Luiz Fernando Caserta Tencatt

A new Corydoras Lacépède, 1803 (Siluriformes: Callichthyidae) from the rio São Francisco basin, Brazil

A new species of Corydoras is described from the rio Sao Francisco basin in northeastern Brazil, Minas Gerais and Bahia States. The new species is distinguished from most of its congeners by the anterior portion of the infraorbital 1 very large, conspicuously expanded towards the anteroventral margin of the snout and almost entirely covering its lateral margin. Other characters that distinguish the new species are the infraorbital 2 slender on its dorsal tip, contacting only sphenotic and not compound pterotic; and the presence of two laterosensory canals on trunk. A phylogenetic analysis including the new species found it sister-group of C. flaveolus, and both species sister-group of C. paleatus. An identification key to the species of the rio Sao Francisco basin is also provided. Uma especie nova de Corydoras e descrita da bacia do rio Sao Francisco no nordeste do Brasil, estados de Minas Gerais e Bahia. A especie nova se distingue da maioria de suas congeneres por apresentar a porcao anterior do infraorbital 1 muito desenvolvida, expandindo-se conspicuamente em direcao a margem anteroventral do focinho, quase cobrindo completamente sua margem lateral. Outros caracteres que distinguem a especie nova sao o infraorbital 2 estreito em sua extremidade dorsal, em contato apenas com o esfenotico e nao com o pterotico composto, e presenca de somente dois canais latero-sensoriais no tronco. Uma analise filogenetica incluindo a especie nova encontrou-a como grupo-irmao de C. flaveolus, e ambas como grupo-irmao de C. paleatus. Uma chave para identificacao das especies da bacia do rio Sao Francisco tambem e fornecida.

A new unicuspid-toothed species of Hypostomus Lacépède, 1803 (Siluriformes: Loricariidae) from the rio Paraguai basin

A new unicuspid-toothed armored catfish species of Hypostomus is described from the Bodoquena Plateau, rio Paraguai basin, Mato Grosso do Sul State, Brazil. The new species is distinguished from its congeners, with exception of H. fonchii, by having unicuspid teeth (vs.bicuspid teeth); from H. fonchii it is distinguished by having median series of lateral plates with 26-27 (vs. 28); by lower number of premaxillary and dentary teeth (7-10 vs. 18-21; 8-13 vs. 18-25, respectively); for possessing more depressed head (head depth 15.8-18.1% SL vs. 19.1-22.0% SL); and by the presence of median buccal papilla (vs. absence).

Effects of long and short flooding years on the feeding ecology of piscivorous fish in floodplain river systems

Floodplain river systems are extremely dynamic environments, where alternating dry and flooded periods affect the availability of food resources for fish. For piscivores, during drought years, a decreased availability of prey is expected, resulting in diets dominated by fewer items, narrower trophic niches with high dietary overlap. During floods, habitats become more similar, and, combined with increased connectivity, provide a wider diversity of prey to piscivores, decreasing dietary overlap and presenting wider trophic niches. This study aimed to evaluate the potential impacts of long periods of flooding on the trophic ecology of nine piscivorous fish in the upper Paraná River basin. In drought years, diets were dominated by small characids, presenting narrower niches with higher dietary overlap. The opposite situation was observed during wet years, with different species responses, likely due to species-specific feeding strategies. High niche overlap was observed between native and non-native species, suggesting competition. The inclusion of non-native species in the native piscivorous diet is a concerning fact, as its causes and possible impacts are still unknown. In conclusion, long flooding pulses affect the diets of piscivorous fish in different ways by either increasing or decreasing niche breadth and overlap according to species-specific characteristics.

First record of the camboatá Megalechis picta (Müller & Troschel, 1849) (Siluriformes: Callichthyidae) for the Pantanal, Brazil

Herein we report the first record of Megalechis picta in the Brazilian Pantanal based in a single specimen captured in a tributary to the rio Miranda, municipality of Corumba, rio Paraguay basin, State of Mato Grosso do Sul, Brazil. Additional discussion about its co-occurrence with M. thoracata is also provided.

A new species of Corydoras Lacépède, 1803 (Siluriformes: Callichthyidae) from the upper rio Paraná basin, Brazil

Uma especie nova de Corydoras e descrita de tres tributarios da drenagem do rio Ivai, bacia do alto rio Parana, estado do Parana, Brasil. A especie nova se diferencia da maioria de suas congeneres por apresentar tres poros nasais. Outras caracteristicas diagnosticas sao o menor numero de serrilhas na margem posterior dos espinhos peitoral e dorsal e presenca de quatro a seis manchas pretas pequenas ao longo da linha mediana do flanco. A possivel relacao mimetica entre a especie nova e Characidium heirmostigmata e discutida.

