Mountains as Islands: Species Delimitation and Evolutionary History of the Ant-Loving Beetle Genus Panabachia (Coleoptera, Staphylinidae) from the Northern Andes

The ant-loving beetle genus Panabachia Park 1942 is a poorly studied beetle lineage from the new world tropics. We recently collected Panabachia from several previously unrecorded locations in the paramo biome of the high Ecuadorian Andes, with males exhibiting great morphological variation in the distribution of the foveae and depressions in the pronotum, as well as aspects of the male genitalia. Here, we employ phylogenetic and species delimitation methods with mitochondrial (COI) and nuclear protein-coding (wingless) gene sequences to examine the concordance of morphological characters and geography with hypothesized species boundaries. Three methods of species delimitation (bPTP, GMYC and Stacey) were used to estimate the number of species, and divergence times between putative species using molecular clock calibration. Phylogenetic analysis revealed two parallel radiations, and species delimitation analyses suggest there are between 17 and 22 putative species. Based on clade support and concordance across species delimitation methods we hypothesize 17 distinct clusters, with allopatric speciation consistent with most geographic patterns. Additionally, a widespread species appears to be present in northern paramo sites, and some sister species sympatry may indicate other diversification processes have operated on certain lineages of Panabachia. Divergence time estimates suggest that Panabachia originated in the Miocene, but most species analyzed diverged during the Pliocene and Pleistocene (5.3-0.11 Mya), contemporaneous with the evolution of paramo plant species.