Montana Field Guide

A small shell, to about 5 mm diameter and 2.5 mm in height, flattened heliciform with a low spire, surface with narrow widely-spaced axial grooves but no fine spiral striae, about 3 1/2 to 4 whorls, the last rapidly increasing in width. Shell coloration is translucent to transparent pale amber to brownish. Aperture is oblique crescent-shaped, wider than tall and without teeth (denticles), lip not thickened, periphery rounded; umbilicus is relatively narrow, about 1/6 the shell diameter. Animal is dark to blackish on the head and tentacles. All generic forms previously referred to as “hammonis” are treated here as Nesovitrea electrina, although the name may have been applied by some authors to N. binneyana (Hendricks 2012, Burke 2013). Internal anatomy is described by Pilsbry (1946).

A combination of small size (< 5.5 mm diameter), narrow umbilicus, small number of whorls (3.5 to 4.0), whorls increasing in size with the last obviously enlarged, transparent and shiny shell lacking spiral striations or riblets, distinguish Nesovitrea from other genera. N. electrina differs from N. binneyana by having a shell diameter > 4.0 mm, shell a pale amber to brownish color, and the live animal blackish on head and tentacles.

A variety of wooded locations, often more restricted to moister sites, such as riparian zones, than Nesovitrea binneyana. Canopy species include Engelmann spruce, Douglas-fir, western larch, aspen, cottonwood, and Rocky Mountain juniper; secondary canopy includes paper birch, alder, and willow. Found under woody debris, rocks, bryophyte mats, in leaf litter or duff (Hendricks 2012).