Montana Field Guide

A large shell, to 28 mm in diameter and 22 mm in height, heliciform with up to 6 whorls. Shell is opaque, pale or creamy brown, with a chitinous layer (periostracum) that may become lost with age and wear, the shell appearing grayish or chalky (sometimes difficult to separate from large Oreohelix). There is a pale spiral band above the rounded periphery that is bordered by two, and sometimes obscure, reddish-brown bands (in some shells these are visible inside the aperture); the undersurface lacks reddish bands (often present in Oreohelix in similar habitat). The shell is covered with a series of low axial riblets, including on the last half whorl of two protoconch (embryonic) whorls; umbilicus is deep, relatively narrow, and not obscured by the aperture lip, aperture round. Head and body are brownish, the tentacles darker (Hendricks 2012, Burke 2013). Internal anatomy is described by Pilsbry (1948).

The subspecies in Montana is Anguispira kochi occidentalis (see Burke 2013) but the vality of this designation has been questioned by some authorities.

Large size and aperture lacking a reflected lip distinguishes this shell from all others except some of the large Oreohelix (O. strigosa and O. subrudis) and Haplotrema. In live animals, the chitinous and opaque shell differs from the chalky gray or white shells of Oreohelix, although both have spiral bands (which may be faded or absent in dead and sun-bleached shells). The distinct rib-like sculpting on the embryonic whorls of Anguispira also help differentiate the two. Haplotrema has a flattened spire and a yellowish to olive-green color and no spiral banding.

Mostly in mesic mixed conifer forest, typically near water such as stream-side riparian, and seeps. Canopy species include western redcedar, western hemlock, Engelmann spruce, Douglas-fir, grand fir, western larch, lodgepole pine, black cottonwood and paper birch, and a secondary canopy including alder, dogwood and mountain maple. Found most often under woody debris or rocks in leaf litter and duff (Hendricks 2012).