A new species of Satanoperca (Teleostei: Cichlidae) from the Rio Tocantins basin, Brazil

A new species of Satanoperca is described from the Rio Araguaia, Rio Tocantins basin, Brazil, and non-native records are available in the upper Rio Paraná basin. It differs from congeneric species by color pattern characters, such as head and flank marks. It is included in the Satanoperca jurupari species group, characterized by the absence of black rounded blotches on the flank, and low meristic values. A description of the ontogeny of melanophore marks of the S. jurupari species group revealed two different types of arrangement on the flank and numerous melanophore marks on the head. A discussion on morphologically diverse assemblages in the S. jurupari species group is also provided.(AU)

Uma nova espécie de Satanoperca é descrita do rio Araguaia, bacia do rio Tocantins, Brasil, e registros não-nativos estão disponíveis para a bacia do alto rio Paraná. Pode ser diagnosticada de suas congêneres por caracteres do padrão de colorido como marcas na cabeça e flanco. É incluída no grupo Satanoperca jurupari pela ausência de máculas pretas arredondadas no flanco e menores valores de contagens. Uma descrição da ontogenia das marcas melanofóricas do grupo S. jurupari revelou dois tipos diferentes de arranjos no flanco e várias marcas melanofóricas na cabeça. Uma discussão sobre assembleias morfologicamente diversas no grupo S. jurupari também é fornecida.(AU)

Areas of endemism for Anablepidae (Teleostei: Cyprinodontiformes): A monophyletic family of freshwater fishes in the Neotropics.

Knowledge on the hydrological evolution of the Neotropical region was used along with the current distribution of the anablepid species to investigate the historical biogeography of this family. Areas of endemism were delimited by endemicity analysis resulting in seven individual areas of endemism and three consensus areas located in northwestern Argentina, southern Brazil, and northern South America. These areas were discussed in the context of anablepid species diversification, especially for the genus Anableps and the subgenera Jenynsia and Plesiojenynsia. The existence of areas of endemism for the family analyzed reveals an intimate association with historical events that occurred in the geological evolution of South America, which can be associated with the main diversification patterns and historical hypotheses in the context of Neotropical freshwater fishes biogeography.

Redescription of Astyanax gymnogenys Eigenmann, 1911 (Characiformes: Characidae), a senior synonym of Astyanax longirhinus Garavello amp; Sampaio, 2010.

Astyanax gymnogenys Eigenmann was described from the middle rio Iguaçu basin, based on two specimens and A. longirhinus Garavello Sampaio was described from the upper, middle and lower rio Iguaçu, based on several specimens. Due to their morphological similarity, including overlapping diagnostic characters between the two nominal species, allied to their occurrence in the same basin, doubts of their validity as independent taxa emerged. The validity of both taxa was analysed through the examination of type-material of both nominal species and additional material from the rio Iguaçu basin. The present study failed to support the recognition of A. longirhinus as a valid species and consequently, the latter species is herein considered a junior synonym of A. gymnogenys. The type-series of A. longirhinus was found to be composed of several Astyanax species. Astyanax gymnogenys can be differentiated from its congeners occurring at the rio Iguaçu basin by a combination of characters, including presence of vertically-elongated dark humeral blotch, margin of the third infraorbital distant from the margin of preopercle, leaving a broad naked area between these bones more than 25% of the depth of third infraorbital, body deepest at dorsal-fin origin or slightly ahead, and seven to 10 gill rakers on lower arch. We also examined all paratypes of A. scabripinnis paranae from the rio Iguaçu and conclude that they are not conspecific with the holotype, and consequently, that the species does not occur in the rio Iguaçu basin.

Cytogenetics and DNA barcode reveal an undescribed Apareiodon species (Characiformes: Parodontidae).

