New small-sized species of Astyanax (Characiformes: Characidae) from the upper rio Paraguai basin, Brazil, with discussion on its generic allocation

A new species of Astyanax is described from the rio Salobra, tributary of rio Cuiabá, rio Paraguai basin. The new taxon can be distinguished from its congeners by having a well-defined dark midlateral stripe on body extending from the posterior margin of the opercle to the base of middle caudal-fin rays and a single vertical elongate humeral blotch. Although the new species is described in Astyanax, some specimens present an incomplete or a discontinuous series of perforated scales in the lateral line. Therefore, a discussion on its generic allocation is presented. Comments on different patterns of coloration among dark-striped species of Astyanax are also provided. The discovery of a new species in an underwater tourist point relatively near a large urban center underscores that even fish species daily observed by hundreds of people in limpid waters may lack a formal taxonomic identity. Such finding also highlights how the megadiverse Brazilian freshwater ichthyofauna still needs efforts and investments to identify and describe new taxa.(AU)

Uma nova espécie de Astyanax é descrita do rio Salobra, afluente do rio Cuiabá, bacia do rio Paraguai. O táxon novo pode ser diferenciado de seus congêneres por apresentar uma faixa médio-lateral escura bem definida no corpo, se estendendo da margem posterior do opérculo até a base dos raios medianos da nadadeira caudal e por possuir uma mancha umeral verticalmente alongada. Apesar da espécie nova ser descrita em Astyanax, alguns exemplares apresentam uma série incompleta ou descontínua de escamas perfuradas na linha lateral. Assim, uma discussão sobre sua alocação genérica é apresentada. Comentários sobre os diferentes padrões de coloração de espécies de Astyanax com faixa escura também são fornecidos. A descoberta de uma espécie nova em um ponto turístico subaquático relativamente próximo a um grande centro urbano ressalta que mesmo as espécies de peixes observadas diariamente por centenas de pessoas em águas límpidas podem não ter uma identidade taxonômica formal. Tal achado também evidencia o quanto a megadiversa ictiofauna de água doce brasileira ainda precisa de esforços de coleta adicionais e investimentos para identificar e descrever os táxons novos.(AU)

A new species of Knodus Eigenmann (Characiformes: Characidae: Stevardiinae) with comments on nuptial tubercles and gill gland in characiform fishes.

Knodus nuptialis n. sp. is described from the Rio Curuá drainage, Rio Xingu basin, Brazil. It can be diagnosed from its congeners by having dentary teeth decreasing gradually in size posteriorly, outer premaxillary teeth row with five cusps, 12-15 branched anal-fin rays and a single humeral spot. The species presents notable sexual dimorphism consisting of densely concentrated nuptial tubercles on head, body, and fins, gill-gland, and bony hooks in the anal fin of mature males. It was found that these sexually dimorphic features are useful and functional in males of the new species only during the reproductive season and after this period, they become atrophied, and eventually disappear. The list of characiform species presenting breeding tubercles is updated and nine species and two genera of the Characidae, Deuterodon and Bryconacidnus, are for the first time reported to have breeding tubercles.

Moenkhausia lepidura (Kner, 1858) (Characiformes, Characidae): osteology and relationships / Moenkhausia lepidura (Kner, 1858) (Characiformes, Characidae): osteologia e relações de parentesco

Abstract Cladistic analysis of fishes are mostly based on osteological studies. Phylogenetic relationships within the family Characidae are poorly known in part due to the lack of anatomical studies of its members, including osteology. The present contribution aims to offer a detailed description of all bony complexes of Moenkhausia lepidura. Two remarkable morphological conditions present in the species are discussed: a bony lamella on the proximal portion of the ribs and a basal expansion of the gill rakers. A morphological survey of several species of Characidae along with available phylogenetic information of the family indicates the putative relationships of Moenkhausia lepidura with other small characids presenting bony lamella on ribs and a dark mark on the caudal fin.

Resumo Análises cladísticas morfológicas de peixes são, em grande parte, baseadas em estudos osteológicos. As relações filogenéticas em Characidae são pouco conhecidas, em parte devido à falta de estudos anatômicos de seus representantes, incluindo a osteologia. O presente estudo tem por objetivo oferecer uma descrição detalhada dos complexos ósseos de Moenkhausia lepidura. Duas condições morfológicas notáveis presentes na espécie são discutidas: uma lamela óssea na porção proximal das costelas e uma expansão basal dos rastros branquiais. Um estudo morfológico de diversas espécies de Characidae, juntamente com informações filogenéticas disponíveis na família, indica a possível relação de M. lepidura com pequenos caracídeos que apresentam lamelas ósseas nas costelas e marcas escuras na nadadeira caudal.

