A Pliocene-Pleistocene continental biota from Venezuela.

The Pliocene-Pleistocene transition in the Neotropics is poorly understood despite the major climatic changes that occurred at the onset of the Quaternary. The San Gregorio Formation, the younger unit of the Urumaco Sequence, preserves a fauna that documents this critical transition. We report stingrays, freshwater bony fishes, amphibians, crocodiles, lizards, snakes, aquatic and terrestrial turtles, and mammals. A total of 49 taxa are reported from the Vergel Member (late Pliocene) and nine taxa from the Cocuiza Member (Early Pleistocene), with 28 and 18 taxa reported for the first time in the Urumaco sequence and Venezuela, respectively. Our findings include the first fossil record of the freshwater fishes Megaleporinus, Schizodon, Amblydoras, Scorpiodoras, and the pipesnake Anilius scytale, all from Pliocene strata. The late Pliocene and Early Pleistocene ages proposed here for the Vergel and Cocuiza members, respectively, are supported by their stratigraphic position, palynology, nannoplankton, and 86Sr/88Sr dating. Mammals from the Vergel Member are associated with the first major pulse of the Great American Biotic Interchange. In contrast to the dry conditions prevailing today, the San Gregorio Formation documents mixed open grassland/forest areas surrounding permanent freshwater systems, following the isolation of the northern South American basin from western Amazonia. These findings support the hypothesis that range contraction of many taxa to their current distribution in northern South America occurred rapidly during at least the last 1.5 million years.

Putative poison gland in the thorny catfish Acanthodoras spinosissimus (Siluriformes: Doradidae) / Suposta glândula de veneno no bagre rebeca Acanthodoras spinosissimus (Siluriformes: Doradidae)

Acanthodoras is the only genus of catfish known to secrete a conspicuous and abundant milky-looking substance through an axillary pore located just below the base of the posterior cleithral process. Despite this remarkable feature, there is no published information on the anatomical structures that produce the secretion and its possible biological/ecological functions. Dissection and histological analysis of preserved specimens of A. spinosissimus revealed the presence of a saccular axillary gland with large, binuclear secretory cells, similar to those found in other poisonous catfish. Secretory cells near the lumen appear to lose nuclei and become filled with secretory products, possibly with proteinaceous elements, as indicated by their eosinophilic appearance. As far as we know, the saccular morphology of the gland appears to constitute a unique characteristic of Acanthodoras among Doradidae catfishes. Further studies are necessary to determine the chemical composition of the secretion, as well as its possible uses by the catfish in its natural environment.

Acanthodoras é o único gênero de bagre conhecido por secretar uma substância de aparência leitosa conspícua e abundante através de um poro axilar localizado logo abaixo da base do processo cleitral posterior. Apesar dessa característica marcante, não há informações publicadas sobre as estruturas anatômicas que produzem a secreção, nem sobre suas possíveis funções biológicas/ecológicas. A dissecção e análise histológica de espécimes preservados de A. spinosissimus revelaram a presença de uma glândula axilar sacular com células secretoras binucleares, semelhantes às encontradas em outros bagres venenosos. As células secretoras próximas ao lúmen parecem perder os núcleos e são preenchidas com produtos secretores, possivelmente com elementos proteicos, conforme indicado por sua aparência eosinofílica. Até onde sabemos, a morfologia sacular da glândula parece constituir uma característica única de Acanthodoras entre os bagres Doradidae. Mais estudos são necessários para determinar a composição química da secreção, bem como seus possíveis usos pelo bagre em seu ambiente natural.

Putative poison gland in the thorny catfish Acanthodoras spinosissimus (Siluriformes: Doradidae)

ABSTRACT Acanthodoras is the only genus of catfish known to secrete a conspicuous and abundant milky-looking substance through an axillary pore located just below the base of the posterior cleithral process. Despite this remarkable feature, there is no published information on the anatomical structures that produce the secretion and its possible biological/ecological functions. Dissection and histological analysis of preserved specimens of A. spinosissimus revealed the presence of a saccular axillary gland with large, binuclear secretory cells, similar to those found in other poisonous catfish. Secretory cells near the lumen appear to lose nuclei and become filled with secretory products, possibly with proteinaceous elements, as indicated by their eosinophilic appearance. As far as we know, the saccular morphology of the gland appears to constitute a unique characteristic of Acanthodoras among Doradidae catfishes. Further studies are necessary to determine the chemical composition of the secretion, as well as its possible uses by the catfish in its natural environment.

