Does the thistledown velvet ant (Hymenoptera: Mutillidae) mimic Creosote bush seeds? A phylogenetic approach

Dasymutilla species are well known for their bright setal and integumental color patterns, which, for females, likely serve a warning function to potential predators. Males, which are not protected by a vicious sting, often have similar color patterns to their conspecific females and may be Batesian mimics. In some mutillid species, however, males and females have drastically different color patters, causing a phenomenon known as dual sex-limited mimicry. This mimicry system is readily recognized in Dasymutilla gloriosa. Here, we examined the species limits and color variation seen in D. gloriosa and D. pseudopappus, another species with similar female coloration, using morphological and molecular similarity. We discovered that D. chisos is a synonymous male color variant of D. gloriosa. Dasymutilla pseudopappus, previously known only from females, is associated with the male species D. phaon. With a more full understanding of variation within these species, we used Bayesian phylogenetic methods and morphological comparisons to examine the potential models for each sex in D. gloriosa and D. pseudopappus. Males of these species appear to be Batesian mimics of related female Dasymutilla taxa. Females, which have been suggested to be mimics of Creosote bush (Larrea tridentata) seeds, appear to have obtained this unique coloration independently from establishment of Creosote bush in North America. We hypothesize that the stark white coloration of females serves as an aposematic warning, rather than camouflage.