Plectostoma stenotoreton (Vermeulen, 1994)
Beluru area, Sarawak, Malaysia.
Beluru area, Sarawak, Malaysia.
By Vermeulen (1994)
"Spire conical with about flat to concave sides. Apex not oblique. Whorls 5 5/8 - 6, convex; last whorl
rounded. Constriction with a transverse palatalis. Tuba gradually narrowed towards the constriction,
slightly angular below. Radial ribs on the spire widely spaced (2 ribs/0/5 mm on the penultimate whorl),
with a (deeply) trough-shaped projection on the lower half of the whorl, abrading to a (deeply) looped scar, those on the shell is observed in front view; those on the tuba widely spaced (1/2 ribs/0.5 mm half-way), with a longer, curved projection, other wise similar. Spiral striation present. Umbilicus open, 0.15-0.20 mm across. Aperture tilted 30-45 degrees with regard to the coiling axis, its upper margin below the level of the apex, circular to elliptic. Peristome distant from spire, double; outer peristome slightly to moderately spreading beyond the inner, usually gradually narrowed towards, and narrow or absent along the right side of the aperture; inner peristome slightly protruding from the outer, (widely) spreading. Spire: height 2.1-2.5 mm; width 1.3-1.4 mm; index 1.5-1.9. Total width 2.8-3.1 mm. Height aperture 0.6-0.9 mm, width 0.7-0.8 mm."