RESUMO Acanthodoras é o único gênero de bagre conhecido por secretar uma substância de aparência leitosa conspícua e abundante através de um poro axilar localizado logo abaixo da base do processo cleitral posterior. Apesar dessa característica marcante, não há informações publicadas sobre as estruturas anatômicas que produzem a secreção, nem sobre suas possíveis funções biológicas/ecológicas. A dissecção e análise histológica de espécimes preservados de A. spinosissimus revelaram a presença de uma glândula axilar sacular com células secretoras binucleares, semelhantes às encontradas em outros bagres venenosos. As células secretoras próximas ao lúmen parecem perder os núcleos e são preenchidas com produtos secretores, possivelmente com elementos proteicos, conforme indicado por sua aparência eosinofílica. Até onde sabemos, a morfologia sacular da glândula parece constituir uma característica única de Acanthodoras entre os bagres Doradidae. Mais estudos são necessários para determinar a composição química da secreção, bem como seus possíveis usos pelo bagre em seu ambiente natural.

Taxonomic revision of Hopliancistrus Isbrücker & Nijssen, 1989 (Siluriformes, Loricariidae) with redescription of Hopliancistrus tricornis and description of four new species.

Hopliancistrus is an Ancistrini genus diagnosed by having few and very strong cheek odontodes on interopercular area, and a patch of strong and stiff odontodes on the antero-lateral border of the snout. The type species is herein redescribed based on types and recently collected specimens. In addition, four new congeneric species are described based on specimens collected in other parts of the Rio Xingu and Rio Tapajós basins. Hopliancistrus tricornis is distributed in the lower Rio Tapajós and is diagnosed by the possession of four branched anal-fin rays and relatively large white to yellow spots on trunk and pectoral and pelvic fins, and dark brown spots on dorsal, caudal and anal fins. Hopliancistrus munduruku is described based on specimens from Rio Jamanxim (Rio Tapajós basin) and Rio Curuá (Rio Xingu basin) and is diagnosed by the possession of five branched anal-fin rays and large yellow blotches on trunk and dark brown to black spots over the fins. Hopliancistrus wolverine is distributed in the rapids of the lower and middle Rio Xingu and is diagnosed by the possession of five branched anal-fin rays and conspicuous small yellow dots on head, trunk and fins. Hopliancistrus xikrin is distributed in medium- to small-sized tributaries of the lower portion of Rio Xingu basin, and is diagnosed by absence of contact between the transverse process of the first dorsal-fin pterygiophore and the transverse process of the second pterygiophore. Hopliancistrus xavante is distributed in the tributaries of upper Rio Xingu basin, and is diagnosed by having a thick skin covering the nuchal plate; by having large white spots on trunk and fins; and by the possession of five branched anal-fin rays. An osteological description and a key for species identification are also provided.

Integrative taxonomy reveals a new species of Neotropical headstanding fish in genus Schizodon (Characiformes: Anostomidae)

Abstract Schizodon encompasses approximately 15 species of Neotropical headstanding fishes. Integrative taxonomy, combining molecular and morphometric analyses with traditional taxonomic methods, was used to investigate Schizodon vittatus and its potential new sister species. Molecular differences between the two species in the barcode are greater than intra-specific variation recovered in species of Schizodon, and the two species represent distinct lineages for approximately one million years. The two species are morphologically very similar, and the meristic data showed great overlap. Morphometric analyses also showed overlap among the putative species but indicated differences in caudal-peduncle depth, orbital diameter, and length of anal-fin rays. Color pattern seems to provide a clear diagnostic feature for the two species. Schizodon vittatus usually has four dark brown transversal bars on body, and its sister species has three conspicuous bars, with the fourth, if present, inconspicuous and dorsal to the lateral line. Schizodon vittatus is redescribed based on the type and recently collected specimens, its type locality is revisited, and its known distribution restricted to the Araguaia and Tocantins drainages. The new species, sister to S. vittatus, distributed in the Xingu and Tapajós drainages, is described. A key for the identification of the Amazon clade species of Schizodon is provided.

