Osmia nigrobarbata Cockerell, 1916:53, ♀. Type ♀, Claremont, California (leg. Baker). - Sandhouse, 1924Sandhouse, G. 1924. Bees of the genus Osmia in the collection of the California Academy of Sciences. Proceedings of the California Academy of Sciences ser. 4: v. 13 (22):341-372. (distribution); Michener, 1949Michener, C.D. 1949. Records and descriptions of american Megachilid bees (Hymenoptera). Journal of the Kansas Entomological Society 22 (2):41-59. (distribution); Ayala & Griswold, 2005Ayala, R. & T. Griswold 2005. Nueva especie de abeja del género Osmia (Hymenoptera: Megachilidae) de México. Folia Entomológica Mexicana 44 (Supl. 1):139-145. (distribution); Esperanza de Pedro, 2021Esperanza de Pedro, D. 2021. . :. (distribution); Nava-Bolaños & Osorio-Olvera, 2022Nava-Bolaños, A. & L. Osorio-Olvera 2022. Estado del arte del conocimiento de biodiversidad de los polinizadores de México. Revista Mexicana de Biodiversidad 93:1-77. (distribution).
Osmia vanduzeei Sandhouse, 1924:343, ♂. Holotype ♂, San Miguel Island, California, May 20, 1919 (Mus. Calif. Acad. Sci., No. 1548, leg. E.P. Van Duzee). Synonymized with Osmia nigrobarbata Cockerell, 1916 by Michener, 1949Michener, C.D. 1949. Records and descriptions of american Megachilid bees (Hymenoptera). Journal of the Kansas Entomological Society 22 (2):41-59.:55.