Opisthostoma hypermicrum van Benthem Jutting, 1961
“Opisthostoma (O.) hypermicrum is smaller than either O. (O.) obtusum v. B. Jutting, O. (O.) platycephalum v. B. Jutting or O. (O.) uranoscopium v. B. Jutting. In shape it is nearest to O. (O.) platycephalum and not so high as the other two species just mentioned. The distal part of the last whorl is not so trumpet-shaped as in O. (O.) platycephalum. The ribs are placed closer together than in O. (O.) obtusum or O. (O.) atalum n.sp.” (Benthem-Jutting, 1961)
Benthem-Jutting (1961) original descriptions on Opisthostoma (Opisthostoma) hypermicrum – “Shell short-cylindrical, slightly oblique, white, not or hardly shining or transparent. First whorl smooth, subsequent ones ornamented with fine, white, transverse ribs, close together on the early whorls, and not much wider apart (not so wide as in O. (O.) obtusum v. B. Jutting or O. (O.) atalum n.sp.) on the last whorl. With a very delicate spiral sculpture. Whorls 3 ½-4, convex. The top whorls in one plane and somewhat oblique on the axis of the shell. Suture deep, Last whorl widened towards the aperture, but not so trumpet-shaped as in O. (O.) platycephalum v. B. Jutting. The aperture is directed to the sky. It is round and adnate to the penultimate whorl, reaching about halfway up the height of that whorl. Peristome continuous, circular to rounded-triangular, duplex. Operculum unknown.”
Opisthostoma (Opisthostoma) hypermicrum – “Dimensions: Height 0.5-0.6 mm, Width 0.9-1.0 mm, Diam. apert. 0.3-0.4 mm.” (Benthem-Jutting, 1961)
Type locality – “Malaya: Bukit Chintamani, Pahang” (Benthem-Jutting, 1961)