Resumo Schizodon engloba aproximadamente 15 espécies de peixes neotropicais. A taxonomia integrativa, combinando análises moleculares e morfométricas com métodos taxonômicos tradicionais, foi utilizada para investigar Schizodon vittatus e sua potencial espécie irmã. As diferenças moleculares (DNA barcoding) entre as duas espécies são maiores do que a variação intraespecífica observada em espécies congêneres, e as duas espécies representam linhagens distintas por aproximadamente um milhão de anos. As duas espécies são morfologicamente muito similares e os dados merísticos mostram grande sobreposição. As análises morfométricas também mostraram sobreposição entre as duas espécies, mas indicaram diferenças na altura do pedúnculo caudal, no diâmetro interorbital, e no comprimento dos raios da nadadeira anal. O padrão de colorido parece fornecer uma característica diagnóstica clara para as duas espécies. Schizodon vittatus normalmente possui quatro faixas escuras transversais no corpo e sua espécie irmã tem três faixas, com a quarta, se presente, inconspícua e dorsal à linha lateral. Schizodon vittatus é redescrita com base no tipo e em espécimes coletados recentemente; sua localidade tipo é revisitada e a sua distribuição conhecida é restringida às drenagens do Araguaia e Tocantins. A nova espécie, irmã de S. vittatus e distribuída nas drenagens do Xingu e Tapajós, é descrita. Uma chave para a identificação das espécies do clado amazônico de Schizodon é apresentada.

A new endangered species of Megaleporinus (Characiformes: Anostomidae) from the Rio de Contas basin, eastern Brazil.

A new species of Megaleporinus is described from the Rio de Contas, a coastal drainage of eastern Brazil, and its phylogenetic relationships are studied using molecular data. The new species is unique among Anostomidae by possessing two exclusive features: an irregular dark longitudinal stripe from supracleithrum to second midlateral blotch and anterior cranial fontanel partially closed. In addition, the new species is diagnosed by having three premaxillary teeth, three dentary teeth, 37 or 38 scales in lateral line, 16 scale rows around caudal peduncle, three dark midlateral blotches on body, and red fins in life. The new species is closely related to M. obtusidens from the São Francisco basin, corroborating previous studies that indicated that the latter represents a species complex as currently defined. The new species exhibits the first rib enlarged in mature males, a feature described for some congeners. The new species is herein considered to be Endangered under the IUCN criteria.

New species of Leporinus (Characiformes: Anostomidae) from the highlands of the Guiana Shield in Venezuela

A new species of Leporinus is described using morphological data and compared to all other species of the family. Specimens were illustrated using digital photograph, measured using digital calipers, and had teeth, scales, and fin rays counted under a stereomicroscope. The new species is distinguished from all other Anostomidae, except Anostomus anostomus, A. brevior, A. ternetzi, Hypomasticus despaxi, Leporinus arcus, and L. striatus, by having four dark longitudinal stripes on body. The new species is distinguished from aforementioned species by having terminal mouth with four teeth on the premaxilla, 12 series of scales around caudal peduncle, and 34 to 36 scales in the lateral line. The new species is remarkably similar to Leporinus arcus, which occurs on the opposite side of Guyana Shield highlands. The new species and L. arcus are possibly closely related to Leporinus gomesi, L. granti, L. lebaili, L. melanostictus, L. nijsseni, and L. santosi.(AU)

Uma espécie nova de Leporinus é descrita usando dados morfológicos e comparações entre todas as espécies da família. Exemplares foram ilustrados com fotografia digital, medidos com paquímetro digital e seus dentes, escamas e raios das nadadeiras foram contados sob estereomicroscópio. A espécie nova distingue-se dos demais Anostomidae, exceto Anostomus anostomus, A. brevior, A. ternetzi, Hypomasticus despaxi, Leporinus arcus e L. striatus, por apresentar quatro faixas longitudinais no corpo. A nova espécie distingue-se das espécies mencionadas por ter boca terminal com quatro dentes no osso pré-maxilar, 12 séries de escamas ao redor do pedúnculo caudal e 34 a 36 escamas na linha lateral. A espécie nova é particularmente similar à Leporinus arcus, que ocorre no lado oposto das terras altas do Escudo da Guiana. A espécie nova e L. arcus, possivelmente, são relacionadas proximamente à Leporinus gomesi, L. granti, L. lebaili, L. melanostictus, L. nijsseni e L. santosi.(AU)

Preface: How far has Neotropical Ichthyology progressed in twenty years?

Studies on the diversity, taxonomy, phylogeny, and biogeography of Neotropical Fishes have thrived over the twenty years that have elapsed since the first symposium on their phylogeny and classification in Porto Alegre, Brazil. Here, we review recent advances in the study of Neotropical fishes and assess the known diversity of freshwater species in that region. 6,255 valid freshwater species have been discovered in the Neotropics so far, and we estimate that over 9,000 species will be known when the inventory is complete. We also summarize the events of the second Symposium on Phylogeny and Classification of Neotropical Fishes that took place last year in Londrina, Brazil. Along with invited talks on the biodiversity of all major groups of Neotropical fishes, a series of presentations on the development of fish collections, and numerous contributed talks, the meeting included a special session to honor Dr. Richard Vari, who was one of the most prolific and beloved members of our community.(AU)

