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Montana Field Guide

Montana Field Guides

Variable Vertigo - Vertigo gouldii
Other Names:  Pupa gouldii, Pupa coloradensis, Vertigo gouldi

Native Species

Global Rank: G5
State Rank: SNR

Agency Status

External Links

General Description
A very small shell, to about 1.0 mm diameter and 1.9 mm in height, subcylindrical (pupiform) and tapering with nearly regular axial striae-riblets, about 4 1/2 to 5 whorls. Shell coloration is silky pale brown to reddish-brown. Aperture subovate, with 4-6 (usually 4-5) teeth (denticles: parietal, columellar, upper palatal, lower palatal, sometimes a subcolumellar), palatal callus more or less distinct, sinulus weak, crest usually moderate, lip slightly thickened and weakly flared; umbilicus very small or closed (Hendricks 2012, Burke 2013).

Two subspecies may be present in Montana: Vertigo gouldii basidens and Vertigo gouldii coloradensis.

Diagnostic Characteristics
Combination of size (height < 3.0 mm) and shape, presence of teeth in a subovate aperture, 4-5 whorls, and an indentation in palatal lip distinguish Vertigo from similar appearing shells. Combination of weak or absent sinulus, more or less distinct palatal callus, shell height < 2.2 mm (to 1.9 mm for this species) and aperture with 4-5 teeth differentiate this from the similar V. binneyana.

Species Range
Montana Range


Range Comments
North America south to Kansas, Missouri, and Alabama, in the west Rocky Mountains to Arizona and New Mexico. In Montana, reported on both sides of the Continental Divide from five counties: Carter, Fergus, Lake, Lewis and Clark, Stillwater. Elevation range is 931 to 1731 m (3055 to 5680 ft). Range and abundance in Montana poorly documented; current status needs investigation. Only a few specimens have been reported at any locality. Recent genetic analyses indicate Montana specimens of Vertigo gouldii should be considered V. arthuri or V. coloradensis (Hendricks 2012).

Observations in Montana Natural Heritage Program Database
Number of Observations: 8

(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 Variable Vertigo (Vertigo gouldii). 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
Forests, aspen stands, damp sites. Canopy tree species include aspen and ponderosa pine. Found under woody debris, in leaf litter, moss, and duff. Habitat in Montana is poorly documented (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.
    • 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
    Do you know of a citation we're missing?
    • Beetle, D. E. 1961. Mollusca of the Big Horn Mountains. The Nautilus 74:95-102.
    • Beetle, D.E. 1997. Recolonization of burned aspen groves by land snails. Yellowstone Science 5 (summer):6-8.
    • Beetle, D.E. 1989. Checklist of recent Mollusca of Wyoming, U.S.A. The Great Basin Naturalist 49(4):637-645.
    • Forsyth, R.G. 2004. Land snails of British Columbia. Royal British Columbia Museum: Victoria, British Columbia, Canada. 188 pp.
    • Nekola, J.C. and B.F. Coles. 2010. Pupillid land snails of eastern North America. American Malacological Bulletin, 28(2):29-57
    • Nekola, J.C., B.F. Coles, and U. Bergthorsson. 2009. Evolutionary pattern and process within the Vertigo gouldii (Mollusca: Pulmonata, Pupillidae) group of minute North American land snails. Molecular Phylogenetics and Evolution 53:1010-1024
    • Pilsbry, H.A. 1948. Land Mollusca of North America (north of Mexico), Volume II Part 2. The Academy of Natural Sciences of Philadelphia Monograph Number 2(2): 521-1113.
    • Sterki, V. 1890b. On Some Northern Pupidae, with Descriptions of New Species. The Nautilus 3:123-126.
    • 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:
Variable Vertigo — Vertigo gouldii.  Montana Field Guide.  .  Retrieved on , from