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Montana Field Guide

Montana Field Guides

Spruce Snail - Microphysula ingersolli
Other Names:  Thysanophora ingersolli, Helix ingersolli

Native Species

Global Rank: G5
State Rank: S5

Agency Status

External Links

General Description
A small shell, to about 5 mm diameter and 2.5 mm in height, flattened-heliciform, to about 5 1/2 tightly-coiled whorls. Shell is translucent, appears smooth (without magnification) and whitish; periphery is rounded. The aperture is crescent-shaped, higher than broad, lip not thickened and lacking teeth; umbilicus is about 1/4 the shell diameter. Head is pale gray, tentacles darker, inner whorls of live shells appear pinkish (Hendricks 2012, Burke 2013). Internal anatomy is described by Pilsbry (1940).

Diagnostic Characteristics
A combination of size (to about 5 mm diameter), color (whitish), narrow umbilicus, low spire (almost flattened), no teeth in aperture nor a reflected lip, and 5 tighly-coiled whorls differentiate this species from all others.

Species Range
Montana Range


Range Comments
British Columbia and Alberta through Washington, eastern Oregon and Nevada, and the Rocky Mountain states to Arizona and New Mexico (Burke 2013). In Montana, reported from 19 counties on both sides of the Continental Divide. Elevation range is 655 to 2394 m (2150 to 7855 ft). May be abundant locally; 63 were reported at one site in Granite County in late July (Hendricks 2012).

Observations in Montana Natural Heritage Program Database
Number of Observations: 165

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



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

Predicted Distribution in Montana
Predicted distribution model for Spruce Snail (Microphysula ingersolli). 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
Occupies both wooded and open sites, to above tree line. Canopy species include Douglas-fir, Engelmann spruce, subalpine fir, western larch, ponderosa pine, whitebark pine, lodgepole pine, black cottonwood, aspen, western redcedar and western hemlock; secondary canopy includes alder, willow, hawthorn, and dogwood. Found under woody debris and rocks (sometimes in rotten wood or talus slopes), in leaf litter or duff; most common in areas with moisture and limestone (Forsyth 2004, Hendricks 2012).

One of the few native land snails found above tree line in Montana (Hendricks 2012).

  • 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.
    • Pilsbry, H.A. 1940. Land Mollusca of North America (north of Mexico), Volume 1 Part 2. Monograph of the Academy of Natural Sciences of Philadelphia Monograph Number 3(1): 574-994.
  • Additional ReferencesLegend:   View Online Publication
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    • 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.
    • 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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  • Additional Sources of Information Related to "Snails / Slugs"
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Citation for data on this website:
Spruce Snail — Microphysula ingersolli.  Montana Field Guide.  .  Retrieved on , from