Estudos sobre diversidade, taxonomia, filogenia e biogeografia de peixes neotropicais prosperaram nos últimos vinte anos, desde o primeiro simpósio sobre filogenia e classificação em Porto Alegre, Brasil. Aqui, os novos avanços nos estudos de peixes neotropicais são discutidos e a diversidade conhecida reavaliada para espécies de água doce. Foram descobertas 6.255 espécies de peixes de água doce para na região Neotropical até o momento, e estimamos que haja mais de 9.000 espécies quando o inventário estiver completo. Nós resumimos as informações do segundo Simpósio sobre Filogenia e Classificação de Peixes Neotropicais ocorrido no ano passado em Londrina, Brasil. Além de apresentações de convidados sobre Biodiversidade dos grandes grupos de peixes Neotropicais, de uma série de apresentações sobre o estado da arte das coleções científicas, e de diversas outras apresentações, o simpósio incluíu uma sessão especial em homenagem ao Dr. Richard Vari, um dos membros mais prolíficos e amados da nossa comunidade.(AU)

A new genus of Anostomidae (Ostariophysi: Characiformes): Diversity, phylogeny and biogeography based on cytogenetic, molecular and morphological data.

A new genus of Anostomidae (Characiformes) is described to include ten valid extant species previously classified in Leporinus or Hypomasticus and distributed throughout most major river basins in South America: L. brinco, L. conirostris, L. elongatus, H. garmani, L. macrocephalus, L. muyscorum, L. obtusidens, L. piavussu, L. reinhardti, and L. trifasciatus. The monophyly of Megaleporinus is well-supported in a phylogenetic analysis based on two mitochondrial and three nuclear genes, as well as its sister group relationship to Abramites. Megaleporinus is diagnosed by having the exclusive combination of three unicuspid teeth on each premaxillary and dentary bone and a color pattern composed of one to four dark midlateral blotches. Additional distinguishing features and possible synapomorphies include a unique ZZ/ZW sex chromosome system confirmed for six congeners and a drumming apparatus wherein the first rib is elongated and associated with hypertrophied intercostal muscles, which was confirmed for three congeners as exclusive to mature males. Furthermore, our study identified at least four undescribed cryptic species, emphasizing the need for further taxonomic work and genetic analyses. A time-calibrated phylogenetic and biogeographical analysis of the new genus suggests that speciation in the proto-Amazon-Orinoco lineage was primarily driven by paleogeographic processes, such as the formation of the Orinoco and Tocantins basins. Dispersal and diversification of the genus in coastal basins draining the Eastern Brazilian Shield appears to have been facilitated by connections between paleo-basins during low sea level periods and headwater captures between coastal and inland watersheds. The present contribution demonstrates the importance of integrating data from morphology, DNA sequences and cytogenetics to advance the taxonomy and systematics of any complex species group.

Systematic assessment of the Leporinus desmotes species complex, with a description of two new species

Members of the Leporinus desmotes species complex can be distinguished from other barred or banded congeners by the combination of nine distinct black bars across the head and trunk and long, pointed, laterally compressed and upward curving symphyseal dentary teeth. A taxonomic reassessment of this complex revealed two new species, one from the Orinoco and Negro rivers of Venezuela and Brazil, and the other from the Xingu and Tapajós rivers of Brazil. Both species are similar to L. desmotes and L. jatuncochi, but differ significantly in body shape morphology, coloration, and/or circumpeduncular scale counts. Genetic evidence also contributes to the recognition of both new species. This contribution also maps the geographic distribution of the four known species, and highlights the presence of an unusual meristic polymorphism within Leporinus desmotes sensu stricto that may suggest the presence of even more unrecognized diversity.(AU)

As espécies do complexo Leporinus desmotes diferem da maioria dos congêneres com base nas nove barras transversais escuras ao redor da cabeça e do corpo, e do dente sinfisiano do dentário alongado, comprimido lateralmente e ligeiramente curvado para cima. Uma revisão taxonômica desse complexo revelou a existência de duas espécies novas, uma dos rios Orinoco e Negro na Venezuela e Brasil, e outra das drenagens dos rios Xingu e Tapajós, no Brasil. As duas espécies novas são similares à L. desmotes e L. jatuncochi, das quais diferem significativamente por uma combinação de forma do corpo, coloração e número de séries de escamas ao redor do pedúnculo caudal. Dados genéticos também corroboram o reconhecimento das duas espécies novas. Esta contribuição ainda traz novos dados sobre a distribuição geográfica de cada uma das espécies do complexo, e discute a presença de um incomum polimorfismo no número de escamas ao redor do pedúnculo caudal em Leporinus desmotes stricto sensu, que sugere a presença de uma diversidade ainda maior de espécies não descritas.(AU)

Two new species of Leporinus Agassiz, 1929 (Characiformes: Anostomidae) from tributaries of the lower Amazon basin in Brazil.

