BackgroundWith nearly 1,100 species, the fish family Characidae represents more than half of the species of Characiformes, and is a key component of Neotropical freshwater ecosystems. The composition, phylogeny, and classification of Characidae is currently uncertain, despite significant efforts based on analysis of morphological and molecular data. No consensus about the monophyly of this group or its position within the order Characiformes has been reached, challenged by the fact that many key studies to date have non-overlapping taxonomic representation and focus only on subsets of this diversity.ResultsIn the present study we propose a new definition of the family Characidae and a hypothesis of relationships for the Characiformes based on phylogenetic analysis of DNA sequences of two mitochondrial and three nuclear genes (4,680 base pairs). The sequences were obtained from 211 samples representing 166 genera distributed among all 18 recognized families in the order Characiformes, all 14 recognized subfamilies in the Characidae, plus 56 of the genera so far considered incertae sedis in the Characidae. The phylogeny obtained is robust, with most lineages significantly supported by posterior probabilities in Bayesian analysis, and high bootstrap values from maximum likelihood and parsimony analyses.ConclusionA monophyletic assemblage strongly supported in all our phylogenetic analysis is herein defined as the Characidae and includes the characiform species lacking a supraorbital bone and with a derived position of the emergence of the hyoid artery from the anterior ceratohyal. To recognize this and several other monophyletic groups within characiforms we propose changes in the limits of several families to facilitate future studies in the Characiformes and particularly the Characidae. This work presents a new phylogenetic framework for a speciose and morphologically diverse group of freshwater fishes of significant ecological and evolutionary importance across the Neotropics and portions of Africa.

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Foram amostrados 17 trechos de riachos com 100 m de extensão, todos de ordem igual ou menor a três, ao longo de ambas as margens do canal principal do Rio Paranapanema, SP e PR. O ponto médio de cada trecho foi georreferenciado via satélite com receptor GPS e o uso de metodologia padronizada de coleta de dados ambientais e peixes (baseada principalmente na pesca elétrica), possibilitou a obtenção das seguintes informações em cada local: 1) composição taxonômica da ictiofauna e contribuição, em termos de número de indivíduos e biomassa, de cada espécie para a ictiofauna local como um todo; 2) documentação fotográfica de espécimes representativos de cada espécie coletada com sua coloração natural; 3) descrição de cada ambiente coletado, com ilustrações fotográficas coloridas, e seus principais parâmetros bióticos e abióticos. No total foram coletados 3.683 exemplares, pertencentes a seis ordens, 16 famílias, 37 gêneros e 52 espécies, com biomassa total de 16,8 kg. Das espécies coletadas, aproximadamente 36% pertencem a ordem Siluriformes, 36% a Characiformes, 11% a Gymnotiformes, 10% a Perciformes, 4% a Cyprinodontiformes e 2% a Synbranchiformes. As espécies mais abundantes em termos de número de indivíduos foram Astyanax altiparanae (15,2%) e Astyanax sp. 1 (12,3%); aquelas com maior biomassa foram A. altiparanae (28%) e Geophagus brasiliensis (13%). A composição da ictiocenose em termos de abundância e biomassa por família indica a predominância expressiva de Characidae, seguida por Loricariidae, Pimelodidae e Cichlidae. Dentre os trechos amostrados, o trecho 14 (24 espécies) e o 13 (cinco espécies), apresentaram a maior e a menor riqueza em espécies, respectivamente, coincidindo com os valores obtidos para o índice de diversidade específica de Shannon-Wienner (H´= 0,99 e 0,32, respectivamente). A riqueza média encontrada foi de 11 espécies por trecho de riacho. Na estimativa de riqueza por extrapolação para o conjunto total de riachos amostrados na bacia do rio Paranapanema, obtivemos um valor de 69 espécies (erro padrão igual a quatro) indicando ser necessário um esforço amostral adicional moderado para atingir a assíntota da curva. Das 52 espécies coletadas, oito (aproximadamente 15% do total) são seguramente novas, cinco (aproximadamente 10% do total) possuem “status” taxonômico ainda indefinido, enquanto outras três (aproximadamente 6% do total) são espécies introduzidas. Analisando a estrutura trófica e espacial da ictiocenose estudada, as 10 espécies numericamente dominantes nos riachos estudados dividem-se, em ordem decrescente de importância numérica, em quatro guildas: onívoros nectônicos; invertívoros bentônicos; perifitívoros; e onívoros bentônicos. Uma chave de identificação para todas as espécies de peixes coletadas durante este estudo é fornecida ao final deste trabalho.

