Convergent and environmentally associated chromatic polymorphism in Bryconops Kner, 1858 (Ostariophysi: Characiformes: Iguanodectidae).

Bryconops Kner, 1858, includes two well defined subgenera based on morphological evidence, with each containing at least one species (B. (Bryconops) caudomaculatus and B. (Creatochanes) melanurus) with a very wide distribution, within which regional populations present color variations. To test if phenotypic variation is related to cladogenetic events, we performed tests for phylogenetic independence and determined the strength of convergence for color characters in relation to water type, as the variation between clear, black and white waters is considered to be one of the major driving forces in the evolution of Amazonian fishes. Color characters for fins above the median line of the body were generally found to be independent from phylogeny and the Wheatsheaf test strongly supports convergence of the dorsal fin color between populations of species in the same type of water, with a similar trend suggested for the color of the dorsal lobe of the caudal fin. This means that simple color characters cannot necessarily be relied upon for taxonomic revisions of the genus as local phenotypic variants may represent environmentally determined plasticity or convergent evolution. Further studies are required to determine the validity of these characters.

Phylogenomics, evolution of trophic traits and divergence times of hemiodontid fishes (Ostariophysi: Characiformes).

The South American characiform family Hemiodontidae comprises five genera and 34 species. The family lacks comprehensive phylogenetic hypotheses resolving its species relationships. The studies that addressed these questions exhibited a narrow taxon sampling or used single-locus markers. Herein we surveyed hundreds of ultraconserved elements (UCEs) loci to provide the first molecular phylogenetic hypothesis and divergence time estimates for hemiodontids encompassing all its genera and most species (27 of the 34 valid species). We also tracked the history of the protractile upper jaw in the genera Argonectes and Bivibranchia across the recovered phylogenies through ancestral state reconstruction. Our results corroborate the monophyly of Hemiodontidae and the genera Argonectes and Bivibranchia in all phylogenetic methods with maximum clade support. The genera Anodus and Hemiodus were not monophyletic because Anodus elongatus was sister to the monotypic Micromischodus instead of A. orinocensis, and H. immaculatus did not form a clade with its other congeners, but instead was sister to the clade including Anodus and Micromischodus. All remaining species of Hemiodus were placed together into a monophyletic group, where they were arranged into four major subclades. The relationship in the family is summarised as: (Bivibranchia, (Argonectes, ((H. immaculatus, (Anodus, Micromischodus)), Hemiodus clade))), in discordance with the morphological phylogeny that placed all genera monophyletic and resolved the family as: ((Anodus, Micromischodus), (Hemiodus, (Argonectes, Bivibranchia))). The origin of Hemiodontidae was estimated from the Late Cretaceous to the Middle Paleogene, with the mean age in the Paleocene, while the origin of most hemiodontid genera except Bivibranchia occurred in the Miocene. Unordered parsimony and likelihood reconstruction indicates that Argonectes and Bivibranchia developed their protractile upper jaw independently.

Ontogeny of the swim bladder of the Plainfin Midshipman, Porichthys notatus (Percomorphacea: Batrachoidiformes).

The batracoidid Plainfin Midshipmen Porichthys notatus Girard has been extensively studied due to the sound production abilities and specializations of its swim bladder. The present study describes three-dimensional variations of the morphology of the swim bladder and sonic muscles of P. notatus during its post-hatch larval development, with the use of three-dimensional computed tomography. This study also includes descriptions of the relative position of the swim bladder to other visceral organs. The swim bladder, digestive tract, and liver were already present in the smallest examined specimens (5.9 mm; newly hatched larvae) along with the yolk sac. In the smallest specimens, the digestive tract is straight, but from 7.1 mm TL, the digestive tract forms the first intestinal loops, and at 25.5 mm TL, a second intestinal loop. In smallest specimens, the swim bladder is oval, but at 7.1 mm TL, the anterior margin starts invaginating, forming a pair of anterior lobes. The first appearance of the intrinsic sonic muscles in swim bladder occurs at 13.1 mm TL. Additionally, we provide comparisons between the shape of the swim bladder of P. notatus and other species. The shape of the swim bladder of P. notatus and other members of Porichthyinae have an ovoid posterior region with two anterior lobes and differs from the cordiform or semiconected/bilobed the swim bladders observed in the other Batrachoididae.

