Diadasia vallicola Timberlake, 1940:24, ♂. Holotype ♂, near Westmoreland, Imperial County, California, May 31, 1930 (leg. Timberlake). - Timberlake, 1940Timberlake, P.H. 1940. New species of bees of the genus Diadasia from California (Hymenoptera, Apoidea). Bulletin of the Brooklyn Entomological Society 35 (1):22-30. (distribution); Cockerell, 1941Cockerell, T.D.A. 1941. Observations on plants and insects in northwestern Baja California, Mexico, with descriptions of new bees. Trans. San Diego Soc. Nat. Hist. 9 (31):337-352. (distribution); Timberlake, 1941Timberlake, P.H. 1941. Synoptic table of North American species of Diadasia (Hymenoptera, Apoidea). Bulletin of the Brooklyn Entomological Society 36 (1):2-11. (distribution); Linsley & MacSwain, 1957Linsley, E.G. & J.W. MacSwain 1957. The nesting habits, flower relationships, and parasites of some North American species of Diadasia (Hymenoptera: Anthophoridae). The Wasmann Journal of Biology 15 (2):199-235. (distribution); Krombein et al., 1979Krombein, K.V., P.D. Hurd, D.R. Smith & B.D. Burks 1979. Catalog of Hymenoptera in America North of Mexico. Volume 2. Apocrita (Aculeata). Smithsonian Institution Press, Washington D.C. 1199-2209. (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).