Montana Field Guide

The shell is small, to 12.5 mm diameter and 7 mm in height; flattened heliciform with up to 5 whorls, umbilicus narrow and deep (contained about 4 1/2 times in the diameter), aperture oval to nearly circular, periphery strongly carinate or keeled. The surface is with coarse wrinkles but few spiral striae, the last whorl descends slightly or not at all to the aperture. Shell opaque and chalky, color is brownish-gray (dead shells to pearly white), with a series of reddish-brown spiral bands, that may be very pale or absent entirely, probably from abrasion and exposure to sunlight. Smaller shells may have a brownish cuticle that is lost in larger individuals. Head, neck, and tentacles are grayish-brown, darker than the shell (Hendricks 2012; Burke 2013). Internal anatomy described by Pilsbry (1934, 1939).

Active in wet and cool weather; otherwise not described.

In the field best identified based upon a combination of size, location and habitat. Combination of strong keel on body whorl, absence of prominent spiral raised ridges (lirae), presence of prominent coarse and irregular growth wrinkles, and relatively small size help separate this species from other Oreohelix (Hendricks 2012; Burke 2013).

Non-migratory.

Often associated with south-facing limestone talus and rocks, sometimes under an open tree canopy in relatively dry sites. Tree canopy includes Rocky Mountain juniper, ponderosa pine, and Douglas-fir. Ground cover varies but includes scattered sagebrush, Oregon grape, balsamroot, and bunch grasses. Live animals present mostly under shrubs, prostrate limbs of low-stature trees, rocks, and in duff or soil accumulations under some form of cover; sun-bleached shells may be found under rocks or on the surface (Hendricks 2012).

Not described.

Hermaphroditic (Pilsbry 1934, 1939), otherwise not described.

The known sites are on or near private timberland, Lolo National Forest land, state land, Bureau of Land Management land, and private non-timber land. None of these sites have special protection.

Habitat occupied by Oreohelix carinifera may be threatened by logging, grazing, weed control, highway development, home development, and fire. Grazing and logging in the species' limited habitat, road construction and maintenance, and urban encroachment have already reduced existing populations, and drought has reduced its habitat; species is extinct over much of its remaining area due to grazing, although dead shells can still be found, suggesting recent increased impact (Frest & Johannes 1995).