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Extensive new collections of specimens of Rhinebothroides spp. from a wide range of Neotropical freshwater potamotrygonid stingrays in numerous localities permitted critical evaluation of the validity of the 7 nominal species in the genus. Some qualitative characters previously used in the taxonomy of this group are highly variable within and among populations, and most morphometric and meristic characters thought to have taxonomic value for this group overlapped among several previously defined nominal species. Characters that were consistent throughout populations and that clearly define morphotypes supported recognition of four species: R. freitasi (syn. R. circularisi and R. venezuelensis), R. glandularis (syn. R. mclennanae), R. moralarai, and R. scorzai. We provide a taxonomic review of the genus, 8 additional host records, 7 new localities, and an identification key.