Phylogeny and biogeography of the ant genus Stenamma: Uncovering the evolutionary origins of Mesoamerican taxa

Stenamma comprises a group of cold-tolerant myrmicine ants that are most often encountered in samples of moist leaf litter. The genus is exceptional among ants in that it is frequently the dominant leaf litter inhabitant at higher elevations and latitudes. Stenamma includes forty-eight described species, most of which are confined to the Holarctic region. However, six described species and more than thirty newly discovered morphospecies are known from Central and northern South America. To prepare for a thorough taxonomic revision of the Neotropical species and to investigate hypotheses about the biogeographic history of the genus, I have constructed a comprehensive molecular phylogeny that employs six genes (28S, Arg K, CAD, COI, LwRh, Wg) and includes taxa from North America, Europe, Asia, Central America, and South America. I have also conducted divergence date estimations of the major taxonomic splits to make correlations with important geological events. The primary result of these analyses is that the Neotropical species form a well-supported clade that is either sister to the rest of the genus or only to the North American species. Also, I have discovered that the Asian species make Stenamma a polyphyletic assemblage. Consequently, new characters need to be discovered that better identify the genus.