Taxonomic review of Copella (Characiformes: Lebiasinidae) with an identification key for the species.

A taxonomic review of Copella is presented based on the analysis of the type material of all nominal species and extensive material from South American drainages. Six out of ten nominal species are recognized as valid: Copella arnoldi, C. callolepis, C. compta, C. eigenmanni, C. nattereri, and C. vilmae. Copella carsevennensis is a junior synonym of C. arnoldi, C. nigrofasciata and 'Nannostomus' stigmasemion are junior synonyms of C. callolepis, C. metae is junior synonym of C. eigenmanni, and C. meinkeni is junior synonym of C. nattereri. Species of Copella occur in the rio Amazonas and Orinoco basins, and coastal drainages of Guyana, French Guiana, Surinam, and Venezuela. An identification key is provided.

A new species of Moenkhausia Eigenmann, 1903 (Characiformes, Characidae) from the rio Amazonas basin, Brazil.

Moenkhausia abyss is herein described from the rio Amazonas basin lowlands. The new species can be distinguished from the congeners by presenting the combination of the following characters: a dark blotch located on the upper caudal-fin lobe and the lower lobe hyaline, 25-29 branched anal-fin rays, humeral spot rectangular, vertically oriented, extending horizontally through two or two and a half scales and located over the third to the fifth lateral line scales, five longitudinal scale rows above the lateral line, predorsal scales arranged in a single not interrupted median row and 30-34 perforated lateral line scales. Brief comments on Moenkhausia megalops are provided.

Reconciling more than 150 years of taxonomic confusion: the true identity of Moenkhausia lepidura, with a key to the species of the M. lepidura group (Characiformes: Characidae).

Moenkhausia lepidura (Kner) is redescribed based on the examination of the type and other specimens from several localities of the Amazon and Orinoco basins. The species is readly diagnosed from congeners by a combination of a dark blotch on the upper caudal-fin lobe, lower lobe hyaline, and by the arrangement of predorsal scales, in which scales of anterior portion of predorsal area are arranged in pairs, followed by a single median row of scales extending to dorsal-fin origin. The analysis of the type material of Gymnotichthys hildae Fernández-Yépez and Knodus calliurus Ahl demonstrated the former is a junior synonym of Moenkhausia lepidura, whereas the latter should be removed from its synonymy. An identification key to the Moenkhausia lepidura-group is provided.

A new species of Moenkhausia Eigenmann (Characiformes: Characidae) from the upper rio Machado at Chapada dos Parecis, rio Madeira basin, Brazil

A new species of Moenkhausia is described from the upper rio Machado at Chapada dos Parecis, rio Madeira basin, Rondônia State, Brazil. Among congeners, the new species is similar to Moenkhausia chlorophthalma, M. cotinho , M. lineomaculata , M. plumbea, and M. petymbuaba by having dark blotches on the anterior portion of the body scales, which are absent in the remaining species of the genus. The new speciesdiffers from aforementioned species by possessing blue eyes in life, 15-18 branched anal-fin rays, and a well-defined, round caudal-peduncle spot that does not reach the upper and lower margins of the caudal peduncle and does not extend to the tip of the middle caudal-fin rays.

Uma espécie nova de Moenkhausia é descrita do alto rio Machado na Chapada dos Parecis, bacia do rio Madeira, Rondônia, Brasil. Entre as congêneres, a espécie nova é semelhante à Moenkhausia chlorophthalma , M. cotinho , M. lineomaculata , M. plumbea e M. petymbuaba por ter manchas escuras na região anterior das escamas, que estão ausentes nas demais espécies do gênero. A espécie nova difere das espécies mencionadas acima por possuir olhos azuis em vida, 15-18 raios ramificados na nadadeira anal e uma mancha arredondada bem definida no pedúnculo caudal, que não alcança o limite superior e inferior do pedúnculo caudal, e não se estende sobre os raios medianos da nadadeira caudal.

