Plectostoma lissopleuron lissopleuron (Vermeulen, 1994)  

By Vermeulen (1994)

"Spire conical with concave to slightly convex sides. Apex slightly oblique or not. Whorls 5 3/8 - 6 7/8, convex; last whorl rounded to slightly angular. Constriction with a parietalis, a longitudinal and a transverse palatalis, a columellaris which continues as a knob- to ridge-shaped transverse basalis. tuba gradually narrowed towards the constriction, rounded to angular below. Radial ribs on the spire closely placed to moderately spaced (3-8 ribs/0.5 mm on the penultimate whorl), sinuous or not, those on the tuba rather closely placed to moderately spaced (3-6 ribs/0.5 mm half-way), sinuous or with a shallow to deep, semi-circular loop below, and sometimes with a short projection. Spiral striation inconspicuous to distinct. umbilicus open, 0.35-0.55 mm across. Aperture tilted up to 45 degrees with regard to the coiling axis, circular to elliptic. Peristome distant from spire, double; outer peristome hardly to distinctly spreading beyond the inner, gradually narrowed towards, and absent or very narrow along the right side of the aperture, often with a widely rounded wing along the upper side of the aperture, and sometimes a similar but less conspicuous wing along the lower side; inner peristome hardly to moderately protruding from the outer, at most with inconspicuous lamellae on its outer surface, spreading. Spire: height 1.7-2.4 mm; width 1.1-1.6 mm; index 1.3-1.7. Total width 2.2-3.2 mm. Height and width aperture 0.5-0.7mm"