Parodontidae is a small group of fish and some species are particularly difficult to identify due to the lack of sufficiently consistent morphological traits. Cytogenetically, the species possess 2n = 54 chromosomes and are either sex-homomorphic or sex-heteromorphic (regarding its chromosomes). We evaluated data on color, tooth morphology, cytogenetics, and mitochondrial markers (COI) in Apareiodon specimens from the Aripuanã River (Amazon basin) and the results were compared to other congeneric taxa. Morphological results show an overlap of body color and tooth morphology to other known Apareiodon. The cytogenetics data showed that the 2n = 54 chromosomes, 50 m/sm + 4 st and, a ZZ/ZW sex chromosome system in Apareiodon sp. are common to other species of the genus. However, the number and chromosomal localization of the 45S ribosomal and pPh2004 satellite DNA sites, in addition to W chromosome localization of the pPh2004 appear to be exclusive cytogenetic features in Apareiodon sp. Our phylogenetic tree revealed well-supported clades and confirmed, by barcode species delimitation analysis, a new Molecular Operational Taxonomic Unit (MOTU) for Apareiodon sp. (Aripuanã River). As a whole, the above features support the occurrence of a new species of the Apareiodon, thus far unknown for the Parodontidae.

A multiple hypothesis approach to explain species richness patterns in neotropical stream-dweller fish communities.

Several hypotheses are used to explain species richness patterns. Some of them (e.g. species-area, species-energy, environment-energy, water-energy, terrestrial primary productivity, environmental spatial heterogeneity, and climatic heterogeneity) are known to explain species richness patterns of terrestrial organisms, especially when they are combined. For aquatic organisms, however, it is unclear if these hypotheses can be useful to explain for these purposes. Therefore, we used a selection model approach to assess the predictive capacity of such hypotheses, and to determine which of them (combined or not) would be the most appropriate to explain the fish species distribution in small Brazilian streams. We perform the Akaike's information criteria for models selections and the eigenvector analysis to control the special autocorrelation. The spatial structure was equal to 0.453, Moran's I, and require 11 spatial filters. All models were significant and had adjustments ranging from 0.370 to 0.416 with strong spatial component (ranging from 0.226 to 0.369) and low adjustments for environmental data (ranging from 0.001 to 0.119) We obtained two groups of hypothesis are able to explain the richness pattern (1) water-energy, temporal productivity-heterogeneity (AIC = 4498.800) and (2) water-energy, temporal productivity-heterogeneity and area (AIC = 4500.400). We conclude that the fish richness patterns in small Brazilian streams are better explained by a combination of Water-Energy + Productivity + Temporal Heterogeneity hypotheses and not by just one.

Molecular phylogeny of Planaltina Böhlke (Characidae: Stevardiinae) and comments on the definition and geographic distribution of the genus, with description of a new species.

A molecular phylogeny of Planaltina, including the three previously described species and an undescribed species, is presented. The monophyly of the genus, included in Diapomini, is strongly supported. Its sister group, the remaining Diapomini, includes only species without modified caudal-fin squamation in the present analysis (species of Diapoma with caudal organs were not sampled). Creagrutus is sister to Planaltina plus remaining Diapomini instead of Planaltina being sister to Creagrutus plus Diapomini, as a previous analysis had suggested. Species of Planaltina form two clades: P. britskii plus the new species, with low support (< 50%); and P. myersi plus P. glandipedis, with higher support. Planaltina is rediagnosed from all Characidae based on the morphology of the caudal organ, the absence of a humeral spot and the presence of a complete lateral line. Comments on the caudal-fin squamation of Diapoma and Lepidocharax burnsi, on the type-series of L. burnsi and on the geographic distribution of Planaltina and Lepidocharax species are provided. Finally, a formal description of the aforementioned new species and a novel identification key to Planaltina are presented.

Peixes da planície de inundação do alto rio Paraná e áreas adjacentes: revised, annotated and updated

The book "Peixes da planície de inundação do alto rio Paraná e áreas adjacentes" represents the most cohesive data compilation for the rio Paraná floodplain. However, considering the dynamicity of the taxonomy of freshwater fishes, several new records and taxonomic changes occurred along the past years. Therefore, the results of that publication were revisited, providing an update of the species list, their taxonomic status, records and geographic distribution, and also new keys for genera and species. The species included were those recorded in the rio Paraná basin, from the mouth of the rio Paranapanema to the Itaipu Reservoir, following the general methodology presented in the book. A total of 10 orders, 41 families, 126 genera, and 211 species were registered, with an increase of one order, six families, 14 genera, and 29 species when compared to the book. Additionally, four new genera recently described, five synonymization proposals, 14 new identifications, four new combinations, 12 new species recently described, 34 new records, and nine misidentified species were recorded. These results are associated with the redirection of human and financial resources to that area, which enabled monitoring and intensive exploration of its watercourses; as well as training of taxonomists, and new taxonomic resolutions.(AU)

