Seventeen species of Megachile (Dasymegachile) are recognized, twelve species from Chile, nine species from Argentina, three from Peru and one from Bolivia. Descriptions, illustrations, and keys for the identification for the Argentinean species are provided. The geographical distributions in Argentina are revised; M. cinerea and M. melanotricha are recorded for the first time from Argentina. Two species are also newly recorded from Chile.

Se reconocen 17 especies para el subgénero Megachile (Dasymegachile), de las cuales 12 se distribuyen en Chile, nueve en Argentina, tres en Perú y una en Bolivia. Se brindan descripciones, ilustraciones y claves para la identificación de las especies argentinas. Se revisan las distribuciones geográficas; M. cinerea y M. melanotricha, son citadas por primera vez para Argentina. Dos nuevas especies son citadas para Chile.

Comparative study of the structures of male genitalia in Pseudocentron species (Hymenoptera, Megachilidae). Male genitalia of twenty two species of Pseudocentron Mitchell, 1934 belonging to seven subgenera are analysed. The diagnostic characters are described and illustrated. The study shows that the male genitalia provides diagnostic characters at generic, subgeneric and specific levels.