Diaphera helenae Vermeulen, 1990
“Most similar to D. wilfordii. It differs from that species mainly in the larger number of whorls and the more narrowly ellipsoid, almost cylindrical outline of the shell. The two species are strictly allopatric. At two or three stages during their development the juveniles develop a thickened and reflected peristome. The dentition in the aperture differs from that of the adults. The peristome has a knob-like thickening on the palatal side. Four teeth are present: one angularis, one columellaris, two basalis. In general the juveniles are remarkably similar to the juveniles of some W. Malaysian Sinoennea perakensis (Godwin Austen & Nevill, 1879).” (Vermeulen, 1990)
Vermeulen (1990) original descriptions on Diaphera helenae – “Shell ellipsoid to somewhat obovoid. Apex somewhat oblique. Whorls 8.25-10, convex, top whorls more or less smooth; next whorls with the suture crenulated; crenulations often (not always) continuing as inconspicuous, thin radial riblets over the entire width of the whorl; the last 1.25-1.5 whorl with an approximately sharp, crenulated lower margin; radial riblets very distinct on the last 0.5 whorl. Umbilicus rather wide. Aperture approximately orbicular to obliquely ovate. Peristome somewhat thickened on the palatal side. Teeth three; one distinct, projecting angularis starting on the peristome; one deeply set columellaris; one deeply set palato-basalis.”
“Measurements. - Height 6.8-8.3 mm; height minus detached portion 5-7.1 mm; width 2.5-3.1 mm; height of aperture: 1.4-1.7 mm; width of aperture 1.4-1.6 mm.” (Vermeulen, 1990)
Type locality – “SABAH. Tawau Zone: G. Madai” leg. H. Duistermaat & J. J. Vermeulen (Vermeulen, 1990)
Other localities - ”Segarong Hills 25 km ESE of Kunak, Batu Tengar” and “Bt. Pababola” leg. H. Duistermaat & J. J. Vermeulen (Vermeulen, 1990)
Segarong Hills, Sabah, Malaysia.
"Calcicole.” (Vermeulen, 1990)
"on coastal or inland limestone outcrops.” (Vermeulen, 1990)