Plectostoma brevituba (Vermeulen, 1994)  

Description by Vermeulen (1994)

"Spire conical with flat to convex sides. Apex slightly oblique or not. Whorls 5 1/4- 6 1/4, convex; last whorl rounded. Constriction with a parietalis, a longitudinal and a transverse palatalis, a distinct columellaris. Tuba gradually narrowed towards the constriction, rounded below. Radial ribs (moderately) spaced (4-6 ribs/0.5 mm on the penultimate whorl and half-way on the tuba), not or hardly sinuous. Spiral striation fine. Umbilicus open, 0.20-0.30 mm across. Aperture hardly tilted with regard to the coiling axis, circular to elliptic, often slightly angular. Peristome almost touching the spire or somewhat distant from it, double; outer peristome slightly spreading beyond the inner, but gradually narrowed towards, and narrow or absent along the right side of the aperture, moderately widened or with a small wing along the upper side, and somewhat less widened along the lower side; inner peristome moderately protruding from the outer, spreading. Spire: height 1.8-2.3 mm; width 1.3-1.5 mm; index 1.3-1.6. Total width 2.2-2.4 mm. Height and width aperture 0.5-0.6 mm"