Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: > 300
Comments: Hubricht (1985) includes only Pleistocene fossil occurrences in Illinois, Indiana, Iowa, Kansas, Kentucky, Missouri, Nebraska, North Dakota, Oklahoma, and Texas. Nekola (2004) documented it from a single population in northeastern Wisconsin in Longlade Co., with the nearest known extant colonies approximately 150 km north on the northern tip of the Keweenaw Peninsula, 250 km northwest on the north shore of Lake Superior in northeastern Minnesota, and 300 km east on Manitoulin Island (Nekola et al., 1999) (this is one of the few non-Pleistocene fossil occurrences in the central U.S.). The subspecies parietalis is also known from Pleistocene deposits in the Black Hills of Fall River/Custer Cos., South Dakota (Jass et al., 2002). According to Oliver and Bosworth (1999), eleven Utah occurrences of this species have been published (all except one the parietalis form): the central and southern portions of the Wasatch Range, in Weber, Salt Lake, Wasatch and Utah Cos., and in the Uinta Mountains in Summit Co., with other populations in Sevier Co. in central Utah and Kane and San Juan Cos. in southern Utah (Binney, 1886; Pilsbry and Vanatta, 1900; Ferriss, 1920; Chamberlin and Jones, 1929; Chamberlin and Berry, 1930; Berry, 1931; Jones, 1940; Woolstenhulme, 1942a; 1942b). The San Juan County records represent the only occurrence of the subspecies insculpta in Utah. Nekola (1998) also lists parietalis from the Niagara Escarpment in the upper peninsula of Michigan. Nekola et al. (1999) list three new sites in Minnesota (Cascade River Cliff and Mt. Josephine Talus in Cook Co.; and Manitou River Falls in Lake Co.) for subspecies modesta. Nekola and Coles (2010) note that all prior records for Vertigo modesta from the New England states (e.g., Pilsbry, 1948; Martin, 2000) likely represent the large morph of Vertigo cristata, which they have seen throughout the high mountains of this region. Also, Nekola and Coles (2010 have not seen Vertigo modesta south of the Gulf of St. Lawrence. Baxter (1987) cites occurrences in Alaska in the North Gulf Coast, Aleutian Islands, and southeast; and also Attu (Aleutian Islands) (Roth and Lindberg, 1981). Forsyth (2004; 2005) documented it (usually the parietalis form) in the Upper Fraser Basin of central British Columbia and in the Peace River- northern Rockies region (Forsyth, 2005) but is known elsewhere up to the tree line at 1700 m. In Alberta, it occurs from near Pincher Creek to southwest of Calgary towards Kananaskis, Lake Louise, Jasper, and east to Edmonton (Lepitzki, 2001). Roth and Sadeghian (2003) cite the castanea form from California in Siskiyou, Modoc, Shasta, Lassen, Tehama, Plumas, Lake, Nevada, Placer, El Dorado, Mono, Mariposa, Fresno, Inyo, and San Bernardino Cos.