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During an expedition to the headwaters of the Rio das Mortes, Mato Grosso, in the Brazilian Shield, a new species of Serrapinnus was found. The new species is distinguished from all congeners by having eight branched dorsal-fin rays, three premaxillary teeth, and a conspicuous dark stripe extending from the eye to the caudal-fin median rays. Among congeners, a similar coloration pattern is present only in S. sterbai, but in that species the stripe usually originates posterior to the eye, on the opercle, and extends to the caudal-fin median rays. In the single locality where the new species was captured, it occurs syntopically with Hyphessobrycon cf. vilmae, another small characid in which a dark midlateral stripe is quite remarkable. Both species were captured together and were observed in situ swimming in mixed shoals. Thus, it is suggested that both species increase their individual chances of survival through the strategy of “protective association” via numeric mimicry.

Serrapinnus sp. 2 Fig. 10 Body elongated; greatest body depth contained 2.8 to 3.9 and caudal peduncle depth 8.0 to 10.7 times in SL; head length 4.0 to 4.6, predorsal distance 1.8 to 2.0 and caudal peduncle length 9.7 to 10.8 in SL; snout length 3.1 to 3.9, horizontal orbital diameter 2.0 to 2.6 and least interorbital width 2.5 to 3.5 in HL. Mouth terminal; premaxilla with 4 or 5, dentary with 6, and maxilla with 2 teeth. Lateral line incompletely pored, with 6 or 7 pored scales; longitudinal series with 31-34 scales; transverse series above lateral line with 3½ scale rows and below with 3 or 3½ scale rows. Dorsal fin with 11, pectoral fin with 12 or 13, pelvic fin with 8 or 9, anal fin with 20-22 and caudal fin with 19 rays. Ground color whitish; dark-brown longitudinal stripe on flank, from pseudotympanum to caudal peduncle; dark-brown rounded blotch on posterior portion of caudal peduncle and caudal-fin base, not extended to median caudal-fin rays. Hyaline fins; dorsal and anal fins with distal portion black (Graça, Pavanelli, 2007). Maximum standard length. 29.0 mm (Graça, Pavanelli, 2007). Distribution. Upper rio Paraná basin., 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 39, 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."]}

Serrapinnus notomelas (Eigenmann, 1915) Fig. 10 Body elongated; greatest body depth contained 2.4 to 2.8 and caudal peduncle depth 8.2 to 8.6 times in SL; head length 3.5 to 4.0, predorsal distance 1.8 to 2.0 and caudal peduncle length 9.5 to 10.3 in SL; snout length 3.5 to 3.8, horizontal orbital diameter 2.3 to 3.2 and least interorbital width 2.6 to 3.0 in HL. Mouth terminal; premaxilla with 4 or 5, dentary with 6 or 7 and maxilla with 1 or 2 teeth. Lateral line incompletely pored, with 5-7 pored scales; longitudinal series with 30-34 scales; transverse series above lateral line with 3½ or 4 scale rows and below with 3 or 3½ scale rows. Dorsal fin with 10 or 11, pectoral fin with 12 or 13, pelvic fin with 8 or 9, anal fin with 19-24 and caudal fin with 19 rays. Ground color whitish; dark-brown diffuse longitudinal stripe on flank, from pseudotympanum to caudal peduncle; black rounded blotch on posterior portion of caudal peduncle and caudal-fin base, not extended to median caudal-fin rays. Dorsal fin with black chromatophores along two unbranched and first branched rays and proximal half of remaining; pectoral, pelvic, anal and caudal fins yellowish (Graça, Pavanelli, 2007). Maximum standard length. 40.0 mm (Graça, Pavanelli, 2007). Distribution. Upper rio Paraná basin., 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 39, DOI: 10.1590/1982-0224-20170094, http://zenodo.org/record/3678395, {"references":["Eigenmann CH. The Cheirodontinae, a subfamily of minute characid fishes of South America. Mem Mus Comp Zool. 1915; 7 (1): 1 - 100.","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."]}

Serrapinnus heterodon (Eigenmann, 1915) Fig. 10 Body elongated; greatest body depth contained 3.3 to 4.0 and caudal peduncle depth 8.6 to 10.5 times in SL; head length 4.1 to 4.4, predorsal distance 1.9 to 2.0 and caudal peduncle length 5.0 to 6.4 in SL; snout length 2.8 to 3.2, horizontal orbital diameter 2.8 to 3.2 and least interorbital width 3.0 to 3.5 in HL. Mouth terminal; premaxilla with 5 or 6, dentary with 4-8 teeth with expanded tips, and maxilla with 1 to 3 teeth. Lateral line completely pored, with 32-36 pored scales; longitudinal series with 32-36 scales; transverse series above lateral line with 6 scale rows and below with 3-4 scale rows. Dorsal fin with 11, pectoral fin with 10-12, pelvic fin with 8, anal fin with 19-22 and caudal fin with 19 rays. Ground color whitish; dark-brown longitudinal stripe on flank, from pseudotympanum to caudal peduncle; black oval, horizontally elongated, blotch on posterior portion of caudal peduncle and caudal-fin base, not extended to median caudal-fin rays. Maximum standard length. 30.9 mm. Biological data. Feeding habit omnivorous; total spawning, and spawning period during rainy season (Gonçalves et al., 2011). Distribution. Upper rio Paraná and rio São Francisco basins, and coastal drainages of the Rio Grande do Norte State, Northeastern Brazil. Remarks. Some specimens of Serrapinnus heterodon were identified as Odontostilbe sp. (now as O. avanhandava) by Graça, Pavanelli (2007). Both species occur in the upper rio Paraná floodplain, where S. heterodon has been captured since 2008 by the Nupélia staff. Serrapinnus heterodon can be distinguished by having the dentary teeth with three wide central cusps of same size and two small lateral ones, caudal peduncle blotch oval-shaped, reaching median caudal-fin rays, and mature males with a ventrally arched caudal peduncle (one of the synapomorphies for the genus, according to Malabarba, 1998) (vs. dentary teeth slender and pointed, with one central cusp longer than the four lateral ones, caudal peduncle blotch rounded, not reaching the median caudal-fin rays, and mature males not having the caudal peduncle arched, in Odontostilbe avanhandava). The confusion between the specimens of the upper rio Paraná floodplain can be associated with the completely pored lateral line. This character is common in Odontostilbe, whereas the number of pored scales is reduced in Serrapinnus. The only exception in Serrapinnus is found in S. heterodon, which has a completely pored lateral line., 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 37, DOI: 10.1590/1982-0224-20170094, http://zenodo.org/record/3678395, {"references":["Eigenmann CH. The Cheirodontinae, a subfamily of minute characid fishes of South America. Mem Mus Comp Zool. 1915; 7 (1): 1 - 100.","Goncalves CS, Souza UP, Braga FMS. Population structure, feeding and reproductive aspects of Serrapinnus heterodon (Characidae, Cheirodontinae) in a Mogi Guacu reservoir (SP), upper Parana River basin. Acta Limnol Bras. 2011; 23 (1): 13 - 22.","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.","Malabarba LR. Monophyly of the Cheirodontinae, characters and major clades (Ostariophysi: Characidae). In: Malabarba LR, Reis RE, Vari RP, Lucena ZMS, Lucena CAS, editors. Phylogeny and classification of Neotropical fishes. Porto Alegre: Edipucrs; 1998. p. 193 - 233."]}

The study of the life history attributes directed to the growth and reproduction of semiarid animals may facilitate the understanding of how individuals remain in environmental conditions that influence their survival. The aim of this work was to analyze how occur the reproductive and somatic investment of Serrapinnus and Poecilia fish species in two hydroperiods of an intermittent stream, and to compare these investments not only interspecifically but also intra and intergenerally. Specimens of the species were collected in the Mundaú river basin to evaluate life history attributes related to growth (weight, length and relation between parameters) and reproduction (sex, stage of macroscopic and histological maturation and gonadosomatic relation). The reproduction of S. heterodon indicated to occur during the flood, while in the dry period the species invests in growth. The S. piaba species, as well as of the same genus, also showed to reproduce in the full river period, however invested in growth and somatic maintenance in both periods. Poecilia vivipara showed different results from those found for the two previous ones, with mature and pregnant females in both periods, with more fertilized females found in the dry season and more mature oocytes during the flood. Concerning to growth, P. vivipara indicated to invest more during the flood. It can also be observed that the females of the three analyzed species have a smaller maturation size than those found in the literature, and may indicate that the intermittent river environment selects individuals that anticipate their maturation size. O estudo dos atributos de história de vida direcionados ao crescimento e reprodução de animais do semiárido podem facilitar o entendimento de como os indivíduos se mantêm em condições ambientais que influenciam sua sobrevivência. Com isso, o presente trabalho teve como objetivo analisar como se dá o investimento reprodutivo e somático de espécies de peixes dos gêneros Serrapinnus e Poecilia em dois hidroperíodos de um rio intermitente, e comparar esses investimentos não somente interespecificamente como também intra e intergenericamente. Exemplares das espécies foram coletados na bacia do rio Mundaú para então serem avaliados atributos de história de vida relacionados a crescimento (peso, comprimento e a relação entre os parâmetros) e reprodução (sexo, estágio de maturação macroscópico e histológico e relação gonadossomática). A reprodução de S. heterodon indicou ocorrer durante a cheia, enquanto no período seco a espécie investe em crescimento. A espécie S. piaba, assim como a de mesmo gênero, também demonstrou reproduzir-se no período cheio do rio, entretanto investiu em crescimento e manutenção somática em ambas as épocas. Já Poecilia vivipara mostrou resultados diferentes dos encontrados para as duas anteriores, com fêmeas maduras e grávidas em ambos os períodos, sendo mais fêmeas fertilizadas encontradas na época seca e mais ovócitos maduros durante a cheia. Quanto ao crescimento, a espécie indicou investir mais durante a cheia. Como as fêmeas das três espécies analisadas possuem comprimento de primeira maturação menores que encontrados na literatura, em outros locais, pode-se indicar que o ambiente de rio intermitente seleciona indivíduos de modo a anteciparem tamanho de maturação.

