrally and caudally; more pronounced in smaller specimens. Anterior 80% of dorsum (anterior to anal-fin clear patch) without banding. Three bands from either side meet on ventral midline, between the anus and anal-fin origin. One band lies posterior to last analfin ray. Head not banded or blotched; ground color dark brown dorsally grading to lighter brown ventrally, without freckles and with numerous speckles distributed over branchiostegal membranes and ventral surface of head. Pectoral-fin rays brown or gray, interradial membranes hyaline. Anal-fin membrane uniformly light brown to dusky gray. Comparisons with other species. In terms of salient features of color pattern and general body proportions, G. pantanal most closely resembles G. anguillaris from which it differs by character states provided in the Diagnosis. Gymnotus anguillaris and G. pantanal can be differentiated from other members of the G. pantherinus species-group by the following unique combination of characters: no pale band at nape, pale bands not extending above lateral line on anterior half of body, adult body size greater than 200 mm total length, fewer ventral lateral-line rami (7-18 vs. 19-30), fewer anterior anal-fin rays without multiple branching (10-17 vs. 18-26), and a single row (vs. two rows) of conical teeth along outer margin of dentary. On morphometric grounds, G. pantanal can be separated from sympatric congeners (i.e., G. carapo, G. inaequilabiatus, and G. sylvius) of similar size (130-250 mm TL) by a shorter head (head length 8.6-10.1% vs. 10.5-14.0 total length) and a more slender body (BD 9.0-9.5 vs. 10.0-13.0% total length. Among species of Gymnotus, G. pantanal most closely resembles G. anguillaris from Surinam, in terms of morphometric, meristic, and color variables. Gymnotus pantanal shares several meristic counts with other species from southern Brazil, including the number of the pectoral-fin rays (16-18) and number of scales above the lateral line at midbody (7-8). Juvenile specimens of G. pantanal also share 21-26 oblique bands (or band pairs) with sympatric congeners and G. anguillaris from Surinam. Karyological features: Diploid number of 2n=40 chromosomes, arranged in seven pairs of metacentric/submetacentric and 13 pairs of subtelocentric/acrocentric chromosomes. Chromosome pair 19 with a secondary constriction on the short arms, at the site of active NORs (evidenced after silver staining). A third active NOR is also present in one of the homologues of the larger pair of metacentric/ submetacentric on the terminal region of the long arm. The C-bands evidence the constitutive heterochromatin distribution in the pericentromeric region of all chromosome pairs. The karyological features observed in the holotype (MZUSP 67874) are illustrated in Fig. 2 and summarized in Table 2. According to data available in the literature, G. pantanal shares the diploid number of 2n=40 chromosomes with G. sylvius. However, the chromosome morphology differs greatly between these two species. Gymnotus pantanal possesses seven pairs of metacentric/submetacentric and 13 pairs of subtelocentric/acrocentric chromosomes, whereas G. sylvius possesses 14 pairs of metacentric, 5 pairs of submetacentric and 1 pair of subtelocentric/acrocentric chromosomes. The occurrence of constitutive heterochromatin in the pericentromeric region of the chromosomes is shared with the other species from southern Brazil (see Fernandes-Matioli et al. 1998). G. pantanal also possesses a unique cytological characteristic among the species chromosomally characterized; the presence of 3 active NORs in the metaphase plates (only two active NORs is observed in the other species). Molecular characterization: Amplification of the microsatellite marker micro11 (Fernandes-Matioli et al. 2000) using the SPAR-PCR technique resulted in a unique pattern of two amplified bands (fragments) of relatively high molecular weight, 800 base pairs (bp) and 1,370 bp. This pattern was observed in ten individuals analyzed (Table 2, Fig. 3). The molecular marker micro11 exhibits species-specific patterns among members of the Gymnotidae (Fernandes-Matioli et al. 2000). The micro11 pattern observed in all