By Vermeulen (1994)
"As the type subspecies, but spire with slightly concave to convex sides. Constriction with a distinctly knob-shaped basalis. Radial ribd on the spire rather closely placed to moderately spaced (3-6 ribs/0.5 mm on the penultimate whorl), slightly sinuous, but those close to the tuba often not or hardly sinuous; those on the tuba moderately to widely spaced (2-4 ribs/0.5 mm half-way). umbilicus 0.30-0.40 mm across. Aperture tilted up to 80 degrees with regard to the coiling axis. Peristome (widely) distant from the spire, outer peristome somewhat spreading beyond the inner or not, sometimes slightly widened along the upper side of the aperture; inner peristome hardly protruding from the outer. Spire: height 1.6-2.1 mm; width 1.2-1.4 mm; index 1.2-1.5. Total width 2.0-2.6 mm. height and width aperture 0.5-0.7 mm"