This study investigated the feeding habits of Serrapinnus microdon and S. calliurus and possible seasonal differences (rainy and dry seasons) in the utilization of food. The fish were collected monthly in Cancela stream, in the basin of the Manso/Cuiabá rivers in the State of Mato Grosso, from March 2003 to February 2004. Both species preferentially consumed resources of autochthonous origin, independently of the season. The diet of S. microdon was basically composed by immature forms of aquatic insects, with Chironomidae and Ephemeroptera predominating during the entire study period, thus showing a restricted diet (Ba = 0.27 in the rainy season, and 0.29 in the dry season). For S. calliurus, aquatic insects (especially Ephemeroptera) were equally important, but algae and detritus were also prominent depending on the season, showing a less specialized diet (Ba = 0.44 in the rainy season, and Ba = 0.48 in the dry season). Both fish species presented a benthivorous feeding habit; however, everything indicates that they live together without competition, because the food on which they depend is widely available. Serrapinnus calliurus was susceptible to seasonal changes in the availability of food resources.This study investigated the feeding habits of Serrapinnus microdon and S. calliurus and possible seasonal differences (rainy and dry seasons) in the utilization of food. The fish were collected monthly in Cancela stream, in the basin of the Manso/Cuiabá rivers in the State of Mato Grosso, from March 2003 to February 2004. Both species preferentially consumed resources of autochthonous origin, independently of the season. The diet of S. microdon was basically composed by immature forms of aquatic insects, with Chironomidae and Ephemeroptera predominating during the entire study period, thus showing a restricted diet (Ba = 0.27 in the rainy season, and 0.29 in the dry season). For S. calliurus, aquatic insects (especially Ephemeroptera) were equally important, but algae and detritus were also prominent depending on the season, showing a less specialized diet (Ba = 0.44 in the rainy season, and Ba = 0.48 in the dry season). Both fish species presented a benthivorous feeding habit; however, everything indicates that they live together without competition, because the food on which they depend is widely available. Serrapinnus calliurus was susceptible to seasonal changes in the availability of food resources.

Serrapinnus lucindai Jerep & Malabarba n. sp. Figs. 2c–d, 4b, 5b, 6, 7 Holotype. UFRGS 19198, 21, 1 mm SL, Município de Piranhas, tributary of rio Piranhas, between Piranhas and Bom Jardim de Goiás, 16°21’43.3”S 51°55’10.2972”W, 7 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep. Paratypes. All from Brazil, rio Tocantins-Araguaia basin. Goiás State: UFRGS 12029, 14, 14.7–29.6 mm SL, Município de Aragarças, córrego Capivara, between Aragarças and Jussara, 15°54’34.5”S 52°5’34.6”W, 5 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep. UFRGS 16444, 7, 22.5–26.3 mm SL, Município de Jussara, tributary of rio Claro, 15°58’0.0”S 50°48’59.7”W, 6 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep. UFRGS 16445, 35, 15.3–25.2 mm SL, collected with holotype. Tocantins State: UFRJ 2128, (3, 19.6–22.8 mm SL), Ilha do Bananal, Fazenda Canguçu, margin of rio Javares, 17 Feb 1994, W. Costa, G. Brasil & C. Campinha. UNT 4135, 3, 18.3–22.5 mm SL, Município de Brejinho de Nazar, córrego Sussuarana, 15 Feb 2002, NEAMB-UFT. UNT 4136, 2, 21.3–21.4 mm SL, Município de Guara, córrego Barreiro, 20 Oct 2000, NEAMB-UFT. UNT 4137, 1, 20.0 mm SL, Município de Lageado, rio Tocantins, close to UHE Lageado, rio Tocantins bottleneck, 27 Jan 2000, NEAMB-UFT. UNT 4745, 1, 25.3 mm SL, Município de Paraná, córrego Lageado, 7 Aug 2000, NEAMB-UFT. UNT 4759, 5, 16.1–19.7 mm SL, Município de Peixe, Fazenda Água Branca, lagoa Dionísio, 11 Sep 2001, NEAMB-UFT. UNT 6630, 4, 17.7–18.9 mm SL, Município de Tocantinópolis, córrego Santana, 29 Jun 2000, NEAMB-UFT. UNT 6927, 1, 21.7 mm SL, Município de Porto Nacional, rio Tocantins, 8 Oct 2002, NEAMB-UFT. UNT 7328, (1, 25.6 mm SL), Município de Porto Nacional, Fazenda Don Augusto, rio das Éguas, 19 Sep 2002, NEAMB-UFT. Mato Grosso State: MCP 40302, 44, 10.7–27.9 mm SL, Município de Porto Alegre do Norte, rio Xavantino 16 km south of Porto Alegre do Norte in highway BR 158, 11°01’30’’S 51°38’47’’W, 27 Oct 2005, J. P. Silva. UFRGS 12020, 7, 23.5–24.7 mm SL, Mato Grosso, Município de Pontal do Araguaia, stream tributary of rio das Garças, 15°54’27.9”S 52°15’51”W, 8 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep. UFRJ 1260, 58, 15.9–34.5 mm SL, (22, 22.1–34.5 mm SL, 4c&s 24.8–25.4 mm SL), creek 13 km west of rio das Mortes, left margin, between Água Boa and Cocalinho, 20 Feb 1993, W. Costa, C. Bore, R. Cunha & C. Muratori. Diagnosis. Serrapinnus lucindai is primarily distinguished from its congeners by the 17 to 19 ventral procurrent caudal-fin rays (vs. less than 17). Furthermore, the species can also be diagnosed from the remaining species of the genus by the presence of anal-fin hooks on the first unbranched and five branched rays of mature males (vs. anal-fin hooks on at least the anterior six branched rays on the remaining species of the genus), the absence of a continuous mid-lateral black stripe extending from the opercular region to the caudal-peduncle spot (vs. presence of a stripe in S. sterbai), the presence of 9 to 11 cusps on the premaxillary teeth (vs. 5 in S. microdon and S. potiguar, 7 in S. aster, 7 to 9 in S. calliurus, S. heterodon, S. kriegi, S. micropterus, S. notomelas and S. piaba, and 10 to 12 in S. gracilis and S. littoris), the dentary teeth without expanded cusps forming a sharp cutting edge and the incomplete lateral line (vs. dentary teeth with expanded cusps forming a sharp cutting edge and complete lateral line in S. heterodon), the hyaline dorsal fin (vs. fin with a proximal black blotch in S. notomelas), and an absence of a black spot in the posteroventral region of the abdomen (vs. the presence of a black spot in that region in S. kriegi). Description. Morphometric data in Table 2. Body elongated and compressed. Greatest body depth at dorsal-fin origin. Dorsal profile of head strongly convex from tip of snout to vertical through anterior margin of anterior nares; gently convex from that point to base of supraoccipital process, then straight to slightly concave along length of supraoccipital process. Predorsal profile convex. Profile straight to slightly convex along dorsal-fin base. Dorsal profile from last dorsal-fin ray insertion to adipose fin slightly convex in immatures and females, deeply convex in adult males with ventrally arched caudal peduncle. Dorsal profile straight to slightly concave from end of adiposefin base to anteriormost dorsal procurrent caudal-fin ray. Ventral profile of head convex along anterior region of lower jaw, gently convex from that point to pelvic-fin insertion. Ventral region straight to slightly concave from pelvic-fin insertion to anal-fin origin in immatures and females, deeply concave in mature males. Anal-fin base slightly concave in immatures and females; conspicuously convex in mature males along anterior region supporting hypertrophied anal-fin rays and then straight posteriorly. Ventral profile of caudal-peduncle slightly concave in immatures and females, convex in mature males due to hypertrophied procurrent caudal-fin rays extending ventrally through muscle and skin. Caudal peduncle slightly longer than deep; ventrally arched in alcohol preserved mature males. Posterior margin of opercle sinusoidal with upper portion concave and lower portion convex. Mouth terminal; mouth slit on horizontal through middle of pupil. Maxilla angled posteroventrally; posterior tip falling short of vertical through anterior border of eye and horizontal through ventral border of eye. All teeth multicuspidate, pedunculate, compressed and distally expanded (Fig. 7). Premaxillary teeth 4(4), with 9 to 11 cusps; central cusp slightly longer and wider than lateral cusps. Two (3) or 3(1) maxillary teeth with 5 to 11 cusps. Large dentary teeth 4(2) or 5(2) with 7 to 9 cusps, followed by one (4) tooth with 5 cusps, and 1 to 3 smaller teeth with 1 to 3 cusps. Small lateral cusp of dentary teeth overlapping adjacent tooth cusps, other than on posterior teeth. All dentary tooth cusps pointed upward or slightly recurved towards interior of mouth. Dorsal-fin rays ii,9*(31). Dorsal-fin origin slightly anterior to vertical through midlength of SL. First unbranched dorsal-fin ray about half length of second unbranched dorsal-fin ray. Second unbranched dorsal-fin ray longest in fin; branched rays slightly decreasing in size posteriorly. Adipose-fin origin on vertical through base of last anal-fin ray in females and posterior to that point in males. Anal-fin origin posterior to vertical through base of last dorsal-fin ray. Anal-fin rays iii*-iv,17*(2), 18(9), 19(13), 20(5) or 21(2). Distal border of anal-fin concave; last unbranched and anterior 5–8 branched rays longer than posterior rays. Tip of longest ray of depressed anal-fin of mature males falling short vertical through base