O livro "Peixes da planície de inundação do alto rio Paraná e áreas adjacentes" representa a compilação de dados mais coesa para esta área. No entanto, considerando a dinamicidade da taxonomia de peixes de água doce, vários novos registros e alterações taxonômicas ocorreram ao longo desses dez anos. Assim, os resultados daquela publicação foram revisitados, fornecendo uma atualização da lista, status taxonômico, registros e distribuição geográfica das espécies, além de novas chaves de identificação para espécies e gêneros. Foram incluídas as espécies registradas na bacia do rio Paraná, entre a foz do rio Paranapanema e o reservatório de Itaipu, seguindo a metodologia geral apresentada no livro. Foi registrado um total de 10 ordens, 41 famílias, 126 gêneros e 211 espécies, com um aumento de uma ordem, seis famílias, 13 gêneros e 29 espécies quando comparado à primeira versão. Além disso, quatro gêneros novos descritos recentemente, cinco sinonimizações, 14 novas propostas de identificação, quatro novas combinações, 12 espécies novas descritas recentemente, 34 novos registros e nove espécies identificadas erroneamente foram registradas. Estes resultados estão associados ao redirecionamento de recursos humanos e financeiros para esta área, o que permitiu o monitoramento e exploração intensiva de seus corpos d'água; bem como a formação de taxonomistas e novas resoluções taxonômicas.(AU)

Molecular identification of cryptic diversity in species of cis-Andean Mylossoma (Characiformes: Serrasalmidae).

Mylossoma is a Serrasalmidae genus with only two current valid species in the cis-Andean region but with several available names, today considered as junior synonymous. Morphological information combined with single-locus DNA sequences of cytochrome c oxidase I gene analysed by Barcode Index Number and General Mixed Yule Coalescent model were used in the present study to help the recognition of Operational Taxonomic Units (OTUs) in cis-Andean Mylossoma and discuss species boundaries within the genus. Five OTUs were recognized based on both morphological and molecular approaches. The analysis using the Barcode Index Number resulted in five OTUs, with M. duriventre being split in one unity in the Amazon, one in the Orinoco, one in Paraná-Paraguay and one in Tocantins-Araguaia which is coherent with our morphological results.

Revisionary study of the armored catfish Corydoras paleatus (Jenyns, 1842) (Siluriformes: Callichthyidae) over 180 years after its discovery by Darwin, with description of a new species

The taxon known as Corydoras paleatus carries one of the most complex taxonomic histories among Corydoradinae catfishes. A comprehensive review of specimens attributed to that species from several localities was carried out, allowing the clear recognition of C. paleatus and also of a new species previously misidentified as C. paleatus , described herein. Corydoras paleatus can be distinguished from its congeners by presenting the following unique combination of features: perpendicularly directed serrations along entire posterior margin of the pectoral spine; three large black blotches along midline of flank; hyaline or black pectoral fin; and transversal black bars on caudal-fin lobes. Corydoras paleatus is known from the lower rio Paraná basin, coastal rivers from Southern Brazil and Uruguay and rio Uruguai basin. The new species can be distinguished from its congeners by having the following unique combination of features: three large black blotches along midline of flank; three nasal pores; mesethmoid short; infraorbital 2 not in contact with compound pterotic; striated black spots from the snout tip to nuchal plate region; markedly rounded snout; and anterior portion of dorsal fin spotted. The new species is known from the upper rio Uruguai basin, from the rivers Canoas, do Peixe and Pelotas.

