“The smaller size, more distant sculpture, and the more uncoiled last whorl distinguish this species from O. baritense; also in that form the body-whorl is not produced upward so much anteriorly, the top of the peristome being about on a level with the second suture, whereas in the present species it almost reaches the third.” (E. A. Smith, 1894)
E.A. Smith (1894) original descriptions on Opisthostoma depauperatum – “Testa O. baritense similis, sed minor, minus elongata, lamellis distantioribus ornata, anfractu ultimo valde soluto, antice magis ascendente.”
Kobelt (1902) descriptions on Opisthostoma (Plectostoma) depauperatum – “Schale der vou O. (P.) baritense ähnlich, aber kleiner, wenig verlängert, mit weitläutigeren Lamellen. letzte Windung sehr abgelöst, vorn mehr emporsteigend.”
Vermeulen (1994)'s description
"Shell often reddish-brown. Spire conical with slightly convex sides, or with convex sides near the apex, slightly concave lower down. Apex slightly oblique or not. Whorls 5 3/8-6 1/4, convex; last whorl rounded. Constriction with a parietalis, a longitudinal and a transverse palatalis, a distinct columellaris. Tuba gradually narrowed towards the constriction, rounded below. Radial ribs (moderately) spaced (3-5 ribs/0.5 mm on the penultimate whorl, 3-4 ribs/0.5 mm half-way on the tuba), not or very slightly sinuous. Spiral striation absent or inconspicuous. Umbilicus open, 0.20-0.25 mm across. Aperture hardly tilted with regard to the soiling axis, circular, elliptic, or slightly angular. Peristome (widely) distant from the spire, rarely only slightly distant, double; outer peristome usually somewhat spreading beyond the inner, but gradually narrowed towards, and absent along the right side of the aperture, often slightly widened along the upper side; inner peristome usually moderately protruding from the outer, rarely only slightly protruding, spreading. Spire: height 1.5-2.3 mm; width 1.2-1.5 mm; index 1.3-1.6. Total width 2.2-2.6 mm. Height and width aperture 0.5-0.6 mm."
Opisthostoma (Plectostoma) depauperatum – “H. 1.5, Durchm. 2 mm.” (Kobelt, 1902)
Shell height – 1.5 mm; Shell width – 1-2 mm. Aperture diameter – 0.67 mm
Type locality – “Barit Mountain, North-west Borneo” (E. A. Smith, 1894)