RESUMO: A classification of 17 species-groups within the genus Athyreus is proposed, along with a key for their identification. Groups arretado, bellator, conspicuus, hemisphaericus, pyriformis, and unicornis have one species each; groups forcipatus, tuberifer, and vavini have two species; groups armatus, chalybeatus, and fritzi have three species; group aeneus and bifurcatus with four species; group tridens with five species; group tribuliformis with eight species; group bilobus with nine species; and three species are incertae sedis. With these species groups, we revised two of them: group aeneus with a new species, A. boillyi sp. nov.; and group bilobus with five new species: A. felipeorum sp. nov., A. furtadoi sp. nov., A. paraguayensis sp. nov., A. periotoi sp. nov., and A. xomano. We provide illustrations and identification keys for species of these groups.