O táxon conhecido como Corydoras paleatus carrega uma das histórias taxonômicas mais complexas dentre os bagres Corydoradinae. Uma revisão abrangente de espécimes atribuídos a essa espécie, de várias localidades, foi conduzida. A análise do material colhido permitiu o reconhecimento claro de C. paleatus e também de uma espécie nova, previamente identificada erroneamente como C. paleatus , aqui descrita. Corydoras paleatus pode ser distinguida de suas congêneres por possuir a seguinte combinação única de características: serrilhas perpendicularmente direcionadas ao longo de toda a margem posterior do acúleo peitoral; três manchas pretas grandes ao longo da linha mediana do flanco; nadadeira peitoral hialina ou preta; e barras transversais pretas nos lobos da nadadeira caudal. Corydoras paleatus é conhecida da bacia do baixo rio Paraná, rios costeiros do sul do Brasil e Uruguai, e bacia do rio Uruguai. A espécie nova pode ser distinguida de suas congêneres por possuir a seguinte combinação única de caracteres: três manchas pretas grandes ao longo da linha mediana do flanco; três poros nasais; mesetmóide curto; infraorbital 2 não contatando o pterótico composto; manchas pretas estriadas da ponta do focinho até a região da placa nucal; focinho marcadamente arredondado; e porção anterior da nadadeira dorsal com manchas. A espécie nova é conhecida da bacia do alto rio Uruguai, dos rios Canoas, do Peixe e Pelotas.

Neotropical Siluriformes as a Model for Insights on Determining Biodiversity of Animal Groups.

We performed an analysis of the descriptions of new species of Neotropical Siluriformes (catfishes) to estimate the number of new species that remain to be described for a complete knowledge on biodiversity of this order, to verify the effectiveness of taxonomic support, and to identify trends and present relevant information for future policies. We conducted a literature review of species descriptions between January 1990 and August 2014. The following metadata were recorded from each article: year of publication, number of species, journal and impact factor, family(s) of the described species, number of authors, age of the authors and coauthors, country of the first author's institution and ecoregion of the type-locality. From accumulation of descriptions, we built an estimate model for number of species remaining to be described. We found 595 described species in 402 articles. The data demonstrated that there has been an increased understanding of the diversity of Siluriformes over the last 25 years in the Neotropical region, although 35% of the species still remain to be described. The model estimated that with the current trends and incentives, the biodiversity will be known in almost seven decades. We have reinforced the idea that greater joint efforts should be made by society and the scientific community to obtain this knowledge in a shorter period of time through enhanced programs for promoting science, training and the advancement of professionals before undiscovered species become extinct. The model built in this study can be used for similar estimates of other groups of animals.

Widening the geographical distribution of Pimelodus mysteriosus Azpelicueta 1998 (Siluriformes: Pimelodidae) to the upper Paraná River, with diagnosis for syntopic congeners / Ampliando a distribuição geográfica de Pimelodus mysteriosus Azpelicueta 1998 (Siluriformes: Pimelodidae) para a bacia do alto rio Paraná, com diagnose para congêneres sintópicas

Pimelodus mysteriosus Azpelicueta 1998, previously known only from the lower Paraná and Paraguay River basins, has been also recorded in the upper Paraná River floodplain. The only congeners occurring in syntopy with P. mysteriosus in the upper Paraná River basin are P. maculatus and P. ornatus. New diagnostic characters between P. mysteriosus and P. maculatus are provided.

Pimelodus mysteriosus Azpelicueta 1998, previamente conhecida apenas das bacias do baixo rio Paraná e do rio Paraguai, foi também registrada na planície de inundação do alto rio Paraná. As únicas congêneres que ocorrem em sintopia com P. mysteriosus na bacia do alto rio Paraná são P. maculatus e P. ornatus. Novos caracteres diagnósticos entre P. mysteriosus e P. maculatus são fornecidos.

Redescription of Corydoras guapore Knaack, 1961 (Siluriformes: Callichthyidae), a midwater Corydoradinae species from the rio Guaporé basin

Corydoras guapore was described from the rio Guaporé, Rondônia State, Brazil, based only in three specimens, two of them merely examined alive in an aquarium and apparently not preserved posteriorly. The current location of these two paratypes is uncertain. In the original description, no standard diagnosis was presented and the descriptive information available is scarce and based only in external morphology. Thus, the aim of this study is to provide a redescription of C. guapore based in several topotypes. Corydoras guapore can be distinguished from its congeners by the presence of a short mesethmoid, with the anterior tip poorly developed; posterior margin of pectoral spine with conical serrations directed towards the origin of the spine; and by the lateral portion of caudal peduncle almost entirely blackened. Information about C. guapore ecology and conservation status are also provided.

