Species of the velvet ant genus Dasymutilla exhibit extreme sexual dimorphism and many are known from only one sex. Several sets of species from the southwestern U.S. have been suspected of being conspecific based on similar geographic ranges. Here we present DNA sequence data to show that D. candida Mickel is a junior synonym of D. thetis (Blake), D. errabunda Mickel is a junior synonym of D. heliophila (Cockerell), D. caneo (Blake) is a junior synonym of D. monticola (Cresson), D. dugesii (Cockerell and Casad) is a junior synonym of D. foxi (Cockerell), and D. reclusa (Mickel) is a junior synonym of D. birkmani (Melander). Based on genetic and morphological similarity, we also find that D. paenulata Mickel is a junior synonym of D. monticola. Based on a pair taken in copula, D. bollii (Fox) is a junior synonym of D. creon (Blake). Complete diagrams and descriptions of the male genitalia are given for the first time for each species.