Montana Field Guide

The shell is large, to 28 mm diameter, height to 13 mm, but usually about 22 mm in diameter and 10 mm in height, heliciform with up to 5 to 5 1/2 whorls (new-born young about 3.5 mm in diameter, with 2 to 2 1/2 whorls), strongly depressed with a low spire, acutely carinate, with an open umbilicus to 6 mm diameter. Shell opaque and chalky, color is pale grayish to nearly white, sometimes with a very pale pinkish undertone; smaller shells may have a brownish cuticle that is lost in mature individuals. Inner (embryonic) whorls smooth then unevenly striate, later whorls lack spiral bands and are coarsely and irregularly ribbed on upper and lower surfaces, the last whorl descending somewhat to the aperture; the aperture is angular at the keeled periphery. Description for an alpine population on the Scapegoat Plateau is much as above except the shells are much smaller, to 15 mm diameter, 6.5 mm in height, and 4 1/2 whorls, but usually 10.5 mm diameter, 5 mm in height, and 4 whorls or less (Hendricks 1998, 2012; Hendricks et al. 2008; Burke 2013). Internal anatomy described by Pilsbry (1939) and Fairbanks (1984).

Active in wet and cool weather; otherwise not described.

A combination of shell shape (flattened heliciform or flattened conic), large size (except alpine form, which is medium 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, 2012; Burke 2013). Oreohelix elrodi is very unique in appearance from other Montana Oreohelix. It is medium to large and stongly depressed (flattened), acutely carinate (keeled), and the later whorls are coarsely sculptured with a series of ribs especially evident on the underside.

Non-migratory. May may vertical movements through talus and boulder fields (Hendricks 1998).

Described originally as exposed limestone talus below tree line, but examination of the rock at four of five sites revealed they are predominantly argillite, sometimes with diorite or minor amounts of limestone. Occupied sub-alpine talus sites may lack forest canopy altogether or occur under an open mixed conifer canopy including Douglas-fir, western larch, ponderosa pine, western redcedar (near streams), with aspen, paper birch and mock orange scattered along the margins of talus slopes. The exception is an expanse of limestone well above tree line on the Scapegoat Plateau. Live animals present mostly within the talus under or on rocks, or in accumulations of duff within the talus (Hendricks 1998, 2012; Hendricks et al. 2008).

Not described. May feed on leaf detritis and duff (Hendricks 1998).

Hermaphroditic (Pilsbry 1939; Fairbanks 1984), otherwise not described.

Habitat occupied by Oreohelix elrodi (low-elevation slopes of mixed conifers, especially Douglas-fir, Ponderosa Pine and Western Larch) is threatened to some extent by logging, grazing, and fire, although occupied habitat is often in talus surrounded by mixed coniferous forest. Habitat requirements and food habits are poorly understood, however. Fire suppression efforts (especially use of fire retardants) and talus destabilization (trail maintenance, modification) could have negative impacts, as could chemical control of weeds (Frest and Johannes 1995; Hendricks 2003). The alpine site on the Scapegoat Plateau is most threatened by changes in climate.