of last anal-fin ray. Males with acute, elongate, retrorse hooks on distal half of anal-fin rays. Hooks posterolaterally arranged on last unbranched to 4 th or 5 th, rarely 7 th* (2) branched rays (Fig. 4b). Two or three unpaired hooks per ray segment of each contralateral lepidotrichia. Hooks generally located on posterior margin of posterior branches of anal-fin rays. Hook bearing anal-fin ray segments and branches progressively fused in course of maturation of males. Mature males with hypertrophied soft whitish tissue on interradial membrane anterior to anal-fin hooks. Pectoral-fin rays i,9*(19) or 10(12). Tip of pectoral fin falling short of pelvic-fin origin in immatures and females, but extending beyond that point in mature males. Pelvic-fin rays i,6(3) or 7*(28). Pelvic-fin origin slightly anterior to dorsal-fin origin. Longest pelvic-fin ray falling short of anal-fin origin in immatures and females, but extending beyond that point in adult males. Males with one or two acute elongate and ventral-medially placed hooks per segment of lepidotrichia on branched pelvic-fin rays. One specimen with hook on unbranched pelvic-fin ray. Adult males with hypertrophied soft whitish tissue anterior to hooks on ventral surface of pelvic-fin. Principal caudal-fin rays 18(1), 19*(29) or 20(1). Procurrent caudal-fin rays: dorsal 12(1), 13(1), 14(1) or 15(1); ventral 17(1), 18(2) or 19(1). Adult males with ventral procurrent caudal-fin rays hypertrophied, typically fused to each other and distal tips extending through ventral muscles and skin of caudal-peduncle (Figs. 2c, 6). Hypertrophied ventral procurrent caudal-fin rays elongated, rod-shaped, straight, proximally acute and round to flat distally. Scales cycloid; similar in size over all of body. Lateral line partially pored with 8*(13), 9(13) or 10(5) pored scales and 31(6), 32*(12), 33(7) or 34(6) in lateral-line scale series. Predorsal series in regular row 10(3), 11*(21) or 12(7). Scale rows between lateral line and dorsal-fin origin 5*(27) or 6(4). Scale rows between lateral line and pelvic-fin origin 4*(28) or 5(3). Scale rows around caudal peduncle 12(5), 13(11) or 14*(15). Axillary scale on pelvic-fin base extending posteriorly for one or two scales. Scales along anal-fin base 9(1), 10(3), 11(15), 12(7), 13(3) or 14(1). Counts based on four clear and stained specimens: Supraneurals 4(4); abdominal vertebrae 15(2) or 16(2); caudal vertebrae 17(2) or 18(2). Color in alcohol. Overall ground coloration of body pale yellow; darker dorsally from head to end of caudal peduncle. Body with faint dark, rarely silver, midlateral stripe. Longitudinal stripe extending from region slightly anterior to vertical through dorsal-fin origin to light pigmented area preceding caudal spot. Scale series above longitudinal line with higher concentration of darker chromatophores. Abdominal region ventral to longitudinal line lighter. Caudal spot rounded and black, preceded by lightly pigmented area and situated over posterior portion of caudal peduncle and base of central portion of caudal fin, not reaching dorsal or ventral margins of caudal peduncle. Fins mostly hyaline with scattered, sparse dark chromatophores. Dorsal fin with higher concentration of dark chromatophores along unbranched and first branched rays. Adipose fin with few sparse dark chromatophores. Caudal fin with dark chromatophores along fin rays, except for clear areas at base of each caudal-fin lobe. Humeral region with triangular, dark area resulting from pseudotympanum within musculature (Fig. 6). Sexual dimorphism. Mature males of S. lucindai have caudal peduncle ventrally arched, as in other species of Serrapinnus. Males also have hooks on the pelvic and anal-fin rays. The hook bearing anal-fin rays are hypertrophied, expanded in the sagittal plane, and commonly have the ray segments fused. The ventral procurrent caudal-fin rays of mature males are hypertrophied and extend ventrally beyond caudal peduncle muscle and skin (Figs. 2c–d, 4b, 6). Distribution. Serrapinnus lucindai is distributed in several tributaries of the rio Tocantins-Araguaia basin (Fig. 5b). Etymology. The species name lucindai is in honor to the Brazilian ichthyologist Paulo Henrique Franco Lucinda (UNT), in recognition of his contribution to the taxonomy of Neotropical freshwater fish, mainly those of the rio Tocantins basin.

Serrapinnus tocantinensis Malabarba & Jerep n. sp. Figs. 2g –h, 4d, 5d, 10, 11 Holotype. UFRGS 16442, 32.5 mm SL, male, Brazil, Mato Grosso, Município de Barra do Garças, córrego Fundo, tributary of rio das Garças, 16°52’40.5’’S 52°18’15.1’’W, 8 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep. Paratypes. All from Brazil, rio Tocantins-Araguaia basin. Goiás State: MCP 19987, 3, 33.5 –37.0 mm SL, rio Tocantins, 3 km down on Serra da Mesa Dam, Município de Minaçú, 13°50’51’’S 48°16’60’’W, 6 Nov 1996, C. A. S. Lucena & J. F. P. Silva. MCP 19988, 8, 28.5–37.3 mm SL (6, 34.8–37.5 mm SL), rio Tocantins, at porto do Rubão, Município de Minaçú, 13°44’31’’S 48°8’29’’W, 7 Nov 1996, C. A. S. Lucena & J. F. P. Silva. MCP 42175, 1, 25.0 mm SL, headwaters of córrego Salobrona, tributary of rio Claro, Município de Montes Claros de Goiás, 16°02’38’’S 51°22’11’’W, 5 Jun 2007, G. A. Pereira. MCP 42269, 2, 24.8–31.6 mm SL, córrego Salobrona, tributary of rio Claro, Município de Montes Claros de Goiás, 15°56’19’’S 51°20’58’’W, 5 Jun 2007, G. A. Pereira. MCP 42360, 6, 16.0– 29.4 mm SL, córrego Varginha, tributary of rio Claro, Município de Montes Claros de Goiás, 15°57’52’’S 51°18’40’’W, 5 Jun 2007, G. A. Pereira. MZUSP 4826, 33, 14.1–32.6 mm SL, rio Araguaia, Município de Aruan, 15–19 Sep 1966, Exc. DZ. MZUSP 40362, 27, 23.6–29.8 mm SL, 4c&s, 26.0– 30.1 mm SL (6, 26.6–29.9 mm SL), marginal lagoon of riacho Seco, close to bridge on highway GO 447, Município de Galheiros, 14 Jan 1989, J. C. Oliveira & W. Costa. MZUSP 40378, 36, 13.2–21.8 mm SL, rio Macacos (also Macaquinhos), tributary at right margin of rio Paraná, Fazenda Fortaleza, Município de Flores de Goiás, 10 Sep 1988, J. C. Oliveira & W. Costa. MZUSP 40497, 12, 14.3–21.9 mm SL, rio Paraná, waterfall at Fazenda Olho d`Água, Município de Flores de Goiás, 12 Sep 1988, J. C. de Oliveira & W. J. M. Costa. MZUSP 40547, 5, 17.9–22.2 mm SL, rio Prata, bridge on highway GO 112, Município de Iaciara, 14 Sep 1988, J. C. Oliveira & W. J. M. Costa. MZUSP 40704, 4, 31.1–34.2 mm SL, rio Bezerra, tributary at right margin of rio Paraná, Município de Flores de Goiás, 22 Sep 1988, J. C. Oliveira & W. Costa. MZUSP 40858, 6, 20.9 –26.0 mm SL, rio Paraná, between rio Macaco and rio Bezerra, Município de Monte Alegre de Goiás, Sep 1988, J. C. Oliveira & W. Costa. UFRGS 12021, 7, 27.9–31.3 mm SL, same data as holotype. UFRGS 12028, 20, 14.1–26.3 mm SL, rio das Almas, between Aragarças and Jussara, Município de Aragarças, 15°52’2.4’’S 51°38’57.7’’W, 6 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep. UFRGS 12035, 5, 26.8–32.8 mm SL, stream tributary of rio Claro, between Aragarças and Jussara, Município de Aragarças, 15°52’10.8’’S 51°32’56.6’’W, 6 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep. Tocantins State: MZUSP 115013, 2, 26.5–27.3 mm SL, temporary pond on rio Paraná and rio Bezerra confluence, Município de Arraias, 11 Jan 1989, J. C. Oliveira & W. Costa. UFRJ 1708, 24, 20.8–29.8 mm SL, tributary of rio Verde, 50 km from São Miguel do Araguaia, 28 Aug 1993, W. Costa, E. Vicente, M. Britto, F. Autran & R. D`Arrigo. UNT 4143, 2, 25.1–25.2 mm SL, Lagoa Dionísio, Fazenda Água Branca, Município de Peixe, 11 March 2000, NEAMB-UFT. UNT 4265, 18, 20.0– 26.8 mm SL, Lagoa Maranhão, Fazenda Traçada, Município de Paraná, 18 Nov 1998, NEAMB. UNT 4757, 30, 16.7–27.2 mm SL, Lagoa Água Branca at Fazenda Água Branca, Município de Peixe, 21 Aug 2001, NEAMB-UFT. UNT 7321, 20, 18.2–26.1 mm SL, rio Tocantins, Fazenda Traçada, Município de Paraná, 10 May 2000, NEAMB-UFT. Mato Grosso State: MCP 34172, (4, 29.2–31.7 mm SL), córrego Barreiro, tributary of rio São João on road to Vila Berrante, ribeirão Cascalheira 12°57’39’’S 51°40’56’’W, 28 Jul 2003, T. Carvalho & G. Carvalho. MCP 40417, 58, 19.2–36.2 mm SL (8, 32.5–36.1 mm SL, 3c&s, 30.6–33.4 mm SL), stream on highway BR158, 61 km south of Porto Alegre do Norte, 11°22’28’’S 51°39’42’’W, 28 October 2005, J. F. P. Silva. MCP 40473, (4, 25.9–30.3 mm SL), córrego Pium, 22 km south of Posto da Mata, on highway BR158 between Posto da Mata and Al Brasil, 11°53’58’’S 51°39’26’’W, 29 Oct 2005, J. F. P. Silva. MCP 40263, 89, 16.1–25.4 mm SL, rio Crisostomo on highway BR158 between Vila Rica and Confresa, Município de Vila Rica, 10°14’33’’S 51°10’08’’W, 26 Oct 2005, J. F. P. Silva. MCP 44522, 62, 9.4–20.4 mm SL, ribeirão São Marcos on highway BR158 between Confresa and Vila Rica, Município de Vila Rica, 10°06’05’’S 51°06’00’’W, 23 Apr 2006, J. F. P. Silva & L. Cotrim. MCP 44526, 32, 9.8 –19.0 mm SL, ribeirão Santana 30 km north of Vila Rica on highway BR158, Município de Vila Rica, 09°49’11’’S 51°03’21’’W, 23 Apr 2006, J. F. P. Silva & L. Cotrim. MCP 44527, 21, 15.8–23.1 mm SL, rio Crisostomo on highway BR158 between Vila Rica and Confresa, 10°14’33’’S 51°10’08’’W, 22 Apr 2006, J. F. P. Silva & L. Cotrim. MCP 44530, 8, 10.6–19.1 mm SL, rio Tapirapé, Município de Porto Alegre do Norte, 10°51’00’’S 51°37’00’’W, 22 Apr 2006, J. F. P. Silva & L. Cotrim. MCP 44532, 3, 11.1–28.8 mm SL, rio Preto on highway BR158, 72 km south of Porto Alegre do Norte, 11°27’47’’S 51°40’42’’W, 21 Apr 2006, J. F. P. Silva & L. Cotrim. MCP 44534, 20, 18.6–30.1 mm SL, rio Paciguara 2 km north of Confresa on highway BR158, Município de Confresa, 10°37’34’’S 51°32’51’’W, 22 Apr 2006, J. F. P. Silva & L. Cotrim. MCP 44535, 10, 9.5–22.6 mm SL, rio Xavantinho 16 km South of Porto Alegre do Norte, 11°01’30’’S 51°38’47’’W, 21 Apr 2006, J. F. P. Silva & L. Cotrim. Par State: INPA 20976, 32, 27.9–36.4 mm SL (8, 30.6–35.1 mm SL), Igarapé Canoal, Município de Breu Branco, 12 Nov 1981, equipe de Ictiologia INPA. INPA 20977, (6, 28.3–34.4 mm SL), Igarapé tributary of rio Sossego, Município de Parauapebas, Cana Carajás, 14 Mar 2002, G. Mendes. INPA 20978, 13, 18.4–32.7 mm SL (4, 29.1–31.7 mm SL), Igarapé tributary of rio Sossego, Município de Parauapebas, Cana dos Carajás, 14 Mar 2002, G. M. Santos. INPA 20979, 7, 24.5–35.3 mm SL, Igarapé Bacuri, 6 Jul 1982, equipe de Ictiologia INPA. INPA 20984, 20, 31.5–36.8 mm SL (5, 32.2–36.5 mm SL), Igarapé Bacuri, 26 Nov 1981, Eq. Ictiologia INPA. INPA 20986, 27, 32.4–39.8 mm SL (7, 35.0– 39.7mm SL, 3c&s, 34.3–35.0 mm SL), Igarapé Bacuri, close to DNER, 26 Nov 1981, equipe de Ictiologia INPA. MCP 24199, 8, 28.9–32.8 mm SL, Igarapé Cinzento, tributary on left margin of rio Itacaiúnas, 05°51’1’’S 50°32’7’’W, Jul 1997, P. S. Pompeu. MZUSP 4936, 188, 11.4–34.6 mm SL, tributary of rio Araguaia, highway Belém-Brasilia, 30 km North of Gurupi, 31 May 1966, Expedition DZUSP. MZUSP 18144, 30, 21.8–29.4 mm SL, lagoon in front of Jatobal, 17 Sep 1970, EPA. Distrito Federal: USNM 292213, 1, 33.8 mm SL, rio Maranhão, about 35 km north of Brasília, 15°30’S 47°50’W, 14 Nov 1984, W. C. Starnes, M. Ribeiro, R. Mendonça, et al . Diagnosis. Serrapinnus tocantinensis can be diagnosed from its congeners by the elongation of the unbranched dorsal and pelvic-fin rays into filaments in mature males. Furthermore S. tocantinensis can be distinguished from S. sterbai by the absence of a continuous mid-lateral black stripe extending from the opercular region to the caudalpeduncle spot, and from the remaining species of the genus by the presence of 9 to 11 cusps in the premaxillary teeth (vs. 5 in S. microdon and S. potiguar, 7 in S. aster, 7 to 9 in S. calliurus, S. heterodon, S. kriegi, S. micropterus, S. notomelas and S. piaba and 10 to 12 in S. gracilis and S. littoris), dentary teeth without expanded cusps forming a sharp cutting edge (vs. dentary teeth with expanded cusps forming a sharp cutting edge in S. heterodon), hyaline dorsal fin (vs. with a proximal black blotch in S. notomelas), and the absence of a black spot on the posteroventral region of the abdomen (vs. the presence of a black spot in that region in S. kriegi). Description. Morphometric data presented in Table 4. Body elongated and compressed. Greatest body depth at dorsal-fin origin. Snout anteriorly rounded in lateral profile. Dorsal profile of head gently convex from vertical through posterior margin of posterior nares to base of supraoccipital spine, then straight to slightly concave to tip of supraoccipital spine. Predorsal profile slightly convex between tip of supraoccipital spine and dorsal-fin origin. Straight to slightly convex along dorsal-fin base. Dorsal profile from insertion of last dorsal-fin ray to adipose fin slightly convex in immatures and females; deeply convex in mature males with ventrally arched caudal peduncle. Dorsal profile straight to slightly concave from adipose-fin base to most anterior dorsal procurrent caudal-fin ray. Distal tip of lower jaw convex. Ventral profile of head straight to gently convex along ventral profile lower jaw to vertical through posterior margin of eye; convex from that point to pelvic-fin origin. Ventral region from pelvic-fin insertion to anal-fin origin slightly concave to straight in immature and females; deeply concave in mature males. Anal-fin base slightly concave in immature and females; distinctly convex anteriorly and straight posteriorly in mature males. Ventral profile of caudal-peduncle slightly concave in females; distinctly convex in mature males due to hypertrophied procurrent caudal-fin rays extending ventrally through muscles and skin (Figs. 2g –h, 10). Caudal peduncle slightly longer than deep; ventrally arched in alcohol preserved mature males. Head anteriorly tapered in lateral view. Posterior margin of opercle sinusoidal with upper portion concave and lower portion convex. Mouth terminal, mouth slit just below horizontal through middle of pupil. Maxilla angled posteroventrally; posterior tip reaching vertical through anterior border of orbit and horizontal through ventral border of orbit. All teeth multicuspidate, pedunculate, compressed and expanded distally (Fig. 11). Premaxillary teeth 5(5) with 9 to 11 cusps; central cusp slightly longer and wider than lateral cusps. Two (4) maxillary teeth with 7 to 9 cusps. Dentary teeth 6(1), 7(2) or 8(3) with 7 to 9 cusps, rarely followed by one smaller tricuspid teeth. Lateral small cusps of dentary teeth overlapping adjacent tooth cusps; overlap usually not present on posterior teeth. All dentary tooth cusps dorsally pointed or slightly recurved towards interior of mouth. Dorsal-fin rays ii,8(2), 9*(65). Dorsal-fin origin slightly anterior to vertical through midlength of standard length. First unbranched dorsal-fin ray about one-half length of second unbranched dorsal-fin ray. Second unbranched dorsal-fin ray longest in fin with branched rays slightly decreasing in size posteriorly. Second unbranched dorsal-fin ray elongated into small filament in mature males. Adipose-fin origin slightly anterior to vertical through base of last anal-fin ray in females and slightly posterior to that point in males. Anal-fin origin posterior to vertical through base of last dorsal-fin ray. Anal-fin rays iii–iv,15*(1), 17(2), 18(19), 19(33), 20(10) or 21(1). Distal border of anal-fin concave; last unbranched and anterior 5–6 first branched rays longest; ray length abruptly decreasing after sixth ray with remaining rays decreasing in size to end of anal fin. Distal tip of longest anal-fin ray of mature males reaching to vertical through base of last anal-fin ray; sometimes reaching ventral procurrent caudal-fin rays when caudal peduncle deeply arched. Males with acute, elongate, retrorse hooks on distal half of anal-fin rays; hooks posterolaterally arranged on last unbranched to 11 th or 17 th branched rays. Two or 3 unpaired hooks per ray segment of each contralateral lepidotrichia (Fig. 4d). Hooks generally situated on posterior margin of posterior ray branches. Hook bearing ray segments and branches progressively fused during maturation of males. Mature males with hypertrophied soft whitish tissue on interradial membrane anterior to analfin hooks. Pectoral-fin rays i,9*(18), 10(36) or 11(13). Pectoral-fin ray reaching pelvic-fin origin in immatures and females, but extending beyond that point in adult males. Pelvic-fin rays i,6(2) or 7*(65). Pelvic-fin origin slightly anterior to vertical through dorsal-fin origin. Pelvic fin falling short of anal-fin origin in immature and females; extending far beyond that point in adult males. Males with one or two acute, elongate, ventral-medially situated hook per lepidotrichia segment on all pelvic-fin rays. Adult males with hypertrophied soft whitish tissue anterior to hooks on ventral surface of pelvic fin. Principal caudal-fin rays 17(2) or 19*(65). Procurrent caudal-fin rays: dorsal 12(2), 13(1) or 15(3); ventral 12(1), 13(2) or 14(3). Adult males with ventral procurrent caudal-fin rays hypertrophied, commonly fused, with distal tips extending beyond muscles and skin of caudal-peduncle. Hypertrophied ventral procurrent caudal-fin rays elongated, rod-shaped, anteriorly bent, proximally acute and slightly expanded distally (Fig. 2g). Scales cycloid; similar in size over all body. Lateral line partially pored with 8(1), 11(5), 12(2), 14(7), 15(4), 16(2), 17(6), 18(2), 19(2), 20(2), 21(1), 23(1), 32(5), 33(7), 34(11), 35*(7) or 36(2) pored scales. Scales in lateralline series 31(3), 32(9), 33(22), 34(16), 35*(15) or 36(2). Predorsal series in regular row 8(1), 9*(9), 10(34) or 11(23). Scale rows between lateral line and dorsal-fin origin 5(49) or *6(18). Scale rows between lateral line and pelvic-fin origin 4*(64) or 5(3). Scale rows around caudal peduncle 12(3), 13(24), 14*(36) or 15(4). Axillary scale on pelvic fin base extending posteriorly one or two scales. Scales along anal-fin base 9(4), 10(12), 11(24), 12(14), 13(6), 14(2), 15*(3) or 17(1). Counts based on six clear and stained specimens: supraneurals 4(4) or 5(2); abdominal vertebrae 15(5) or 16(1); caudal vertebrae 19(4) or 20(2). Color in alcohol. Overall ground coloration of body pale yellow, darker dorsally from head to caudal peduncle. Body with faint dark, sometimes silver, midlateral stripe usually forming black line along middle longitudinal body axis. Longitudinal stripe extending from