Plectostoma wilfordi (Vermeulen, 1994)
Beluru area, Sarawak, Malaysia.
Beluru area, Sarawak, Malaysia.
(By Vermeulen, 1994)
"Spire conical with flat to concave sides. Apex not oblique. Whorls 4 7/8 - 6, convex; last whorl
rounded. Constriction with a transverse palatalis. Tuba free from spire, gradually narrowed towards the
constriction, rounded below. Radial ribs on the spire rather closely placed to widely spaced (3-8
ribs/0.5 mm on the penultimate whorl), not sinuous, but widely spaced (2-3 ribs/0.5 mm) on the last
whorl; those on the tuba (rather) widely spaced (3-4 ribs/0.5 mm half-way), not or hardly sinuous.
Spiral striation present, often very fine. Umbilicus open, 0.25-0.35 mm across. Aperture tilted up to 45
degree with regard to the coiling axis, its upper margin widely below the level of the apex, circular to elliptic. Peristome double, outer peristome slightly to moderately spreading beyond the inner, but gradually narrowed towards, and absent along the right side of the aperture, sometimes slightly widened along the upper side; inner peristome slightly to moderately protruding from the outer, moderately spreading, usually somewhat drawn out on the right side of the aperture. Spire: height 1.4-1.8 mm; width 0.5 mm; index 1.2-1.7. Total width 2.0-2.3 mm. Height aperture 0.4-0.5 mm; width 0.5 mm."