Apis pensylvanica De Geer, 1773:575, pl. 28, fig. 12, sex not indicated.Pensylvanie (leg. M. Acrelius). - As Apis pennsylvanicus: - Lutz & Cockerell, 1920Lutz, F.E. & T.D.A. Cockerell 1920. Notes on the distribution and bibliography of North American bees of the families, Apidae, Meliponidae, Bombidae, Euglossidae, and Anthophoridae. Bull. Amer. Mus. Nat. Hist 42 (15):491-641.:504 ( listed as synonym of Bombus americanorum (Fabricius, 1775)). - As Bombus pennsylvanicus: - Cresson, 1863Cresson, E.T. 1863. A communication on some Bombus with description of a new species. Proceedings of the Entomological Society of Philadelphia 2 (3):164-166. (distribution); Cresson, 1872Cresson, E.T. 1872. Hymenoptera Texana. Transactions of the American Entomological Society 4:153-292. (distribution); Handlirsch, 1888Handlirsch, A. 1888. Die Hummelsammlung des k. k. naturhistorischen Hofmuseums. Annalen des Naturhistorischen Museums in Wien 3:209-250. (distribution); Dalla Torre, 1896Dalla Torre, C.G. 1896. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus, X. Apidae (Anthophila). Sumptibus Guilelmi Engelmann, 1-643. (distribution); Cockerell, 1899Cockerell, T.D.A. 1899. The bees of Kansas. Entomological News 10 (1):3-4. (distribution); Franklin, 1913Franklin, H.J. 1913. The Bombidae of the New World. Transactions of the American Entomological Society 38 (3/4):177-486. (distribution); Bequaert, 1920Bequaert, J.C. 1920. Hymenoptera collected near Boston, Mass., with description of a variety of Bombus affinis. Psyche 27 (1):6-12.:9 ( listed as synonym of Bombus americanorum (Fabricius, 1775)); Mitchell, 1962Mitchell, T.B. 1962. Bees of the Eastern United States. Volume II. Technical bulletin (North Carolina Agricultural Experiment Station) 152:1-557. (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.:2204 (emendation); Pascarella et al., 1999Pascarella, J.B., Waddington, K.D. & Neal, P.R. 1999. The Bee Fauna (Hymenoptera: Apoidea) of Everglades National Park, Florida and adjacent areas: Distribution, Phenology, and Biogeography. Journal of the Kansas Entomological Society 72 (1):32-45. (distribution); Abrahamovich & Díaz, 2002Abrahamovich, A.H. & N.B. Díaz 2002. Bumble bees of the Neotropical Region (Hymenoptera: Apidae). Biota Colombiana 3 (2):199-214. (distribution); Hall & Ascher, 2010Hall, H.G., & J.S. Ascher 2010. Surveys of bees (Hymenoptera: Apoidea: Anthophila) in natural areas of Alachua County in North-Central Florida. The Florida Entomologist 93 (4):609-629. (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). - As Bombus pennsylvanicus pennsylvanicus: - 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); Ruíz-Cancino & Coronado-Blanco, 2002Ruíz-Cancino, E. & J.M. Coronado-Blanco 2002. Artrópodos terrestres de los estados de Tamaulipas y Nuevo León, México. Serie Publicaciones Cientificas No. 4:1-376. (distribution); Yáñez-Ordóñez & Hinojosa-Díaz, 2004Yáñez-Ordóñez, O. & I. Hinojosa-Díaz 2004. La colección himenopterológica (Insecta) del Museo de Zoología Alfonso L. Herrera de la Facultad de Ciencias, UNAM, México. Acta Zoológica Mexicana (nueva serie) 20 (1):167-197. (distribution); Pascarella, 2006Pascarella, J.B. 2006. The bees of Florida. . (distribution). - As Bombus pensylvanicus: - Cresson, 1863Cresson, E.T. 1863. List of North American species of Bombus and Apathus. Proceedings of the Entomological Society of Philadelphia 2:83-116. (distribution); Hall & Ascher, 2011Hall, H.G., & J.S. Ascher 2011. Surveys of wild bees (Hymenoptera: Apoidea: Anthophila) in organic farms of Alachua County in north-central Florida. The Florida Entomologist 94 (3):539-552. (distribution); Warriner, 2012Warriner, M.D. 2012. Bumble bees (Hymenoptera: Apidae) of Texas: Historical distributions. The Southwestern Naturalist 57 (4):442-445. (distribution); Dardón et al., 2016Dardón, M.J., C.L. Yurrita & M. Vásquez 2016. Catalogue of the bees of the genus Bombus Latreille, 1802 (Hymenoptera: Apoidea: Apidae) in Guatemala. Revista Cientifica 26 (1):9-19. (distribution); Sagot et al., 2018Sagot, P, J. Mérida, R. Ayala & R. Vandame 2018. Situación actual del conocimiento de la fauna de abejas (Apoidea: Anthophila) del estado de Chiapas, México. In: (Ed.). Memorias X Congreso Mesoamericano sobre Abejas Nativas. 191-2011. (distribution); Dardón et al., 2020Dardón, M.J., C.L. Yurrita, P. Landaverde-González P. & A.R. Vásquez M. 2020. Rediscovering the diversity of Guatemalan bumble bees (Hymenoptera: Apoidea: Bombus Latreille, 1802). International Journal of Scientific Research in Biological Sciences 7 (2):1-14. (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).
