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Gymnotus is the most studied genus of the order Gymnotiformes, but the morphological similarities of the different species make it difficult to identify taxa reliably. The present study is a continuation of the ongoing research into the taxonomic diversity of the stocks of Gymnotus sold as live bait in the Pantanal, Brazil. These studies have been based on cytogenetic analyses, DNA barcoding, and the analysis of coloration patterns. The results of the cytogenetic analysis confirmed the presence of three distinct strains, recognized as Gymnotus paraguensis, G. sylvius, and G. pantanal. However, the results revealed that the molecular operational taxonomic units identified as G. paraguensis actually include a relatively diverse set of fish, separated by considerable genetic distances. As the G. paraguensis specimens also presented considerable variation in coloration patterns, further genetic diversity analyses were conducted on these individuals, to test the hypothesis that more than one species is present in this cytotaxonomic unit. The haplotype network revealed a regional pattern in the distribution of this species. The results indicate that the observed variation in coloration patterns is associated with a high degree of phenotypic plasticity in G. paraguensis. These findings emphasize the importance of using an integrative approach for a more accurate diagnosis of Gymnotus, in particular, the species marketed as live bait for the fisheries of the upper Paraguay River basin in the Brazilian Pantanal.

Studies of pulse-type gymnotiform electric fishes have suggested that electric organ discharge waveforms (EODw) allow individuals to discriminate between conspecific and allospecific signals, but few have approached this experimentally. Here we implement a phase-locked playback technique for a syntopic species pair, Brachyhypopomus gauderio and Gymnotus omarorum. Both species respond to changes in stimulus waveform with a transitory reduction in the interpulse interval of their self-generated discharge, providing strong evidence of discrimination. We also document sustained rate changes in response to different EODws, which may suggest recognition of natural waveforms.

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

Some fish communicate using pulsatile, stereotyped electric organ discharges (EODs) that exhibit species- and sex-specific time courses. To ensure reproductive success, they must be able to discriminate conspecifics from sympatric species in the muddy waters they inhabit. We have previously shown that fish in both Gymnotus and Brachyhypopomus genera use the electric field lines as a tracking guide to approach conspecifics (electrotaxis). Here, we show that the social species Brachyhypopomus gauderio uses electrotaxis to arrive abreast a conspecific, coming from behind. Stimulus image analysis shows that, even in a uniform field, every single EOD causes an image in which the gradient and the local field time courses contain enough information to allow the fish to evaluate the conspecific sex, and to find the path to reach it. Using a forced-choice test, we show that sexually mature individuals orient themselves along a uniform field in the direction encoded by the time course characteristic of the opposite sex. This indicates that these fish use the stimulus image profile as a spatial guidance clue to find a mate. Embedding species, sex and orientation cues is a particular example of how species can encode multiple messages in the same self-generated communication signal carrier, allowing for other signal parameters (e.g. EOD timing) to carry additional, often circumstantial, messages. This ‘multiple messages’ EOD embedding approach expressed in this species is likely to be a common and successful strategy that is widespread across evolutionary lineages and among varied signaling modalities.

The aim of this study was to report the first record of Trichodina heterodentata in banded knifefish Gymnotus carapo. Banded knifefish cultivated in the municipality of Jataí, state of Goiás, in the central western region of Brazil, experienced fish mortality rates of 3-4% per tank. Macroscopic analysis found that fish had lesions on their skin and gills. Smears of the integument and gills were confectioned and air-dried at room temperature and impregnated with silver nitrate to identify the Trichodinidae species causing the lesions. The trichodinid were identified as T. heterodentata, and their characteristics were compared to those from T. heterodentata recorded from other species of host fish. It was observed that the presence of T. heterodentata was associated with inadequate fish management, low water quality, high rates of stocking density, and inadequate nutritional management. Resumo O objetivo deste estudo foi relatar o primeiro registro de Trichodina heterodentata em tuviras Gymnotus carapo. Um cultivo de tuviras no município de Jataí, estado de Goiás, na região Centro-Oeste do Brasil, apresentou taxas de mortalidade de peixes de 3-4% por tanque. A análise macroscópica constatou que os peixes tinham lesões na pele e brânquias. Raspados do tegumento e brânquias foram confeccionadas e secas ao ar à temperatura ambiente e impregnadas com nitrato de prata para identificar as espécies de Trichodinidae causadoras das lesões. Os tricodinídeos foram identificados como T. heterodentata, e suas características foram comparadas com as de T. heterodentata registradas para outras espécies de peixes hospedeiros. Observou-se que a presença de T. heterodentata estava associada ao manejo inadequado dos peixes, baixa qualidade da água, altas taxas de densidade de estocagem e manejo nutricional inadequado.