Corydoras guapore foi descrita do rio Guaporé, estado de Rondônia, Brasil, com base em somente três exemplares, sendo dois deles apenas examinados vivos em um aquário e aparentemente não preservados posteriormente. A atual localização desses dois parátipos é incerta. Na descrição original, uma diagnose padrão não foi apresentada e as informações descritivas disponíveis são escassas e baseadas apenas em morfologia externa. Dessa forma, o objetivo desse estudo é fornecer uma redescrição de C. guapore baseada em vários topótipos. Corydoras guapore pode ser distinguida de suas congêneres pela presença de mesetmóide curto, com a extremidade anterior pouco desenvolvida, margem posterior do acúleo peitoral com serrilhas cônicas voltadas em direção à origem do acúleo, e pela porção lateral do pedúnculo caudal quase totalmente enegrecida. Informações sobre a ecologia e status de conservação de C. guapore também são fornecidas.

Taxonomy of Pimelodus brevis Marini, Nichols & La Monte, 1933 (Siluriformes: Pimelodidae), an uncertain species from the rio Paraná basin

Pimelodus brevis Marini, Nichols & La Monte, 1933 was described from the río de la Plata, Departamento San Fernando, Argentina, based only on the holotype, which is missing since 1960s. This species has been cited in the literature and is considered valid despite of no voucher specimen has been found in museum. A taxonomic analysis comprising material from the rio Paraná basin provided additional specimens that made it possible to demonstrate the identity of P. brevis. Based on the original description and illustration of the holotype, we performed an allometric analysis and then we were able to compare the data with the similar sympatric congeners. Those comparisons allowed us to conclude that P. brevis is a junior synonym of P. argenteus Perugia, 1891, described from the río Paraná, Colonia Resistencia, Argentina. Comments on the status of congeners and taxonomic recommendations are provided.

Pimelodus brevis Marini, Nichols & La Monte, 1933 foi descrita do rio de la Plata, San Fernando, Argentina, com base apenas no holótipo, que está desaparecido desde a década de 1960. Esta espécie é considerada válida, a despeito da ausência de espécimes-testemunhos em coleções. Uma análise compreendendo material da bacia do rio Paraná forneceu espécimes adicionais, possibilitando reconhecer a identidade taxonômica de P. brevis. Com base na descrição original e na ilustração do holótipo, foi realizada uma análise alométrica e comparação dos dados com as congêneres simpátricas similares. Essas comparações permitiram concluir que P. brevis é sinônimo júnior de P. argenteus Perugia, 1891, descrita do rio Paraná, Colonia Resistencia (atual Departamento San Fernando), Argentina. Comentários sobre o status de congêneres e recomendações taxonômicas são fornecidas.

Nucleotide diversity of Hemigrammus cf. marginatus (Characiformes, Characidae) in the upper Paraná river floodplain / Diversidade nucleotídica de Hemigrammus cf. marginatus (Characiformes, Characidae) na planície de inundação do alto rio Paraná

Characidae is the largest and more diversified family from Characiformes and presents several classification problems, with several genera currently allocated as incertae sedis, such as the genus Hemigrammus. The upper Paraná river floodplain is an environment with high fish diversity. There is at least one species of Hemigrammus, however there are divergences among some authors about the number and the identification of the species from this genus. Therefore the goal of this study was to characterize, using a molecular approach, individuals of Hemigrammus from the upper Paraná river floodplain and to compare them with individuals from the type locality of Hemigrammus marginatus, since this is the only species distributed in this floodplain. For this, the DNA was extracted and a partial region from the mitochondrial genes ATPase 6 and ATPase 8 were amplified and sequenced. The results evidenced the existence of two species of Hemigrammus in the floodplain, although impossible to be distinguished only through morphological traits. High nucleotide diversity among individuals from the upper Paraná river in relation to those from the type locality was also observed, indicating that both species of Hemigrammus present in the upper Paraná river floodplain are not Hemigrammus marginatus.