Two new species of Leporinus (Characiformes, Anostomidae) are described. Both new species are diagnosed by having one dark blotch on midline of anterior portion of the flank (between opercle and pelvic-fin origin) surrounded by five to seven dark blotches; and a subinferior mouth with three premaxillary teeth. Leporinus multimaculatus, new species, is distributed in small and medium-sized tributaries of the rio Tocantins and rio Xingu basins, and also in the rio Jari and coastal drainages of Amapá state, whereas L. torrenticola, new species, is endemic to the rapids of the rio Xingu and its main tributaries. The number of scale rows around the caudal peduncle is the main feature distinguishing L. multimaculatus from L. torrenticola. Comments on the diagnostic features of the newly described species are provided. In addition, the phylogenetic position and generic assignment of the new species are discussed based on available information from recent morphological and molecular analyses.

Redescription of Astyanax guianensis Eigenmann 1909 (Characiformes: Characidae), a poorly known and widespread fish from the Amazon, Orinoco and Guiana Shield drainages.

Astyanax guianensis is redescribed based on the holotype, paratypes, and additional specimens from the rio Essequibo in Guyana, rio Orinoco in Venezuela and from several localities in the Amazon river basin in Brazil, Colombia and Bolivia. Astyanax guianensis is diagnosed by having five to 10 maxillary teeth, 31 to 35 pored lateral-line scales, 21 to 25 branched anal-fin rays, and a dark vertical humeral blotch followed by a clear area and then by a dark longitudinal stripe, ending before the caudal-fin rays. In addition, comments on the importance of revisionary studies on the species of the Characidae are provided.

Phylogenetic relationships of the South American Doradoidea (Ostariophysi: Siluriformes)

A phylogenetic analysis based on 311 morphological characters is presented for most species of the Doradidae, all genera of the Auchenipteridae, and representatives of 16 other catfish families. The hypothesis that was derived from the six most parsimonious trees support the monophyly of the South American Doradoidea (Doradidae plus Auchenipteridae), as well as the monophyly of the clade Doradoidea plus the African Mochokidae. In addition, the clade with Sisoroidea plus Aspredinidae was considered sister to Doradoidea plus Mochokidae. Within the Auchenipteridae, the results support the monophyly of the Centromochlinae and Auchenipterinae. The latter is composed of Tocantinsia, and four monophyletic units, two small with Asterophysus and Liosomadoras, and Pseudotatia and Pseudauchenipterus, respectively, and two large ones with the remaining genera. Within the Doradidae, parsimony analysis recovered Wertheimeria as sister to Kalyptodoras, composing a clade sister to all remaining doradids, which include Franciscodoras and two monophyletic groups: Astrodoradinae (plus Acanthodoras and Agamyxis) and Doradinae (new arrangement). Wertheimerinae, new subfamily, is described for Kalyptodoras and Wertheimeria. Doradinae is corroborated as monophyletic and composed of four groups, one including Centrochir and Platydoras, the other with the large-size species of doradids (except Oxydoras), another with Orinocodoras, Rhinodoras, and Rhynchodoras, and another with Oxydoras plus all the fimbriate-barbel doradids. Based on the results, the species of Opsodoras are included in Hemidoras; and Tenellus, new genus, is described to include Nemadoras trimaculatus, N. leporhinus and Nemadoras ternetzi. Due to conflicting hypotheses of the phylogenetic position of Acanthodoras, Agamyxis, and Franciscodoras, these are considered as incertae sedis in Doradidae. All suprageneric taxa of the Doradoidea are diagnosed based on synapomorphic morphological characteristics...

