Opisthostoma cryptodon Vermeulen, 1991
Bau, Sarawak, Malaysia.
Bau, Sarawak, Malaysia.
Vermeulen (1991)'s description
"shell white, slightly translucent. Whorls 3-3 5/8 (tuba not included); top whorls somewhat oblique, moderately elevated; body whorls forming an often slightly obliquely cylindrical body, convex, well rounded, with the suture well impressed. Constriction rather distinct, gradual. Tuba consisting of approximately 1/2 whorl (rarely somewhat less), touching the body whorls over its entire length, approximately circular in section. Shell with rather narrow radial ribs, which are moderately to widely spaced near top, densely placed to widely spaced and low on the upper body whorl (17-55 ribs present on this whorl), approximately similar but widely spaced on the lower body whorl and over the area of the constriction, and widely spaced and more prominent on tuba. Ribs crossed by fine spiral striation. umbilicus open, deep, narrow. Aperture with the imaginary plane through the inner peristome tilted up to 15 degrees wiht regard to the coiling axis of the body whorls; with the upper margin not or hardly protruding beyond the plane perpendicular to the coiling axis of the body whorls as well as through the apex; subtrangular; one apertural tooth: a very short, knob-like one along the upper margin, close to the peristome; inner peristome moderately thinkened, moderately reflected; outer peristome distinctly flaring on the palatal side. Constriction inside with three teeth: one longitudinal, long, lamella-like parietalis, starting at the constriction and projecting into the tuba, but ending well before reaching the peristome (the end only just visible deep inside the aperture); one distinct, oblique, short, rater high infracolumellaris; one transverse, long palatalis. Measurements. - Height of body whorls 1.0-1.3 mm; width including tuba 1.3-1.8 mm, without tuba 0.8-1.1 mm; height of aperture 0.6-0.8 mm; width of aperture 0.6-0.7 mm."