new synonymy:
Roeboides microlepis (Reinhardt, 1851)
is a senior synonym of
Roeboides bonariensis (Steindachner, 1879)

published in:
Lucena, C.A.S. (2003):
Revisão taxonômica e relações filogenéticas das espécies de Roeboides grupo-microlepis (Ostariophysi, Characiformes, Characidae).
Iheringia, Sér. Zool. 93 (3): 283-308

abstract (from publication):
The Roeboides microlepis species-group is revised. Four species are recognized: R. myersii Gill, 1870 from the Amazon basin, R. microlepis (Reinhardt, 1851) from river Paraguay, middle and lower river Paraná, R. araguaito sp. nov. from the river Orinoco basin, and R. margareteae sp. nov. known only from Rio Parnaíba and Pindaré-Mearim, northeastern Brazil. The type-locality of R. microlepis is restricted to river Paraguay; R. bonariensis (Steindachner, 1879) is considered a synonym of R. microlepis. The phylogenetic analysis indicates that R. myersii and R. araguaito are most parsimoniously related and may be a sister group. These two species are here considered as sister group of the monophyletic lineage which includes R. microlepis and R. margareteae. A key to the microlepis species-group genus Roeboides is given.