First record and extended distribution of Otothyropsis piribebuy (Loricariidae: Hypoptopomatinae) in Brazil

Cascudinhos are a group of small benthic fishes included in the Hypoptopomatinae subfamily, inhabiting small to moderate streams and rivers within the Neotropical region, from Venezuela to Northern Argentina. Until now, Otothyropsis piribebuy originally described from the rio Paraguay basin, in Paraguay, is the only species of the genus not recorded in Brazil. Recent samples in the rio Tererê, rio Paraguay basin, Brazil, revealed a population of Otothyropsis with uncertain taxonomic identity. Therefore, the study aimed to unveil the distribution of Otothyropsis within Brazilian territory. External morphology, osteology, measurements, and counts (plates, teeth, and rays) of these specimens from rio Tererê were compared to data from the original description of O. piribebuy, and also with specimens of O. piribebuy sampled in Paraguayan territory. Observations indicated no differences among the analyzed specimens. Furthermore, a Principal Component Analysis (PCA), carried out using log-transformed measures from Brazilian and Paraguayan specimens, showed no separation of these populations, also indicating that all analyzed specimens pertain to the same species. Based on this, a prediction map of distribution, using Maximum Entropy, was produced. The correct identification of spatial range of occurrence is an essential step to ensure the conservation of species, and the extended distribution of Otothyropsis piribebuy was confirmed, enhancing the list of neotropical fish from Brazil.(AU)

First record and extended distribution of Otothyropsis piribebuy (Loricariidae: Hypoptopomatinae) in Brazil

Cascudinhos are a group of small benthic fishes included in the Hypoptopomatinae subfamily, inhabiting small to moderate streams and rivers within the Neotropical region, from Venezuela to Northern Argentina. Until now, Otothyropsis piribebuy originally described from the rio Paraguay basin, in Paraguay, is the only species of the genus not recorded in Brazil. Recent samples in the rio Tererê, rio Paraguay basin, Brazil, revealed a population of Otothyropsis with uncertain taxonomic identity. Therefore, the study aimed to unveil the distribution of Otothyropsis within Brazilian territory. External morphology, osteology, measurements, and counts (plates, teeth, and rays) of these specimens from rio Tererê were compared to data from the original description of O. piribebuy, and also with specimens of O. piribebuy sampled in Paraguayan territory. Observations indicated no differences among the analyzed specimens. Furthermore, a Principal Component Analysis (PCA), carried out using log-transformed measures from Brazilian and Paraguayan specimens, showed no separation of these populations, also indicating that all analyzed specimens pertain to the same species. Based on this, a prediction map of distribution, using Maximum Entropy, was produced. The correct identification of spatial range of occurrence is an essential step to ensure the conservation of species, and the extended distribution of Otothyropsis piribebuy was confirmed, enhancing the list of neotropical fish from Brazil.

First record and extended distribution of Otothyropsis piribebuy (Loricariidae: Hypoptopomatinae) in Brazil

Abstract Cascudinhos are a group of small benthic fishes included in the Hypoptopomatinae subfamily, inhabiting small to moderate streams and rivers within the Neotropical region, from Venezuela to Northern Argentina. Until now, Otothyropsis piribebuy originally described from the rio Paraguay basin, in Paraguay, is the only species of the genus not recorded in Brazil. Recent samples in the rio Tererê, rio Paraguay basin, Brazil, revealed a population of Otothyropsis with uncertain taxonomic identity. Therefore, the study aimed to unveil the distribution of Otothyropsis within Brazilian territory. External morphology, osteology, measurements, and counts (plates, teeth, and rays) of these specimens from rio Tererê were compared to data from the original description of O. piribebuy, and also with specimens of O. piribebuy sampled in Paraguayan territory. Observations indicated no differences among the analyzed specimens. Furthermore, a Principal Component Analysis (PCA), carried out using log-transformed measures from Brazilian and Paraguayan specimens, showed no separation of these populations, also indicating that all analyzed specimens pertain to the same species. Based on this, a prediction map of distribution, using Maximum Entropy, was produced. The correct identification of spatial range of occurrence is an essential step to ensure the conservation of species, and the extended distribution of Otothyropsis piribebuy was confirmed, enhancing the list of neotropical fish from Brazil.