Eighteen 100 m long streams stretches, none of an order higher than three, were sampled in three tributaries (six stream stretches sampled in each one) of the left margin of the main channel of Rio Grande (Rios Turvo, Pardo and Sapucaí) in the State of São Paulo, southeastern Brazil. Each stream stretch had its midpoint located with a GPS satellite receiver and had its fish fauna sampled via a standardized environmental data and fish collection methodology (primarily utilizing electrofishing) with the aim of providing the following information about each stream: 1) the taxonomic composition of the fish fauna and the contribution of each species in that stream in terms of both number of individuals and biomass; 2) a photographic documentation of the live coloration of representative specimens of each collected species; and 3) the description of each sampled environment, with colored photographic illustrations and details of the main biotic and abiotic parameters. Overall 3,070 fishes were collected, belonging to six orders, 18 families, 44 genera, and 64 species, with a total biomass of 14.3 kg. Of the collected species, approximately 50% were Characiformes, 26.5% Siluriformes, 11% Perciformes, 6% Gymnotiformes, 5% Cyprinodontiformes, and 1.5% Synbranchiformes. The most abundant species in terms of total number of individuals were Astyanax altiparanae (17.4%) and Hypostomus ancistroides (9%); the species with the largest biomasses were Astyanax altiparanae (35%) and Geophagus brasiliensis (9%). In terms of abundance and biomass collected for each family, the Characidae was clearly the predominant family followed by the Loricariidae, and Cichlidae. Among the sampled stream stretches, locality SG6 with 26 species and locality PG4 with three species yielded the highest and lowest richness in terms of species numbers, respectively. This coincides with the values obtained for the ShannonWiener index of specific diversity (H´ = 1.08 and 0.26, respectively). The median species richness for all streams stretches was 12. In the species richness estimate by extrapolation for all 18 sampled stream stretches, a value of 93 species was obtained (with a standard error of three) indicating the need for an additional moderate sampling effort to reach the asymptote of the curve. Of the 64 collected species, four (approximately 6% of the total) are clearly new to science and seven other species (approximately 11% of the total) are of indefinite taxonomic status and require further analysis. Two of the captured species are certainly introduced (approximately 3% of the total). Analysis of the trophic and spatial structure of the studied fish fauna indicates that the 10 numerically dominant species in the sampled streams can be grouped, based on published data, into five guilds that are in decreasing order of numeric importance: nektonic omnivores; benthic invertivores; periphytovores; algivores and benthic omnivores. An identification key for all the species of fish collected during this study is provided.

The Neotropics harbor the most species-rich freshwater fish fauna on the planet, but the timing of that exceptional diversification remains unclear. Did the Neotropics accumulate species steadily throughout their long history, or attain their remarkable diversity recently? Biologists have long debated the relative support for these museum and cradle hypotheses, but few phylogenies of megadiverse tropical clades have included sufficient taxa to distinguish between them. We used 1,288 ultraconserved element loci (UCE) spanning 293 species, 211 genera and 21 families of characoid fishes to reconstruct a new, fossil-calibrated phylogeny and infer the most likely diversification scenario for a clade that includes a third of Neotropical fish diversity. This phylogeny implies paraphyly of the traditional delimitation of Characiformes because it resolves the largely Neotropical Characoidei as the sister lineage of Siluriformes (catfishes), rather than the African Citharinodei. Time-calibrated phylogenies indicate an ancient origin of major characoid lineages and reveal a much more recent emergence of most characoid species. Diversification rate analyses infer increased speciation and decreased extinction rates during the Oligocene at around 30 million years ago (Ma) during a period of mega-wetland formation in the proto-Orinoco-Amazonas. Three species-rich and ecomorphologically diverse lineages (Anostomidae, Serrasalmidae, and Characidae) that originated more than 60 Ma in the Paleocene experienced particularly notable bursts of Oligocene diversification and now account collectively for 68% of the approximately 2,150 species of Characoidei. In addition to paleogeographic changes, we discuss potential accelerants of diversification in these three lineages. While the Neotropics accumulated a museum of ecomorphologically diverse characoid lineages long ago, this geologically dynamic region also cradled a much more recent birth of remarkable species-level diversity.

