“Compared with O. (O.) tenerum, O. (O.) perlisianum differs in the following points: the apex is less projecting, the third whorl is broader, bulging out in the shell profile and the aperture is facing obliquely up and backward. Compared with O. (O.) javanum v. B. Jutting the new species has a less projecting apex, a wider umbilicus, more distantly placed ribs and a broader third whorl which bulges out in the shell profile.” (Benthem-Jutting, 1961)
Benthem-Jutting (1961) original descriptions on Opisthostoma (Opisthostoma) perlisianum – “Shell short-cylindrical, pupaeform, with little elevated apex, very similar to, but less elevate than O. (O.) tenerum v. B. Jutting. White or very light-yellow. First whorl smooth, later ones transversely ribbed with fine, white ribs, placed close together on the upper whorls, but more distantly on the last. Between the ribs there is a delicate spiral striation. Not or little transparent, not shining. Whorls 5, convex. First two placed a little obliquely on the shell. Spire a little elevated (not so much as in O. (O.) tenerum). Third whorl broader than the preceding or the following ones. Hence it bulges out in the shell profile. Suture deep. Last whorl somewhat constricted in the middle, then widening again and deviating, so that the aperture faces obliquely upwards and backwards, falsely suggesting a sinistral shell. Umbilicus open, but not wide. Aperture round, somewhat oblique, adnate to the upper part of the third whorl. Peristome continuous, circular, or rounded-triangular, duplex. Operculum unknown.”
Opisthostoma (Opisthostoma) perlisianum – “Dimensions: Height 0.8-1.0 mm, Width 1.2-1.3 mm, Diam. apert. 0.4-0.5 mm.” (Benthem-Jutting, 1961)
Type locality – “Malaya: Bukit Lagi, Perlis” (Benthem-Jutting, 1961)