Genetic Pattern and Demographic History of Salminus brasiliensis: Population Expansion in the Pantanal Region during the Pleistocene.

Pleistocene climate changes were major historical events that impacted South American biodiversity. Although the effects of such changes are well-documented for several biomes, it is poorly known how these climate shifts affected the biodiversity of the Pantanal floodplain. Fish are one of the most diverse groups in the Pantanal floodplains and can be taken as a suitable biological model for reconstructing paleoenvironmental scenarios. To identify the effects of Pleistocene climate changes on Pantanal's ichthyofauna, we used genetic data from multiple populations of a top-predator long-distance migratory fish, Salminus brasiliensis. We specifically investigated whether Pleistocene climate changes affected the demography of this species. If this was the case, we expected to find changes in population size over time. Thus, we assessed the genetic diversity of S. brasiliensis to trace the demographic history of nine populations from the Upper Paraguay basin, which includes the Pantanal floodplain, that form a single genetic group, employing approximate Bayesian computation (ABC) to test five scenarios: constant population, old expansion, old decline, old bottleneck following by recent expansion, and old expansion following by recent decline. Based on two mitochondrial DNA markers, our inferences from ABC analysis, the results of Bayesian skyline plot, the implications of star-like networks, and the patterns of genetic diversity (high haplotype diversity and low-to-moderate nucleotide diversity) indicated a sudden population expansion. ABC allowed us to make strong quantitative inferences about the demographic history of S. brasiliensis. We estimated a small ancestral population size that underwent a drastic fivefold expansion, probably associated with the colonization of newly formed habitats. The estimated time of this expansion was consistent with a humid and warm phase as inferred by speleothem growth phases and travertine records during Pleistocene interglacial periods. The strong concordance between our genetic inferences and this historical data could represent the first genetic record of a humid and warm phase in the Pantanal in the period since the Last Interglacial to 40 ka.

Structure of aquatic vegetation of a large lake, western border of the Brazilian Pantanal / Estrutura da vegetação aquática em uma grande lagoa, borda oeste do Pantanal brasileiro

Studies on Neotropical aquatic macrophytes have increased in recent decades, however species richness in wetlands of South America is far from being fully known. In addition, studies having an ecological approach are scarce in the Pantanal. Rapid assessments are essential for gaining knowledge of the biodiversity in the region. This study was performed in five sites of the Baía do Castelo, the western border of the Brazilian Pantanal, which included wild-rice patches, floating mats and floating meadows. At each site, plots of 0.5 × 0.5 m were set (n = 137), species of aquatic macrophytes were identified, their coverage was measured and the plot depth was estimated. We recorded 57 species in 26 families, of which Poaceae was the richest. The most frequent and abundant species was Commelina schomburgkiana; the second most frequent was Oryza latifolia,followed by Leersia hexandra, Enydra radicans and Pityrogramma calomelanos. The latter species was second in cover, followed by Pontederia rotundifolia, Eichhornia azurea, E. crassipes and Enydra radicans. These five species and C. schomburgkiana (the most abundant) together represent more than half of the coverage on the lake. Pontederia rotundifolia, Ludwigia helminthorrhiza, Pistia stratiotes, E. azurea, E. crassipes, Enydra radicans and Panicum elephantipes were strongly associated with deeper areas, while Oryza latifolia, Leersia hexandra and Salvinia auriculata were prevalent in shallow areas. Pityrogramma calomelanos, Ludwigia nervosa, Ipomoea alba, Cayaponia podantha, Polygonum acuminatum, Rhynchanthera novemnervia and Ludwigia leptocarpa were highly correlated with floating meadows. The structure of the habitat, natural dynamics and zonation of aquatic vegetation in the Baía do Castelo seems to be influenced by a variation in water levels, which promotes spatial segregation, most likely due to competition and/habitat preference.