Fishes of the genus Gymnotus have been suggested as a good model for biogeographic studies in the South American continent. In relation to heterochromatin, species of this genus have blocks preferably distributed in the centromeric region. The content of these regions has been shown to be variable, with description of transposable elements, pseudogenes of 5S rDNA and satellite sequences. In G. carapo Clade, although geographically separated, species with 2n = 54 chromosomes share the distribution of many 5S rDNA sites, a unique case within the genus. Here, repetitive DNA sequences from G. sylvius (2n = 40) and G. paraguensis (2n = 54) were isolated and mapped to understand their constitution. The chromosome mapping by FISH showed an exclusive association in the centromeres of all chromosomes. However, the cross-FISH did not show positive signs of interspecific hybridization, indicating high levels of heterochromatic sequence specificity. In addition, COI-1 sequences were analyzed in some species of Gymnotus, which revealed a close relationship between species of clade 2n = 54, which have multiple 5S rDNA sites. Possibly, the insertion of retroelements or pseudogenization and dispersion of this sequence occurred before the geographic dispersion of the ancestor of this clade from the Amazon region to the hydrographic systems of Paraná-Paraguay, a synapomorphy for the group.

The vasopressin-vasotocin (AVP-AVT) and oxytocin-mesotocin-isotocin (OT-MT-IT) families of nonapeptides are of great importance in shaping context-dependent modulations of a conserved and yet highly plastic network of brain areas involved in social behavior: the social behavior network. The nonapeptide systems of teleost fish are highly conserved and share a common general organization. In this study, we first describe the presence of IT cells and projections in the brain of an electric fish, Gymnotus omarorum. Second, we confirm that IT neuron types and distribution in the preoptic area (POA) follow the same general pattern previously described in other teleost species. Third, we show that although IT and AVT neurons occur intermingled within the POA of G. omarorum and can be classified into the same subgroups, they present subtle but remarkable differences in size, number, and location. Finally, we show that unlike AVT, IT has no effect on basal electric signaling, reinforcing the specificity in the actions that each one of these nonapeptides has on social behavior and communication.

Agonistic behavior involves the displays that arise when conspecifics compete for valuable resources such as territory. After conflict resolution, dominants obtain priority access to the resource while subordinates lose it. We aimed to evaluate how agonistic encounters mediate the acquisition of different sized territories in the weakly electric fish, Gymnotus omarorum, a species that displays a well-documented non-breeding agonistic behavior very unusual among teleosts. When tested in intrasexual and intersexual dyads in small arenas, a sex-independent dominant-subordinate status emerged after highly aggressive contests in which subordinates signaled submission by retreating and emitting submissive electric signals. We staged dyadic agonistic encounters in a large arena, in which the initial interindividual distance resembled the one observed in nature. We observed the emergence of a dominant-subordinate status after longer but milder contests with rare electric signaling of submission. We found the persistence of dominance over time with no outcome reversion. We observed how dominants exclude subordinates from their conquered resource during all the recording time. Although the territorial behavior of Gymnotus has been put forth since pioneer reports, this is the first study to show how agonistic behavior depends on the territory size in this genus. Agonistic encounters of G. omarorum in the small arena resemble the characteristics of violent-like behaviors. The ease of shifting from mild to high levels of aggression due to confinement, together with the use of electrical signaling of submission, makes this species an excellent model to explore new perspectives in territoriality assessment.

