Megachile Casadæ Cockerell, 1898:127, ♂. Holotype ♂, Las Cruces, New Mexico (New Mexico Experiment Station, leg. probably Prof. Townsend); 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.:350, Type ♂ (Cockerell). - Cockerell, 1899Cockerell, T.D.A. 1899. Notes on american bees (Concluded from p. 129). The Entomologist 32:154-159. (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); 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. (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); 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 populi Cockerell, 1900:17, ♀. ♀, Mesilla Park, campus of New Mexico Agricultural College, April 16. - Cockerell, 1906Cockerell, T.D.A. 1906. The bees of New Mexico. Transactions of the American Entomological Society 32:289-314. (distribution); 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.:348 ( listed as synonym of Megachile casadae Cockerell, 1898); 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 casadae Cockerell, 1898); Raw, 2002Raw, A. 2002. New combinations and synonymies of leafcutter and mason bees of the Americas (Megachile, Hymenoptera, Megachilidae). Zootaxa 71:1-43.:17 ( listed as synonym of Megachile casadae Cockerell, 1898).
Megachile opuntiarum Cockerell, 1906:229, ♀. ♀, Boulder, Colorado, July 3, 1905 (leg. W.P. Cockerell). Synonymized with Megachile populi Cockerell, 1900 by Cockerell, 1908Cockerell, T.D.A. 1908. Descriptions and records of bees. - XVIII. The Annals and Magazine of Natural History ser. 8: v. 1 (3):259-267.:265. - Cockerell, 1907Cockerell, T.D.A. 1907. The bees of Boulder County, Colorado. University of Colorado Studies 4:239-259. (distribution); 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.:348 ( listed as synonym of Megachile casadae Cockerell, 1898); 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 casadae Cockerell, 1898); Raw, 2002Raw, A. 2002. New combinations and synonymies of leafcutter and mason bees of the Americas (Megachile, Hymenoptera, Megachilidae). Zootaxa 71:1-43.:17 ( listed as synonym of Megachile casadae Cockerell, 1898).
Megachile austinensis Mitchell, 1927:105, ♀. Holotype ♀, Austin, Texas, May 8, 1901 (Mus. Com. Zool., No. 15707, leg. C.T. Brues). - 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.:348 ( listed as synonym of Megachile casadae Cockerell, 1898); 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 casadae Cockerell, 1898); Raw, 2002Raw, A. 2002. New combinations and synonymies of leafcutter and mason bees of the Americas (Megachile, Hymenoptera, Megachilidae). Zootaxa 71:1-43.:17 ( listed as synonym of Megachile casadae Cockerell, 1898).