region slightly anterior to vertical through dorsal-fin origin to caudal spot. Scale series above longitudinal line with darker chromatophores mostly on posterior border of scales, resulting in faint reticulated pattern. Abdominal region ventral to longitudinal line more lightly colored and without pigmentation. Caudal spot rounded, black, situated over posterior of caudal peduncle and base of middle caudal-fin rays, but falling short of upper or lower margin of peduncle. Fins mostly hyaline with scattered, sparse, dark chromatophores. Adipose fin unpigmented. Caudal fin with dark chromatophores along fin rays, except for clear areas on base of each caudal-fin lobe. Humeral region with triangular, dark area due to pseudotympanum in musculature (Fig. 10). Sexual dimorphism. Mature males of S. tocantinensis have hooks on the pelvic and anal-fin rays. The caudal peduncle is ventrally arched, as commonly observed in species of Serrapinnus. The hook bearing anal-fin rays are hypertrophied, expanded in the sagittal plane, and sometimes have fused ray segments. Adult males also have the last unbranched dorsal-fin ray and the first pelvic-fin ray elongated, sometimes in a short filament. The ventral procurrent caudal-fin rays are hypertrophied in mature males, and extend ventrally through the caudal peduncle muscles and skin (Figs. 2g –h, 4d, 10). Distribution. Serrapinnus tocantinensis is distributed throughout the rio Tocantins-Araguaia basin, from the upper to the lower portions of the system (Fig. 5d). Etymology. The species name, tocantinensis, refers to the restricted geographic distribution of the species to the rio Tocantins-Araguaia basin. A noun in apposition., Published as part of Malabarba, Luiz R. & Jerep, Fernando C., 2014, Review of the species of the genus Serrapinnus Malabarba, 1998 (Teleostei: Characidae: Cheirodontinae) from the rio Tocantins-Araguaia basin, with description of three new species, pp. 57-79 in Zootaxa 3847 (1) on pages 71-75, DOI: 10.11646/zootaxa.3847.1.3, http://zenodo.org/record/4928753

Serrapinnus sterbai Zarske, 2012 Figs. 2e–f, 4c, 5c, 8, 9 Serrapinnus sterbai Zarske, 2012: 4 (original description; type locality: Araguaya [misspelled locality name Araguaia] - Gebiet, Ostbrasilien(?), Import Firma Glaser, Holotype: UFRJ 8516, 34.1 mm SL [fig. 1 of an alcohol preserved specimen labeled as the holotype is actually one paratype, male, from MTD F 32658-32664; figs. 3 and 4 of a radiographed specimen and a live specimen in aquarium correspond to the holotype UFRJ 8516. See Remarks below]). Diagnosis. Serrapinnus sterbai is distinguished from all congeners by the presence of a wide, black, lateral stripe extending from the region of the supracleithrum to the dark spot on the caudal peduncle (Fig. 8). Description. Morphometric data in Table 3. Body short and compressed. Greatest body depth at dorsal-fin origin. Snout slightly rounded to pointed. Dorsal profile of head gently convex from tip of snout to vertical through anterior nares, slightly convex from that point to anterior portion of supraoccipital bone, with posterior region of supraoccipital spine slightly concave. Predorsal profile slightly convex between tip of supraoccipital spine and dorsal-fin origin, slightly convex to straight along dorsal-fin base, straight to slightly convex from last dorsal-fin ray insertion to caudal-fin origin, but ventrally arched in mature males. Ventral profile convex from mouth opening to isthmus, convex from that point to pelvic-fin origin, then straight until vertical through anal-fin origin in immatures and females and slightly concave in mature males. Anal-fin base straight to slightly concave in immatures and females, but distinctively convex along anterior portion and ventrally arched along posterior portion in mature males. Caudal peduncle slightly longer than deep. Dorsal and ventral profiles of caudal-peduncle straight to lightly concave in immatures and females, but dorsal profile ventrally arched and ventral profile distinctly convex due to ventral procurrent caudal-fin rays hypertrophy in mature males (Fig. 2e, 8). Head relatively small. Posterior margin of opercle sinusoidal with upper portion concave and lower portion convex. Mouth terminal, mouth slit just above horizontal through middle of pupil. Maxilla angled posteroventrally, posterior tip reaching vertical close to anterior border of orbit and horizontal through ventral border of orbit. All teeth pedunculated, distally expanded and similar in shape (Fig. 9). Premaxillary teeth 4(2) or 5(2) with 9 or 11 cusps, lateralmost tooth rarely with 5 cusps; central cusp longer and wider than other cusps. Two (4) maxillary teeth with 7 cusps; a third conical tooth in one specimen. Large anterior dentary teeth 5(3) or 6(1) with 7 cusps; these followed by 1(2) or 2(2) teeth with 3 or 5 cusps. Smaller cusps of dentary teeth overlapping adjacent tooth cusps. All dentary tooth cusps pointed dorsally or slightly curved towards interior of mouth. Dorsal-fin rays ii,9(30). Dorsal-fin origin at midlength of SL. First unbranched dorsal-fin ray about one-half length of second unbranched dorsal-fin ray; following branched rays decreasing in size posteriorly. Adipose-fin origin slightly posterior to or along vertical through base of last anal-fin ray. Anal-fin rays iii–iv,16(1), 17(3), 18(8), 19(17) or 21(1). First unbranched anal-fin ray only observable in cleared and stained specimens. Distal border of anal-fin concave; last unbranched and 5–6 anterior branched rays longest; remaining rays decreasing in size posteriorly. Tip of depressed anterior anal-fin rays of mature males laterally overlapping last anal-fin rays; sometimes reaching ventral procurrent caudal-fin rays in arched caudal peduncle. Anal-fin origin posterior to vertical through insertion of last dorsal-fin ray. Males with acute, elongate, retrorse hooks on anal-fin rays; hooks posterolaterally arranged on last unbranched to 7 th or 8 th branched rays (Fig. 4c). Two or three unpaired hooks per lepidotrichia segment on each contralateral half of ray. Hooks distributed along distal half of anal-fin rays on posterior and rarely anterior margins of rays. Rays segments and branches bearing hooks progressively fused during maturation. Mature males with hypertrophied soft tissue on interradial membrane anterior to hook bearing anal-fin rays. Pectoral-fin rays i,9(18), 10(11) or 11(1). Tip of pectoral fin reaching pelvic-fin origin in immature and females; extending beyond that point in mature males. Pelvic-fin rays i,7(30). Pelvic-fin origin anterior to vertical through dorsal-fin origin. Longest pelvic-fin ray not reaching anal-fin origin in immature and females, but extending beyond that point in mature males. Males with one or two acute elongate hooks per lepidotrichia segment of all pelvic-fin rays; hooks ventral-medially aligned. Mature males with hypertrophied soft tissue on interradial membrane anterior to hooks and ventral surface of pelvic fin. Principal caudal-fin rays 19(29) or 20(1). Procurrent caudal-fin rays: dorsal 12(3) or 13(1); ventral 15(3) or 17(1). Mature males with ventral procurrent caudal-fin rays hypertrophied and contralateral elements fused; rays extending beyond ventral caudal-peduncle muscles and skin. Hypertrophied ventral procurrent rays rod-shaped, sometimes fused, anteriorly bent along their axes, proximally acute, slight expanded distally and ending in rounded to flat distal tip (Fig. 2e). Scales cycloid, similar in size over all body. Lateral line partially pored with 7(3), 8(9), 9(15), 10(3) pored scales, or rarely completely pored (MZUSP 83894, 83971). Scales in lateral-line series 31(4), 32(8), 33(10), 34(7) or 35(1). Predorsal scales in regular row 9(17), 10(10) or 11(3). Scale rows between lateral line and dorsal-fin origin 5(21) or 6(9). Scale rows between lateral line and pelvic-fin origin 4(30). Scale rows around caudal peduncle 12(1), 13(10) or 14(19). Axillary scale on pelvic fin base extends posteriorly over 1–2 scales. Scales along anal-fin base 9(1), 10(10), 11(8), 12(7), 13(3) or 15(1). Counts based on four clear and stained specimens: Supraneurals 3(1) or 4(3); abdominal vertebrae 15(2) or 16(2); caudal vertebrae 17(2), 18(1) or 19(1). Color in alcohol. Overall ground coloration of body pale yellow. Dorsal region of head and body with higher concentration of melanophores. Body with longitudinal, midlateral dark stripe extending from posterior margin of opercle to caudal spot. Longitudinal black stripe one or one and half scale wide. Black, horizontally elongated spot at base of caudal fin extending posteriorly until midlength of central caudal-fin rays. Scales above longitudinal line with melanophores primarily along posterior border, resulting in faint reticulated pattern. Abdominal region lightly colored, almost without pigmentation. Dorsal, pectoral and pelvic fins mostly hyaline, with scattered melanophores along fin rays. Adipose fin not pigmented. Caudal fin covered with diffuse melanophores along fin rays, except for clear areas at base of each caudal-fin lobe just posterior of caudal-fin spot. Humeral region with triangular, dark area due to pseudotympanum within