Este estudo avaliou os parasitos endohelmí­­nticos do peixe nativo Gymnotus spp. coletados de diferentes isqueiros comerciais na bacia do Pantanal, Mato Grosso do Sul, Brasil Central. De 99 peixes coletados para análise parasitológica, todos estavam parasitados por pelo menos um parasito por hospedeiro. Um total de 4504 parasitos foi coletado compreendendo os seguintes táxons: Digenea, Nematoda, Pentastomida e Acanthocephala. Rondonia rondoni e Goezia sp. bem como Alofia sp. foram registrados pela primeira vez em Gymnotus spp. A diversidade de espécies de parasitos no hospedeiro é discutida neste estudo.

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.

Made available in DSpace on 2020-12-10T19:41:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-07-03 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Complete mitochondrial genomes of the characiform fishes Astyanax fasciatus, Astyanax altiparanae, Hoplias malabaricus (Karyomorph A) and the Gymnotiformes species Gymnotus sylvius and Gymnotus cuia were characterized in the present study. The whole mitogenomes varied from 16,400bp (A. fasciatus) to 17,730 bp (A. altiparanae) long and all of them consisted of 13 protein-coding genes, 22 tRNAs, 2 rRNAs genes, a control region, and origin of light-strand replication. The gene order was similar among all the analyzed species. The nucleotide content of all mitogenomes was also similar, with 29.58-30.95% for A, 27.02-28.65% for T, 26.29-29.99% for C, and 14.41-15.67% for G. Univ Estadual Paulista, Fac Ciencias, Dept Ciencias Biol, Bauru, SP, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Morfol, Botucatu, SP, Brazil Univ Fed Rural Rio de Janeiro, Dept Genet, Seropedica, Brazil Univ Estadual Paulista, Fac Ciencias, Dept Ciencias Biol, Bauru, SP, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Morfol, Botucatu, SP, Brazil FAPESP: 2018/03365-3 CNPq: 405334/2018-4

Most vertebrates use active sensing strategies for perception, cognition and control of motor activity. These strategies include directed body/sensor movements or increases in discrete sensory sampling events. The weakly electric fish, Gymnotus sp., uses its active electric sense during navigation in the dark. Electric organ discharge rate undergoes transient increases during navigation to increase electrosensory sampling. Gymnotus also use stereotyped backward swimming as an important form of active sensing that brings objects toward the electroreceptor dense fovea-like head region. We wirelessly recorded neural activity from the pallium of freely swimming Gymnotus. Spiking activity was sparse and occurred only during swimming. Notably, most units tended to fire during backward swims and their activity was on average coupled to increases in sensory sampling. Our results provide the first characterization of neural activity in a hippocampal (CA3)-like region of a teleost fish brain and connects it to active sensing of spatial environmental features.

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.

The present study describes the life history of Gymnotus refugio, a species classified as Endangered in the last published list of threatened species of the Brazilian fauna. The study was conducted at a conservation unity that protect one of the last remaining semideciduous forests in the region. The reproductive period was estimated as occurring from the end of winter to the last summer months. Gymnotus refugio exibited fractional spawning, the lowest relative fecundity registered among the Gymnotifomes species studied at the present, and male parental care behavior. The analyses showed a seasonal pattern on the species diet, associating different food categories to winter, autumn, and spring. According to food items analysis and estimated intestinal quotient, G. refugio was classified as invertivorous, feeding mainly on autochthonous insects. The results obtained herein suggest that the position of G. refugio as an Endangered species might be influenced by its territoriality, habitat specificity, parental care behavior, and low fecundity, reinforcing the importance of swampy forest environment conservation as the only means of the species maintenance.

