- Helix townsendiana I. Lea 1839: 99, pl. 23, fig. 80.
- Polygyra townsendiana var. brunnea Vanatta (1924): 25.
- Allogona (Dysmedoma) townsendiana form frustrationis Pilsbry (1940): 885, figs 509f , 510(1, 1a, 3).
Identification. Shell depressed-heliciform. Spire conical. Whorls c. 6, rounded. Last whorl descending at aperture. Suture moderately impressed. Periphery rounded. Teleoconch with wide, not quite evenly spaces, low, axial riblets, coarser and less even than in A. ptychophora; spaces granular between striae (below suture and in the umbilical region), with closely spaced, spiral striae. Aperture subovate, edentulous, nearly as high as wide. Palatal and basal lips thickened, expanded, slightly recurved, contracted behind. Umbilicus open, overhung by columellar lip. Periostracum without hairs. Shell pale brown or yellowish brown, eroding greyish, with pale, straw-yellow streaks. Width to 26–33 mm (wider than high).
Animal greyish brown; tentacles and spaces between tubercles darker.
This species differs from A. ptychophora in having a larger shell, with coarser, more irregular axial riblets below the sutures and more pronounced malleation.
Habitat. In moist forests. Often especially common in patches of stinging nettle.
Geographic range. South-western British Columbia: Hope and west in the Fraser Valley to Burnaby and Port Coquitlam. On Vancouver Island, at Westholme, north of Duncan. BC south through coastal Washington to northwestern Oregon (Pilsbry 1940).
Etymology. This species was named after John Kirk Townsend (1809–1851), ornithologist and naturalist from Philadelphia, who accompanied the 1834–1835 Wyeth Expedition across the Rockies to Fort Vancouver on the Columbia River west to Oregon and collected biological samples (Moring 2002).
Remarks. Pilsbry (1940) recognized two forms (but not subspecies): brunnea Vanatta, 1924, and frustrationis Pilsbry, 1940. The brunnea form is characterized by having a darker shell, which occurs with normally pigmented shells in some populations throughout the range of the species, and it is almost certainly nothing other than a colour variant. Likely an ecophenotype, frustrationis was proposed for a form from Cape Disappointment, Washington, which was said to be relatively thinner and smoother shelled (Pilsbry 1940). Recently, Burke (2013) recognized this taxon as a putative subspecies, Allogona townsendiana frustrationis, although his reasons for this separation seem weak. No subspecies are used here.
This species was first reported from BC by Whiteaves (1906) who mentioned a collection of “Polygyra ptychophora” from Mission Junction (present-day Mission), in the Fraser Valley. This record is most certainly within the range of A. townsendiana.
COSEWIC (2002, 2013) assessed this species as Endangered in 2002 and again in 2013.
References
- Burke TE (2013) Land snails and slugs of the Pacific Northwest. Oregon State University Press, Corvallis, Oregon, USA, 344 pp.
- COSEWIC (2002) COSEWIC assessment and status report on the Oregon Forestsnail Allogona townsendiana in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa, Ottawa, ON, Canada, vi + 20 pp.
- COSEWIC (2013) COSEWIC. 2013. COSEWIC assessment and status report on the Oregon Forestsnail Allogona townsendiana in Canada. Committee on the Status of Endangered Wildlife in Canada, Ottawa, ON, Canada, xii + 87 pp.
- Lea I (1839 “1838”) Description of new freshwater and land shells. Transactions of the American Philosophical Society (New Series) 6: 1–154, pls 1–24. https://doi.org/10.2307/1005319
- Moring J (2005) Early American naturalists: exploring the American West, 1804–1900. Taylor Trade Publications, Lanham, MD, USA, 260 pp.
- Pilsbry HA (1940) Land Mollusca of North America (north of Mexico), Volume I, Part 2. The Academy of Natural Sciences of Philadelphia, Monographs 3: i–viii + 1–994 + i–ix.
- Vanatta EG (1924) Descriptions of four new American shells. Proceedings of the Academy of Natural Sciences of Philadelphia 76: 25–27.
- Whiteaves JF (1906) Notes on some land and fresh water shells from British Columbia. The Ottawa Naturalist 20: 115–119.