The biogeography of colletid bees as a whole can be explained by several South American-Australian trans-Antarctic interchanges. Within Colletidae, neopasiphaeine bees form a large group that has not been adequately studied, even though they are interesting both from the biogeographical viewpoint for fitting well the austral Gondwanan track and for their associations to host plants. The present paper integrates phylogenetic, biogeographic and paleontological data to reconstruct the evolutionary history of Neopasiphaeinae, with special emphasis on the New World taxa, relating the evolution of these bees to changes, such as the Andes uplift and expansion of open vegetation biomes. First, we propose a phylogenetic hypothesis for the Neopasiphaeinae using one mitochondrial and five nuclear loci. Phylogenetic relationships and divergence time estimation were simultaneously inferred in a Bayesian framework, and the tempo of neopasiphaeine diversification was investigated using lineage-through-time plots. The historical biogeography of neopasiphaeine bees was investigated in a likelihood framework. The clade represented by Neopasiphaeinae is strongly supported within Colletidae, and the bulk of their genera can be divided into two major sister-clades that diverged during the Eocene: one endemic to the Australian region and the other to the Neotropical region. Divergence times among most neotropical genera of Neopasiphaeinae indicate that they differentiated and started their diversification during the Miocene. Our results depict a complex process of geographic evolution in the Neotropical clade, which probably relates to important changes in the neotropical climates and biota beginning at the Oligocene and became more marked in the Miocene. We present a scenario of the neotropical Neopasiphaeinae initially associated with areas of open vegetation in subtropical and temperate portions of South America, followed by multiple separations of lineages east and west of the Andes, and more recent occupations of habitats in tropical portions of the continent. K E Y W O R D S Australia, biogeography, Colletinae, Neotropics, Paracolletinae, phylogeny | 227 ALMEIDA Et AL.

Within Leptoceridae, the genus Oecetis contains about 500 species around the world, including 53 in the Neotropics. In Brazil, there are 15 recorded species of Oecetis. These species were described over several decades by numerous authors with the results that descriptions are not comparable and diagnoses are incomplete. Also, the apparently unbranched M vein, in the forewing, a diagnostic character for Oecetis pointed by McLachlan, is controversial and no consensus has been reached about its homology. Additionally, the only revision for the genus was never published; thus the information and proposed taxa are not available according to the International Code of Zoological Nomenclature. We analyzed specimens collected in the Brazilian Northeast Region and compared these with described species and literature descriptions and Oecetis from other regions. We provide herein the description of five new species, additional characters for diagnosing seven of the species recorded from Brazil, new distributional records, and a dichotomous key to the Brazilian species. Additionally, we contrast the two hypotheses of forewing M vein homology and support the unbranched hypothesis. In this way, we improve the knowledge of the genus in the Neotropics, making the species descriptions comparable in a way that facilitates species identification.