Apis americanorum Fabricius, 1775:380,America (leg. Lewin). - Cresson, 1863Cresson, E.T. 1863. List of North American species of Bombus and Apathus. Proceedings of the Entomological Society of Philadelphia 2:83-116.:94 ( listed as synonym of Bombus pensylvanicus (De Geer, 1773)); Handlirsch, 1888Handlirsch, A. 1888. Die Hummelsammlung des k. k. naturhistorischen Hofmuseums. Annalen des Naturhistorischen Museums in Wien 3:209-250.:238 ( listed as synonym of Bombus pennsylvanicus (De Geer, 1773)); Franklin, 1913Franklin, H.J. 1913. The Bombidae of the New World. Transactions of the American Entomological Society 38 (3/4):177-486.:399 ( listed as synonym of Bombus pennsylvanicus (De Geer, 1773)); Mitchell, 1962Mitchell, T.B. 1962. Bees of the Eastern United States. Volume II. Technical bulletin (North Carolina Agricultural Experiment Station) 152:1-557.:524 ( listed as synonym of Bombus pennsylvanicus (De Geer, 1773)); 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.:2204 ( listed as synonym of Bombus pennsylvanicus pennsylvanicus (De Geer, 1773)). - As Bombus americana: - 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.:2204 (lapsus calami). - As Bombus americana: - 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.:2204 (lapsus calami). - As Bombus americanorum: - Smith, 1854Smith, F. 1854. Catalogue of Hymenopterous Insects in the Collection of the British Museum. Part II. Apidae. London. 465 pp, 8 pl. (distribution); Cresson, 1872Cresson, E.T. 1872. Hymenoptera Texana. Transactions of the American Entomological Society 4:153-292.:285 ( listed as synonym of Bombus pennsylvanicus (De Geer, 1773)); Cockerell & Porter, 1899Cockerell, T.D.A. & Porter, W. 1899. Contributions from the New Mexico Biological Station. - VIII. The New Mexico bees of the genus Bombus. The Annals and Magazine of Natural History ser. 7: v. 4:386-393. (distribution); Cockerell, 1901Cockerell, T.D.A. 1901. Flower and insect records from New Mexico. Entomological News 12 (2):38-43. (distribution); Cockerell, 1906Cockerell, T.D.A. 1906. The bees of New Mexico. Transactions of the American Entomological Society 32:289-314. (distribution); Cockerell, 1907Cockerell, T.D.A. 1907. The bees of Boulder County, Colorado. University of Colorado Studies 4:239-259. (distribution); Cockerell, 1911Cockerell, T.D.A. 1911. Records of bees. The Canadian Entomologist 43 (11):389-391. (distribution); Cockerell, 1917Cockerell, W.P. 1917. Collecting bees in southern Texas. Journal of the New York Entomological Society 25:187-193. (distribution); Lutz & Cockerell, 1920Lutz, F.E. & T.D.A. Cockerell 1920. Notes on the distribution and bibliography of North American bees of the families, Apidae, Meliponidae, Bombidae, Euglossidae, and Anthophoridae. Bull. Amer. Mus. Nat. Hist 42 (15):491-641. (distribution); Bequaert, 1920Bequaert, J.C. 1920. Hymenoptera collected near Boston, Mass., with description of a variety of Bombus affinis. Psyche 27 (1):6-12. (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); Ruíz-Cancino & Coronado-Blanco, 2002Ruíz-Cancino, E. & J.M. Coronado-Blanco 2002. Artrópodos terrestres de los estados de Tamaulipas y Nuevo León, México. Serie Publicaciones Cientificas No. 4:1-376. (distribution).