Estudos sobre macrófitas aquáticas Neotropicais aumentaram nas últimas décadas; todavia, a riqueza de espécies em áreas úmidas da América do Sul está longe de ser plenamente conhecida. Além disso, trabalhos com abordagem ecológica são escassos no Pantanal. Por essa razão, levantamentos rápidos são essenciais para o conhecimento sobre a biodiversidade. Este estudo foi realizado em cinco pontos na Baía do Castelo, borda oeste do Pantanal brasileiro, os quais incluíram arrozal, camalotal e baceiros. Em cada ponto, foram estabelecidas parcelas 0.5 × 0.5 m (n = 137), onde foram identificadas as espécies de macrófitas aquáticas, estimada a cobertura e tomada a profundidade. Registramos 57 espécies distribuídas em 26 famílias, das quais a mais rica foi a Poaceae. A espécie mais frequente e abundante foi Commelina schomburgkiana; a segunda mais frequente foi Oryza latifolia, seguida por Leersia hexandra, Enydra radicans e Pityrogramma calomelanos. Essa última espécie foi a segunda com maior cobertura, seguida por Pontederia rotundifolia, Eichhornia azurea, E. crassipes e Enydra radicans. Essas cinco espécies juntamente com C. schomburgkiana (a mais abundante) representam mais da metade da cobertura na Baía do Castelo. Pontederia rotundifolia, Ludwigia helminthorrhiza, Pistia stratiotes, E. azurea, E. crassipes, E. radicans e Panicum elephantipes foram fortemente relacionadas às áreas mais profundas, enquanto Oryza latifolia, Leersia hexandra e Salvinia auriculata foram relacionadas a areas mais rasas. Pityrogramma calomelanos, Ludwigia nervosa, Ipomoea alba, Cayaponia podantha, Polygonum acuminatum, Rhynchanthera novemnervia e Ludwigia leptocarpa foram altamente correlacionadas com baceiros. A estrutura do habitat, a dinâmica natural e a zonação da vegetação aquática aparentam ser influenciadas pela variação nos níveis d'água na Baía do Castelo, os quais promovem a segregação espacial, provavelmente pela competição e/ou preferência por habitat.

Effect of abiotic variables on fish eggs and larvae distribution in headwaters of Cuiabá River, Mato Grosso State, Brazil

Researches on ichthyoplankton seems to be an important tool to identification of spawning areas and periods for freshwater fish. Ichthyoplankton was sampled monthly in the headwaters of the Cuiabá River, upper Paraguay River basin, (Mato Grosso State, Brazil), and in four of its tributaries, between November 2007 and March 2008, to evaluate the spatial and temporal distribution of fish eggs and larvae and the influence of regional and local variables on their distribution. In total, 22,067 eggs and 1,045 larvae were collected. A significant negative correlation was found between egg density and the variables of river level and flow volume. Larval density was not significantly correlated with any of the regional variables. The egg and larval densities were significantly higher at the sampling sites in the main river. The highest densities were found in environments with greater river widths, intermediate depths and lowest values of dissolved oxygen, electrical conductivity, and transparency. Anostomidae, Zungaro zungaro, Bryconamericus spp., Pimelodus spp., Pimelodidae, Auchenipteridae, and Siluriformes were the most abundant groups of larvae, and were observed at the sampling sites in the main river. The study site is an important spawning area for migratory and, non-migratory fish species, and highlight the importance of the main river to the reproductive event, by the influence of local variables transparency and river width, which in turn maybe temporally influenced by the river level.(AU)