A new species of Moenkhausia is described from tributaries of the rio Paraguay, Brazil. The new species is diagnosed from congeners by characters related to body coloration, the number of lateral line scales, the degree of poring of the lateral line, and number of scales rows above and below the lateral line. Molecular analyses using partial sequences of the mitochondrial gene Cytochrome Oxidase I from specimens of the new species and specimens belonging to morphologically similar species demonstrated that the new species is easily differentiated by their high genetic distance and by their position in the phylogenetic hypothesis obtained through the Maximum Parsimony methodology. The analyses of three samples of M. oligolepis also revealed that they have high genetic distances and belong to different monophyletic groups suggesting that this species corresponds to a species complex rather than a single species.Uma nova espécie de Moenkhausia é descrita de tributários do rio Paraguai, Brasil. Essa nova espécie é diagnosticada de seus congêneres por caracteres relacionados ao padrão de colorido do corpo, número de escamas da linha lateral, grau de desenvolvimento dos poros sensoriais na linha lateral e número de séries de escamas acima e abaixo da linha lateral. Um análise molecular usando sequências parciais do gene mitocondrial Citocromo Oxidase I de espécimes representativos da nova espécie e espécimes pertencentes a espécies morfologicamente similares demonstrou que a nova espécie é facilmente diferenciada por sua elevada distância genética e por sua posição na hipótese filogenética obtida pelo método de máxima parcimônia. A análise de três amostras de M. oligolepis também revelou que estas apresentam distâncias genéticas elevadas e pertencem a grupos monofiléticos distintos, sugerindo que esta espécie corresponda a um complexo de espécies e não uma única espécie.

A new species of Tetragonopterus Cuvier, 1816 (Characiformes: Characidae: Tetragonopterinae) from the rio Jari, Amapá, northern Brazil Bruno F. Melo, Ricardo C. Benine, Tatiane C. Mariguela and Claudio Oliveira A new species of Tetragonopterus is described from the rio Jari, a tributary to the left margin of rio Amazonas, at the border between Amapá and Pará States, northern Brazil. It is morphologically diagnosed from the other species of the genus (T. argenteus, T. chalceus, and T. rarus new combination) by the lozenge-shaped spot on the caudal peduncle vs. rounded to square spot on the other species. Partial sequences of the mitochondrial gene Cytochrome Oxidase C subunit I, from representatives of all valid species of Tetragonopterus, including this new species, were analyzed. The obtained results revealed a significant genetic distance between the new species and its congeners. A discussion on the new combination, Tetragonopterus rarus, is also provided. Uma espécie nova de Tetragonopterus é descrita do rio Jari, um tributário da margem esquerda do rio Amazonas, na divisa entre os Estados do Amapá e Pará, norte do Brasil. Esta é morfologicamente diferenciada das outras espécies do gênero (T. argenteus, T. chalceus e T. rarus combinação nova) pelo formato losangular da mancha no pedúnculo caudal contra uma mancha arredondada a quadrangular nas demais espécies. Sequências parciais do gene mitocondrial citocromo oxidase C subunidade I de representantes de todas as espécies válidas de Tetragonopterus, incluindo esta espécie nova, foram analisadas. Os resultados obtidos revelaram uma significante distância genética entre esta espécie nova e as demais do gênero. É apresentada uma discussão sobre a nova combinação, Tetragonopterus rarus.

A new genus and species of glandulocaudine, Lophiobrycon weitzmani, is described based on specimens collected in headwater tributary streams of the rio Grande, upper rio Paraná system, State of Minas Gerais, southeastern Brazil. The inclusion of the new species in the phylogeny of the subfamily Glandulocaudinae proposed by Weitzman & Menezes (1998), reveals a sister group relationship between the new genus and the monophyletic group composed of Glandulocauda and Mimagoniates that currently form the tribe Glandulocaudini. The new species can be readily distinguished from all other species of the tribe by the autapomorphic presence in adult male individuals (with more than 23.9 mm standard length) of an adipose-fin whose base extends for almost the entire distance between the posterior terminus of the base of the dorsal fin and the base of the upper lobe of the caudal fin and averages approximately 25% standard length, along with the presence of globular expansions formed by the lepidotrichia and hypertrophied soft tissue in the middle portions of the first and second pectoral-fin rays. The diagnosis of the tribe Glandulocaudini is modified to accommodate the new genus.
Um novo gênero e espécie de glandulocaudine, Lophiobrycon weitzmani, é descrito com base em exemplares coletados em riachos de cabeceira da drenagem do rio Grande, sistema do alto rio Paraná, Estado de Minas Gerais, sudeste do Brasil. A inclusão desta nova espécie na filogenia da subfamília Glandulocaudinae, proposta por Weitzman & Menezes (1998), revela uma relação de grupos irmãos entre o novo gênero e o grupo monofilético formado por Glandulocauda e Mimagoniates, atualmente compondo a tribo Glandulocaudini. A nova espécie pode ser facilmente distinguida das demais da tribo pela posse autapomórfica, nos machos adultos (com mais de 23,9 mm de comprimento padrão), de uma nadadeira adiposa com a base estendendo-se por praticamente a totalidade da distância entre a terminação posterior da base da nadadeira dorsal e base do lobo caudal superior, equivalendo em média a aproximadamente 25% do comprimento padrão, juntamente com a presença de expansões globulares, formadas por lepidotríquios e tecido mole hipertrofiado, na porção média do primeiro e segundo raios da nadadeira peitoral. A diagnose da tribo Glandulocaudini é modificada para acomodar o novo gênero