Characidae é a maior e mais diversificada família de Characiformes e apresenta vários problemas de classificação, com inúmeros gêneros alocados atualmente como incertae sedis, dentre estes Hemigrammus. A planície de inundação do alto rio Paraná é um ambiente com alta diversidade de peixes. Existe neste ambiente pelo menos uma espécie de Hemigrammus, entretanto, existem divergências entre alguns autores quanto ao número e a identificação das espécies deste gênero. Portanto, o objetivo deste trabalho foi realizar a caracterização molecular de indivíduos de Hemigrammus da planície de inundação do alto rio Paraná e compará-los com exemplares da localidade-tipo de Hemigrammus marginatus, tendo em vista ser esta a única espécie identificada de Hemigrammus com distribuição na referida planície. Para isso, foi extraído o DNA, amplificado e sequenciado uma região parcial dos genes mitocondriais ATPase 6 e ATPase 8. Os resultados demonstraram a existência de duas espécies de Hemigrammus na planície de inundação do alto rio Paraná, embora impossíveis de serem diferenciadas apenas pelos caracteres morfológicos utilizados atualmente. Alta diversidade nucleotídica entre os exemplares do alto rio Paraná em relação aos da localidade-tipo também foi observada, indicando que ambas as espécies de Hemigrammus presente na planície de inundação do alto rio Paraná não são da espécie Hemigrammus marginatus.

A new dark-saddled species of Hypostomus (Siluriformes: Loricariidae) from the upper rio Paraguay basin

A new Hypostomus species is described from the rio Cuiabá, upper rio Paraguay basin, Mato Grosso State, Brazil. The new species is distinguished from all other Hypostomus species, with exception of young specimens of H. latifrons, by the presence of a wide dark transverse bars on laterals of body and fins; and conspicuous dark vermiculations on abdominal region. From H. latifrons it differs by having just one pre-dorsal plate surrounding supraoccipital bone and by the maintenance of the dark saddles in adults. Added to the other fish species recently described from the upper rio Paraguay basin, this work helps to highlight that the region still functions as a potential source of new species.

Uma espécie nova de Hypostomus é descrita do rio Cuiabá, bacia do alto rio Paraguai, Estado do Mato Grosso, Brasil. A espécie nova é diagnosticada de todas as outras congêneres, com exceção de H. latifrons, pela presença de amplas barras escuras transversais nas laterais do corpo e nadadeiras, e pelas conspícuas vermiculações escuras na região abdominal. De H. latifrons ela difere por ter somente uma placa pré-dorsal margeando o osso supraoccipital e pela manutenção das barras escuras transversais nos adultos. Somada a outras espécies de peixes recentemente descritas na bacia do alto rio Paraguai, este trabalho demonstra que a região ainda funciona como uma fonte potencial de espécies novas.

A new Tatia (Ostariophysi: Siluriformes: Auchenipteridae) from the rio Iguaçu basin, Paraná State, Brazil

A new species of Tatia is described from the lower rio Iguaçu basin, Paraná State, Brazil. The new species is distinguishable from congeners by having large, irregular pale blotches over dark brown base coloration, absent longitudinal stripe, caudal fin with round to striate dark brown spots over light base in adults or entirely dark in juveniles, and by having a long humeral process. Sexual dimorphism of the new species is marked by differences among genital and urinary apertures, size proportions between upper and lower lobe of caudal fin, and size, width and presence of antrorse and retrorse spines on anal-fin rays.

Uma nova espécie de Tatia é descrita da bacia do baixo rio Iguaçu, Estado do Paraná, Brasil. A nova espécie é diagnosticada de suas congêneres por apresentar grandes manchas claras e irregulares sobre um fundo marrom escuro, faixa longitudinal ausente, nadadeira caudal com manchas arredondadas a estrias marrons escuras sobre uma base clara nos adultos ou completamente negra nos jovens, e por apresentar o processo umeral longo. O dimorfismo sexual da nova espécie é marcado por diferenças entre as aberturas genitais e urinárias, proporções de tamanho entre o lobo superior e inferior da nadadeira caudal e tamanho, largura e presença de espinhos antrorsos e retrorsos nos raios da nadadeira anal.

