Japonia hyalina Vermeulen & Junau, 2007
“Easily recognizable among Bornean Japonia because by the following combination of characters: shell small, glassy, white without any brown markings, peripherial keel distinct, periostracum very thin, translucent. The shells resemble Craspedotropis andrei Vermeulen, 1999 (Sarawak: Gunung Mulu N.P.) which, however, has a more angular peristome and weaker spiral sculpture above the peripherial keel. In spite of the resemblance, we think that both Japonia species presently described are, indeed, Japonia rather than Craspedotropis because they have a distinct notch in the peristome, near the suture; a character typical for Japonia but absent in Craspedotropis. The two genera also differ in operculum structure but, onfortunately; no operculums are available of the two species described here.” (Vermeulen & Junau, 2007)
Vermeulen & Junau (2007) original descriptions on Japonia hyalina – “Shell very small, conical with concave sides, translucent white, shiny. Whorls 4 1/8-4 5/8, the first whorls convex, the last distinctly keeled at the periphery, slightly convex above and below. Suture impressed. Sculpture protoconch: surface minutely verrucate. Radial sculpture teleoconch: the first whorls with fine, densely placed and regularly spaced riblets, later whorls with growth lines, only locally grading into riblets. Spiral sculpture teleoconch: the first whorls with 6-9 about equally strong spiral ridges with a minutely erose crest; in the later whorls the lowermost developing into the peripheral keel and above this 2-6 continuing, those closest to the periphery strongest and leaving the area below the suture without spiral sculpture; below the periphery with c. 3 spiral ridges: 2 near the periphery and a third, very weak, basal. Umbilicus open, 0.7-0.9 mm diam. Aperture subcircular. Peristome triple; the inner two little reflected, close together, not reflected, a circular rim with a notch at the level of the suture; the outer distinctly widened and reflected, flat or slightly convex, widening towards the palatal side, deeply notched near the suture. Periostracum very thin, translucent, virtually without appendages.”
Japonia hyalina – “Height 2.9-3.5 mm; width (excl. peristome) 3.6-4.4 mm. Apertural height 1-1.2 mm, width 1.1-1.3 mm.” (Vermeulen & Junau, 2007)
Type locality – “Malaysia, Sarawak, 2nd div.: Bukit Anyi, NW. side” (Vermeulen & Junau, 2007)
Other localities – “Malaysia, Sarawak, 2nd div.: Lower Tatau River valley, Bukit Sarang group” leg. S. Lee (Vermeulen & Junau, 2007); “Malaysia, Sarawak, 2nd div.: Lower Bukit Lebik, ground level” (Vermeulen & Junau, 2007)
Ecology – “Lowland rainforest on and near limestone bedrock.” (Vermeulen & Junau, 2007)