A new species of Moenkhausia Eigenmann (Characiformes: Characidae) from the rio Arinos basin, Brazil

A new species of Moenkhausia is described from the rio Arinos drainage, rio Tapajós basin, Mato Grosso, Brazil. The new species is diagnosed from all congeners, except M . hemigrammoides , M . nigromarginata , and Moenkhausia rubra by having intense diffuse dark pigmentation on the dorsal and anal fin-rays. The new species can be distinguished from the above mentioned species by the combination of 20-23 branched anal-fin rays, presence of a vertically elongate roughly rectangular humeral spot surpassing the lateral line ventrally, absence of a well-defined black spot on the distal portion of the dorsal fin and lack of a series of longitudinal dark zigzag stripes on body. The new species is herein described along with a report and discussion of a possible connection between the rio Tapajós and rio Paraguay basins, near Diamantino Municipality, Mato Grosso.

Uma espécie nova de Moenkhausia é descrita das drenagens do rio Arinos, bacia do rio Tapajós, Mato Grosso, Brasil. A nova espécie é diagnosticada de todas as congêneres, exceto M . hemigrammoides , M . nigromarginata , e Moenkhausia rubra por possuir pigmentação escura intensa e difusa nos raios das nadadeiras dorsal e anal. A nova espécie pode ser distinguida das espécies supracitadas pela combinação da presença de 20-23 raios ramificados na nadadeira anal, presença de uma mancha umeral aproximadamente retangular, ultrapassando a linha lateral ventralmente, ausência de uma mancha negra conspícua na porção distal da nadadeira dorsal e pela ausência de uma série de linhas longitudinais negras em forma de zigue-zague no corpo. A nova espécie é aqui descrita, juntamente com o relato de uma possível conexão entre as bacias dos rios Tapajós e rio Paraguay, próximo ao município de Diamantino, Mato Grosso.

A new species of Moenkhausia Eigenmann (Characiformes: Characidae) from the upper rio Juruena basin, Central Brazil.

Moenkhausia lineomaculata, new species, is described herein from the upper rio Juruena, upper rio Tapajós basin. The new species seems to be part of a monophyletic group formed by M. cosmops, M. cotinho, M. diktyota, M. forestii, M. oligolepis, M. sanctaefilomenae, and M. pyrophthalma, the Moenkhausia oligolepis/M. sanctaefilomenae complex, by sharing a reticulated color pattern on body and the presence of a light area preceding a wide, dark caudal-peduncle blotch. The new species is distinguished from these species, except M. cotinho, by the presence of longitudinal series of dark dots on body, and from M. cotinho by the humeral blotch evenly pigmented along its length and by having the dark line along horizontal septum starting approximately at the vertical through dorsal-fin origin. The new species presents intraspecific variation in lateral-line scales perforation, a feature often present in species of the aforementioned group.

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.

A new species of hyphessobrycon durbin (characiformes: characidae) from the middle rio São Francisco and upper and middle rio Tocantins basins, Brazil, with comments on its biogeographic history

A new species of Hyphessobrycon Durbin is described from tributaries of the rio Grande (rio São Francisco basin) draining east to the Serra Geral de Goiás, of the rio São Domingos (upper rio Tocantins basin) and rio do Sono basins (middle rio Tocantins basin). Hyphessobrycon diastatos can be diagnosed from its congeners by the absence of humeral spot, 15-18 branched anal-fin rays, 1-3 maxillary conical to tricuspid teeth, a relatively well-defined dark caudal-peduncle spot, and elongation of dorsal- and anal-fin rays in mature males. The biogeographical significance of the distribution of the new species is evaluated and discussed.

Uma espécie nova de Hyphessobrycon Durbin é descrita dos tributários do rio Grande (bacia do rio São Francisco) que drenam a leste a Serra Geral de Goiás, das bacias dos rios São Domingos (bacia do alto rio Tocantins) e rio do Sono (bacia do médio rio Tocantins). Hyphessobrycon diastatos pode ser diagnosticada de seus congêneres pela ausência de mancha umeral, 15-18 raios ramificados na nadadeira anal, 1-3 dentes maxilares cônicos ou tricuspidados, uma mancha escura relativamente bem definida no pedúnculo caudal e alongamento das nadadeiras dorsal e anal em machos maduros. O significado biogeográfico da distribuição da espécie nova é avaliado e discutido.

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.

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. .

New species of Pyrrhulina (Ostariophysi: Characiformes: Lebiasinidae) from the Brazilian Shield, with comments on a putative monophyletic group of species in the genus.

Pyrrhulina marilynae, new species, is described. The new species can be distinguished among congeners mainly by presenting a conspicuous, dark, zigzag shaped primary stripe, extending to distal end of median caudal-fin rays, reduction of the number of precaudal vertebrae, absence of postecleithrum 2, and nine principal rays on caudal-fin dorsal lobe. The putative relationship of the new species with Pyrrhulina australis, P. vittata and P. zigzag, three small-sized species of the genus, is discussed.

