Wilhelminaia muscorum (van Benthem Jutting, 1959)
“Microcystina muscorum is higher conical than M. exigua (Moellendorff), M. nana (Moellendorff) or M. gratilla van Benthem-Jutting, and has better developed spiral sculpture than any of these. From M. circumlineata (Moellendorff) and M. fruhstorferi (Moellendorff) it differs in the smaller size. From M. circumlineata which is also spirally striated, it differs in the flatter shape, both above and below the periphery.” (Benthem-Jutting, 1959)
Benthem-Jutting (1959) original descriptions on Microcystina muscorum – “Shell small, low-conical, reddish-brown, shining and transparent. From the very beginning the whorls are striated, on both upper and basal sides, by spiral and radial lines of about equal strength. The spiral striae are undulating and appear as rows of minute pits. Whorls 4 ¼-4 ½, top whorl not mamillar as in Microcystina consobrina n.sp. All whorls slightly convex (less convex than in preceding species) with distinct suture. This suture is falsely marginate on account of the previous whorl shining through. It is mostly lined with a narrow red thread. Top blunt, base rounded. Umbilicus narrow. Aperture oblique, broad sickle-shaped, evenly rounded. Peristome sharp, not continuous, the two ends connected by a thin membrane against the previous whorl. Columellar side a little reflected, and with a minute tongue-shaped projection in the umbilical region, partly hiding the umbilical opening.”
Microcystina muscorum – “Height 1.0-1.4 mm, width 1.7-2.3 mm, height of aperture 0.7-0.9 mm” (Benthem-Jutting, 1959)
Type locality – “Hanna Estate, near Membang Muda, Sumatra’s East Coast” leg. J. P. van Niel (Benthem-Jutting, 1959)
“in grooves in the bark, among moss covering a Mango tree.” (Benthem-Jutting, 1959)