Material seen. — KALIMANTAN. Kalimantan Selatan: 7 km N. of Kintap (V 3673/>10, HOLOTYPE RMNH 56910); limestone escarpments along road Benualawas-Limbungan (V 2856/>10).
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 3 3/8-3 5/8, 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 mm on the penultimate whorl, 4-7 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. Peristome distant from the spire, double, outer peristome 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 distinctly protruding from the outer, somewhat spreading. Spire: height 0.8-1.0 mm; width 0.6-0.8 mm; index 1.2-1.3. Total width 1.2-1.4 mm. Height aperture 0.3 mm; width 0.25-0.35 mm.
Distribution. — Borneo: Kalimantan, K. Selatan, S. and E. flanks of the Meratus Mts.
Notes. — 1. In 0. telestoma the penultimate whorl of the spire hardly bulges to the right when the shell is observed in front view. It also has a wider umbilicus. 2. The name refers to the entirely free tuba.