G. pantanal individuals analyzed, with two bands of relatively high molecular size (800 bp and 1,370 bp, Table 2), differs conspicuously from its congeners (Fig. 3). Amplified fragments with high molecular weight, albeit with different size, are also observed in G. carapo (one of two bands with 1,476 bp), in G. inaequilabiatus (one of four bands with 1,968 bp) and in G. pantherinus (one of four bands with 1,150 bp). The molecular micro11 pattern observed in G. pantanal is unique among congeners in southern Brazil. Distribution: Known from the Parana-Paraguay system of Brazil and Paraguay, and the Rio Chapare-Mamoré of Bolivia. Etymology: The specific epithet pantanal from the Pantanal Matogrossense of Brazil, the hydrological region of the type locality. A noun in apposition. Discussion Among congeners, G. pantanal most closely resembles G. anguillaris from the area of the type locality in Surinam in aspects of coloration, and also in several morphometric and meristic features associated with a highly elongate body (i.e., body slender, body cavity long, and relative head length short). In combination, these particular features are known to have diagnostic value for differentiating other Gymnotus species living in sympatry, under conditions when species-identities are well established from additional electric signal, chromosomal, or molecular data (Albert et al. 1999; Albert & Crampton, 2001). Gymnotus pantanal also differs from G. anguillaris in several features known to have diagnostic value at the species level within Gymnotus: i.e., interorbital distance, size of the branchial opening, pectoral-fin length, number of fin pectoral-fin rays, and lateral-line scale counts. At present it is not possible to determine whether phenotypic intergrades occur between G. pantanal and G. anguillaris. Specimens of the G. anguillaris species-complex are absent from collections from the central and eastern Amazon (Crampton, 1998; Albert & Crampton, 2001), including from the extensive INPA collections of these areas (JSA and WGRC, pers. obs.). Undescribed populations resembling G. anguillaris are known from tributaries of the Napo and Madeira rivers in the Amazon basin (Fig. 4), each possessing distinct phenotypes. The morphological, cytogenetic, and molecular data reported here indicate that the populations described here as G. pantanal represent a distinct species (i.e., a separately evolving evolutionary lineage) rather than a geographic variant of G. anguillaris. This hypothesis will be tested with future collections of the G. pantherinus species-group from across its range, and by comparisons of molecular sequence data.

Gymnotus ardilai new species (Figs. 1���3). Holotype. ��� IAvHP 3477 (CAR 05), 430 mm TL. Female. Colombia, Santander, Gir��n, R��o de Oro, collected by Carlos Ardila, 6 January 2000. Paratypes. ��� IAvHP 4001 (2, 219.2 ��� 329 mm TL, males). Colombia, Santander, Gir��n, R��o de Oro, collected by Carlos Ardila, 4 January 2004. Diagnosis. ��� Gymnotus ardilai differs from all congeners in possessing the following unique combination of characters: 1, a clear patch at the caudal end of the anal fin; 2, two laterosensory canal pores (from the preopercular��mandibular series) in the dorso��posterior portion of the preopercle; 3, progressive loss of alternating dark and light pigment bands with the size, with no pigment bands in individuals more than 350 mm TL (a pattern that is readily distinguishable from all other described species of the G. carapo ��species group except populations of G. esmeraldas from the Guayaquil basin); 4, a long head (HL 10.2��� 11.2 % TL total length vs. 7.9���11.8 % in all other species except G. carapo and G. a r a �� paima); 5, many (9���10) scales over anal fin pterygiophores (vs. 4���9 in all other species except G. arapaima); 6, few (47���48) pored lateral��line scales to first ventral ramus (vs. 32 ���38 [median 37] in G. mamiraua, vs. 42���52 [median 48] in G. carapo, and vs. 50���64 in all other species); 7, a low (84 n = 1) total number of pored lateral��line scales (84 n = 1 vs. 93 ���108 [median 98] in G. carapo, and vs. 106���140 in all other species except G. mamiraua); and 8, a relatively