Robust Lancetooth - Haplotrema vancouverense
Helix vancouverensis, Helix vellicata, Macrocyclis vancouverensis, Circinaria vancouverensis
A relatively large shell, diameter 20-30 mm and height 8-12 mm. The chitonous or horny shell is a flattened heliciform of up to 5 1/2 whorls, the final portion expanded near the lip, the aperture lip slightly thickened, with the upper margin slightly down-turned. The shell is dull to slightly shiny, yellow to olive-green with low wrinkles and microscopic spiral striae, sometimes with streaks, but no spiral bands. Head, neck, and body are creamy white, the tentacles darker (pale bluish) (Hendricks 2012, Burke 2013). Internal anatomy is described by Pilsbry (1946).
A dark-brown form, H. v. chocolata, described from Alaska and appearing also in western Oregon and Washington, appears to be a color variant within typically-colored populations.
A combination of large size, flattened spire, and an unbanded yellowish to greenish shell are unique in Montana, as is the strikingly creamy-white coloration of the live animal.
Aleutian Islands and coastal Alaska south to northwestern California, east to northern Idaho and northwestern Montana (Burke 2013). In Montana, 11 records in two counties west of the Continental Divide: Lincoln (5), Sanders (6). Elevation range is 664 to 1140 m (2180 to 3740 ft). The Idaho and Montana populations may be isolated from the main coastal range of the species. First reported from Montana in 1956 (Brunson and Osher 1957); not reported again until 2006. As many as nine individuals were found at two sites in Lincoln County in mid-October (Hendricks 2012).
Observations in Montana Natural Heritage Program Database
Number of Observations:
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Map Help and Descriptions
(Observations spanning multiple months or years are excluded from time charts)
Predicted Distribution in Montana
Predicted distribution model for Robust Lancetooth (Haplotrema vancouverense)
Records were spatially unique and had a locational uncertainty of ≤ 400 meters.
Hotter colors indicate areas that are predicted to have more suitable habitat for the species.
Black dots are positive data used to build the model.
Gray dots are locations where a survey capable of detecting the species has been performed.
Landownership, a shaded relief map, and county lines are included for reference.
Details of the modeling effort, a description of the environmental layers used, and a more thorough interpretation
of model outputs can be found in the report Land Mollusk Surveys and Predicted Distribution Models on USFS Northern Region Lands: 2007
More model output for this species
Mostly in mesic mixed conifer forest, typically near water such as stream-side riparian, seeps and wetlands, sometimes near areas of human activity such as campgrounds. Canopy species include western redcedar, western hemlock, grand fir, Douglas-fir, black cottonwood, paper birch, and a secondary canopy including aspen and alder. Found in leaf litter, under woody debris, rocks, and bryophyte mats (Forsyth 2004, Hendricks 2012).
- Literature Cited AboveLegend: View Online Publication
- Brunson, R.B., and U. Osher. 1957. Haplotrema from western Montana. Nautilus 70: 121-123.
- Burke, T. E. 2013. Land snails and slugs of the Pacific Northwest. Corvallis, OR: Oregon State University Press. 344 p.
- Forsyth, R.G. 2004. Land snails of British Columbia. Royal British Columbia Museum: Victoria, British Columbia, Canada. 188 pp.
- Hendricks, P. 2012. A Guide to the Land Snails and Slugs of Montana. A report to the U.S. Forest Service - Region 1. Montana Natural Heritage Program, Helena, MT. vii + 187 pp. plus appendices.
- Pilsbry, H.A. 1946. Land Mollusca of North America (north of Mexico), Volume II Part 1. Academy of Natural Sciences of Philadelphia Monograph Number 3 (2):1-520.
- Additional ReferencesLegend: View Online Publication
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- Bland, T. and J.G. Cooper. 1861. Notice of land and freshwater shells collected by Dr. J.G. Cooper in the Rocky Mountains, etc, in 1860. Annals of the Lyceum of Natural History of New York 7:362-370.
- Frest, T.J. and E.J. Johannes. 2001. An annotated checklist of Idaho land and freshwater mollusks. Journal of the Idaho Academy of Science 36(2):1-51.
- Hendricks, P., B.A. Maxell, and S. Lenard. 2006. Land mollusk surveys on USFS Northern Region lands. A report to the USDA Forest Service, Northern Region. Montana Natural Heritage Program, Helena, Montana. 11 pp. plus appendices.
- Hendricks, P., B.A. Maxell, S. Lenard, and C. Currier. 2007. Land mollusk surveys on USFS Northern Region lands: 2006. A report to the USDA Forest Service, Northern Region. Montana Natural Heritage Program, Helena, Montana. 11 pp. plus appendices.
- Additional Sources of Information Related to "Snails / Slugs"