Active sensing behaviors reveal what an animal is attending to and how it changes with learning. Gymnotus sp., a gymnotiform weakly electric fish, generates an electric organ discharge (EOD) as discrete pulses to actively sense its surroundings. We monitored freely behaving gymnotid fish in a large dark “maze” and extracted their trajectories and EOD pulse pattern and rate while they learned to find food with electrically detectable landmarks as cues. After training, they more rapidly found food using shorter, more stereotyped trajectories and spent more time near the food location. We observed three forms of active sensing: sustained high EOD rates per unit distance (sampling density), transient large increases in EOD rate (E-scans) and stereotyped scanning movements (B-scans) were initially strong at landmarks and food, but, after learning, intensified only at the food location. During probe (no food) trials, after learning, the fish's search area and intense active sampling was still centered on the missing food location, but now also increased near landmarks. We hypothesize that active sensing is a behavioral manifestation of attention and essential for spatial learning; the fish use spatial memory of landmarks and path integration to reach the expected food location and confine their attention to this region.

Trichlorfon (TRF) is a pesticide widely used in aquaculture to control fish ectoparasites. This pesticide is an inhibitor of acetylcholinesterase, an essential enzyme for termination of nerve impulses. High rates of TRF use generate risks to the environment and human health. In the environment, pesticides can affect the local fauna and generate an ecological breakdown. There are several studies performed with fish production; however, gaps are created for native fish with other commercial values. The tuvira (Gymnotus carapo) is a fish native to Brazilian fauna and has great commercial importance in sport fishing. The present study aimed to determine the lethal concentration of trichlorfon (Masoten) in Gymnotus carapo and its sublethal effects on the enzyme AChE. In this study, the acute toxicity (the concentrations to kill 50% of the fish LC50) of TRF in tuviras (Gymnotus carapo) and acetylcholinesterase inhibition in liver and muscle tissue of tuviras submitted to sublethal concentrations were evaluated. For the acute assay, concentrations of 0.0, 5.0, 7.5, 15, 22.5, 30, 37.5 and 45 mg L-1 were used for a period of 96 h. After the acute exposure period, a LC50 of 6.38 mg L-1 was determined. In the sublethal assay, concentrations of 0.0, 0.238, 0.438 and 0.638 mg L-1 were used, based on 10% of the LC50, over a period of 14 days. Two collections were performed: one at seven days and the other at the end (day 14). Inhibition of acetylcholinesterase in the liver was only shown (p < 0.05) for the treatment with 0.638 mg L-1 after 14 days of exposure. At seven days, muscle activity showed a significant difference only for the treatments 0.438 and 0.638 mg L-1, compared with the treatment 0.238 mg L-1 and control. At 14 days of exposure, only the treatment 0.638 mg L-1 showed significant differences in relation to the other groups, thus showing that enzyme recovery had occurred. The value found in the acute test allowed the conclusion that TRF presents moderately toxic characteristics to Gymnotus carapo. The toxicity parameter values calculated in the present study assisted in estimation of maximum allowable limits in bodies of water when combined with test data from other non-target organisms. -- Resumo: O triclorfon (TRC) é um pesticida muito utilizado na aquicultura para o controle de ectoparasitos de peixes. Este pesticida é um inibidor da acetilcolinesterase, uma enzima essencial para a finalização de impulsos nervosos. As altas concentrações utilizadas de TRC geram riscos ao meio ambiente e à saúde humana. No ambiente, os pesticidas podem afetar a fauna local e gerar um colapso ecológico. Existem vários estudos com peixes de produção, no entanto, há lacunas para peixes nativos com outros valores comerciais. A tuvira (Gymnotus carapo) é um peixe nativo da fauna brasileira e possui grande importância comercial na pesca esportiva. O presente trabalho, delineado para determinar a concentração letal de triclorfon (Masoten?) em Gymnotus carapo e seus efeitos subletais na enzima AChE, avaliou a toxicidade aguda (concentrações para matar 50% dos peixes CL50) do TRC em tuviras (Gymnotus carapo) e a inibição da acetilcolinesterase no fígado e tecido muscular de tuviras. Para o ensaio agudo, foram utilizadas concentrações de 0,0, 5,0, 7,5, 15, 22,5, 30, 37,5 e 45 mg L-1 por um período de 96 horas. Após o período de exposição aguda, foi determinado uma CL50 de 6,38 mg L-1. No ensaio subletal, foram utilizadas concentrações de 0,0, 0,238, 0,438 e 0,638 mg L-1, com base em 10% do CL50, durante um período de catorze dias. Foram realizadas duas colheitas: uma aos sete dias e a outra ao final (décimo quarto dia). A inibição da acetilcolinesterase no fígado foi demonstrada apenas (p

