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Yavapai Mountainsnail - Oreohelix yavapai


Global Rank: G5
State Rank: SNR

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General Description
The shell is medium to large, up to 23 mm diameter but usually less than 21 mm (newborn young about 2 or 3 mm diameter), and to 11 mm in height but usually less than 10 mm; flattened heliciform (spire only moderately elevated) with up to 5 1/2 whorls, the sutures generally filled by the keel of the previous whorl. Umbilicus is broad, a little larger than 1/4 the shell diameter, aperture is very oblique and oval, periphery of body whorl keeled but more weakly on the last quarter turn. Shell opaque and chalky, color is brownish-gray to whitish (dead shells to pearly white), with two reddish-brown spiral bands, one on the upper surface and a prominent band near the periphery on the lower surface. The last whorl has a cord-like keel on the periphery and sometimes descends below the periphery to the aperture. The surface is wrinkled with fine spiral striae (Hendricks 2012, Burke 2013). Internal anatomy is described by Pilsbry (1939).

There are two subspecies: O. y. extremitatis and O. y. mariae.

Diagnostic Characteristics
Medium to large size, calcareous whitish to gray, flattened spire, variable banding, broad umbilicus, absence of refelcted lip, surface sculpture (including an obvious keel), and oblique oval aperture help distinguish this from other larger shells, including typical O. subrudis and O. strigosa.

Species Range
Montana Range

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Range Comments
Montana and Wyoming south to Arizona and New Mexico. In Montana, about 13 records from about six sites in two counties east of the Continental Divide: Carbon (1), Gallatin (5). Elevation range is 1513 to 1890 m (4965 to 6200 ft). Moderately abundant at some localities; as many as 56 (live and shells) were seen at one site in Gallatin County in late August (Hendricks 2012). O. y. mariae was originally described in 1916 from specimens collected above Storm Castle Creek (formerly Squaw Creek) in Gallatin County (Bartsch 1916).

Summary of Observations Submitted for Montana
Number of Observations: 11

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Relative Density

Recency

 

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



Habitat
Associated primarily with dry limestone outcrops and rocky soils. Tree canopy absent to scattered; canopy species where present include scattered Douglas-fir, Rocky Mountain juniper, and Utah juniper. Ground cover scattered but includes sagebrush and bunch grasses. Live animals occur mostly under junipers in duff or soil accumulations under rocks; sun-bleached shells may be found on the surface (Beetle 1987, Hendricks 2012).

References
  • Literature Cited AboveLegend:   View Online Publication
    • Bartsch, P. 1916. Two new land shells from the Western States. Proceedings of the U. S. National Museum 51:331-333.
    • Beetle, D.E. 1987. The genus Oreohelix (Pulmonata: Oreohelicidae) in two western canyons of the Big Horn Mountains, Wyoming. Festivus 19(7):66-72.
    • 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.
    • Pilsbry, H.A. 1939. Land Mollusca of North America (North of Mexico), Volume 1, Part 1. Monograph of the Academy of Natural Sciences of Philadelphia Monograph Number 3 (1): 1-573.
  • 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. 1989. Checklist of recent Mollusca of Wyoming, U.S.A. The Great Basin Naturalist 49(4):637-645.
    • Frest, T.J. and E.J. Johannes. 1995. Interior Columbia Basin mollusk species of special concern. Final report to the Interior Columbia Basin Ecosystem Management Project, Walla Walla, WA. Contract #43-0E00-4-9112. 274 pp. plus appendices.
    • Henderson, J. 1924. Mollusca of Colorado, Utah, Montana, Idaho, and Wyoming. University of Colorado Studies 13(2):65-223.
    • Henderson, J. 1933. Mollusca of the Yellowstone Park, Teton Park and Jackson Hole region. Nautilus 47:1-3.
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Citation for data on this website:
Yavapai Mountainsnail — Oreohelix yavapai.  Montana Field Guide.  .  Retrieved on , from