large eye (orbital diameter 8.5 ���9.0 % HL vs. 6.0���7.0 % in G. carapo). Description. Body shape and pigment patterns illustrated in Figs. 1 and 2. Morphometrics and meristics data for the holotype and paratypes are presented in Tables 2 and 3. Size of maturity and sexual dimorphism unknown. However, the holotype which corresponds to a female, presents a developed gonad that is present in 2 / 4 of the body and presents a yellow color. Scales cycloid, ovoid, present on entire post��cranial portion of body from nape to tip of caudal appendage. Scales on dorsal surface relatively large at midbody, eight to nine rows from lateral��line to dorsal midline. Scales small over pterygiophores, nine to 10 scale rows. Lateral��line scales approximately 4.3 mm high by 4.0 mm long in humeral region (n = 1); 5.6 mm high by 6.3 mm long at midbody (n = 1); 3 mm high by 3.5 mm long dorsal to anterior margin of clear patch on anal��fin (n = 1). Gape size in mature specimens large, extending beyond posterior nares. Mouth position superior, lower jaw longer than upper, rictus decurved. Chin fleshy and bulbous with thick pad of electroreceptor organs and support tissues overlying tip of snout and oral jaws. Anterior narial pore included within gape in large narial fold. Anterior nares large, subequal to diameter of eye. Branchial opening moderate (31.2���38.8 % HL). Circumorbital series ovoid. Ethmoid region between anterior nares moderate, its anterior margin rounded. Eye position lateral, lower margin of eye slightly ventral to rictus. Eye relatively large, orbital diameter 8.5 ���9.0 % HL. Premaxilla and dentary with one row of large, slightly recurved, conical teeth. Premaxilla with 14���22 (n = 2) teeth disposed in single row along outer margin. Dentary with 17���26 (n = 3) teeth disposed in single row along outer margin. Color in life. Head not banded, spotted or blotched, uniformly dark brown but slightly paler in gular region (Fig. 3). Numerous minute chromatophores speckled over branchiostegal membranes and ventral surface of head. Pectoral��fin rays dark brown or black, interradial membranes hyaline. Anal��fin never blotched, spotted or marked. Analfin rays and membrane dark gray or black on anterior 80 % of its length, translucent on posterior 20 %. Color variation is progressively correlated with size with larger individuals losing the light bands. Juvenals (34 mm TL) with 15���17 thin well��defined pale bands (Fig. 4). Electric organ discharge. Unknown Distribution. Gymnotus ardilai is known only from the R��o de Oro, where it meets the R��o Lebrija, in the Magdalena Basin, Colombia (Fig. 5). Habitat and Ecology. The type and only known locality is an Andean whitewater river (c. 1000 meters above sea level, 1.5 meters deep) with low flow, low transparency and high sediment load. Gymnotus ardilai is found free swimming along the river margin. The species coexists with Eigenmannia virescens, Pimelodella chagresi, Rhamdia quelen, Chaetostoma thomsoni, Dolicancistrus carnegiei, Geophagus steindachneri, Aequidens pulcher, Creagrutus magdalenae and Poecilia reticulata. The type locality is heavily polluted from effluents of the municipalities of Pie de Cuesta, Floridablanca and Gir��n. The effect of pollution on the ecology of G. ardilai is unknown, although this species is very rarely collected and presumably present in low population densities. Examination of the stomach content of the Paratype (212.9 mm TL) shows a diet consisting mostly of aquatic invertebrates, especially larval Odonata. Common name. Lamprea. Etymology. Specific epithet in honor to Dr. Carlos A. Ardila Rodriguez, President of the Colombian Ichthyological Association (ACICTIOS), who has contributed to the knowledge of Colombian ichthyology., Published as part of Maldonado-Ocampo, Javier A. & Albert, James S., 2004, Gymnotus ardilai: a new species of Neotropical electric fish (Ostariophysi: Gymnotidae) from the Rio Magdalena Basin of Colombia, pp. 1-10 in Zootaxa 759 on pages 5-9, DOI: 10.5281/zenodo.158333

