Opisthostoma semisolutum Vermeulen, 1994
“Similar in some aspects to O. acolaston.” (Vermeulen, 1994)
Vermuelen (1994) original descriptions on Opisthostoma semisolutum – “Spire cylindrical. Apex (slightly) oblique. Whorls 3¼-3½, convex last whorl rounded, Constriction with a transverse palatalis. Tuba about half-way leaving a small gap between the luba and the spire, gradually narrowed towards the constriction, rounded below. Radial ribs moderately spaced (4-6 ribs/0.5 mm on the penultimate whorl as well as halfway the tuba), not sinuous. Spiral striation present, fine. Umbilicus open, 0.1 mm across. Aperture tilted up to 60° with regard to the coiling axis, its upper margin usually widely above the level of the apex, somewhat elliptic. Peristome touching the spire, double, outer peristome spreading beyond the inner, but gradually narrowed towards and absent along the right side of the aperture: inner peristome distinctly protruding from the outer, somewhat spreading.”
Opisthostoma semisolutum – “Spire: height 0.8-0.9 mill: width 0.7-0.8 mm; index 1.1-1.3. Total width 1.1-1.2 mm. Height aperture 0.25-0.35 mm; width 0.35-0.40 mm.” (Vermeulen, 1994)
Type locality – “Kalimatan Selatan, Nateh near Batu Tangga, approximately 18 km E. of Barabai” leg. Vermeulen (Vermeulen, 1994)
West flank of Meratus Mountain, Kalimantan Selatan, Indonesia.