Apis antiguensis Fabricius, 1775:380,Antigua (leg. Drury). - 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.:2204 ( listed as synonym of Bombus pennsylvanicus pennsylvanicus (De Geer, 1773)). - As Bombus antiguensis: - Smith, 1854Smith, F. 1854. Catalogue of Hymenopterous Insects in the Collection of the British Museum. Part II. Apidae. London. 465 pp, 8 pl. (distribution); Cresson, 1863Cresson, E.T. 1863. List of North American species of Bombus and Apathus. Proceedings of the Entomological Society of Philadelphia 2:83-116. (distribution); Cresson, 1879Cresson, E.T. 1879. Catalogue of North American Apidae. Transactions of the American Entomological Society and Proceedings of the Entomological Section of the Academy of Natural Sciences 7:215-232. (distribution); Dalla Torre, 1896Dalla Torre, C.G. 1896. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus, X. Apidae (Anthophila). Sumptibus Guilelmi Engelmann, 1-643. (distribution); Ashmead, 1900Ashmead, W.H. 1900. Report upon the aculeate Hymenoptera of the islands of St. Vincent and Grenada, with additions to the parasitic Hymenoptera and a list of the described Hymenoptera of the West Indies. Transactions of the Entomological Society of London pt. II:207-367. (distribution); Friese, 1909Friese, H. 1909. Beitrag zur Bienenfauna der Kleinen Antillen und der Bermudas. Zoologische Jahrbücher Suppl. 11 (Erstes Heft):34-40. (distribution).
Apis nidulans Fabricius, 1798:274, sex not indicated.America boreali. - Franklin, 1913Franklin, H.J. 1913. The Bombidae of the New World. Transactions of the American Entomological Society 38 (3/4):177-486.:399 ( listed as synonym of Bombus pennsylvanicus (De Geer, 1773)); Lutz & Cockerell, 1920Lutz, F.E. & T.D.A. Cockerell 1920. Notes on the distribution and bibliography of North American bees of the families, Apidae, Meliponidae, Bombidae, Euglossidae, and Anthophoridae. Bull. Amer. Mus. Nat. Hist 42 (15):491-641.:504 ( listed as synonym of Bombus americanorum (Fabricius, 1775)); Mitchell, 1962Mitchell, T.B. 1962. Bees of the Eastern United States. Volume II. Technical bulletin (North Carolina Agricultural Experiment Station) 152:1-557.:524 ( listed as synonym of Bombus pennsylvanicus (De Geer, 1773)); 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.:2204 ( listed as synonym of Bombus pennsylvanicus pennsylvanicus (De Geer, 1773)); Schwarz et al., 1996Schwarz, M., F. Gusenleitner, P. Westrich & H. Dathe 1996. Katalog der Bienen Österreichs, Deutschlands und der Schweiz (Hymenoptera, Apidae). Entomofauna Suppl. 8:1-398.:136 ( listed as synonym of Amegilla quadrifasciata (de Villers, 1789)).