Neural mechanisms underlying spatial navigation in fish are unknown and little is known, for any vertebrate, about the relationship between active sensing and the formation of spatial maps. The weakly electric fish, Gymnotus Carapo, uses their active electric sense for spatial navigation. The electric organ discharge rate (EODr) undergoes transient increases during navigation to enhance electrosensory sampling. Gymnotus also uses stereotyped forward/ backward swimming as a second form of active sensing that brings objects towards the electroreceptor-dense head region. We wirelessly recorded neural activity from the pallium of freely swimming Gymnotus. Spiking activity was sparse and occurred only during swimming. Notably, some units exhibited significant place specificity and/or association with both forms of active sensing. Our results provide the first characterization of neural activity in a hippocampal-like region of a teleost fish brain and connects active sensing via sensory sampling rate and directed movements to higher order encoding of spatial information.

Integrative taxonomy uses several sources of information to establish more robust species delimitation criteria. In this study, we followed that approach to describe two new species of allocreadiid trematodes from freshwater fish distributed in locations across Middle America. The new species were first recognized by using sequences of the domains D1–D3 of the ribosomal 28S rRNA gene and then, morphological data (light and scanning electron microscopy (SEM)), host association, and geographical distribution were considered as additional sources of information to complement the species delimitation and description. Auriculostoma tica n. sp. was found in the intestine of Gymnotus maculosus Albert and Miller in Costa Rica, while Wallinia anindoi n. sp. was found in the intestine of Astyanax aeneus (Gunther) in Oaxaca and Chiapas, Mexico, as well as in a location of Guatemala. A phylogenetic analysis combining newly generated sequences of the two new species along with those available for other allocreadiids in GenBank, revealed that isolates of each species are reciprocally monophyletic, and also their interrelationships: Au. tica n. sp. is a sister taxon of Auriculostoma totonacapanensis Razo-Mendivil et al., 2014, and W. anindoi n. sp. is a sister taxon of Wallinia brasiliensis Dias, et al., 2018. Genetic distances for the 28S rRNA gene were estimated among the American species of allocreadiids and further supported the validity of the new species.

Made available in DSpace on 2018-11-26T17:52:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-08-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Microsatellites show great abundance in eukaryotic genomes, although distinct chromosomal distribution patterns might be observed, from small dispersed signals to strong clustered motifs. In Neotropical fishes, the chromosome mapping of distinct microsatellites was employed several times to uncover the origin and evolution of sex and supernumerary chromosomes, whereas a detailed comparative analysis considering different motifs at the chromosomal level is scarce. Here, we report the chromosomal location of several simple sequence repeats (SSRs) in distinct electric knife fishes showing variable diploid chromosome numbers to unveil the structural organization of several microsatellite motifs in distinct Gymnotus species. Our results showed that some SSRs are scattered throughout the genomes, whereas others are particularly clustered displaying intense genomic compartmentalization. Interestingly, the motifs CA, GA, and GAG exhibited a band-like pattern of hybridization, useful for the identification of homologous chromosomes. Finally, the colocalization of SSRs with multigene families is probably related to the association of microsatellites with gene spacers in this case. Sao Paulo State Univ, Inst Biosci Botucatu, Dept Morphol, Lab Biol & Genet Peixes, BR-04026002 Botucatu, SP, Brazil Univ Fed Para, Inst Ciencias Biol, Ctr Estudos Avancados Biodiversidade, Lab Citogenet, Belem, PA, Brazil Sao Paulo State Univ, Inst Biosci Botucatu, Dept Morphol, Lab Biol & Genet Peixes, BR-04026002 Botucatu, SP, Brazil