Uma análise filogenética com base em 311 caracteres morfológicos é apresentada para a maioria das espécies de Doradidae, todos os gêneros de Auchenipteridae e representantes de outras 16 famílias de Siluriformes. A hipótese de consenso entre as seis árvores mais parcimoniosas corrobora o monofiletismo do grupo Sul-americano Doradoidea (Doradidae mais Auchenipteridae), bem como o de Doradoidea mais a família Africana Mochokidae. O clado de Sisoroidea mais Aspredinidae é considerado como grupo-irmão de Doradoidea mais Mochokidae. Dentre os Auchenipteridae, os resultados corroboraram o monofiletismo de Centromochlinae e Auchenipterinae. Esta última inclui Tocantinsia e outros quarto grupos monofiléticos, um com Asterophysus e Liosomadoras, um com Pseudotatia e Pseudauchenipterus, e outros dois maiores com os demais gêneros da subfamília. Dentre os Doradidae, a análise de parcimônia recuperou Wertheimeria como grupo-irmão de Kalyptodoras, formando um clado irmão de todos os demais doradídeos, que incluem Franciscodoras e dois grupos: Astrodoradinae (mais Acanthodoras e Agamyxis) e Doradinae (arranjo novo). Wertheimerinae, subfamília nova, é descrita para os gêneros Kalyptodoras e Wertheimeria. Doradinae é corroborada como monofilética e composta por quatro grupos de espécies, o primeiro com Centrochir e Platydoras, o segundo com os doradídeos de grande porte (exceto Oxydoras), o terceiro com Orinocodoras, Rhinodoras e Rhynchodoras, e o quarto com Oxydoras e os doradídeos de barbilhões fimbriados. Com base nos resultados, Opsodoras é considerado como sinônimo júnior de Hemidoras; e Tenellus, gênero novo, é descrito para Nemadoras trimaculatus, N. leporhinus e Nemadoras ternetzi. Devido à existência de hipóteses conflitantes para a posição filogenética de Acanthodoras, Agamyxis e Franciscodoras, estes são considerados como incertae sedis em Doradidae. Todos os grupos supra-genéricos de Doradoidea são diagnosticados com base em caracteres morfológicos sinapomórficos...

Redescription of leporinus jamesi (characiformes: anostomidae), a poorly known species of leporinus from the lowlands of the central Amazon, Brazil

The poorly known Leporinus jamesi is redescribed. The species was originally described based on a single specimen collected in the rio Solimões at Manacapuru, in the central Amazon, Brazil. The holotype went missing before the species description was finished and published, and remained lost for more than a hundred years. Leporinus jamesi is distinguished from its congeners by having pectoral and pelvic fins dark, 42 to 45 scales on the lateral line, 16 scale series around the caudal peduncle, a body with two conspicuous dark midlateral blotches (the blotch on the caudal peduncle absent or inconspicuous), and four teeth on the premaxilla and dentary, including a bicuspid symphyseal tooth on the premaxilla. A principal component analysis on morphometric traits between combined samples of L. jamesi and L. amazonicus was performed showing significant morphometric differences between these species. In addition, inaccuracies in Borodin's descriptions of various species of the genus Leporinus are discussed.

Leporinus jamesi, uma espécie pouco conhecida, é redescrita. A espécie foi originalmente descrita com base em um único exemplar procedente do rio Solimões em Manacapuru, na Amazônia central, Brasil. O holótipo da espécie foi perdido antes de sua descrição ter sido concluída e publicada, assim permanecendo por mais de cem anos. Leporinus jamesi distingue-se dos congêneres por apresentar as nadadeiras peitorais e pélvicas escuras, 42 a 45 escamas na linha lateral, 16 séries de escamas ao redor do pedúnculo caudal, duas manchas escuras conspícuas na lateral do corpo (mancha do pedúnculo caudal ausente ou inconspícua) e quatro dentes no pré-maxilar e no dentário , incluindo um dente bicúspide sinfisiano. Uma análise de componentes principais de características morfológicas realizada entre amostras combinadas de L. jamesi e L. amazonicus revelou diferenças significativas entre estas espécies. Além disso, imprecisões nas descrições de diversas espécies de Leporinus apresentadas por Borodin são discutidas.

Hemigrammus ataktos: a new species from the rio Tocantins basin, central Brazil (characiformes: characidae)

A new species of hemigrammus is described from the middle rio Tocantins basin, central Brazil. The new species can be distinguished from all congeners by having a black midlateral stripe on the body extending from the posterior margin of the eye to the median caudal-fin rays. Mature males possess dorsal-, pelvic-, and anal-fin rays elongate, features that also help to recognize the new species. Although the new species is described in Hemigrammus, some specimens present a complete series of pored scales in the lateral line. A discussion about the generic allocation of the new species is presented.

Uma espécie nova de hemigrammus é descrita da bacia do médio rio Tocantins, Brasil central. A espécie nova distingue-se de seus congêneres por apresentar uma faixa mediana negra na lateral do corpo desde a margem posterior do olho até os raios medianos da nadadeira caudal. Machos maduros apresentam os raios das nadadeiras dorsal, pélvica e anal alongados, características que também auxiliam o reconhecimento da espécie. Apesar da espécie nova ser descrita em Hemigrammus, alguns exemplares possuem série completa de escamas perfuradas na linha lateral. Uma discussão sobre o posicionamento genérico da espécie nova é apresentada.