Bombus sonòrus Say, 1837:413, ♀. ♀, Mexico; Franklin, 1913Franklin, H.J. 1913. The Bombidae of the New World. Transactions of the American Entomological Society 38 (3/4):177-486.:407, [type] lost. - Smith, 1854Smith, F. 1854. Catalogue of Hymenopterous Insects in the Collection of the British Museum. Part II. Apidae. London. 465 pp, 8 pl. (distribution); Cresson, 1863Cresson, E.T. 1863. List of North American species of Bombus and Apathus. Proceedings of the Entomological Society of Philadelphia 2:83-116. (distribution); Cresson, 1879Cresson, E.T. 1879. Catalogue of North American Apidae. Transactions of the American Entomological Society and Proceedings of the Entomological Section of the Academy of Natural Sciences 7:215-232. (distribution); Handlirsch, 1888Handlirsch, A. 1888. Die Hummelsammlung des k. k. naturhistorischen Hofmuseums. Annalen des Naturhistorischen Museums in Wien 3:209-250.:238 ( listed as synonym of Bombus pennsylvanicus (De Geer, 1773)); Fox, 1893Fox, W.J. 1893. Report on some mexican Hymenoptera, principally from lower California. Proceedings of the California Academy of Sciences ser.2 (4):1-25. (distribution); Cockerell, 1899Cockerell, T.D.A. 1899. Catálogo de las Abejas de Mexico. Biblioteca Agricola de las Secretaria de Fomento, Mexico, 1-20. (distribution); Cockerell & Porter, 1899Cockerell, T.D.A. & Porter, W. 1899. Contributions from the New Mexico Biological Station. - VIII. The New Mexico bees of the genus Bombus. The Annals and Magazine of Natural History ser. 7: v. 4:386-393. (distribution); Cockerell, 1902Cockerell, T.D.A. 1902. Flowers and insects in New Mexico. American Naturalist 36 (430):809-817. (distribution); Cockerell, 1904Cockerell, T.D.A. 1904. Some bees from San Miguel County, New Mexico. The Entomologist 37 (488):5-9. (distribution); Cockerell, 1904Cockerell, T.D.A. 1904. The bees of southern California. V. Bulletin of the Southern California Academy of Science 3 (6):86-90. (distribution); Cockerell, 1906Cockerell, T.D.A. 1906. The bees of New Mexico. Transactions of the American Entomological Society 32:289-314. (distribution); Franklin, 1913Franklin, H.J. 1913. The Bombidae of the New World. Transactions of the American Entomological Society 38 (3/4):177-486. (distribution); Lutz & Cockerell, 1920Lutz, F.E. & T.D.A. Cockerell 1920. Notes on the distribution and bibliography of North American bees of the families, Apidae, Meliponidae, Bombidae, Euglossidae, and Anthophoridae. Bull. Amer. Mus. Nat. Hist 42 (15):491-641. (distribution); Cockerell, 1925Cockerell, T.D.A. 1925. Bees in the collection of California Academy of Sciences. Proceedings of the California Academy of Sciences ser. 4: v. 14 (11):185-215. (distribution); Estrada de Léon & Ayala Barajas, 1995Estrada de Léon, M. & R. Ayala Barajas 1995. Abejas silvestres (Hymenoptera: Apoidea) de la Sierra del Tigre, Jalisco. Apicultura Moderna 7:12-24. (distribution); Warriner, 2012Warriner, M.D. 2012. Bumble bees (Hymenoptera: Apidae) of Texas: Historical distributions. The Southwestern Naturalist 57 (4):442-445. (distribution); Dardón et al., 2016Dardón, M.J., C.L. Yurrita & M. Vásquez 2016. Catalogue of the bees of the genus Bombus Latreille, 1802 (Hymenoptera: Apoidea: Apidae) in Guatemala. Revista Cientifica 26 (1):9-19.:16 ( listed as synonym of Bombus pensylvanicus (De Geer, 1773)); Dardón et al., 2020Dardón, M.J., C.L. Yurrita, P. Landaverde-González P. & A.R. Vásquez M. 2020. Rediscovering the diversity of Guatemalan bumble bees (Hymenoptera: Apoidea: Bombus Latreille, 1802). International Journal of Scientific Research in Biological Sciences 7 (2):1-14.:10 ( listed as synonym of Bombus pensylvanicus (De Geer, 1773)). - As Bombus pennsylvanicus sonorus: - Dalla Torre, 1896Dalla Torre, C.G. 1896. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus, X. Apidae (Anthophila). Sumptibus Guilelmi Engelmann, 1-643. (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); Vergara & Ayala, 2002Vergara, C.H. & R. Ayala 2002. Diversity, Phenology and Biogeography of the bees (Hymenoptera: Apoidea) of Zapotitlán de las Salinas, Puebla, Mexico. Journal of the Kansas Entomological Society 75 (1):16-30. (distribution); Ruíz-Cancino & Coronado-Blanco, 2002Ruíz-Cancino, E. & J.M. Coronado-Blanco 2002. Artrópodos terrestres de los estados de Tamaulipas y Nuevo León, México. Serie Publicaciones Cientificas No. 4:1-376. (distribution); Yáñez-Ordóñez & Hinojosa-Díaz, 2004Yáñez-Ordóñez, O. & I. Hinojosa-Díaz 2004. La colección himenopterológica (Insecta) del Museo de Zoología Alfonso L. Herrera de la Facultad de Ciencias, UNAM, México. Acta Zoológica Mexicana (nueva serie) 20 (1):167-197. (distribution).