[[Gymnotus]] The weakly electric Neotropical fish genus Gymnotus has been the subject of several taxonomic studies in recent years (Mago-Leccia 1994; Albert & Miller 1995; Campos da Paz 1996; Campos da Paz & Costa 1996; Fernandes-Matioli et al.,1998a; 1998b; Albert et al., 1999; Campos da Paz 2000; Fernandes-Matioli et al., 2000; Albert 2001; Albert & Crampton 2001; Fernandes-Matioli & Almeida-Toledo 2001; Campos da Paz 2002; Albert & Crampton 2003; Campos da Paz 2003). Until recently Gymnotus was recognized as the only genus in the family Gymnotidae. The monotypic genus Electrophorus Gill, comprising the single strongly electric species Electrophorus electricus (L.) was recently included in the Gymnotidae (Albert 2001). There are currently 27 valid species of Gymnotus found throughout the humid Neotropics (Albert 2003), of which nine are found in Colombia (Maldonado-Ocampo & Albert 2003). Albert (2001) and Albert and Crampton (2001) summarize the diagnostic characters of Gymnotus. Albert and Miller (1995) and Albert (2001) recognize three species groups within the genus based on color pattern and body proportions. These are the G. cylindricus, G. pantherinus, and G. carapo species-groups. The species composition and geographical range of these groups are summarized in Table 1. The G. cylindricus species-group is endemic to both Atlantic and Pacific drainages of Middle America and comprises just two species. The G. pantherinus species-group is represented by 12 species with distributions from Panama to Paraguay. The G. carapo species-group is endemic to South America and is represented by 13 species distributed from the Pacific slope of Colombia to the Pampas of Argentina. Species in the G. carapo species-group can be distinguished from those in the other two species-groups by the possession of: a clear or pale patch near the caudal end of the anal fin, most visible in juveniles and subadults (60-150 mm); two (vs. one) laterosensory canal pores from the preopercular-mandibular series in the dorsoposterior portion of preopercle.

[[Gymnotus]] The weakly electric Neotropical fish genus Gymnotus has been the subject of several taxonomic studies in recent years (Mago-Leccia 1994; Albert & Miller 1995; Campos da Paz 1996; Campos da Paz & Costa 1996; Fernandes-Matioli et al.,1998a; 1998b; Albert et al., 1999; Campos da Paz 2000; Fernandes-Matioli et al., 2000; Albert 2001; Albert & Crampton 2001; Fernandes-Matioli & Almeida-Toledo 2001; Campos da Paz 2002; Albert & Crampton 2003; Campos da Paz 2003). Until recently Gymnotus was recognized as the only genus in the family Gymnotidae. The monotypic genus Electrophorus Gill, comprising the single strongly electric species Electrophorus electricus (L.) was recently included in the Gymnotidae (Albert 2001). There are currently 27 valid species of Gymnotus found throughout the humid Neotropics (Albert 2003), of which nine are found in Colombia (Maldonado-Ocampo & Albert 2003). Albert (2001) and Albert and Crampton (2001) summarize the diagnostic characters of Gymnotus. Albert and Miller (1995) and Albert (2001) recognize three species groups within the genus based on color pattern and body proportions. These are the G. cylindricus, G. pantherinus, and G. carapo species-groups. The species composition and geographical range of these groups are summarized in Table 1. The G. cylindricus species-group is endemic to both Atlantic and Pacific drainages of Middle America and comprises just two species. The G. pantherinus species-group is represented by 12 species with distributions from Panama to Paraguay. The G. carapo species-group is endemic to South America and is represented by 13 species distributed from the Pacific slope of Colombia to the Pampas of Argentina. Species in the G. carapo species-group can be distinguished from those in the other two species-groups by the possession of: a clear or pale patch near the caudal end of the anal fin, most visible in juveniles and subadults (60-150 mm); two (vs. one) laterosensory canal pores from the preopercular-mandibular series in the dorsoposterior portion of preopercle., Published as part of Javier A. Maldonado-Ocampo & James S. Albert, 2004, Gymnotus ardilai: a new species of Neotropical electric fish (Ostariophysi: Gymnotidae) from the Rio Magdalena Basin of Colombia., pp. 1-10 in Zootaxa 759 on pages 1-2