A massive invasion of fish species after eliminating a natural barrier in the upper rio Paraná basin

Based on long-term studies in the upper rio Paraná basin, in addition to a broad review of literature and other information, we were able to identify 33 species of native fishes in the lower rio Paraná basin that successfully colonized the upper rio Paraná after Itaipu impoundment, that flooded the natural geographic barrier constituted by the Sete Quedas Falls. These species belong to six Orders, encompassing two of Myliobatiformes, six of Characiformes, 17 of Siluriformes, six of Gymnotiformes, one of Perciformes, and one of Pleuronectiformes. Extensive remarks regarding each species, including their influence upon the native assemblage, in addition to comments on other non-indigenous species, are also provided. We conclude that, in spite of its widespread neglected by environmental impact studies, massive invasion of species is a real possibility when natural barriers are suppressed by reservoirs.(AU)

Baseando-se em pesquisas de longa duração na bacia do alto rio Paraná, em adição à ampla revisão bibliográfica e outras informações, pudemos reconhecer 33 espécies nativas da bacia do baixo rio Paraná que colonizaram o alto Paraná com sucesso, após a construção de Itaipu, que inundou a barreira geográfica natural constituída pelos Saltos de Sete Quedas. Estas espécies pertencem a seis ordens, incluindo duas de Myliobatiformes, seis de Characiformes, 17 de Siluriformes, seis de Gymnotiformes, uma de Perciformes, e uma de Pleuronectiformes. Extensas observações sobre cada espécie, incluindo a influência delas sobre a assembleia nativa, além de comentários sobre outras espécies não-indígenas são igualmente fornecidos. Nós concluímos que, embora geralmente negligenciadas pelas análises de impactos ambientais, invasões massivas são possibilidades reais quando barreiras naturais são suprimidas por reservatórios(AU)

A redescription of Astyanax gymnodontus (Eigenmann, 1911), new combination, a polymorphic characid fish from the rio Iguaçu basin, Brazil

Astyanax gymnodontus (Eigenmann, 1911), new combination, a polymorphic characid fish endemic to the Rio Iguaçu basin in Southern Brazil, is redescribed. The species was originally described as belonging to the monotypic genus Psalidodon, distinguished from Astyanax by the possession of a single series of teeth on the premaxilla (vs. two series), by the presence of relatively compressed teeth on the premaxillary and dentary bones (vs. relatively bulky teeth), and by the absence of lips (vs. lips present). Examination of a large number of specimens from the rio Iguaçu basin that present dental and lip features that were intermediate between Psalidodon and Astyanax indicated that specimens attributed to Psalidodon show extreme characters observed within a polymorphic Astyanax species. Accordingly, the genus Psalidodon is synonymized under Astyanax. Specimens of "Astyanax sp. F" morphotype from the rio Iguaçu basin belong to the species Astyanax gymnodontus and display a regular tooth arrangement and morphology, and their lip development is similar to that of other Astyanax species.(AU)

Astyanax gymnodontus (Eigenmann, 1911), combinação nova, um peixe caracídeo polimórfico, endêmico da bacia do rio Iguaçu no sul do Brasil, é redescrito. A espécie foi originalmente descrita como pertencente ao gênero monotípico Psalidodon, diagnosticado de Astyanax pela posse de uma única série de dentes no pré-maxilar (vs. duas séries), pela presença de dentes relativamente comprimidos nos ossos pré-maxilar e dentário (vs. dentes relativamente robustos), e pela ausência de lábios (vs. lábios presentes). O exame de um grande número de espécimes da bacia do rio Iguaçu, apresentando características dentárias e labiais intermediárias entre Psalidodon e Astyanax, indicou que espécimes atribuídos a Psalidodon mostram caracteres extremos observados em uma espécie de Astyanax. Assim, o gênero Psalidodon é sinonimizado sob Astyanax. Espécimes do morfótipo "Astyanax sp. F" da bacia do rio Iguaçu pertencem à espécie Astyanax gymnodontus e exibem dentes com arranjo e morfologia regular, bem como lábios com desenvolvimento similar a outras espécies de Astyanax.(AU)

Occurrence of two cytotypes in Bryconamericus aff. iheringii (Characidae): karyotype analysis by C- and G-banding and replication bands.

