Origin and diversification of the true horse flies (Diptera: Tabanidae: Tabanini)

The common and cosmopolitan Tabanus constitutes one of the most diverse genera of flies. Adult females can be nuisances and mechanically transmit diseases such as anthrax and tularemia to humans. The venomous larvae are common predators in various aquatic environments and some have adapted to withstand arid conditions. The sheer magnitude of this group has stymied efforts to classify the 1340 known species of Tabanus and describe further species diversity, particularly in the tropics. Furthermore, continuing investigation into the evolution history of Tabanidae shows that Tabanus includes at least thirteen other genera containing over 900 species. Formerly placed in a separate tribe, the distinctive and species rich Haematopota may also be included within Tabanus. Further phylogenetic studies will inform a more practical and natural genus level classification. A dataset of 66 species of Tabanus and related genera for 6 kb of nucleotide data and morphology was compiled to uncover monophyletic units and investigate biogeographic and morphological factors contributing to the success of this group. Unclear placement of several small, geographically restricted, and highly apomorphic genera such as Euancala, Heptatoma, and Therioplectes impedes resolution of some parts of the tree and methods for mitigating these effects are presented. Haematopota is recovered inside the Tabanus group, however its placement is not clear. Conflicting support for the sister groups to the Tabanus group and to Haematopota is explored. Originating in the Neotropical region in the early Paleogene, the Tabanus group underwent an explosive diversification and spread to every biogeographic region by 40 mya.