Traumatomutilla is a diverse genus of Neotropical velvet ants (Mutillidae). Here we revise the T. americana species group, recognizing three species. Mutilla dubia Fabricius, 1804, M. simulans Smith, 1855, M. albata Smith, 1879, and M. obsoleta (Klug, 1821) are proposed as junior synonyms of Traumatomutilla americana (Linnaeus, 1758). Traumatomutilla maula Casal, 1969, Ephuta punctosignata André, 1906, Mutilla latevittata Cresson, 1902, and M. oculifera Smith, 1855 are proposed as junior synonyms of Traumatomutilla quadrum (Klug, 1821). Mutilla acara Cresson, 1902, M. polita Smith, 1855, M. gemina Gerstaecker, 1874, M. trinacria Gerstaecker, 1874, M. lasiogastra Burmeister, 1875, and M. cuyana Burmeister, 1875 are proposed as junior synonyms of Traumatomutilla ocellaris (Klug, 1821). Traumatomutilla bellifera (Gerstaecker, 1874) is transferred to the T. trochanterata species-group; T. lunigera (Gerstaecker, 1874) and T. compar (André, 1898) are transferred to the T. inermis species-group. Both sexes are redescribed for all species. Notes on the biology and host association for T. ocellaris are provided. Finally, identification keys to the species and color forms of the T. americana group are provided.
Keywords: Hymenoptera, Sphaeropthalminae, Dasymutillini, Taxonomy, Neotropical, Behavior.