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"]}

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."]}

Made available in DSpace on 2018-12-11T16:40:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-02-01 This study provides the most comprehensive Model-Based Total Evidence (MBTE) phylogenetic analyses of the clade Gymnotiformes to date, reappraising relationships using a dataset comprised of six genes (5277 bp) and 223 morphological characters, and an ingroup taxon sample including 120 of 212 valid species representing 34 of the 35 extant genera. Our MBTE analyses indicate the two main gymnotiform clades are Gymnotidae and Sternopygoidei, the latter comprised of Rhamphichthyoidea (Rhamphichthyidae + Hypopomidae) and Sinusoidea (Sternopygidae + Apteronotidae). Within Gymnotidae, Electrophorus and Gymnotus are sister taxa, and Gymnotus includes the following six clades: (i) G. pantherinus clade, (ii) G. coatesi clade, (iii) G. anguillaris clade, (iv) G. tigre clade, (v) G. cylindricus clade, and (vi) G. carapo clade. Within Rhamphichthyoidea, Steatogenae (Steatogenys + Hypopygus) is a member of Rhamphichthyidae, and Hypopomidae includes the following clades: (i) Akawaio, (ii) Hypopomus, (iii) Microsternarchini, and (iv) Brachyhypopomus. Within Sternopygidae, Sternopygus and Eigenmanninae are sister groups, Rhabdolichops is the sister to other Eigenmanninae, Archolaemus+. Distocyclus is the sister to Eigenmannia, and Japigny is nested within Eigenmannia. Within Apteronotidae, Sternarchorhamphinae (Sternarchorhamphus + Orthosternarchus) is the sister to Apteronotinae, Adontosternarchus is the sister group to other Apteronotinae, Sternarchorhynchini (Sternarchorhynchus + Platyurosternarchus) is the sister to Navajini, and species assigned to Apteronotus are members of two separate clades: (i) A. sensu stricto in the Apteronotini, and (ii) the A. bonapartii clade in the Navajini. Universidade Estadual Paulista - UNESP Instituto de Biociências de Botucatu University of Louisiana at Lafayette Department of Biology Universidade Estadual Paulista - UNESP Instituto de Biociências de Botucatu

In this paper, we suggest a phase difference algorithm inspired by weakly electric fish. Weakly electric fish is a fish which generates electric field though its electric organ in the tail. The weakly electric fish search for prey and detect an object by using electrolocation. The weakly electric fish have Jamming Avoidance Response (JAR) to avoid jamming signal. One of pulse-type weakly electric fish Gymnotus carapo also have JAR to reduce the probability of coincidence of pulses. We analyze this response signal and design the phase difference algorithm. We expect that simple algorithm inspired by weakly electric fish can be used in many engineering fields.

Cell-cell interactions play essential roles in the regulation of gametogenesis. The involvement of junctional complexes in permeability barriers, for example, provides structural and physiological support for male germ-cell development. This study describes morphological characteristics of the reproductive system of Gymnotus carapo, a neo-tropical freshwater fish widely distributed in South and Central America, focusing on the detection of permeability barriers using morphological and biochemical approaches. Ultrastructural analysis of testes treated with the lanthanum nitrate exclusion technique showed that the tracer penetrated the interstitial compartment of the testis, surrounding and appearing within cysts containing spermatogonia and spermatocytes in early stages of meiosis, but was not detected in the spermatid cysts or inside the lumen of spermatogenic tubules. These results suggest the presence of a permeability barrier that is stabilized after meiosis is completed and serves to protect the haploid cells from the vascular system. In the spermatic-duct region, the tracer was obstructed near the lumen of the duct. Junctional complexes and focal tight junctions between adjacent cells were observed in the testis and spermatic duct. Freeze-fracture methods indeed confirmed the presence of tight junctions, which were visualized as parallel rows of individual particles between adjacent cells. More evidence supporting the existence of a permeability barrier was gathered from differences observed in the electrophoretic protein profiles of testis and spermatic-duct fluids compared to blood plasma. Together, these observations demonstrate the existence of a permeability barrier formed by tight junctions in the testis and spermatic duct of G. carapo.

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"]}