Fishes from Baía da Medalha, southern Pantanal, Brazil: A 20 years review

Located in the Pantanal of Miranda-Abobral, the Baia da Medalha is the largest pond close to the Base de Estudos do Pantanal of the Universidade Federal de Mato Grosso do Sul. The Baia da Medalha has been a study site for several didactic and scientific projects for years. Nevertheless, its fish fauna has never been inventoried. Based on data collected from the beginning of the 1990s up to 2011, we provide a list of fish species from the Baia da Medalha. A total of 97 species were recorded, corresponding to about 40% of the species stated for the Pantanal. Characiformes and Siluriformes were the most species-rich orders, being Characidae and Cichlidae the families with the highest number of species. Regional seasonal flood dynamics and the abundance of aquatic macrophytes may be associated with this high diversity. The representative richness found in this lagoon highlights the importance of such taxonomic surveys to preserve the diversity of aquatic habitats within the Pantanal ecosystem.

Ecomorphological differences between Rhamdia (Bleeker, 1858) populations from the Iguaçu River basin

Morphological and genetic evidences suggest that Rhamdia branneri and Rhamdia voulezi, currently considered synonymous of Rhamdia quelen, are in fact two valid species. Furthermore, in the taxonomic revision of R. quelen, no exemplars from the Iguacu River were examined, which makes the synonymy doubtful. Considering the two species as valid, it was hypothesized that R. branneri and R. voulezi have ecomorphological differences, with the objective to verify if they can be considered ecologically distinct. Ecomorphological characterization was conducted using ecomorphological indices. For statistical analysis, a Principal Component Analysis (PCA), a Multiresponse Permutation Procedure (MRPP), and a Discriminant Analysis (DA) were performed. The ordination provided by the PCA evidenced ecomorphological separation, with R. branneri having morphological aspects related to benthic fishes, and R. voulezi having morphological characteristics related to pelagic and lentic habitats. The DA results confirmed the morphological tendencies found in the PCA, and the MRPP showed significant statistical differences between the ecomorphology of Rhamdia species. In this way, the initial hypothesis can be corroborated. These results allied to information about diet, genetics, and reproduction can be helpful for the elucidation of the taxonomic status of R. branneri and R. voulezi.

Wrapped in flames: Corydoras hephaestus , a new remarkably colored species from the Rio Madeira basin (Teleostei: Callichthyidae)

A new species of Corydoras is described from the upper Rio Machado, Rio Madeira basin, Rondônia State, Brazil. The new species can be distinguished from its congeners by the absence of contact between the posterior process of the parieto-supraoccipital and the nuchal plate; a ventral laminar expansion of the infraorbital 1 conspicuously developed; and the posterior margin of the pectoral-fin spine with serrations along almost of its entire length, only lacking in the distal portion. Additionally, Corydoras hephaestus possesses dorsal and pectoral spines short, and exhibits an unusual color pattern in life. The conservation status of the new species and other endemic species are briefly commented.

A new long-snouted species of Corydoras Lacépède, 1803 (Siluriformes: Callichthyidae) from the rio Madeira basin

A new species of Corydoras is described from the rio Aripuanã, rio Madeira basin, Mato Grosso State, Brazil. The new species can be distinguished from its congeners by the presence of the following features: long mesethmoid, with anterior tip well developed, conspicuously larger than 50% of bone length; posterior margin of dorsal-fin spine with serrations directed towards tip of spine; one to two longitudinal black stripes on flanks; absence of a black blotch across the eyes (mask); absence of a large black blotch on dorsal fin; and transversal black bars on caudal fin. Comments on endemism in interfluvial region between Madeira and Tapajós rivers are briefly discussed.

Two new species of Corydoras Lacépède, 1803 (Siluriformes: Callichthyidae) from the rio Madeira basin, Brazil

Two new species of Corydoras are described from the rio Madeira basin, Brazil. The intermediate long-snouted new species can be distinguished from its congeners by presenting the following combination of features: posterior margin of dorsal-fin spine with laminar serrations directed towards the origin of the spine; presence of two longitudinal black stripes on flanks; anterior portion of dorsal fin with sparse black chromatophores, not forming any conspicuous pattern; absence of a conspicuous black marbled coloration pattern on head; black spots on caudal fin, some spots arranged, forming transversal bars; and brownish dorsal-fin spine. The short-snouted new speciescan be distinguished from its congeners by the following combination of features: short mesethmoid; posterior laminar expansion of infraorbital 2 very reduced, not in contact with compound pterotic; two or three longitudinal black stripes on flanks; absence of an oblique or vertical black blotch across the eye; anterior portion of dorsal fin with sparse black chromatophores, not forming any conspicuous pattern; and ventral surface of trunk naked or covered by sparse platelets.