O estudo do ictioplâncton tem se mostrado uma importante ferramenta na identificação de áreas e períodos de desova para as espécies de peixes de água doce.Amostragens de ictioplâncton foram realizadas mensalmente na região de cabeceira do rio Cuiabá, bacia do alto rio Paraguai, (Mato Grosso, Brasil) e em quatro de seus tributários, entre novembro de 2007 e março de 2008, com o objetivo de avaliar a distribuição espaço-temporal de ovos e larvas de peixes. Foram amostrados 22.067 ovos e 1.045 larvas. Identificou-se correlação significativa e negativa entre a densidade de ovos, o nível fluviométrico e a vazão. A densidade de larvas não apresentou correlação significativa com nenhuma das variáveis regionais. As densidades, tanto de ovos quanto de larvas, foram significativamente maiores nos pontos no rio principal. As maiores abundâncias foram observadas em ambientes com maiores valores de largura do rio, valores intermediários de profundidade e menores valores de O2 dissolvido, condutividade e transparência. Os grupos taxonômicos de larvas mais abundantes foram Anostomidae, Zungaro zungaro, Bryconamericus spp., Pimelodus spp., Pimelodidae, Auchenipteridae e Siluriformes, com maiores abundâncias observadas nos pontos no rio principal. Os resultados mostram que o local de estudo é uma importante área de desova para as espécies de peixes migradores e não-migradores, e destacamos a importância do rio principal para o evento reprodutivo, pela influência das variáveis locais, transparência e largura do rio, que por sua vez parecem ser influenciadas temporalmente pelo nível fluviométrico.(AU)

Structure of aquatic vegetation of a large lake, western border of the Brazilian Pantanal

Studies on Neotropical aquatic macrophytes have increased in recent decades, however species richness in wetlands of South America is far from being fully known. In addition, studies having an ecological approach are scarce in the Pantanal. Rapid assessments are essential for gaining knowledge of the biodiversity in the region. This study was performed in five sites of the Baía do Castelo, the western border of the Brazilian Pantanal, which included wild-rice patches, floating mats and floating meadows. At each site, plots of 0.5 × 0.5 m were set (n = 137), species of aquatic macrophytes were identified, their coverage was measured and the plot depth was estimated. We recorded 57 species in 26 families, of which Poaceae was the richest. The most frequent and abundant species was Commelina schomburgkiana; the second most frequent was Oryza latifolia,followed by Leersia hexandra, Enydra radicans and Pityrogramma calomelanos. The latter species was second in cover, followed by Pontederia rotundifolia, Eichhornia azurea, E. crassipes and Enydra radicans. These five species and C. schomburgkiana (the most abundant) together represent more than half of the coverage on the lake. Pontederia rotundifolia, Ludwigia helminthorrhiza, Pistia stratiotes, E. azurea, E. crassipes, Enydra radicans and Panicum elephantipes were strongly associated with deeper areas, while Oryza latifolia, Leersia hexandra and Salvinia auriculata were prevalent in shallow areas. Pityrogramma calomelanos, Ludwigia nervosa, Ipomoea alba, Cayaponia podantha, Polygonum acuminatum, Rhynchanthera novemnervia and Ludwigia leptocarpa were highly correlated with floating meadows. The structure of the habitat, natural dynamics and zonation of aquatic vegetation in the Baía do Castelo seems to be influenced by a variation in water levels, which promotes spatial segregation, most likely due to competition and/habitat preference.

