Anguispira kochi occidentalis

Anguispira (Zonodiscus) kochi occidentalis (E. von Martens, 1882)
Western Banded Tigersnail

  • Patula solitaria var. occidentalis E. von Martens 1882: 140.
  • Anguispira kochi eyerdami Clench & Banks 1939: 285, pl. 36, fig. 3.
Anguispira kochi occidentalis; Grohman Narrows, near Nelson, BC (RGF 677.3001); width 22.0 mm.

Identification. Shell depressed globose. Spire moderately elevated, conic, with sides slightly convex. Whorls ca 5½–6, convex. Periphery medial, convex. Last whorl descending in adults. Teleoconch with coarse, low colabral riblets on early whorls, weaker on later whorls. Aperture rounded-lunate, slightly higher than wide, edentulous. Lip simple, thin but slightly thickened in adults. Umbilicus ca 1/5 of shell width. Shell matte, usually dark brown, with darker, obscure spiral bands, one at periphery and one above, which border a slightly paler band between. Shell to 25.5 mm wide (wider than high).

Animal reddish brown, with darker, greyish tentacles.

Habitat. Moist forests.

Canadian range. South-western British Columbia: Kootenay region, along Kootenay Lake and River and the south-eastern portion of the Columbia River.

La Rocque (1953) gave doubtful mention that “A. kochi kochi” (he called the western populations this subspecies) is in Alberta. However, no published records or specimens are known to confirm this, and it seems possible that specimens of Oreohelix subrudis was mistaken for this species.

Etymology. Latin, occidentalis, “western”.

Remarks. Clench & Banks (1939) described a subspecies from Yakima County, Washington, which was said to differ from A. kochi occidentalis by its smaller, darker, and more depressed shell. However, Pilsbry (1948) examined type material and noted that it fell within the range of variation in A. kochi occidentalis and did not consider it valid. Burke (2013) treated it, unconvincingly, as a subspecies, but it is considered a synonym here.

Following earlier usage by Pilsbry (1948), the western and eastern populations of Anguispira kochi, which are separated by a distributional gap of over 2000 km, are treated as subspecies even though there are no clear morphological characters separating these two taxa (Pilsbry 1948).

  • Burke TE (2013) Land snails and slugs of the Pacific Northwest. Oregon State University Press, Corvallis, 344 pp.
  • Clench WJ, Banks G (1939) A new subspecies of Anguispira kochi from Washington. Memorias de la Sociedad Cubana de Historia Natural 13: 285, pl. 3, fig. 3.
  • La Rocque A (1953) Catalogue of the Recent Mollusca of Canada. National Museum of Canada, Bulletin 129: i–x, 1–406.
  • Martens E von (1882) [Einige Conchylien vor, welche Dr. Aurel und Arthur Krause während ihrer Rückreise von den Küsten des stillen Oceans durch Amerika gesammelt haben]. Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin 1882: 138–143.
  • Pilsbry HA (1948) Land Mollusca of North America (north of Mexico), 2(2). The Academy of Natural Sciences of Philadelphia, Monographs 3: i–xlvii + 521–1113 pp.