Two new species of Leporinus Agassiz (Characiformes: Anostomidae) from eastern basins of Brazil, and redescription of L. melanopleura Günther

Two new species of Leporinus are described from coastal rivers of southern Bahia, Brazil. One of the new species has a bright red blotch immediately dorsal to the pectoral-fin origin in life, three dark blotches along the lateral line that distinctly increase in size posteriorly, and dark longitudinal lines between scale rows on the side of body. The second new species possesses a single broad dark midlateral stripe, encompassing one or two scale rows of depth on the body and centered on the scale row below the lateral line, a dark adipose fin, and a conspicuous dark blotch on the caudal peduncle. The first new species is known only from the rio de Contas and the second from the rio das Almas and rio Jiquiriçá. In addition, Leporinus melanopleura is redescribed based on a designated lectotype and additional specimens collected in the rio Una. Leporinus melanopleura has a single broad dark midlateral stripe, encompassing one or two scale rows of depth on the body, centered on the scale row below lateral line, a hyaline adipose fin (red in life), and an inconspicuous dark blotch on the caudal peduncle.

Duas espécies novas de Leporinus são descritas com base em exemplares de rios costeiros do sudeste da Bahia, Brasil. Uma das espécies novas possui uma mancha vermelho-viva imediatamente dorsal à origem da nadadeira peitoral em vida, três manchas escuras sobre a linha lateral que aumentam de tamanho para trás, e linhas escuras longitudinais entre as séries de escamas na lateral do corpo. A segunda espécie nova apresenta uma única faixa escura sobre o corpo, com altura de uma ou duas fileiras de escamas e centrada na série de escamas da linha lateral, nadadeira adiposa escura, e uma conspícua mancha escura sobre o pedúnculo caudal. A primeira espécie nova é conhecida somente do rio de Contas e a segunda dos rios das Almas e Jiquiriçá. Além disso, Leporinus melanopleura é redescrita com base no lectótipo, designado no presente trabalho, e outros exemplares coletados no rio Una. Leporinus melanopleura possui uma única faixa escura sobre o corpo, com altura de uma ou duas fileiras de escamas e centrada na série de escamas abaixo à linha lateral, nadadeira adiposa hialina (vermelha em vida), e uma mancha escura inconspícua sobre o pedúnculo caudal.

Redescription of Astyanax multidens Eigenmann, 1908 (Characiformes: Characidae), a small characid of the Brazilian Amazon

Astyanax multidens is redescribed based on syntypes and additional specimens from the rio Amazonas at Silves, Amazonas State and Óbidos, Pará State, and the rios Trombetas, Tapajós, Xingú, and Araguaia. Astyanax multidens is distinguished from congeners by the unique combination of five to seven maxillary teeth, 31 to 34 pored lateral-line scales, 20 to 23 branched anal-fin rays, and a dark triangular blotch restricted to the middle caudal-fin rays. Astyanax multidens was collected syntopically with Jupiaba paranatinga in the rio Tapajós basin and with Jupiaba cf. essequibensis in the rio Xingu basin, which have paired anteriorly oriented pelvic-fin spines, a antipredatory mechanism. Based on the external morphological similarity between Astyanax multidens and the two species of Jupiaba, their sympatric occurrence, and their distinct phylogenetic position, we interpret this a case of Batesian mimicry.

Astyanax multidens é redescrita com base no exame dos síntipos e espécimes adicionais do rio Amazonas em Silves, AM e Óbidos, PA e rios Trombetas, Tapajós, Xingú e Araguaia. Astyanax multidens distingue-se dos congêneres pela exclusiva combinação de cinco a sete dentes no maxilar, 31 a 34 escamas perfuradas na linha lateral, 20 a 23 raios ramificados na nadadeira anal, e uma mácula triangular escura restrita aos raios medianos da nadadeira caudal. Astyanax multidens foi coletada sintopicamente com Jupiaba paranatinga na bacia do rio Tapajós, e com Jupiaba cf. essequibensis na bacia do rio Xingu, que possuem espinho pélvico voltado para frente, um mecanismo antipredatório. Baseado na similaridade morfológica externa entre Astyanax multidens e estas duas espécies de Jupiaba, sua ocorrência simpátrica, e sua distante posição filogenética, nós interpretamos como um caso de mimetismo Batesiano. .

