Phylogeography reveals cryptic speciation in Sphaeropthalma arota (Hymenoptera: Mutillidae)

We investigate the phylogeographic patterns among populations of the wide-ranging velvet ant Sphaeropthalma arota using the two rDNA internal transcribed spacer regions (ITS1 & ITS2). We use Bayesian methods to estimate phylogenetic relationships among populations and ecological niche models to understand the factors influencing the distributions of major lineages. Molecular dating techniques were used to estimate divergence dates for major lineages, so these divergences can be linked to historical events. Our analyses indicate that S. arota can be split into four deeply divergent lineages that likely represent distinct species. No morphological characters were found that can be used to identify these four species, making the S. arota species-complex the first documented cryptic species-complex in Mutillidae. Because these cryptic species cannot be distinguished morphologically, we suggest that the members of this group be identified as the S. arota species-complex. Ecological niche models suggest that each of the four species inhabits a distinct habitat. Divergence date estimates indicate that major diversification events in the S. arota species-complex can be linked to late Neogene mountain building and aridification events, specifically the uplift of the mountain ranges in southern California and the expansion of the Bouse Sea. The history of diversification of the S. arota species-complex differs from the history of several other arid-adapted species, because the uplift of the continental divide seems to not have influenced diversification in this group.