Megachile occidentalis Fox, 1894:117, Mitchell, 1937Mitchell, T.B. 1937. A revision of the genus Megachile in the Nearctic Region. Part VIII. Taxonomy of the subgenus Chelostomoides, Addenda and Index (Hymenoptera: Megachilidae). Transactions of the American Entomological Society 63 (4):381-421.:400, Type ♂ (Calif. Ac. Sc.). - Cockerell, 1899Cockerell, T.D.A. 1899. Catálogo de las Abejas de Mexico. Biblioteca Agricola de las Secretaria de Fomento, Mexico, 1-20. (distribution); Cockerell, 1900Cockerell, T.D.A. 1900. The New Mexico bees of the genus Megachile and a new Andrena. The Annals and Magazine of Natural History ser. 7: v. 6:7-20. (distribution); Cockerell, 1906Cockerell, T.D.A. 1906. The bees of New Mexico. Transactions of the American Entomological Society 32:289-314. (distribution); Cockerell, 1924Cockerell, T.D.A. 1924. Expedition of the California Academy of Sciences to the Gulf of California in 1921. The bees (II). Proceedings of the California Academy of Sciences 12 (27):529-560. (distribution); Mitchell, 1937Mitchell, T.B. 1937. A revision of the genus Megachile in the Nearctic Region. Part VIII. Taxonomy of the subgenus Chelostomoides, Addenda and Index (Hymenoptera: Megachilidae). Transactions of the American Entomological Society 63 (4):381-421. (distribution); Brindis, 2019Brindis, A.F. 2019. . Dissertation , , 1-143. La Paz, Baja California Sur. (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). - As Chalicodoma occidentalis: - 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); Snelling, 1990Snelling, R.R. 1990. A review of the native North American bees of the genus Chalicodoma (Hymenoptera: Megachilidae). Contributions in Science, Natural History Museum Los Angeles County 421:1-39. (distribution).
Megachile prosopidis testudinis Cockerell, 1924:550, ♀. Holotype ♀, Tortuga Island, Gulf of California, May 11, 1921 (Mus. Calif. Acad. Sci., No. 1544, leg. Van Duzee). - Mitchell, 1937Mitchell, T.B. 1937. A revision of the genus Megachile in the Nearctic Region. Part VIII. Taxonomy of the subgenus Chelostomoides, Addenda and Index (Hymenoptera: Megachilidae). Transactions of the American Entomological Society 63 (4):381-421.:398 ( listed as synonym of Megachile occidentalis Fox, 1894); 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.:2075 ( listed as synonym of Chalicodoma occidentalis (Fox, 1894)); Snelling, 1990Snelling, R.R. 1990. A review of the native North American bees of the genus Chalicodoma (Hymenoptera: Megachilidae). Contributions in Science, Natural History Museum Los Angeles County 421:1-39.:24 ( listed as synonym of Chalicodoma occidentalis (Fox, 1894)).
Megachile ignacensis Mitchell, 1934:352, ♀. Holotype ♀, San Ignacio, Lower California, April 1909 (A.N.S.P., no. 4163, leg. Haines); Mitchell, 1937Mitchell, T.B. 1937. A revision of the genus Megachile in the Nearctic Region. Part VIII. Taxonomy of the subgenus Chelostomoides, Addenda and Index (Hymenoptera: Megachilidae). Transactions of the American Entomological Society 63 (4):381-421.:415, Type ♀ (A.N.S.P., no. 4163). Synonymized with Chalicodoma occidentalis (Fox, 1894) by Snelling, 1990Snelling, R.R. 1990. A review of the native North American bees of the genus Chalicodoma (Hymenoptera: Megachilidae). Contributions in Science, Natural History Museum Los Angeles County 421:1-39.:24.