A new species of Characidium (Characiformes: Crenuchidae) from the Chapada dos Veadeiros, Goiás, Brazil

A new species of Characidium is described from the tributaries of the rio Tocantinzinho, rio Tocantins basin, located in the southern portion of the Chapada dos Veadeiros, at about 1,200 meters of elevation, Goiás, Brazil. The new species can be diagnosed by an unusual combination of two apomorphic features present in distinct clades of Characidium, the presence of a scaleless isthmus in allied to with a single row of dentary teeth. Additionally, the new species has a unique color pattern of inconspicuous vertical bars disconnected from the dorsal midline, forming seven to nine square blotches along body sides, and the presence of a dark saddle-shaped mark at the dorsal-fin base. Osteologically, it can be diagnosed by having the first and second anal-fin proximal radials fused and contacting the third hemal spine, which is branched. The new species also has a peculiar, unusual variation of fin-ray counts among its congeners.(AU)

Uma nova espécie de Characidium é descrita dos riachos tributários do rio Tocantins, bacia do rio Tocantins, localizados na vertente sul da Chapada dos Veadeiros, a aproximadamente 1.200 metros de altitude, Goiás, Brasil. A nova espécie pode ser diagnosticada pela combinação não usual de dois caracteres apomórficos presentes em clados distintos de Characidium, a presença do istmo sem escama em conjunto com uma única série de dentes no dentário. Adicionalmente, a nova espécie tem um padrão de coloração único de barras verticais desconectadas na região dorsal, formando sete a nove manchas quadradas ao longo do lado do corpo, e pela presença de uma mancha em forma de sela na base da nadadeira dorsal. Osteologicamente, ela pode ser diagnosticada por possuir o primeiro e segundo radiais da nadadeira anal fusionados e em contato com o terceiro espinho hemal, que é ramificado. A espécie nova também possui uma variação peculiar e pouco usual no número de raios das nadadeiras entre os congêneres.(AU)

Rapid assessment of the ichthyofauna of the southern Guiana Shield tributaries of the Amazonas River in Pará, Brazil

The Northern Pará Drainage System encompasses the left-bank tributaries of the Amazonas River in the southern Guiana Shield region of Pará state, Brazil. Five of the region's state protected areas are considered strategic for the conservation of its biodiversity. In the present study, we assessed the ichthyofauna of the five state protected areas of the Northern Pará Drainage System. Seven expeditions were conducted between January 2008 and January 2009, which surveyed stretches of the Cuminá, Cuminapanema, Curuá, Jari, Mapuera, Nhamundá, and Paru rivers. These surveys yielded 286 species belonging to 38 families and eight orders, including seven new records of fish species for Brazil, six of which are also new records for the Amazon basin. Our results provide a valuable database for future research and conservation programs in the protected areas of the region. (AU)

A new miniature species of Odontocharacidium (Characiformes: Crenuchidae) from the Río Orinoco basin, Venezuela

A new species of Odontocharacidium is described from the upper Río Orinoco basin, in Venezuela. The new species is distinguished from its only congener, Odontocharacidium aphanes, by the presence of: the antorbital, the parietal branch of the supraorbital laterosensory canal, the postcleithrum 1, the conspicuous bars extending ventrally below the middle portion of the body posteriorly, and two dark round blotches at the tip of the caudal peduncle. With the recognition of an additional species of Odontocharacidium the diagnostic characters of the genus and the variability in the number of maxillary teeth in specimens are discussed.(AU)

Uma nova espécie de Odontocharacidium é descrita para a bacia do alto rio Orinoco, na Venezuela. A nova espécie se distingue da sua única congênere, Odontocharacidium aphanes, pela presença: do antorbital, do ramo parietal do canal látero-sensorial supraorbital, do pós-cleitro 1, de barras conspícuas estendendo-se ventralmente à porção média do corpo e de duas manchas escuras e arredondadas na margem distal do pedúnculo caudal. Com o reconhecimento de uma espécie adicional de Odontocharacidium, são discutidos os caracteres diagnósticos do gênero e a variação no número de dentes maxilares nos espécimes.(AU)

A new species of Knodus (Characiformes: Characidae: Stevardiinae) from the rio Aripuanã, rio Madeira basin, Brazil

