Phylogenomics of the bee fly genus Lordotus Loew, 1863 (Diptera: Bombyliidae)

Bombyliidae or bee flies are one of the most diverse groups of insects found in deserts across the world. Despite a diversity of over 5,000 species, most are poorly studied and in need of taxonomic and phylogenetic study. The genus Lordotus described in 1863 by Hermann Loew, exemplifies this problem. Lordotus is commonly found throughout the arid and semi-arid regions in the western United States and northern Mexico, these 29 species of Lordotus are classified into three species groups. However, due to the morphological variability in species, Lordotus species have been challenging to group or to establish distinct species delimitations. Beyond what might be implied by the species-group arrangement, the phylogenetic relationships within the genus have not been explored. Here, the first phylogenetic hypothesis of the bee fly genus Lordotus, generated using ultra-conserved elements (UCEs), is presented. A UCE dataset consisting of 936 loci from 76 individuals representing all species of the genus was generated using a combination of flies preserved in ethanol and historic, pinned museum specimens. Maximum likelihood analysis generated a well-resolved phylogeny and a monophyletic genus Lordotus. The three species groups suggested by previous authors were all found to be paraphyletic. These results provide a much-needed foundation for further detailed revision of Lordotus.