Multirib Vallonia - Vallonia gracilicosta
Vallonia costata montana, Vallonia albula, Vallonia sonorana
A small shell, to about 2.9 mm diameter and 1.2 mm in height, flatten heliciform with widely-spaced lamellar axial ribs, about 3 to 3 1/2 whorls, the last strongly expanding and descending to the aperture. Shell coloration is translucent whitish to pale brown. Aperture lip thickened inside with a broad opaque-white rib; umbilicus wide, about 1/3 to 1/2 the shell diameter. Animal is white. Reports of Vallonia costata by Berry are attributed by Henderson to this species (Hendricks 2012, Burke 2013).
Combination of small size (< 3.5 mm diameter), flattened heliciform shape, flared lip, and color (translucent white to pale brown) separate Vallonia from other shells. A thickend lip distinguish V. pulchella and V. gracilicosta from V. cyclophorella and V. perspectiva. V. pulchella has occasional low wrinkles but is unribbed and shiny while V. gracilicosta has widely-spaced axial ribs.
North America south through the northern Midwest and Rocky Mountain states to Arizona and New Mexico (Forsyth 2004, Burke 2013). In Montana, reported on both sides of the Continental Divide (but mostly east) from 12 counties: Broadwater, Carbon, Carter, Fergus, Gallatin, Golden Valley, Lincoln, Madison, Powder River, Stillwater, Wheatland, Wibaux. Elevation range is 823 to 2149 m (2700 to 7050 ft). May be abundant in some sites; 64 shells (live and dead) were reported at one Fergus County site in early 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 Multirib Vallonia (Vallonia gracilicosta)
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
Moist and drier forested sites, aspen stands. Canopy species include aspen, green ash, Douglasfir, ponderosa pine, western larch, Engelmann spruce, western redcedar, subalpine fir, limber pine; secondary canopy includes dogwood, and hawthorn. Found under woody debris and rocks, in leaf litter and duff (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.
- Additional ReferencesLegend: View Online Publication
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- 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.
- Berry, S.S. 1913. A list of Mollusca from the Mussellshell Valley, Montana. Nautilus 26:130-131.
- Berry, S.S. 1916. Notes of Mollusca of central Montana. Nautilus 29:124-128.
- Henderson, J. 1936. Mollusca of Colorado, Utah, Montana, Idaho, and Wyoming, supplement. University of Colorado Studies 23(2): 81-145.
- 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.
- Squyer, H. 1894. List of shells from the vicinity of Mingusville, Montana. The Nautilus 8:63-65.
- Additional Sources of Information Related to "Snails / Slugs"