A new species of the characid genus Knodus is described from the rio Aripuanã (rio Madeira basin). It can be distinguished from its congeners by its very low body depth, the presence of tri- to pentacuspid teeth on the outer premaxillary series, with the median cuspid larger than the lateral ones, the teeth of the inner premaxillary series pentacuspid, distinctly larger than those of the outer series, the maxillary teeth tri- to pentacuspid, with the median cusp slightly larger than the lateral ones, the four anteriormost dentary teeth pentacuspid, the smaller posterior teeth tri- to pentacuspid, a complete lateral line with 36-38 scales, 3 longitudinal scale series from pelvic fin origin to lateral line, and 11-12 circumpeduncular scales. The new species is also compared to incertae sedis species of 'Bryconamericus' from northern South America since phylogenetic studies suggest a closer relationship of those species with Knodus.(AU)

Uma nova espécie de um caracídeo do gênero Knodus é descrita do rio Aripuanã (bacia do rio Madeira). Esta espécie se distingue de suas congeneres por possuir o corpo muito estreito, a presença de dentes tri- a pentacúspides na série externa do pré-maxilar, com a cúspide mediana ligeiramente maior que as cúspides laterais, dentes da série interna pentacúspide, distintamente maiores que os da série externa, dentes do maxilar tri- a pentacúspides com a cúspode central discretamente maior que as laterais, os quatro dentes mais anteriores do dentário pentacuspidados, os dentes mais posteriores tricuspidados a pentacuspidados, a linha lateral complete com 36-38 escamas, 3 séries longitudinais de escamas entre a origem da nadadeira pélvica e a linha lateral, e 11-12 séries longitudinais de escamas circumpedunculares. A nova espécie é comparada com espécies incertae sedis de 'Bryconamericus' do norte da América do Sul uma vez que estudos filogenéticos sugerem a próxima relação daquelas espécies com Knodus.(AU)

Hemiodus bimaculatus, a new species of Hemiodontidae from the Rio Tapajós drainage, Brazil (Ostariophysi: Characiformes).

Hemiodus bimaculatus sp. nov., is described from tributaries of the Rio Juruena and Rio Teles Pires in the upper Rio Tapajós basin. The new species is diagnosed from most congeners, except Hemiodus jatuarana, by having a conspicuous circular or horizontally elongate dark blotch on the caudal peduncle (v. inconspicuous in H. iratapuru and absent in the other species). The new species differs from H. jatuarana by having a round midlateral spot on the flank (v. absent in H. jatuarana), 98-121 perforated scales in the lateral line (v. 66-72 in H. jatuarana), 23-28 scale series above and 14-19 below lateral line (v. 12-13 above and 6-7 below in H. jatuarana). Hemiodus bimaculatus is hypothesised to be related to species of the H. microlepis group, from which it also differs by having 11-25 epibranchial (v. 26-34 in H. argenteus, 29-39 in H. microlepis, 21-42 in H. orthonops and 27-35 in H. parnaguae) and 18-31 ceratobranchial (v. 38-50 in H. argenteus, 43-58 in H. microlepis, 32-52 in H. orthonops and 34-48 in H. parnaguae) gill rakers in the first arch.

A systematic review of Rhinopetitia Géry (Teleostei, Characiformes, Characidae) with descriptions of four new species and redescription of R. myersi Géry.

Rhinopetitia was known for a long time only by R. myersi, its type species, described from the Ilha do Bananal, Rio Araguaia basin, Tocantins, Brazil. Another recently described species, R. potamorhachia, was considered to differ from R. myersi by having the outer and inner rows of premaxillary teeth with seven to nine cusps, a midlateral dark stripe and a dark humeral blotch (versus outer and inner rows of premaxillary and of maxillary teeth with three to five cusps, and the absence of a dark midlateral stripe). Recently collected specimens from the Araguaia and Tocantins river basins are considered to belong to R. myersi, allowing to better characterize this species which is redescribed herein. Four new species are recognized for the genus, all from Brazil: 1) Rhinopetitia paucirastra, new species, collected from the upper Rio Tocantins drainage, state of Goiás, distinguished from all its congeners mainly by the presence of rudimentary and fewer gill rakers in external row on first gill arch; 2) R. oligolepis, new species originating from the Rio Jamanxim, Rio Tapajós drainage, state of Pará, differing from its congeners by having 4 longitudinal scale rows from dorsal-fin origin to lateral line; 3) R. melanohumeralis, new species, collected from small streams tributaries of the upper Rio Tapajós, and the upper Rio Xingu basins, states of Pará and Mato Grosso, that has the body as deep as in R. paucirastra but has well-developed and more gill rakers in the external row on first branchial arch; and 4) R. nigrofasciata, new species, collected in small tributaries of the upper portions of the Rio Tapajós and Rio Xingu basins, states of Pará and Mato Grosso, with the body narrower than in R. paucirastra and R. melanohumeralis.