Redescription of Astyanax guaporensis Eigenmann, 1911 (Characiformes: Characidae), a small characid from the rio Madeira basin.

During recent expeditions to several localities in the rio Madeira basin, a poorly known species of Characidae described more than a century ago, Astyanax guaporensis Eigenmann, was collected. The species is herein redescribed based on the type material and many recently collected specimens. The species seems to occur only in the rio Madeira basin, rio Amazonas drainage. The species is mainly recognized among its congeners by having five to nine maxillary teeth, a series of V-shaped marks on the midlateral line of body, and the absence of a black mark on the caudal peduncle.

New species of miniature fish from Marajo Island, Para, Brazil, with comments on its relationships (Characiformes: Characidae)

A new miniature species of the family Characidae from Marajó Island, Pará State, Brazil is described and assigned to the genus Tyttobrycon. The new species can be distinguished from its congeners primarily by having multicuspid teeth on jaws, and additionally by having the combination of 5-7 premaxillary teeth, dorsal fin only with scattered melanophores and the presence of an adipose fin.

Uma espécie nova miniatura da família Characidae da Ilha do Marajó, Pará, Brasil, é descrita e atribuída ao gênero Tyttobrycon. A espécie nova pode ser diferenciada dos congêneres principalmente por ter dentes multicuspidados nas maxilas e adicionalmente por ter a combinação de 5-7 dentes no pré maxilar, nadadeira dorsal apenas com pequenos cromatóforos escuros dispersos e presença de nadadeira adiposa.

A new species of Moenkhausia Eigenmann (Characiformes: Characidae) from the rio Xingu basin, Brazil

A new species of Moenkhausia from the upper rio Xingu basin is described. Moenkhausia eurystaenia is distinguished from all congeners, except M. heikoi and M. phaeonota, by the presence of a dark, broad longitudinal stripe from the opercle to the end of caudal peduncle. The new species is distinguished from M. heikoi mainly by having 18-21 branched anal-fin rays (vs. 24-26) and the absence of a round blotch at the end of the caudal peduncle (vs. present). Moenkhausia eurystaenia can be distinguished from M. phaeonota mainly by the anterior portion of longitudinal band darker at horizontal septum (vs. darker below horizontal septum), the deep dark pigmentation along horizontal septum extending anteriorly up to humeral region (vs. extending up to vertical through pelvic-fin origin), number of vertebrae 34 (vs. 36-37), and others additional measurements.

Uma espécie nova de Moenkhausia da bacia do alto rio Xingu é descrita. Moenkhausia eurystaenia distingue-se de todas as congêneres, exceto M. heikoi e M. phaeonota, pela presença de uma faixa longitudinal larga e escura que se estende do opérculo ao pedúnculo caudal. A espécie nova distingue-se de Moenkhausia heikoi principalmente por apresentar 18-21 raios ramificados na nadadeira anal (vs. 24-26), e ausência de uma mácula circular no final do pedúnculo caudal (vs. presença). Moenkhausia eurystaenia distingue-se de M. phaeonota principalmente pela porção anterior da faixa longitudinal ser mais escura no septo horizontal (vs. mais escura abaixo do septo horizontal), pigmentação profunda e escura ao longo do septo horizontal se estendendo até a região umeral (vs. se estendendo até a vertical que passa pela origem da nadadeira pélvica), 34 vértebras (vs. 36-37), e outras medidas adicionais.

Astyanax ajuricaba: a new species from the Amazon basin in Brazil (Characiformes: Characidae)

A new Astyanax species is described from several localities in the rio Negro, rio Solimões and lower rio Tapajós basins, Amazon basin, Brazil. The new species is distinguished from all remaining characids by its unique color pattern consisting of the combination of presence of a conspicuous, narrow dark midlateral stripe, a well-developed vertically-elongated dark humeral spot, and upper caudal-fin lobe and middle caudal-fin rays dark, with a rounded clear ocellated spot present at anterior third of caudal-fin lobe.

Uma nova espécie de Astyanax é descrita de diversas localidades nas bacias dos rios Negro, Solimões e baixo Tapajós, bacia Amazônica, Brasil. A nova espécie pode ser distinguida de todos os demais Characidae por um padrão de colorido único, que consiste na combinação da presença de uma linha médio-lateral estreita e escura, uma mácula umeral escura bem desenvolvida e verticalmente alongada e o lobo superior da nadadeira caudal e raios medianos escuros, com uma mancha ocelada clara presente no terço anterior do lobo.