Halictus parallélus Say, 1837:397, ♀. ♀, Indiana; Sandhouse, 1941Sandhouse, G.A. 1941. The american bees of the subgenus Halictus. Entomologica Americana 21:23-38 + 1 pl.:31, lost. - Harvey & Knight, 1897Harvey, F.L. & O.W. Knight 1897. Insects collected at Jackman, Maine. Psyche 8:77-79. (distribution); Cockerell, 1899Cockerell, T.D.A. 1899. The bees of Kansas. Entomological News 10 (1):3-4. (distribution); Cockerell, 1906Cockerell, T.D.A. 1906. The bees of New Mexico. Transactions of the American Entomological Society 32:289-314. (distribution); Cockerell, 1934Cockerell, T.D.A. 1934. Records of Western bees. American Museum Novitates 697:1-15. (distribution); Sandhouse, 1941Sandhouse, G.A. 1941. The american bees of the subgenus Halictus. Entomologica Americana 21:23-38 + 1 pl. (distribution); Michener, 1947Michener, C.D. 1947. Bees of a limited area in southern Mississippi (Hymenoptera; Apoidea). The American Midland Naturalist 38 (2):443-455. (distribution); Mitchell, 1960Mitchell, T.B. 1960. Bees of the Eastern United States. Volume I. Technical bulletin (North Carolina Agricultural Experiment Station) 141:1-538. (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); Pascarella, 2006Pascarella, J.B. 2006. The bees of Florida. . (distribution); Owens et al., 2018Owens, B.E., L. Allain, E.C. van Gorder, J.L. Bossart & C.E. Carlton 2018. The bees (Hymenoptera: Apoidea) of Louisiana: An updated, annotated checklist. Proceedings of the Entomological Society of Washington 120 (2):272-307. (distribution).
Halictus occidentalis Cresson, 1872:250, ♂♀. 4 ♂♀, Texas (leg. Belfrage, Boll); Sandhouse, 1941Sandhouse, G.A. 1941. The american bees of the subgenus Halictus. Entomologica Americana 21:23-38 + 1 pl.:31, Type (Academy of Natural Sciences, Philadelphia). - Robertson, 1893Robertson, C. 1893. Notes on bees, with descriptions of new species. Transactions of the American Entomological Society 20:145-149.:145 ( listed as synonym of Halictus parallelus Say, 1837); Dalla Torre, 1896Dalla Torre, C.G. 1896. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus, X. Apidae (Anthophila). Sumptibus Guilelmi Engelmann, 1-643. (distribution); Cockerell, 1923Cockerell, T.D.A. 1923. Descriptions and records of bees. - XCVII. The Annals and Magazine of Natural History ser. 9: v. 11 (62):263-269. (distribution); Sandhouse, 1941Sandhouse, G.A. 1941. The american bees of the subgenus Halictus. Entomologica Americana 21:23-38 + 1 pl.:30 ( listed as synonym of Halictus parallelus Say, 1837); Mitchell, 1960Mitchell, T.B. 1960. Bees of the Eastern United States. Volume I. Technical bulletin (North Carolina Agricultural Experiment Station) 141:1-538.:335 ( listed as synonym of Halictus parallelus Say, 1837); 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.:1955 ( listed as synonym of Halictus parallelus Say, 1837). - As Lasioglossum occidentale: - 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).