muscular hiatus (Fig. 8). Sexual dimorphism. Sexually mature males have the following dimorphic characters: the presence of hooks on the pelvic and anal-fin rays; the ventrally arched caudal peduncle; the hypertrophied hook bearing anal-fin rays, expanded in the sagittal plane, and sometimes with a fusion of ray segments; the slightly elongate dorsal- and pelvic-fin rays; and the hypertrophied ventral procurrent caudal-fin rays extending ventrally through the musculature and skin (Figs. 2e–f, 4c, 8). Distribution. Serrapinnus sterbai was described based on aquarium specimens. Zarske (2012) states that the imprecise type locality was the “region of Araguaia, eastern Brazil? (our translation). Our new records extend the distribution of S. sterbai to several tributaries and the main course of the rio Tocantins drainage (Fig. 5c). Remarks. Zarske (2012) figured the holotype, a male specimen, three times in his paper: as a preserved specimen (Zarske, 2012: fig. 1), as a radiograph (Zarske, 2012: fig. 3) and as a live specimen in an aquarium (Zarske, 2012: fig. 4). The three images belong, however, to at least two different specimens, since the shape and profile of the procurrent fin rays in the alcohol preserved specimen is clearly different from that in the radiographed and live specimens. The same seems to occur with the female paratype shown as a preserved specimen in Zarske´s fig. 2 and as a radiograph in his fig. 3, since the body shape and body proportions differ between the figured specimens. The holotype catalogued as UFRJ 8516 was examined and photographed by Fernando R. Carvalho at the Museum für Tierkunde, Dresden. The shape and number of anal fin hooks allowed him to recognize it as the specimen showed in radiograph (Zarske, 2012: 7, fig. 3), but not as the specimen labeled as holotype in Zarske (2012: 6, fig. 1). Examining the radiograph in Zarske (2012: fig. 3) we observe that the second and longest unbranched ray of dorsal fin is anomalous at its midlength and near the tip of the first unbranched ray of dorsal fin. The same anomaly can be seen in the specimen photographed alive in Zarske (2012: 8, fig. 4). Accordingly, specimens labeled as the holotype in Zarke´s figs. 3 and 4 are actually images of the holotype. The specimen erroneously listed as the holotype in Zarske (2012: fig. 1) is a paratype male of MTD F 32658 -32664. The female labeled as the allotypus of fig. 2 in Zarske (2012) also does not correspond to the specimen catalogued as allotype under MTD F 32657, but rather to one of the paratypes at MTD F 32658 -32664. Material examined. All from Brazil, rio Tocantins-Araguaia basin. Goiás State: MZUSP 40375, 12, 14.5–20.9 mm SL, rio Macacos, tributary of left margin of rio Paraná, Fazenda Fortaleza, Município de Flores de Goiás. MZUSP 40470, 4, 14.2–21.8 mm SL, Poço da Gandaia, marginal pond of rio Paraná, Fazenda Olho d’água, Município de Flores de Goiás. MZUSP 40511, 13, 11.4–24.9 mm SL (2 males 24.5–24.9 mm SL, 1 female 22.4 mm SL), pond close to highway GO 236, Município de Flores de Goiás. MZUSP 40518, 33, 12.5–22.9 mm SL, tributary of rio Corrente, on highway GO 236, 15 km from Alvorada de Goiás. MZUSP 40701, 2, 23.9–26.5 mm SL, rio Bezerra, tributary on left margin of rio Paraná, Município de Flores de Goiás. Tocantins State: MZUSP 40359, 69, 22.2–26.7 mm SL, 4c&s, 23.6–25.8 mm SL (13, 22.8–25.7 mm SL), Brazil, Tocantins, Município de Arraias, temporary pond on rio Paraná and rio Bezerra confluence, Tocantins drainage. MZUSP 83894, 19 of 52, 23.7–34.5 mm SL, Brazil, Tocantins, Porto Alegre do Tocantins, rio Manuel Alves da Natividade, 11°36’41’’S 47°02’39’’W. MZUSP 83971, 40 of 444, 18.7–35.2 mm SL, Brazil, Tocantins, Porto Alegre do Tocantins, rio Manuel Alves da Natividade, 11°36’41’’S 47°02’39’’W. UFRGS 16447, 24, 28.3–31.7 mm SL (10, 27.8–31.7 mm SL, 2c&s males 28.7–29.7 mm SL, 2c&s females 28.6–28.7 mm SL), Município de Paraná, Maranhão pond, Fazenda Traçadal. UNT 6621, 1, 20.6 mm SL, Município de Peixe, rio Tocantins, near confluence with rio Santa Tereza. UNT 7227, 28, 27.3–32.5 mm SL, Município de Paraná, Maranhão pond, Fazenda Traçadal. UNT 7322, 1, 18.0 mm SL, Município de Porto Nacional, rio Tocantins. UNT 7324, 1, 16.4 mm SL, Município de Ipueiras, rio Tocantins, near confluence with rio Manoel Alves. UNT 7386, 3, 15.5–21.2 mm SL, Município de Paraná, Maranhão pond, Fazenda Traçadal. UNT 7402, 1, 18.2 mm SL, Município de Paraná, Maranhão pond, Fazenda Traçadal. UNT 7403, 4, 19.6–25.2 mm SL, Município de Paraná, Maranhão pond, Fazenda Traçadal. UNT 7412, 1, 29.5 mm SL, Paraná, Maranhão pond, Fazenda Traçadal., Published as part of Malabarba, Luiz R. & Jerep, Fernando C., 2014, Review of the species of the genus Serrapinnus Malabarba, 1998 (Teleostei: Characidae: Cheirodontinae) from the rio Tocantins-Araguaia basin, with description of three new species, pp. 57-79 in Zootaxa 3847 (1) on pages 67-70, DOI: 10.11646/zootaxa.3847.1.3, http://zenodo.org/record/4928753, {"references":["Zarske, A. (2012) Serrapinnus sterbai spec. nov. Beschreibung eines neuen Salmlers (Teleostei: Characiformes: Characidae: Cheirodontinae) aus Brasilien mit Bemerkungen zu S. gracilis (Gery, 1960) comb. nov. und S. littoris (Gery, 1960) comb. nov. Vertebrate Zoology, 62, 3 - 17."]}

Serrapinnus aster Malabarba & Jerep, new species Figs. 1, 2a–b, 3, 4a, 5a Holotype. MZUSP 115011, 22.9 mm SL, male, Brazil, Tocantins State, Município de Arraias, periodic lake at confluence of rio Paraná and rio Bezerra, rio Tocantins drainage, 11 Jan 1989, J. C. Oliveira & W. Costa. Paratypes. All from Brazil, rio Tocantins-Araguaia basin. Goiás State: MCP 41862, (3, 31.6–33.2 mm SL), córrego Volta Grande, tributary of left margin of PCH Piranhas reservoir, Município de Piranhas, 16°35’59’’S 51°48’33’’W, 18 Jul 2007, Equipe CPA ltda. MCP 42033, (3, 28.4–32.7 mm SL), córrego Salobrinha, tributary of rio Claro, Município de Montes Claros de Goiás, 15°58’35’’S 51°24’09’’W, 27 Feb 2007, G. A. Pereira. UFRGS 12015, 22, 23.0– 31.1 mm SL, Município de Piranhas, tributary of rio Piranhas, between Piranhas and Bom Jardim de Goiás, 16°21’43.3”S 51°55’10.2”W, 7 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep. UFRGS 12023, 54, 32.3 – 10.6 mm SL, 2 c&s, 25.3–26.1 mm SL, Município de Montes Claros de Goiás, tributary of rio Claro, 100 km from road intersection to Betânia, between Jussara and Montes Claros de Goiás, 15°55’32.0”S 51°19’25.8”W, 6 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep. UFRGS 12034, 5, 28.5 –31.0 mm SL, Município de Jussara, tributary of rio Claro, 15°58’0.0”S 50°48’59.7”W, 6 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep. Tocantins State: MZUSP 115012, 10, 21.3–26.3 mm SL, 2 c&s, 23.9–25.0 mm SL, same data as holotype. Diagnosis. Serrapinnus aster is distinguished from all congeners except S. potiguar, by the scimitar-shaped ventral procurrent caudal-fin rays of mature males, almost all of which form a semicircle, resulting in a portion of the ventral procurrent caudal-fin rays having a multi-pointed partial star-shaped margin (Fig. 2a) vs. ventral procurrent caudal-fin rays rod-shaped or spatulate, usually parallel to each other, except for the anteriormost procurrent rays being inclined forward in some species. Furthermore S. aster can be diagnosed from S. potiguar and other species of the genus by the presence of 7–9 cusps on the premaxillary teeth (vs. 5 cusps in S. microdon and S. potiguar, 9 to 11 in S. lucindai, S. sterbai and S. tocantinensis and 10 to 12 in S. gracilis and S. littoris), the incomplete lateral line (vs. complete in S. heterodon), the hyaline dorsal fin (vs. with a proximal black blotch in S. notomelas), and the absence of a black spot on the posteroventral region of the abdomen (vs. the presence of a black spot in that region in S. kriegi). Description. Morphometric data in Table 1. Body short and compressed. Greatest body depth at dorsal-fin origin. Snout slightly pointed in profile. Dorsal profile of head gently convex from snout to anterior portion of supraoccipital bone. Posterior portion of supraoccipital slightly concave. Predorsal profile slightly convex from posterior end of supraoccipital to dorsal-fin origin. Dorsal-fin origin located at midbody. Dorsal profile from base of last dorsal-fin ray to caudal-fin origin straight to slightly convex in females and ventrally arched in preserved mature males. Ventral profile of caudal peduncle straight in females, distinctly convex due to hypertrophy of ventral procurrent caudal-fin rays in males. Caudal peduncle slightly longer than deep. Ventral profile of head and body from tip of mouth to pelvic-fin origin convex, then straight until anal-fin origin on females but slightly concave in mature males. Anal-fin base straight to slightly concave in females, anteriorly convex and distinctively concave posteriorly in mature males. Head relatively small. Posterior margin of opercle sinusoidal with upper portion concave and lower portion convex. Mouth terminal, mouth slit situated immediately below horizontal through middle of pupil. Maxilla angled posteroventrally; posterior tip reaching vertical close to anterior border of eye and horizontal through