Mitered Vertigo - Vertigo concinnula
A small shell, to 1.2 mm diameter and 2.3 mm in height, subcylindrical (pupiform) and slightly tapering with moderate and irregular striae, about 5 whorls. Shell coloration is translucent and dull reddish-brown, sometimes with paler flecks. Aperture subovate, with 5 teeth (parietal, columellar, upper palatal, lower palatal, angular), palatal callus absent, but parietal and palatal teeth elongate, sinulus absent or very weak, crest moderate to well-developed (Hendricks 2012, Burke 2013).
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. A sinulus only weakly indented (or not at all) and absence of a palatal callus distinguishish V. concinulla from all but V. modesta, which is slightly larger (height to 2.7 mm) and with a less developed crest. Local variation in the number of teeth is not uncommon. V. concinulla has 5 teeth, V. modesta may have up to 4-5 teeth, but many in Montana have only 2 teeth.
Native to North America; primarily in Rocky Mountains from Idaho to Arizona and New Mexico but also Oregon and South Dakota. In Montana, one report east of the Continental Divide, from Gallatin County: elevation 1158 m (3800 ft). Range and abundance in Montana poorly understood; current status needs investigation (Hendricks 2012).
Observations in Montana Natural Heritage Program Database
Number of Observations:
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Not described for Montana (Hendricks 2012). Moist sites in aspen and riparian willow thickets in Wyoming. Found under woody debris and leaf litter (Beetle 1961, 1989).
- Literature Cited AboveLegend: View Online Publication
- Beetle, D. E. 1961. Mollusca of the Big Horn Mountains. The Nautilus 74:95-102.
- Beetle, D.E. 1989. Checklist of recent Mollusca of Wyoming, U.S.A. The Great Basin Naturalist 49(4):637-645.
- 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
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- 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.
- Henderson, J. 1924. Mollusca of Colorado, Utah, Montana, Idaho, and Wyoming. University of Colorado Studies 13(2):65-223.
- 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.
- Additional Sources of Information Related to "Snails / Slugs"