“The new species is somewhat related to O. (P.) laidlawi, O. (P.) annandalei and O. (P.) decrespignyi, but the spire is more turreted and the free part shorter than in either of these. From O. (P.) tonkinianum Dautz. & Fisch. It differs in the more slender spire and smaller size. Moreover the last whorl is entirely adnate, without free part in O. (P.) tonkinianum.” (Benthem-Jutting, 1952)
Benthem-Jutting (1952) original descriptions on Opisthostoma (Plectostoma) salpidomon – “Shell high-turreted, reddish-brown, yellowish-brown or fawn. First 1 ½ whorl smooth, subsequent ones ornamented with fine white oblique ribs at more or less regular intervals. In fresh condition these ribs stand out wing-like away from the shell. In worn specimens they appear as elevated threads on the whorls. No spiral sculpture between the ribs. Not transparent and only little shining. Whorl 7 ½-8 ½, convex. The first 6 ½-7 ½ regularly increasing in size, the last somewhat constricted at its beginning, then widening again and turning back along the base of the shell as if starting a sinistral spiral. Distal part, just before the aperture ascending, free, like a small trumpet. Top whorls not oblique on the rest of the shell. Suture deep. Umbilicus narrow, in some specimens hidden by the abnormal twist of the last whorl. Aperture vertical or somewhat directed upwards, round. Peristome continuous, almost circular, flanged by a collar-like rib behind the peristome and parallel to it. Operculum unknown.”
“…on renewed investigation, spiral striae proved to be present.” (Benthem-Jutting, 1961)
Opisthostoma (Plectostoma) salpidomon – “Dimensions: Height 3.0-3.4, Breadth 2.4-2.9, Diam. apert. 1.0-1.1 mm.” (Benthem-Jutting, 1952)
Type locality – “Malaya: Gua Bama, near Padang Tengku, Pahang” (Benthem-Jutting, 1952)
Other localities – “Malaya: Gua Tinggi, near Kuala Lipis, Pahang” (Benthem-Jutting, 1952); “Malaya: Goa Siput, near Batu Lompat, Pahang” (Benthem-Jutting, 1952); “Malaya: Gua Che Yatin, Ulu Tembeling, Pahang” (Benthem-Jutting, 1961)