Estudos sobre macrófitas aquáticas Neotropicais aumentaram nas últimas décadas; todavia, a riqueza de espécies em áreas úmidas da América do Sul está longe de ser plenamente conhecida. Além disso, trabalhos com abordagem ecológica são escassos no Pantanal. Por essa razão, levantamentos rápidos são essenciais para o conhecimento sobre a biodiversidade. Este estudo foi realizado em cinco pontos na Baía do Castelo, borda oeste do Pantanal brasileiro, os quais incluíram arrozal, camalotal e baceiros. Em cada ponto, foram estabelecidas parcelas 0.5 × 0.5 m (n = 137), onde foram identificadas as espécies de macrófitas aquáticas, estimada a cobertura e tomada a profundidade. Registramos 57 espécies distribuídas em 26 famílias, das quais a mais rica foi a Poaceae. A espécie mais frequente e abundante foi Commelina schomburgkiana; a segunda mais frequente foi Oryza latifolia, seguida por Leersia hexandra, Enydra radicans e Pityrogramma calomelanos. Essa última espécie foi a segunda com maior cobertura, seguida por Pontederia rotundifolia, Eichhornia azurea, E. crassipes e Enydra radicans. Essas cinco espécies juntamente com C. schomburgkiana (a mais abundante) representam mais da metade da cobertura na Baía do Castelo. Pontederia rotundifolia, Ludwigia helminthorrhiza, Pistia stratiotes, E. azurea, E. crassipes, E. radicans e Panicum elephantipes foram fortemente relacionadas às áreas mais profundas, enquanto Oryza latifolia, Leersia hexandra e Salvinia auriculata foram relacionadas a areas mais rasas. Pityrogramma calomelanos, Ludwigia nervosa, Ipomoea alba, Cayaponia podantha, Polygonum acuminatum, Rhynchanthera novemnervia e Ludwigia leptocarpa foram altamente correlacionadas com baceiros. A estrutura do habitat, a dinâmica natural e a zonação da vegetação aquática aparentam ser influenciadas pela variação nos níveis d'água na Baía do Castelo, os quais promovem a segregação espacial, provavelmente pela competição e/ou preferência por habitat.

Effect of abiotic variables on fish eggs and larvae distribution in headwaters of Cuiabá River, Mato Grosso State, Brazil

Researches on ichthyoplankton seems to be an important tool to identification of spawning areas and periods for freshwater fish. Ichthyoplankton was sampled monthly in the headwaters of the Cuiabá River, upper Paraguay River basin, (Mato Grosso State, Brazil), and in four of its tributaries, between November 2007 and March 2008, to evaluate the spatial and temporal distribution of fish eggs and larvae and the influence of regional and local variables on their distribution. In total, 22,067 eggs and 1,045 larvae were collected. A significant negative correlation was found between egg density and the variables of river level and flow volume. Larval density was not significantly correlated with any of the regional variables. The egg and larval densities were significantly higher at the sampling sites in the main river. The highest densities were found in environments with greater river widths, intermediate depths and lowest values of dissolved oxygen, electrical conductivity, and transparency. Anostomidae, Zungaro zungaro, Bryconamericus spp., Pimelodus spp., Pimelodidae, Auchenipteridae, and Siluriformes were the most abundant groups of larvae, and were observed at the sampling sites in the main river. The study site is an important spawning area for migratory and, non-migratory fish species, and highlight the importance of the main river to the reproductive event, by the influence of local variables transparency and river width, which in turn maybe temporally influenced by the river level.

O estudo do ictioplâncton tem se mostrado uma importante ferramenta na identificação de áreas e períodos de desova para as espécies de peixes de água doce.Amostragens de ictioplâncton foram realizadas mensalmente na região de cabeceira do rio Cuiabá, bacia do alto rio Paraguai, (Mato Grosso, Brasil) e em quatro de seus tributários, entre novembro de 2007 e março de 2008, com o objetivo de avaliar a distribuição espaço-temporal de ovos e larvas de peixes. Foram amostrados 22.067 ovos e 1.045 larvas. Identificou-se correlação significativa e negativa entre a densidade de ovos, o nível fluviométrico e a vazão. A densidade de larvas não apresentou correlação significativa com nenhuma das variáveis regionais. As densidades, tanto de ovos quanto de larvas, foram significativamente maiores nos pontos no rio principal. As maiores abundâncias foram observadas em ambientes com maiores valores de largura do rio, valores intermediários de profundidade e menores valores de O2 dissolvido, condutividade e transparência. Os grupos taxonômicos de larvas mais abundantes foram Anostomidae, Zungaro zungaro, Bryconamericus spp., Pimelodus spp., Pimelodidae, Auchenipteridae e Siluriformes, com maiores abundâncias observadas nos pontos no rio principal. Os resultados mostram que o local de estudo é uma importante área de desova para as espécies de peixes migradores e não-migradores, e destacamos a importância do rio principal para o evento reprodutivo, pela influência das variáveis locais, transparência e largura do rio, que por sua vez parecem ser influenciadas temporalmente pelo nível fluviométrico.