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This study assessed the lapillus otolith shapes of males and females of Scleromystax barbatus from southern and southeastern regions in the Atlantic Rainforest biome employing Fourier and Wavelet descriptors. The utricular otoliths of S. barbatus are ovoid, with the gibbus maculae occupying almost all the ventral portion, similar to most Callichthyidae species. Otoliths of males and females of S. barbatus from the southeastern studied region are more elongated in the anterior-posterior direction and present larger sulcus and gibbus maculae, with heterogeneous borders. We found no sexual-based dimorphism in otolith shape within regions, however regional differences were registered and attributed to variations in fish life history mediated by differences in environmental factors (e.g., climatic conditions) between the southern and southeastern regions in the Atlantic Rainforest biome. Additional studies are suggested to investigate the influence of genetic effects and their environmental interactions to better understand how these factors are related with otolith shape and influence the discrimination among S. barbatus populations. [ABSTRACT FROM AUTHOR]

Cambeva melanoptera sp. nov. is described from stream tributaries of the Rio Iratim, Rio Iguaçu drainage, southern Brazil. This new species is remarkable with a colour pattern not found elsewhere among trichomycterid catfishes, consisting of a broad distal black zone in all unpaired and pectoral fins, strongly contrasting with a pale‐yellow proximal zone. C. melanoptera also differs from all other trichomycterids from eastern South America by the presence of the nasal barbel about thrice longer than the maxillary and rictal barbels. Due to the presence of a similar bicolour caudal fin, the new species is tentatively considered closely related to Cambeva castroi and Cambeva diabola, as well as more closely related to C. castroi than to C. diabola, with the first two species sharing the presence of a curved lateral process of the parurohyal and a trapezoidal projection on the lateral margin of the lateral ethmoid. The great morphological diversity found in Cambeva species endemic to the Rio Iguaçu drainage, including numerous exclusive characteristics not occurring in congeners and in any other species of closely related trichomycterine genera, indicates the need for more studies focusing on possible causal factors responsible for such unique diversification pattern. [ABSTRACT FROM AUTHOR]

Red and black groupers are large-bodied opportunistic ambush predators commonly found in Southwestern Atlantic tropical reefs. We investigated the diet of both species in order to detail ontogenetic, spatial and temporal trends, and to assess the extent of overlap in resource use between these two sympatric predators on the Abrolhos Bank, Brazil. Decapods and fishes were the main food items of Epinephelus morio while fishes were the main prey of Mycteroperca bonaci. Both diets were significantly influenced by body size and habitat, but only smaller individuals of E. morio feed almost exclusively on crustaceans. While the two groupers rely on many of the same prey types, coexistence may be facilitated by E. morio feeding more heavily on crustaceans, particularly the blackpoint sculling crab Cronius ruber, while black grouper take comparatively few crustaceans but lots of fish prey. Predators like red and black groupers could trigger indirect effects in the community and influence a large range of ecological processes, such as linkages between top and intermediate predators, and intermediate predators and their resources. [ABSTRACT FROM AUTHOR]

We analyzed the diet and resource partitioning among five syntopic species of Hypostomus Lacépède, 1803 in the Corumbataí River in southeastern Brazil. The gut contents of 352 individuals were assessed and 21 food items were identified and quantified under an optical microscope. The food items found in the gut contents indicate that these suckermouth loricariids are bottom-dwelling detritivorous/periphytivorous catfishes. PERMANOVA and SIMPER analyses indicated variation in the consumption of some resources, and the contribution of periphytic algae was primarily responsible for such dissimilarity. ECOSIM analyses of dietary overlap showed evidence of resource sharing among all species in the dry and rainy periods. This is most likely the result of the predominance of detritus and autochthonous items such as algae and aquatic immature insects in all gut contents. Our data suggest that trophic resources available in the Corumbataí River are explored and partitioned among Hypostomus species, all specialized in surface-grazing foraging behaviour. [ABSTRACT FROM AUTHOR]

A recent field inventory focusing on catfishes of the trichomycterine genus Cambeva detected the occurrence of two morphotypes, C. barbosae and C. cubataonis, in the Guaratuba-Babitonga-Itapocu area (GBIA) of southern Brazil, reporting some discordance with results of coalescent-based approaches for species delimitation that indicated different estimates of species number. Contrastingly, based on examination of characters taken from the external morphology and osteology, we here recognised six species of Cambeva in GBIA: C. cf. botuvera, a polymorphic and geographically widespread species; C. cubataonis, endemic to the Rio Cubatão do Norte; and four new species, two endemic to the Rio Itapocu basin, one endemic to the Baía de Babitonga system and one endemic to the Baía de Guaratuba system. We performed a molecular phylogenetic analysis indicating that Cambeva comprises three major clades, the alpha-, beta- and gama-clades, with C. cf. botuvera and a clade comprising C. cubataonis and three new species belonging to the beta-clade and another new species belonging to the gama-clade. We concluded that species here recognised are not in fact incongruent with results of that recent study when taxa are correctly identified by a representative sample of morphological characters, highlighting the importance of osteological characters for delimiting trichomycterine species. [ABSTRACT FROM AUTHOR]