New species of Pyrrhulina (Teleostei: Characiformes: Lebiasinidae) from the eastern Amazon, Pará, Brazil

A new species of Pyrrhulina is described based on 60 specimens from tributaries of the rio Amazonas: rio Anapu, rio Capim, rio Guamá and rio Xingu, and coastal drainages in the state of Pará, Brazil. The new species differs from all congeners by having the primary stripe (the horizontal stripe of dark pigmentation extending posteriorly from the snout) terminating at the distal edge of the opercle. In all other species of Pyrrhulina, the primary stripe is either restricted to the snout or continues beyond the head (i.e. at least the anteriormost four scales of the lateral line series).(AU)

Uma nova espécie de Pyrrhulina é descrita baseada em 60 espécimes dos afluentes do rio Amazonas: rio Anapu, rio Capim, rio Guamá e rio Xingu, e drenagens costeiras no estado do Pará, Brasil. A nova espécie distingue-se de todas as congêneres por ter a faixa primária (faixa horizontal de pigmentação escura que se estende posteriormente do focinho) terminando na borda distal do opérculo. Em todas as outras espécies de Pyrrhulina, a faixa primária é restrita ao focinho ou continua além da cabeça (para incluir pelo menos as quatro escamas anteriores da série da linha lateral).(AU)

New species of Creagrutus (Ostariophysi; Characiformes; Characidae) from the Rio Xingu drainage, Brazil.

Creagrutus yudja is described from the Rio Xingu basin, Brazil. It is distinguished from its congeners by the lack of infraorbital 6, the shallower body (13.7-19.2% of SL), the presence of 34-36 perforated lateral line scales, and the presence of 4-6 post-anal scales. The inclusion of the new species on the available, morphology-based phylogenetic study of Creagrutus placed C. yudja as the sister-species of C. nigrotaeniatus, but the clade including those species is not recovered as sister to the pair C. cracentis + C. maxillaris, suggesting independent modifications of the dentition pattern typical of Creagrutus to a condition similar to the plesiomorphic characid condition within the genus.

New species of Characidium (Characiformes: Crenuchidae) from the Rio Tapajós and Rio Xingu drainages, Pará, Brazil.

Characidium nana is described from the Rio Xingu and Rio Tapajós drainages. The new species is distinguished from all its congeners by the absence of the inner series of dentary teeth, the absence of the parietal branch of the supraorbital laterosensory canal, the incomplete lateral line, the lack of an adipose fin, the presence of a conspicuous dark blotch on caudal peduncle as well as an evident dark, midlateral stripe, and the presence of 12 circumpeduncular scales. The relationships of the new species and its inclusion among the species of clade C4 are discussed.

New species of Bryconamericus Eigenmann (Characiformes: Characidae) from the rio Teles Pires, rio Tapajós basin, central Brazil.

A new species of Bryconamericus is described from the rio Teles Pires, a tributary of the rio Tapajós. The new taxon can be distinguished from its congeners by having a short anal fin with 11-13 branched rays, two maxillary teeth, four outer premaxillary teeth, and 34-38 perforated lateral-line scales. Other diagnostic characters of the species are the absence of a caudal-peduncle spot and the presence of a pigmented vertical band at the caudal-fin rays base. The phylogenetic position of the new species is inferred based in two available phylogenetic hypotheses, and a discussion on its generic placement is provided. 

Sperm characteristics as additional evidence of close relationship between lebiasina and piabucina (characiformes: lebiasinidae: lebiasininae)

Spermiogenesis and spermatozoa of representatives of the genera Lebiasina and Piabucina are described. Spermiogenesis is quite similar among all analyzed species of these genera and is identified as Type II. In this type of spermiogenesis, the flagellum of earliest spermatids lies lateral to the nucleus. A slight movement of the nucleus towards the centriolar complex is observed. In late spermatids, the nucleus slightly elongates towards the flagellum. The formation of two striated rootlets apparently occurs in early/intermediate spermatids. The spermatozoa of species of Lebiasina and Piabucina share (1) a drop-shaped slightly elongated nucleus that is laterally positioned relative to the flagellum; (2) a superolateral centriolar complex; (3) two striated rootlets; (4) a basolateral midpiece; (5) oblong mitochondria and (6) a few spherical vesicles. The spermatic characteristics of Lebiasina and Piabucina indicate that spermiogenesis is a homologous process among all species of both genera examined to date and can be considered, along with the spermatozoa morphology, additional evidence indicating a close relationship between Lebiasina and Piabucina.

