Vermuelen (1994) original descriptions on Opisthostoma crassicolle – “Spire broadly spindle-shaped. Apex not or hardly oblique. Whorls 31/4-35/8. convex; the penullimate obtusely angular on thc right side if the spire is observed in front view, the ultimate obtusely angular. Constriction with a transverse palatalis, with a columellaris. Tuba about half-way leaving a small gap between the tuba and the spire. slightly bulging close to lhe constriction and thell rather abruptly narrowed towards it. obtusely angular below. Radial ribs moderately spaced (4-6 ribs/0.5 mm on the penultimate whorl; 4-5 ribs/0.5 mm half-way the. tuba), not or hardly sinuous. Spiral striation present, fine. Umbilicus open but often partly covered by the tuba, 0.1 mm across. Aperture tilted up to 30° with regard to the coiling axis, its upper margin widely above the level of the apex, circular to elliptic. Peristome touching the spire, double, outer peristome widely spreading beyond the inner, but gradually narrowed towards and sometimes almost absent along the right side of the aperture; inner peristome distinctly protruding from the outer, little spreading, its outer surface and the upper surface of the outer peristome with closely placed, slightly irregular lamellae.”
Opisthostoma crassicolle – “Spire: height 1.0-1.1 mm; width 1.0 mm; index 1.0-1.1. Total width 1.2 mm. Height aperture 0.4-0.5 mm: width 0.35-0.40 mm.” (Vermeulen, 1994)
Type locality – “Kalimatan Selatan, Beramban, approximately 13 km E. of Rantau” leg. Vermeulen (Vermeulen, 1994)
West flank of Meratus Mountain. Kalimantan Selatan, Indonesia.