Cytogenetic analyses of Bryconamericus aff. iheringii specimens from the upper Paraná River basin (State of Paraná, Brazil) are provided. They had 2n = 52 chromosomes and two cytotypes with variations in their karyotypic formulae: cytotype I with 12 metacentric, 18 submetacentric, 8 subtelocentric and 14 acrocentric chromosomes with a fundamental number (FN) of 90; cytotype II with 8 metacentric, 28 submetacentric, 6 subtelocentric and 10 acrocentric chromosomes with a fundamental number (FN) of 94. Differences in C- and G-band patterns between the cytotypes, distinguishing marker chromosomes for each karyotype, were reported. The R-band pattern by 5-bromodeoxyuridine incorporation was obtained in chromosomes of the cytotype II sample. In some metaphases, the second pair of submetacentric chromosomes is distinctive: its short arm is heterochromatic (positive C-band), corresponding to a late replication region. In the same cytotype, a G- and R-band size heteromorphism w as recorded in the long arm of pair 9 (submetacentric). These methodologies revealed an actual karyotypic differentiation in the B. aff. iheringii population analyzed. Morphometrical comparative analyses and a discussion of evolutionary aspects of chromosome diversification in species of this genus are provided as well.

Diversidade da ictiofauna do Alto Rio Paraná: composição atual e perspectivas futuras / Ichthyofauna diversity of the upper rio Paraná: present composition and future perspectives

É apresentada uma síntese sobre os peixes do Alto Paraná, com base em dados de coleções, dados de literatura e novas coletas. Trezentas e dez espécies, de 11 ordens e 38 famílias, são referidas para a drenagem, aumentando significativamente números anteriores. Dentre as espécies da área, 236 (76,1 por cento) são autóctones, 67 (21,6 por cento) alóctones e sete (2,3 por cento) exóticas. As principais causas de ocorrência de espécies não nativas (alóctones e exóticas) foram a dispersão a partir do baixo Paraná, após a construção do Reservatório de Itaipu e o escape de pisciculturas. A maior parte das espécies referidas (65 por cento) tem porte pequeno, sendo menor que 21 cm de comprimento; dentre essas, a maioria ocorre apenas em riachos e cabeceiras. Apesar da ictiofauna do Alto Paraná ser uma das melhor conhecidas e mais estudadas, o número de espécies descritas ou referidas para a área tem crescido exponencialmente, o que indica que a riqueza apresentada está longe de representar a realidade. De fato, várias novas espécies têm sido descritas nos últimos anos e cerca de 50 novas espécies, já reconhecidas, estão em fase de descrição. A melhoria no conhecimento sobre a ictiofauna do Alto Paraná é proporcional ao número de pesquisadores envolvidos em estudos na bacia e reflete, de modo inequívoco, iniciativas recentes que têm estimulado e incrementado pesquisas taxonômicas, facilitado o acesso ao material depositado em coleções científicas e aumentado as coletas em áreas e ambientes pouco amostrados. Entretanto, mantido o ritmo de descrições de novas espécies ocorrido até agora nessa última década, as 50 novas espécies já reconhecidas estariam descritas apenas dentro de dez anos, um tempo demasiadamente longo. Por essa razão é muito importante que a comunidade científica e os órgãos de fomento encontrem e viabilizem iniciativas de modo a aumentar esse ritmo de descrições de novos táxons e disponibilizar esses novos nomes mais rapidamente.

A synthesis concerning fishes from Upper Paraná River basin is presented, based on data from fish-collections, literature, and new field samples. Three hundred and ten species, pertaining to 11 orders and 38 families, are referred to the drainage, elevating anterior estimates. Concerning total species, 236 (76.1 percent) are autochthonous, 67 (21.6 percent) are allochthonous, and seven (2.3 percent) are exotic. Principal causes of occurrence of non-native species are: a) dispersal from the Lower Paraná, after the construction of Itaipu dam, and b) escapes from aquaculture farms. Most species (65 percent) are small-sized, having less than 21 cm of length, and the great majority occurs only in headwaters and small streams. One of the best known and most studied in Brazil, Upper Paraná ichthyofauna richness is far from reaching actual numbers, considering the exponential elevation of species presented herein. Indeed, in the last years various new species have been described and around 50 other species, already recognized as new, are now under description. The improvement on the knowledge about Upper Paraná ichthyofauna is proportional to the number of researchers involved with studies in the area and, unequivocally, reflects recent initiatives stimulating and incrementing taxonomic research, and also improving access to fish collections and to poor or never-sampled areas. However, if we are going to maintain the number of species descriptions per year of last decade, the 50 new species already recognized, will be described only in the next ten years, a period too long. In consequence it is very important that scientific community and grant agencies find and offer initiatives in order to elevate the number of new taxa descriptions per year.