A espermiogênese e os espermatozoides de representantes dos gêneros Lebiasina e Piabucina são descritos. O processo de espermiogênese é muito semelhante entre todas as espécies analisadas, sendo descrita como do Tipo II. Nesta variação de espermiogênese o flagelo das espermátides iniciais localiza-se lateralmente ao núcleo. O núcleo movimenta-se ligeiramente sobre o complexo centriolar. Nas espermátides finais, o núcleo alonga-se ligeiramente em direção ao eixo flagelar. A formação de duas raízes estriadas ocorre nas espermátides iniciais/intermediárias. Os espermatozoides das espécies de Lebiasiana e Piabucina compartilham principalmente (1) o núcleo em forma de gota, lateralmente posicionado em relação ao eixo flagelar, e ligeiramente alongado em direção ao flagelo, (2) o complexo centriolar superolateral, (3) duas raízes estriadas surgindo a partir do centríolo distal, (4) peça intermediária basolateral, (5) mitocôndrias oblongas e (6) algumas vesículas esféricas. As características espermáticas de Lebiasina e Piabucina foram observadas comparativamente e permitem concluir que o processo de espermiogênese é homólogo em todas as espécies destes dois gêneros examinadas até o momento. Os espermatozoides e principalmente os dados de espermiogênese são apresentados aqui como evidências adicionais que indicam uma relação estreita entre os gêneros Lebiasina e Piabucina.

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.

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.

New species of Lebiasina (Ostariophysi: Characiformes: Lebiasinidae) from the upper Mazaruni River drainage, Guyana.

Lebiasina ardilai is described from the upper Mazaruni in Guyana. The new species differs from all its congeners by its color pattern consisting of: a narrow, nearly straight primary stripe, extending from posterior to humeral blotch to near the vertical through anal-fin origin, being absent or inconspicuous in females and conspicuously marked in males; the presence of four series of dark blotches at the distal border of the scales of longitudinal series 2-5; the faint secondary stripe running onto scales of second and third longitudinal row of scales; intermediate stripe absent; and the posteriorly displaced caudal blotch, not reaching the posterior tip of caudal peduncle.

Three new species of Lebiasina (Characiformes: Lebiasinidae) from the Brazilian shield border at Serra do Cachimbo, Pará, Brazil

Lebiasina marilynae n. sp., L. melanoguttata n. sp., and L. minuta n. sp. are described from the headwaters of the rio Curuá, in Serra do Cachimbo, Pará, Brazil, and represent the only members of the Lebiasininae in the Brazilian Shied, so far. A close relationship among these species is proposed based on: 1) the presence of a pair of foramina through which the ramus palatinus of the facial nerve passes, a modification unique in Lebiasinidae and apparently in the Characiformes, 2) the enlargement of the extrascapular bone, 3) the absence of the secondary stripe, and 4) the nearly equal length of caudal-fin lobes. Lebiasina marilynae additionally differs from all congeners in having the primary stripe extending from the tip of the snout to the distal border of the caudal-fin peduncle, the possession of two series of dark blotches parallel to the primary stripe, and a rounded dorsal surface of the mesethmoid. Lebiasina melanoguttata and Lebiasina minuta additionally differ from all congeners in the absence of the primary stripe and the caudal blotch, and the presence of three longitudinal series of dark blotches at the base of the scales of series 3-5. Lebiasina melanoguttata differs from Lebiasina minuta in the absence of a dark blotch at the base of the median rays of the dorsal fin, second infrapharyngobranchial bearing conical teeth, the reddish overall coloration of the eye and fins, and the dark blotches never coalescing (vs. dark dorsal-fin blotch present; the second infrapharyngobranchial being edentulous; dark, olive green eyes, and the yellowish overall color of body and fins; and the dark blotches of longitudinal series 3 and 4 coalescing where scales of adjacent longitudinal series overlap). The occurrence of species of the Lebiasininae on the Brazilian Shield is discussed, and the distribution pattern of the species described herein is compared to that of other endemic species of the Serra do Cachimbo, a highly biodiverse area isolated from the rest of the Amazon basin.

