Megachile alata Mitchell, 1934:324, ♂. Holotype ♂, Palm Canyon, California, Apr. 3, 1925 (U.S.N.M., no. 44246, leg. P.H. Timberlake); Mitchell, 1936Mitchell, T.B. 1936. A revision of the genus Megachile in the Nearctic Region. Part V. Taxonomy of subgenus Xeromegachile (Hymenoptera: Megachilidae). Transactions of the American Entomological Society 62 (4):323-382.:371, Type ♂ (U.S.N.M., no. 44246). - 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); Raw, 2002Raw, A. 2002. New combinations and synonymies of leafcutter and mason bees of the Americas (Megachile, Hymenoptera, Megachilidae). Zootaxa 71:1-43. (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).
Megachile redlandica Mitchell, 1934:331, ♀. Holotype ♀, Redlands, California, April 14 (U.S.N.M., no. 39980, leg. F.R. Cole); Mitchell, 1936Mitchell, T.B. 1936. A revision of the genus Megachile in the Nearctic Region. Part V. Taxonomy of subgenus Xeromegachile (Hymenoptera: Megachilidae). Transactions of the American Entomological Society 62 (4):323-382.:371, Type ♀ (U.S.N.M., no. 39980). - 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.:2063 ( listed as synonym of Megachile alata Mitchell, 1934); Raw, 2002Raw, A. 2002. New combinations and synonymies of leafcutter and mason bees of the Americas (Megachile, Hymenoptera, Megachilidae). Zootaxa 71:1-43.:16 ( listed as synonym of Megachile alata Mitchell, 1934).