Bombus pallidus Cresson, 1863:92, ♀. Holotype ♀, St. Louis, Mo. (Coll. E. Norton). - Franklin, 1913Franklin, H.J. 1913. The Bombidae of the New World. Transactions of the American Entomological Society 38 (3/4):177-486.:399 ( listed as synonym of Bombus pennsylvanicus (De Geer, 1773)); Lutz & Cockerell, 1920Lutz, F.E. & T.D.A. Cockerell 1920. Notes on the distribution and bibliography of North American bees of the families, Apidae, Meliponidae, Bombidae, Euglossidae, and Anthophoridae. Bull. Amer. Mus. Nat. Hist 42 (15):491-641.:504 ( listed as synonym of Bombus americanorum (Fabricius, 1775)); Mitchell, 1962Mitchell, T.B. 1962. Bees of the Eastern United States. Volume II. Technical bulletin (North Carolina Agricultural Experiment Station) 152:1-557.:524 ( listed as synonym of Bombus pennsylvanicus (De Geer, 1773)); 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.:2204 ( listed as synonym of Bombus pennsylvanicus pennsylvanicus (De Geer, 1773)).
Bombus sonorensis Fox, 1893:23 - Lutz & Cockerell, 1920Lutz, F.E. & T.D.A. Cockerell 1920. Notes on the distribution and bibliography of North American bees of the families, Apidae, Meliponidae, Bombidae, Euglossidae, and Anthophoridae. Bull. Amer. Mus. Nat. Hist 42 (15):491-641.:533 ( listed as synonym of Bombus sonorus Say, 1837).
Psithyrus cevalliæ Cockerell, 1899:157, ♂. 2 ♂♂, East of Las Cruces, New Mexico, Aug. 23rd (leg. C.H.T. Townsend). - Cockerell, 1906Cockerell, T.D.A. 1906. The bees of New Mexico. Transactions of the American Entomological Society 32:289-314. (distribution); Franklin, 1913Franklin, H.J. 1913. The Bombidae of the New World. Transactions of the American Entomological Society 38 (3/4):177-486.:401 ( listed as synonym of Bombus pennsylvanicus (De Geer, 1773)); Mitchell, 1962Mitchell, T.B. 1962. Bees of the Eastern United States. Volume II. Technical bulletin (North Carolina Agricultural Experiment Station) 152:1-557.:524 ( listed as synonym of Bombus pennsylvanicus (De Geer, 1773)); 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.:2204 ( listed as synonym of Bombus pennsylvanicus pennsylvanicus (De Geer, 1773)).
Bombus titusi Ashmead, 1902:50, ♂. Holotype ♂, Lamar, Colorado, September 10, 1898 (U. S. N. M., No. 5784, leg. Prof. E.G. Titus). - Franklin, 1913Franklin, H.J. 1913. The Bombidae of the New World. Transactions of the American Entomological Society 38 (3/4):177-486.:401 ( listed as synonym of Bombus pennsylvanicus (De Geer, 1773)); Mitchell, 1962Mitchell, T.B. 1962. Bees of the Eastern United States. Volume II. Technical bulletin (North Carolina Agricultural Experiment Station) 152:1-557.:524 ( listed as synonym of Bombus pennsylvanicus (De Geer, 1773)); 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.:2204 ( listed as synonym of Bombus pennsylvanicus pennsylvanicus (De Geer, 1773)).
Bombus sonorus flavodorsalis Franklin, 1913:409 - 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.:2205 ( listed as synonym of Bombus pennsylvanicus sonorus Say, 1837).
Bombus americanorum umbratus Friese, 1931:301 - Mitchell, 1962Mitchell, T.B. 1962. Bees of the Eastern United States. Volume II. Technical bulletin (North Carolina Agricultural Experiment Station) 152:1-557.:524 ( listed as synonym of Bombus pennsylvanicus (De Geer, 1773)). - As Bombus pennsylvanicus umbratus: - 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.:2204 ( listed as synonym of Bombus pennsylvanicus pennsylvanicus (De Geer, 1773)).