Two new genera of South American Eulonchopriini (Hymenoptera: Colletidae)

Two new genera are described and figured for South American eulonchopriine bees. Apatosigynes Engel, new genus, is described for the eastern and southern Brazilian Apatosigynes meloi Engel, new species, and the northern Peruvian Leioproctus (Nomiocolletes) simplicicrus Michener (previously placed in Eulonchopria Brèthes). The genus is differentiated from Eulonchopria most notably by the absence of a preoccipital carina or lamella, absence of a pronotal carina, simple axillae, a rugose propodeum, and narrow metasomal bands. Similarly, Mimozibyne Engel, new genus, is described for the Argentine and Paraguayan L. (Perditomorpha) eulonchopriodes Michener. Mimozibyne is easily confused with Perditomorpha Ashmead or an enigmatic Eulonchopria, and is distinguished on the basis of two submarginal cells (as in Perditomorpha), coarse punctation, presence of yellow metasomal bands with raised margins, and more squat antennal flagellomeres. The following new combinations are established: Apatosigynes simplicicrus (Michener) and Mimozibyne eulonchopriodes (Michener)