Systematics and Biogeography of Colletinae with Revisionary Studies of the Species of Colletes Latreille (Hymenoptera:Colletidae: Colletinae) from Chile and Eastern South America

Colletinae (Hymenoptera: Colletidae) includes c. 545 species, the majority of which (c. 520 species) belong to Colletes Latreille. The generic placement of the other 25 species has been controversial, with the number of recognized genera varying among authors. For this reason, the first major objective of this dissertation is to construct a morphological phylogeny based on parsimony analyses to settle the controversy pertaining to the systematics of Colletinae. Results suggest that the following four genera should be recognized: Colletes, Hemicotelles Toro & Cabezas, Mourecotelles Toro & Cabezas and Xanthocotelles Toro & Cabezas. The first two genera are reciprocally monophyletic, and together they are sister to the last two which are also reciprocally monophyletic. Colletes has a nearly cosmopolitan distribution but is particularly diverse in arid regions of the world, such as the American southwest and central Asia where the genus has been widely studied. On the other hand, the South American Colletes have historically received little attention by bee taxonomists. As a result, a large proportion of the species found in the continent remain undescribed and most of the known ones cannot be unequivocally identified. Thus, the second major objective of this dissertation is to revise as much of the South American species of Colletes as possible. This objective is tackled in two parts: I firstly revised the species of the genus found in Chile (31 species), and then I revised those distributed in Brazil, Paraguay and Uruguay (19 species). Finally, a dated phylogeny of Colletes is provided based on Bayesian analyses of DNA data of six loci. This allowed for the accomplishment of the last two major objectives of this dissertation, namely, to propose an intrageneric classification for Colletes, and to investigate its historical biogeography. The analyses provide strong support for the monophyly of Colletes and show that its phylogeny consists of five major clades. The biogeographic reconstructions suggest that Colletes originated within the Neotropics in the early Oligocene, and that its extant lineages began diversifying in the later Oligocene. They also infer that by the end of the Oligocene Colletes had already colonized both the Nearctic and Palaearctic.