ventral border of eye. All teeth pedunculated, distally expanded. Premaxilla with 4(1) or 5(1) teeth in single row and bearing 7–9 cusps. Midcentral cusp higher and wider than lateral cusps. Maxilla with 2(2) teeth bearing 5–7 cusps. Dentary with 7(2) large teeth bearing 5 or 7 cusps, followed by one smaller tooth with 3 cusps and one conical tooth. Smaller lateral cusps of dentary teeth sometimes overlapping adjacent tooth cusps; overlap usually absent between posteriormost teeth. All dentary tooth cusps upwardly pointed or slightly directed towards interior of mouth (Fig. 3). Dorsal-fin rays ii,8(1), 9*(16). Dorsal-fin origin at midlength of body. First unbranched dorsal-fin ray about one-half length of second unbranched ray; following branched rays progressively decreasing in size. Adipose-fin origin slightly posterior to vertical through end of anal-fin base. Anal-fin rays iii,16(2), 17*(6), 18(7) or 19(2). First unbranched anal-fin ray only observable in cleared and stained specimens. Distal profile of anal-fin slightly concave in females, deeply concave in males. Last unbranched and first 5–6 branched anal-fin rays longer, remaining rays progressively decreasing in size. Tip of longest anal-fin rays of mature males laterally overlapping last anal-fin rays, and sometimes reaching ventral procurrent caudal-fin rays when caudal peduncle arched. Analfin origin posterior to vertical through base of last dorsal-fin ray. Males with acute, elongate, retrorse hooks, posterolaterally arranged on last unbranched to 8 th, 9 th or 10 th branched anal-fin rays (Fig. 4a). Two unpaired hooks present per lepidotrichia ray segment of on each lateral half of ray. Hooks situated along posterior margin and posterior branches of rays; extending from distal half of proximal lepidotrichia segment to distal end of ray. Hookbearing rays with segments and branches progressively fused with increasing maturation of males. Mature males with hypertrophied soft tissue associated with hook-bearing anal-fin rays. Pectoral-fin rays i,9*(6), 10(9), 11(2). Pectoral-fin ray falling short of pelvic-fin origin in females, but extending beyond that point in males. Pelvic-fin rays i,7*. Pelvic-fin origin anterior to vertical through dorsal-fin origin. Pelvic-fin rays of males with 1 or 2 acute, elongate hooks per lepidotrichia segment. Hooks ventromedially placed on all rays, and associated with hypertrophied soft tissue. Principal caudal-fin rays 18(1), 19*(14). Procurrent caudal-fin rays 11(2) dorsal, 13(2) ventral. Ventral procurrent caudal-fin rays hypertrophied in mature males, extending beyond ventral muscles and skin of caudal-peduncle resulting in multi-pointed semicircular star-shaped structure. Hypertrophied ventral procurrent ray scimitar-shaped: anteriorly bent, proximally acute, expanding distally and ending abruptly in pointed distal tip (Fig. 2a). Scales cycloid, similar in size over all of body. Lateral line partially pored with 6*(2), 8(5), 9(8), 11(1), 13(1) pored scales; scales in lateral line scale row 31(3), 32*(6), 33(4), 34(3), 35(1). Predorsal scales 9(7), 10(6), 11(2), 12(1). Scale rows between lateral line and dorsal-fin origin 5(1) or 6*(16). Scale rows between lateral line row and pelvic-fin origin 4*(16) or 5(1). Scale rows around caudal peduncle 12(1), 13*(8), 14(8). Scales along anal-fin base 6(1), 8*(2), 9(3), 10(6), 11(3), 12(1), 13(1). Supraneurals 4 or 5; abdominal vertebrae 15; caudal vertebrae 19 in two clear and stained specimens. Color in alcohol. Overall background body color yellow (Fig. 1). Head with numerous and large melanophores on dorsal and opercular regions. Small, dark melanophores surrounding mouth opening and over maxilla. Scales on dorsum and on rows above lateral line with subtle reticulated color pattern due to concentration of melanophores along distal border of scales. Body with faint dark midlateral stripe, usually in form of narrow black line along middle longitudinal body axis, beginning anterior to dorsal-fin origin and ending in caudal spot. Body with scattered pigmentation ventral of lateral line. Melanophores aligned along myosepta on posteroventral region of body. Black to brown, rounded spot on caudal-fin base; spot not reaching upper or lower margin of caudal peduncle and extending posteriorly over one-half to two-thirds of middle caudal-fin rays. Dorsal, anal, pectoral and pelvic fins scattered with few melanophores between rays. Adipose fin unpigmented. Caudal fin covered with diffuse dark chromatophores along fin rays, except for clear areas on base of caudal-fin lobes just posterior of caudal-fin spot. No humeral spot; triangular, darkened area in humeral region due to presence of pseudotympanum within musculature. Sexual dimorphism. Sexually mature males with hooks on pelvic- and anal-fin rays, ventrally arched caudal peduncle in preserved specimens; hypertrophied hook bearing anal-fin rays, expanded in sagittal plane usually with fused ray segments; and hypertrophied ventral procurrent caudal-fin rays (Figs. 1, 2a–b, 4a). Distribution. Serrapinnus aster is distributed on the upper portions of the rio Tocantins basin, mainly in the tributaries of the rio Paraná and rio Tocantins (Fig. 5a). Etymology. The species name, aster, refers to the star-shaped ventral profile of the set of hypertrophied procurrent caudal-fin rays present in the mature males of the species., Published as part of Malabarba, Luiz R. & Jerep, Fernando C., 2014, Review of the species of the genus Serrapinnus Malabarba, 1998 (Teleostei: Characidae: Cheirodontinae) from the rio Tocantins-Araguaia basin, with description of three new species, pp. 57-79 in Zootaxa 3847 (1) on pages 58-63, DOI: 10.11646/zootaxa.3847.1.3, http://zenodo.org/record/4928753

Serrapinnus potiguar, new species Figs. 1-5 Serrapinnus sp.A. - Dias & Fialho, 2009: 242-248 [trophic category and feeding behavior]. Holotype. MCP 48054, 26.6 mm SL, male, Brazil, Rio Grande do Norte, Taipu, rio Ceará-Mirim, district of Umari, 05°37’47’’S 35°37’09’’W, 15 Oct 2000, H. Gurgel. Paratypes. All from Rio Grande do Norte State, Brazil: MCP 34076, 5, 25.8-27.8 mm SL, Taipu, district of Umari, rio Ceará-Mirim, 5°37’47’’S, 35°37’9’’W, 24 Jul 2001, L. R. Malabarba & H. Gurgel. MCP 43320, 9, 17.5-29.5 mm SL, same as holotype. UFRGS 9216, 13, 22.6-29.5 mm SL (5, 25.6-29.1 mm SL), rio Ceará-Mirim, 5°37’46.9’’S 35°37’9.1’’W, 23 Feb 2002. UFRGS 9219, 27, 18.5- 28.4 mm SL + 10 c&s 25.6-29.1 mm SL (5 measured, 26.2-28.7 mm SL), rio Ceará-Mirim, H. Rangel, Sep 2001. UFRGS 9226, 55, 22.4-32.3 mm SL (20, 26.5-32.3 mm SL), rio Ceará-Mirim, 5°37’46.9’’S 35°37’9.1’’W, H. Rangel, 27 Apr 2002, H. Rangel. Diagnosis. Serrapinnus potiguar is distinguished from all congeners by the shape and arrangement of the ventral procurrent caudal-fin rays on mature males, where the hypertrophied elements are scimitar-shaped and arranged in a semi-circle through the ventral profile of the caudal peduncle (Fig. 2a) (vs. hypertrophied elements rod-shaped or pointed distally, arranged parallel to each other). Additionally S. potiguar can be diagnosed by the presence of 5 cusps in the premaxillary and dentary teeth (vs. 7 to 9 in S. calliurus, S. micropterus, and S. piaba, 9 to 11 in S. sterbai, and 10 to 12 in S. gracilis and S. littoris), terminal mouth (vs. slightly superior mouth in S. microdon), an incomplete lateral line (vs. complete lateral line in S. heterodon), dorsal fin mostly hyaline (vs. dorsal fin with an anterior and proximal dark blotch in S. notomelas), and absence of a black spot in the posteroventral region of the abdomen (vs. presence of a black spot in that region in S. kriegi). Description. Morphometric data on Table 1. Body slightly short and compressed. Greatest body depth at vertical through dorsal-fin origin. Snout slightly rounded. Dorsal profile of head convex from snout to vertical through posterior border of nares, slightly convex from that point to distal tip of supraoccipital bone. Predorsal profile convex from posterior end of supraoccipital to dorsal-fin origin. Dorsal-fin origin located at vertical at midlength of standard length. Dorsal profile from last dorsal-fin ray to adipose-fin base slightly convex in females and strongly ventrally arched on preserved mature males. Caudal-peduncle dorsal profile slightly concave from adipose-fin origin to caudal-fin origin. Caudal-peduncle ventral profile straight to slightly concave in females, pronounced convex with exposed bony spines due to hypertrophy of ventral procurrent caudal-fin rays on males. Caudal peduncle slightly longer than deep. Ventral profile of head slightly convex from mouth to pelvic-fin origin; straight from that point to anal-fin origin in females and concave in mature males. Anal-fin base straight to slightly concave in females, convex anteriorly and deeply concave posteriorly on mature males. Head pointed on lateral view. Mouth terminal, at horizontal line through middle of pupil. Maxilla angled posteroventrally, posterior tip reaching vertical through anterior border of eye and surpassing ventrally the horizontal through ventral border of eye. Teeth pedunculated, distally expanded, with similar shape and cusp number. Four (1), 5(7), or 6(2) premaxillary teeth aligned in one single row, bearing 5 cusps. Midcentral cusp longer and wider than lateral ones. Three (3) or 4(7) maxillary teeth bearing 3 to 5 cusps. Six (8) to 7(2) large dentary teeth bearing 5 cusps, followed posteriorly by one smaller tooth with 3 to 4 cusps and one or two conical teeth. Central cusp larger than lateral cusps. All dentary tooth cusps slightly directed lingually (Fig. 3). Dorsal-fin origin on midlength of standard length. Dorsal-fin rays ii,9*(31). First unbranched dorsal-fin ray about half length of second unbranched dorsal-fin ray, following branched rays gradually decreasing in size posteriorly. Adipose-fin origin slightly posterior to vertical through base of last anal fin. Anal-fin origin posterior to vertical through base of last dorsalfin ray. Anal-fin rays ii(5), iii*(17), or iv(7), 17(1), 18(10), 19*(16), or 20(4). Anal-fin distal profile rounded on anterior lobe and concave posteriorly on females; pointed on anterior lobe and deeply concave posteriorly on males. Last unbranched and first two branched anal-fin rays longer, remaining rays decreasing in size posteriorly. Distal tip of anterior anal-fin rays of mature males overlapping laterally last anal-fin rays, commonly reaching ventral procurrent caudal-fin rays when caudal peduncle deeply arched. Males with acute, retrorse hooks on posterior border and posterior branches of anal-fin rays, posterolaterally arranged on last unbranched to 8 th, 9 th or 10 th branched rays, rarely on 12 th (Fig. 4). Two to three unpaired hooks per ray segment of lepidotrichia. Hooks mostly distributed along middle third of anal-fin ray’s length. Hookbearing rays with segments and branches progressively fused according to degree of maturation on males. Hypertrophied soft tissue associated to hook bearing anal-fin rays. Pectoral-fin rays i*(31), 10*(16), or 11(12), rarely 9(1) or 12(2). Unbranched pectoral-fin ray falling short of pelvic-fin origin on females, and extending beyond that point on adult males. Pelvic-fin origin anterior to vertical through dorsal-fin origin. Pelvic-fin rays i,7*(30), rarely i,8(1). Unbranched and branched pelvic-fin rays with acute hooks on males, 1 pair per segment of lepidotrichia, ventromedially placed on rays, associated with hypertrophied soft tissue. Principal caudal-fin rays 16(1), 17(1), 18(1), 19*(25), or 20(1). Procurrent caudal-fin rays 9(1), 10(4), 11(2), or 12(2) dorsal; 11(5), 12(3), or 13(2) ventral. Ventral procurrent caudalfin rays hypertrophied on mature males, trespassing muscles and skin on ventral margin of caudal-peduncle, resulting in semicircular profile. Hypertrophied ventral procurrent ray scimitar-shaped: anteriorly bent, proximally acute, expanding distally, abruptly ending in pointed distal tip (Fig. 2a). Scales cycloid. Pored scales on lateral line 6*(1), 7(6), 8*(12), 9(10), or 10(2); scales on longitudinal line 30(1), 31(4), 32*(6), 33(13), 34(6), or 35(1); predorsal scales 10*(5), 11(16), or 12(10); scale rows from lateral line to dorsal-fin origin 6(28) or 7*(3); scale rows from lateral line to pelvicfin origin 4*(30) or 5(1); circumpeduncular scale rows 12(2), 13(16), or 14*(13). Scales along anal-fin base 9(1), 10(2), 11*(13), 12(9), 13(5), or 14(1). Supraneurals 4(6) or 5(4); abdominal vertebrae 15(10); caudal vertebrae 18(9) or 19(1). Gill rakers 8(1), 9(2), or 10(2) on lower branch; 3(1) or 4(4) on upper branch. Color in alcohol. Overall body coloration yellowish to dun. Head darker over dorsal region of neurocranium, snout and maxilla, due to higher concentration of dark chromatophores. Dark brown chromatophores sparsely scattered over infraorbitals and opercular apparatus. Opercular apparatus, some infraorbitals and branchiostegal rays silver in some individuals. Ventral region of head and abdomen light. Humeral region with triangular darkened area due to pseudotympanum muscular hiatus. Longitudinal line of dorsum darker than lateral of body. Body scales with higher concentration of black chromatophores on distal margin, resulting in reticulated coloration pattern more conspicuous on upper portion of body. Longitudinal black subcutaneous line on lateral of body extending from vertical through dorsalfin insertion to caudal peduncle spot. Black chromatophores aligned and following line of miosepta on body above anal fin. Caudal spot black, slightly rounded, occupying most of caudal peduncle termination, not reaching upper or lower margins of caudal peduncle. Dorsal, anal, pectoral, pelvic, and caudal fins mostly hyaline, with dark chromatophores scattered on interradial membrane. Unbranched dorsal-fin rays darker than branched rays due to higher concentration of black chromatophores. Adipose fin mostly hyaline, with few black chromatophores distributed near dorsal margin. Caudal fin with clear yellowish areas on base of caudal-fin lobes, bordering caudal-fin spot posteriorly. Distribution. Serrapinnus potiguar is known to inhabit the rio Ceará-Mirim basin, Rio Grande do Norte State, northeastern Brazil. Etymology. The epithet potiguar refers to “potiguar”, a term traditionally used in Brazil to refer to someone born in the Rio Grande do Norte State. An adjective. Ecological notes. The type locality of Serrapinnus potiguar in the rio Ceará-Mirim (05°37’47’’S 35°37’09’’W) was described by Dias & Fialho (2009) as clear and transparent water, sandy bottom high depth 1.2 m. The water current varied from slow to Color in life. Dark pigmentation as described on alcohol preserved specimens. Body light olive brown slightly translucent. Pectoral fin slightly orange or red; dorsal, anal, pelvic and caudal fins intense orange or red (Fig. 5). Distal tip of longest anal- and pelvic-fin rays white or hyaline. Middle caudal-fin rays hyaline. Sexual dimorphism. Bony hooks were only observed on pelvic and anal-fin rays of sexually dimorphic males, as well as hypertrophied and ventrally exposed procurrent caudalfin rays (Fig. 2a). Sexually dimorphic males also present those anal-fin rays that bear bony hooks hypertrophied and expanded in the sagittal plane (Fig. 4). On fixed and preserved specimens the caudal peduncle is generally found arched ventrally only on adult males (Fig. 1a). Furthermore, sexually mature males have gill glands, located on the anteriormost portion of the lower branch of the first gill arch, extending posteriorly through six to eight of gill filaments. moderate and in that stretch the river presented a large amount of floating and submerse vegetation. In that locality S. potiguar is sympatric and syntopic with the cheirodontines Compsura heterura, S. heterodon and S. piaba; and its diet was mainly composed by vegetal matter and algae, but also by insects and microcrustaceans (Dias & Fialho, 2009).

Serrapinnus potiguar, new species, is described from the rio Ceara-Mirim, a coastal drainage in the Rio Grande do Norte State, northeastern Brazil. The new species is distinguished from the other species of the genus by the shape and arrangement of the ventral procurrent caudal-fin rays of the sexually dimorphic males; where the hypertrophied elements present the shape of a series of scimitars arranged radially, forming a semi-circle on the ventral margin of the caudal peduncle. Furthermore, the new species is diagnosed from S. heterodon and S. piaba, sympatric congeners from the northeastern Brazilian drainages, respectively by the presence of incomplete lateral line and teeth bearing at most five cusps. Serrapinnus potiguar, especie nova, e descrita para o rio Ceara-Mirim, uma drenagem costeira localizada no estado do Rio Grande do Norte, na regiao Nordeste do Brasil. A especie nova distingue-se das demais especies do genero pela forma e arranjo dos raios procorrentes ventrais da nadadeira caudal nos machos sexualmente dimorficos; onde os elementos hipertrofiados possuem o formato de uma serie de cimitarras arranjados radialmente na margem ventral do pedunculo caudal, formando um semicirculo. Adicionalmente, a nova especie diferencia-se de S. heterodon e S. piaba, congeneres simpatricos para as drenagens do Nordeste brasileiro, respectivamente pela presenca de linha lateral incompleta e dentes com no maximo cinco cuspides.

Species of the genus Serrapinnus from the rio Tocantins-Araguaia basin are revised and three new species are described. Serrapinnus aster new species is diagnosed by the presence of scimitar-shaped ventral procurrent caudal-fin rays of mature males forming a semicircle and by the presence of 7-9 cusps on the premaxillary teeth; S. lucindai new species is distinguished from its congeners by the presence of a higher number of ventral procurrent caudal-fin rays (17 to 19); and S. tocantinensis new species differs from the remaining species of the genus by the elongation of the unbranched dorsal and pelvic-fin rays into filaments in mature males. Serrapinnus sterbai is recognized as broadly distributed in the Tocantins-Araguaia basin and is redescribed based on specimens from across its entire distribution. A key for the cheirodontines occurring in the Atlantic drainages of northeastern Brazil, from the rio Tocantins-Araguaia to the rio Paraguacu is provided.