Montana Field Guide

The shell is small, to 12 mm diameter but usually less than 10 mm (new-born young about 2 mm diameter), to 7 mm in height but usually less than 5 mm; heliciform with up to 4 1/2 whorls, depressed somewhat in profile with a low spire, umbilicus narrow and deep, aperture oval to nearly circular, periphery rounded or slightly carinate. Shell opaque and chalky, color is brownish-gray (dead shells to pearly white), with a series of reddish-brown spiral bands, two or more on the upper surface, a prominent band near the periphery on the lower surface, and one or more paler bands below that; bands may be evident on penultimate whorl, or 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 dark brown, darker than the shell (Hendricks 2012; Burke 2013). Internal anatomy described by Fairbanks (2002).

Active in wet and cool weather; otherwise not described.

In the field best identified based upon a combination of size, location, and habitat. A combination of shell shape (flattened heliciform or flattened conic), small size, opaque shell color (especially chalky white when dead) with a few bands, absence of reflected lip, and absence of teeth in the aperture distinguishes this from other Montana land snails (Hendricks 2003). Most other species of Oreohelix in Montana are larger and less flattened; Oreohelix alpina appears to be the only member of the genus within its restricted range and alpine habitat, although recent field work on the Scapegoat Plateau in 2007 found Oreohelix elrodi (or a closely related undescribed form) in close proximity (< 50 m) to Oreohelix alpina but with no areas of sympatry or range overlap on the plateau (Hendricks et al. 2008; Hendricks 2012).

Non-migratory.

Limestone talus at and above tree line. Tree canopy absent or minimal; canopy species where present include scattered whitebark pine, Engelmann spruce, and subalpine fir. Ground cover also minimal, but includes scattered dwarf willow, snow cinquefoil, alpine sorrel, mountain avens, stonecrop and moss campion. Live animals occur mostly under rocks and in duff or soil accumulations under rocks, sun-bleached shells may be found on the surface (Hendricks 1998, 2012; Hendricks et al. 2008).

Not described.

Hermaphroditic (Fairbanks 2002), otherwise not described.

Occupied habitat (alpine and high-elevation limestone talus) is not threatened by current land use practices. Probably the greatest threat to species persistence is climate change (Hendricks 2003).