A review of the North and Central American Megachile subgenus Argyropile Mitchell (Hymenoptera: Megachilidae)

We provide a synopsis of Megachile subgenus Argyropile, describe a new species from Mexico and Guatemala, present descriptions for previously unknown males, and explore the internal phylogeny of the group. We also provide an illustrated key in Spanish and English to all of its species. Seven species, including Megachile longuisetosa Gonzalez & Griswold, new species, are recognized herein. Females of M. longuisetosa can be separated from other species of Argyropile by the combination of the following characters: mid basitarsus with anterodistal margin strongly, acutely projected, mesoscutal-mesoscutellar suture with distinct pubescent fascia, and apical margin of sixth sternum abruptly bent dorsally and males by the sixth tergum with preapical carina and apical margin entire, fifth and sixth sterna with simple, unmodified setae, and apex of gonoforceps with long setae. The males of Megachile sabinensis and M. rossi, are described and illustrated for the first time. Megachile asterae and M. tulariana are considered as new synonyms of M. parallela. In a cladistic analysis, two most parsimonious trees were obtained for Argyropile, from 13 morphological characters. Two clades were clearly differentiated: one clade includes M. sabinensis and M. subparallela, while the other one includes the remaining species. The phylogenetic relationship of the new species and the biology of the subgenus are discussed.