A taxonomic study of the species of Roeboides affinis-group is presented. Seven species are recognized: R. affinis (Günther, 1868) which inhabits the Amazonian, Orinoco, and Paraná-Paraguay basins, the rivers of Guyana and Suriname, and Tocantins-Araguaia system; R. biserialis Garman, 1890 from river Amazonas basin, R. descalvadensis Fowler, 1932 which occurs in the Amazonas and Paraná-Paraguay basins; R. oligistos Lucena, 2000 which inhabits the Amazonian basin; R. numerosus Lucena, 2000 of the river Orinoco basin; R. xenodon (Reinhardt, 1851) from the river São Francisco basin, and R. sazimai n. sp., known only from the Parnaíba and Pindaré-Mearim drainages, northeastern Brazil. Roeboides paranensis Pignalberi, 1975 is considered a synonym of R. descalvadensis; Roeboides prognathus and R. thurni Eigenmann, 1912 are synonyms of R. affinis. Lectotypes are designaded to R. affinis, R. biserialis e R. francisci Steindachner, 1908. A identification key to the species of Roeboides affinis-group is given.
Fishes; Neotropical region; taxonomy; nomenclature; South America
