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Montana Field Guide

Montana Field Guides

Western Glass-snail - Vitrina pellucida
Other Names:  Helix pellucida, Vitrina alaskana, Vitrina pfeifferi


Global Rank: G5
State Rank: S5

Agency Status
USFWS:
USFS:
BLM:


 

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General Description
A moderately small shell, up to about 6 mm diameter and 4 mm in height, heliciform with a low and small spire, very fragile, 2 1/2 to 3 whorls, the last rapidly enlarging to form about half of the shell. Shell coloration is pale greenish or yellowish to almost colorless, translucent to transparent, shell smooth and glossy, with low axial wrinkles. Aperture is large and thin, oblique-ovate and rounded, without teeth; umbilicus tiny. Animal brownish, head and tentacles darker grayish (Hendricks 2012, Burke 2013). Internal anatomy is described by Forsyth (2004).

Diagnostic Characteristics
No other land snail in the Pacific Northwest resembles this species in combination of small size, color (pale yellowish to nearly colorless), smooth and glossy shell, and a small number of whorls with the last rapidly expanding to the aperture. Live animals may appear to have a brownish shell, but that is the body color of the animal visible through the shell.

Species Range
Montana Range

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Range Comments
Widespread across Eurasia, in North America from Alaska to California to Rocky Mountains, including Arizona and New Mexico. In Montana, reported from both sides of the Continental Divide in 27 counties. Elevation range is 838 to 2582 m (2750 to 8470 ft). Probably occupies all forested “island” mountain ranges in eastern Montana. May be locally abundant; up to 140 shells (60 live) were located at one site in Lewis and Clark County in early October (Hendricks 2012).

Summary of Observations Submitted for Montana
Number of Observations: 240

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

(Observations spanning multiple months or years are excluded from time charts)


Predicted Distribution in Montana
Predicted distribution model for Western Glass-snail (Vitrina pellucida). 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.

Predicted Distribution Map

More model output for this species
Habitat
Forest with broadleaf or mixed broadleaf-conifer canopy, near moisture; in campgrounds and roadside ditches, isolated aspen stands. Canopy species include cottonwoods, aspen, Douglas-fir, Engelmann spruce, lodgepole pine, ponderosa pine, whitebark pine, subalpine fir and western redcedar, secondary canopy includes alder, paper birch, hawthorn, snowberry, thimbleberry, willow and mountain maple. Often found in more open areas under woody debris and bark, in dense ground vegetation, in leaf litter or duff, grazed and ungrazed sites (Forsyth 2004, Hendricks 2012).

References
  • Literature Cited AboveLegend:   View Online Publication
    • 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.
  • Additional ReferencesLegend:   View Online Publication
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    • Beetle, D. E. 1961. Mollusca of the Big Horn Mountains. The Nautilus 74:95-102.
    • Berry, S.S. 1916. Notes of Mollusca of central Montana. Nautilus 29:124-128.
    • Berry, S.S. 1919. Mollusca of Glacier National Park, Montana. Proceedings of the Academy of Natural Sciences of Philadelphia 71:195-205.
    • 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.
    • 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.
    • Russell, L.S. 1951. Land snails of the Cypress Hills and their significance. The Canadian-Field Naturalist 65:174-175.
    • Russell, R.H. and R.B. Brunson. 1967. A check-list of molluscs of Glacier National Park, Montana. Sterkiana 26:1-5.
    • Vanatta, E.G. 1914. Montana shells. Proceedings of the Academy of Natural Sciences of Philadelphia 66:367-371.
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Citation for data on this website:
Western Glass-snail — Vitrina pellucida.  Montana Field Guide.  .  Retrieved on , from