A taxonomic revision of the dirt ants, Basiceros Schulz, 1906 (Hymenoptera, Formicidae)

The ant genus Basiceros is an exclusively Neotropical group known for its cryptic habits. Based on a recent molecular phylogenetic framework, a comprehensive revisionary study of the genus is presented. Nine species are recognized, two of which are described as new (Basiceros browni sp. nov. and Basiceros tumucumaquensis sp. nov.). Basiceros redux (Donisthorpe 1939) is transferred to the genus Octostruma (O. reducta comb. nov.). As part of this revisionary work, taxonomic keys and images to all species and castes are provided. Castes and sexes (including larvae, males, and intercastes) are described for the first time for several Basiceros species. New records considerably expand the distributional range for most species. Natural history data and comments on character plasticity and convergence are also included.