Lebiasina marilynae n. sp., L. melanoguttata n. sp. and L. minuta n. sp. são descritas das cabeceiras do rio Curuá, na Serra do Cachimbo, Pará, Brasil, e representam os únicos membros de Lebiasininae no escudo brasileiro, até o momento. Uma relação próxima entre estas espécies é proposta com base em: 1) presença de um par de forames por onde passa o ramo palatino do nervo facial, uma modificação única em Lebiasinidae e aparentemente em Characiformes, 2) a expansão do osso extra-escapular, 3) a ausência da faixa secundária, e 4) os lobos da nadadeira caudal com comprimento similar. Lebiasina marilynae difere ainda de seus congêneres pela faixa primária estendendo-se da ponta do focinho à porção distal do pedúnculo caudal, a presença de duas séries de manchas escuras paralelas à faixa primária, e a superfície dorsal do mesetmoide arredondada. Lebiasina melanoguttata e Lebiasina minuta também diferem de seus congêneres pela ausência da faixa primária e da mancha caudal, e pela presença de três séries longitudinais de manchas escuras na base das escamas das séries 3-5. Lebiasina melanoguttata difere de Lebiasina minuta pela ausência de uma mancha escura na base dos raios médios da nadadeira dorsal, presença de dentes cônicos no segundo infra-faringobranquial, a coloração avermelhada dos olhos e nadadeiras e pelas manchas escuras não coalescendo (vs. mancha escura presente na nadadeira dorsal; o segundo infrafaringobranquial sendo edêntulo; olhos escuros em tom oliváceo e coloração amarelada do corpo e nadadeiras; e as manchas escuras nas escamas das séries longitudinais 3 e 4 coalescendo no ponto onde escamas longitudinais adjacentes se sobrepõem). A ocorrência de espécies de Lebiasininae no escudo brasileiro é discutida e o padrão de distribuição das espécies descritas é comparado com o de outras espécies endêmicas da Serra do Cachimbo, uma área de alta biodiversidade isolada do restante da bacia amazônica.

Lebiasina yepezi, a new Lebiasininae (Characiformes: Lebiasinidae) from the Serra Parima-Tapirapecó mountains

Lebiasina yepezi, a new Lebiasininae with a conspicuous color pattern, is described. The new species is endemic of the headwaters of the rio Negro, rio Branco, and rio Orinoco in the Serra Parima-Tapirapecó Mountains, at the border of Brazil and Venezuela. The new species is readily distinguished from all other Lebiasininae by the presence of four black longitudinal stripes on the trunk, and the triangular shaped dorsal surface of the mesethmoid, lacking lateral projections. The unusual color pattern is contrasted with those of other lebiasinin, as well as members of the pyrrhulinin genus Nannostomus. A close relationship between Lebiasina yepezi and the Gran Sabana (Venezuela) species is suggested based in color pattern features. The present contribution corresponds to a further refutation of the type locality of L. intermedia, as suggested on its description, since Lebiasinins, except L. bimaculata, L. boruca, and L. festae, do not occur in low land waters.

Lebiasina yepezi, um novo Lebiasininae com um conspícuo padrão de colorido, é descrito. A nova espécie é endêmica das cabeceiras do rio Negro, rio Branco e rio Orinoco, na Serra Parima-Tapirapecó, ao longo da fronteira entre Brasil e Venezuela. A nova espécie é prontamente diferenciada das demais espécies pela presença de quatro faixas longitudinais escuras ao longo do corpo, e a superfície dorsal do mesetmoide com o formato triangular, não apresentando projeções laterais. O padrão de colorido incomum é comparado com o dos demais Lebiasininae e também com o dos Pyrrhulininae do gênero Nannostomus. Uma próxima relação é proposta entre Lebiasina yepezi e as espécies da Gran Sabana (Venezuela) com base em caracteres de colorido. A presente contribuição corresponde a mais uma refutação da localidade-tipo de L. intermedia conforme sugerida na descrição daquela espécie, uma vez que os lebiasiníneos, com exceção de L. bimaculata, L. boruca e L. festae, não ocorrem em rios de terras baixas.