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 Iguaçu 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.
endemism; Heptapteridae; Rhamdia voulezi; Rhamdia branneri; Rhamdia quelen; ecomorphology
