Technical Abstract: A synopsis of the North and Central American subgenus Megachile (Argyropile) and an illustrated key to the species in Spanish and English are provided, Megachile longuisetosa Gonzalez & Griswold, new species, from Mexico and Guatemala, and the previously unknown males of M. sabinensis and M. rossi are described. Females of M. longuisetosa can be separated from other species of Argyropile by the mid basitarsus with anterodistal margin strongly acutely projected, mesoscutum-mesoscutellum suture with distinct pubescent fascia and the apical margin of sixth sternum directed posteriorly. Males can be distinguished 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. Seven species, including the new species are recognized. Megachile asterae and M. tulariana are considered as new synonyms of M. parallela. In a cladistic analysis, seven most parsimonious trees were obtained for Argyropile, from 13 morphological characters. The monophyly of Argyropile is strongly supported, although the phylogenetic relationships among the species remain unclear.