“In O. telestoma the penultimate whorl of the spire hardly bulges to the right when the shell is observed in front view. It aIso has a wider umbilicus.” (Vermeulen, 1994)
Vermuelen (1994) original descriptions on Opisthostoma asyndeton – “Spire subcylindrical, along its right side with the penultimate whorl distinctly wider than the ultimate if the shell is observed in front view. Apex slightly oblique. Whorls 33/8-35/8, convex; last whorl rounded. Constriction with a transverse palatalis, with a columellaris. Tuba entirely distant from the spire, gradually narrowed towards the constriction, rounded below. Radial ribs rather closely placed to rather widely spaced (4-8 ribs/0.5 min on the pellultimate whorl, 1-7 ribs/0.5 mm half-way the tuba), not sinuous. Spiral striation present. Umbilicus open, 0.05-0.10 mm across. Aperture tilted up to 45° with regard to the coiling axis, its upper margin widely below the level of the apex, circular to slightly angular. Pcristome distants from the spire, double, outer peristome moderately spreading beyond the inner, but gradually narrowcd towards, and absent along the right side of the aperture, sometimes slightly widened along the upper side; inner peristame distinctly protruding from the outer, somewhat spreading.”
Opisthostoma asyndeton – “Spire: height 0.8-1.0 mm; width 0.6-0.8 mm; index l.2-1.3. Total width 1.2-1.4 mm. Height aperture 0.3 mm; width 0.25-0.35 mm.” (Vermeulen, 1994)
Type locality – “Kalimatan Selatan, 7 km N. of Kintap” leg. Vermeulen (Vermeulen, 1994)
Other locality – “Kalimantan Selatan, limestone escarpment along road Benualawas-Limbungan leg. Vermeulen (Vermeulen, 1994)