Haplotrema vancouverense

Haplotrema (Ancomena) vancouverense (I. Lea, 1839)
Robust Lancetooth

  • Helix vancouverensis I. Lea 1838: 87, pl. 23, fig. 72.
  • Circinaria vancouverensis var. chocolata Dall 1905: 34.
  • ? Helix vellicata Forbes 1850: 55, pl. 9, fig. 1a–c.
Haplotrema vancouverense; Goldstream Park, Vancouver Island, BC.

Identification. Shell subdiscoidal. Spire very low, scarcely conical. Whorls ca 5. Last whorl much rapidly enlarging (width from above ca 3× width of penultimate whorl). Suture rather shallow. Protoconch smooth. Teleoconch with low, irregular incremental lines, coarsest near suture, and microscopic spiral striae. Aperture subovate, edentulous. Adult lip slightly thickened; arched forward, straightened or somewhat downward drooping. Umbilicus ca ¼ of shell width. Shell matte or somewhat glossy; ochre to olive brown, often with darker streaks.

Animal pearly whitish with head slightly darker; ocular tentacles mauve-grey; mantle tan to brown with large dark blotches.

This is the largest haplotrematid in Canada, but A. hybridum overlaps with it in size. Shell sculpture differs, however. Haplotrema vancouverense lacks the prominent beading (most clearly seen around the umbilicus) of the two Canadian Ancotrema species.

Habitat. In forests, under rotten logs and around the bases of sword ferns, often deep within leaf litter and loose soil.

Global range. Aleutian Islands and southeast Alaska (Pilsbry 1946) to Del Norte, Humboldt, and Trinity counties, north-western California (Roth & Sadeghian 2003); east through northern Idaho to north-western Montana (Pilsbry 1946, Brunson & Osher 1957). Although Hanna (1925) believed this species native to Unalaska Island in the Aleutian chain, Eyerdam (1933) thought that that this species was introduced, having observed that he found them always near villages or abandoned settlements and not on other islands of the Aleutian chain.

Canadian range. British Columbia: along the entire coast, but it is known (perhaps rare) in the southern Interior mountains south-east of Trail and south of Salmo (Ovaska et al. 2020).

Etymology. Named for Fort Vancouver (now Vancouver, Washington, USA), where the species was originally found.

Remarks. The publication date of this species is usually given to be 1839 (e.g., Pilsbry 1946), but although read before the Society on 21 July 1837, volume 6, part 1 of the Transactions of the American Philosophical Society was published 15 June 1838 (Tryon 1861, Scudder 1885).

Dall (1905) described a dark brown variety from Sitka, Alaska, where it was said to be common, as Circinaria vancouverensis var. chocolata. However, this dark form also occurs in Washington and Oregon (Pilsbry 1946), and it is likely nothing more than a colour morph. Helix vellicata Forbes, 1850 has been synonymised with H. vancouverense for many years (e.g. Pilsbry 1946), but this may be incorrect. Helix vellicata could be a synonym of another species, possibly A. hybridum. Forbes (1850: 55) gave the width of the shell as 22 mm, which is within the range from both H. vancouverense and A. hybridum. However, in his Latin description, he wrote “… sulcato-striatâ, striis minutissimis spiralibus decussatâ …” [furrow-striae, striae minutely spirally decussate]. This suggests that this might be A. hybridum or another haplotrematid having decussate (or beaded) sculpture rather than H. vancouverense, which is much smoother.

References

  • Brunson RB, Osher U (1957) Haplotrema from western Montana. The Nautilus 70: 121–123.
  • Dall WH (1905) Land and fresh water mollusks. Harriman Alaska Expedition. Vol. 13. Doubleday, Page and Co., New York, 1–171, pls 1, 2.
  • Eyerdam WJ (1933) A biological collecting excursion to the Aleutian Islands. The Nautilus 46: 124–128.
  • Forbes E (1850) On the species of Mollusca collected during the surveying Voyages of the Herald and Pandora, by Capt. Kellett, R.N., C.B., and Lieut. Wood, R.N. Proceedings of the Zoological Society of London for 1850 18: 53–56.
  • Hanna GD (1925) Some land shells from the Aleutian Islands, Alaska. The Nautilus 38: 122–127.
  • Lea I (1838) Description of new freshwater and land shells. Transactions of the American Philosophical Society (New Series) 6: 1–154.
  • Ovaska K, Sopuck L, Heron J (2020 “2019”) Surveys for terrestrial gastropods in the Kootenay region of British Columbia, with new records and range extensions. The Canadian Field-Naturalist 133: 221–234.
  • Pilsbry HA (1946) Land Mollusca of North America (north of Mexico). Vol. II, Part 1. The Academy of Natural Sciences of Philadelphia, Monographs 3: i–vi + 1–520.
  • Roth B, Sadeghian PS (2003) Checklist of the land snails and slugs of California. Santa Barbara Museum of Natural History Contributions in Science 3: 1–81.
  • Scudder NP (1885) The published writings of Isaac Lea, LL.D. Bulletin of the United States National Museum 23: i–lix, 1–278.
  • Tryon GW Jr (1861) List of American writers on Recent conchology with the titles of their memoirs and dates of publication. Baillière Brothers, New York, 68 pp.