A new species of Leporinus Agassiz, 1829 (Characiformes: Anostomidae) from the rio Tocantins, Brazil

A new species of Leporinus is described based on specimens from the lower rio Tocantins, Pará State, Brazil. The new species is diagnosed by having conspicuous dark spots on center of scales on anterolateral portion of body, 33 or 34 scales in lateral line, 16 scales rows around caudal peduncle, four scale rows between dorsal-fin origin and lateral line and four between lateral line and pelvic-fin origin, and four teeth on premaxilla and four on dentary. The new species is similar to Leporinus gomesi, L. granti, and L. nijsseni for having three prominent dark midlateral blotches, smaller blotches formed by dermal pigment, five of which form an interrupted "X" between head and first midlateral blotch, small dark spots formed by epidermal pigment, terminal mouth with four teeth on premaxilla and four on dentary, and relatively few scales on lateral line (less than 36). In addition, new data is provided for the type specimens of Leporinus granti and L. megalepis (=Hypomasticus megalepis),, and L. badueli is confirmed as a junior synonym of L. granti.

Uma espécie nova de Leporinus é descrita a partir de exemplares do baixo rio Tocantins, estado do Pará, Brasil. A espécie nova é diagnosticada por possuir conspícuos pontos escuros no centro de cada escama da porção anterolateral do corpo, 33 ou 34 escamas na linha lateral, 16 séries de escamas ao redor do pedúnculo caudal, quatro séries de escamas entre a origem da nadadeira dorsal e a linha lateral e quatro entre a linha lateral e a origem da nadadeira pélvica, quatro dentes no pré-maxilar e quatro no dentário. A espécie nova se assemelha a Leporinus gomesi, L. granti e L. nijsseni por apresentar três manchas escuras laterais no corpo, manchas menores no corpo formadas por pigmentos dérmicos dispostas num "X" entre o opérculo e a primeira mancha lateral, pontos escuros formados por pigmentos epidérmicos, boca terminal com quatro dentes no pré-maxilar e quatro no dentário, e relativamente poucas escamas na linha lateral (menos de 36). Além disso, dados novos sobre as séries de exemplares-tipo de Leporinus granti e L. megalepis (=Hypomasticus megalepis) são apresentados, e L. badueli é confirmado como um sinônimo júnior de L. granti .

A new miniature species of Characidium Reinhardt (Ostariophysi: Characiformes: Crenuchidae) from the headwaters of the rio Araguaia, Brazil.

Characidium inirim is described from the rio das Mortes, rio Araguaia basin in Central Brazil. The new species is distinguished from its congeners by having an incomplete lateral line, a conspicuous dark longitudinal stripe and dark transverse bars not extending ventrally to the lateral line, and by lacking the adipose fin and the dark caudal blotch. A phylogenetic hypothesis based on the available data on the phylogenetic relationships of the subfamily Characidiinae is presented. Results suggest that the new species is closely related to C. bahiensis, C. interruptum, C. lagosantense, C. nupelia, C. lanei, C. laterale, C. occidentale, C. orientale, C. rachovii, C. stigmosun, C. vestigipinne and C. xavante.

Comparative morphology of the gas bladder in driftwood catfishes (Siluriformes: Auchenipteridae).

The gross morphology of the gas bladder is described and illustrated for representatives of most species and all valid genera of the Auchenipteridae (Siluriformes). Although, a simple cordiform gas bladder is present in some species of the family, others are characterized by their distinctive gas-bladder shape and diverticula disposition. An acute posterior end of the gas bladder characterizes Centromochlus heckelii and C. macracanthus, and is variably present in specimens of Auchenipterus. Tocantinsia piresi and Asterophysus batrachus have distinctive gas bladders differing in number of diverticula (two or many). The two species of Trachycorystes are diagnosed based on their gas bladder morphology: T. menezesi has a simple cordiform bladder, whereas T. trachycorystes has a pair of lateral diverticulum and, usually, a well-developed terminal diverticulum. Species of Auchenipterichthys are characterized by having a secondary bladder with simple chamber. Short or elongate and divergent terminal diverticula are exclusive to most cis-andine species of Trachelyopterus. Tetranematichthys and trans-andine species of Trachelyopterus share a well-developed secondary chamber or terminal diverticula ventrally or dorsally connected to the posterior chambers. The small-sized species of Ageneiosus have well-developed gas bladders with a pair of posterior diverticula, whereas large-sized species have a reduced gas bladder with tunica externa varying from non-, partially, or completely ossified. Eight phylogenetic characters are proposed based on the morphology of the gas bladder and associated structures in species of Auchenipteridae, and the evolution of those characters in the family discussed.