Plectostoma everetti (Smith, 1893)
Mount Jambusan, western slope of hill (4km SE of Bau), Sarawak, Malaysia.
Mount Jambusan, western slope of hill (4km SE of Bau), Sarawak, Malaysia.
Smith (1892)'s description
"Testa dextrorsa, conica, rimata, rufescens vel alba; anfractus 5-5 1/2, convexi, primi duo laeves, caeteri lamellis obliquis tenuissimis in medio spiniformibus instructi, ultimus antice longe solutus, versus aperturam retrorsum et sursum contortus, seriebus duobus spinarum ornatus; spinae semitubuliformes, curvatae; series inferior longior, cristam basalum formans; apertura circularis rufescens vel alba; peristoma tenue, undique late expansum et concentrice striatum. Alt. 3 millim., diam. maj. 3 2/3 min., min. 2. Apertura cum perist. 1 1/2 lata."
Vermeulen (1994)'s description
"Spire conical with about flat sides. Apex not oblique. Whorls 4 7/8 - 5 3/8, convex; last whorl rounded. Constriction with an inconspicuous parietalis, a transverse palatalis. Tuba gradually narrowed towards the constriction, slightly angular below. Radial ribs on the spire widely spaced (2-3 ribs / 0.5 mm on the penultimate whorl), with a (deeply) trough-shaped projection half-way the whorls, abrading to a (deeply) looped scar, but those on the last whorl with a double-channeled projection (the lower channel deeper than the upper) abrading to a scar with two adjacent loops when the shell is observed in front view; those on the tuba widely spaced (1-2 ribs/0.5 mm half-way), below with a long, deeply trough-shaped to almost tubular, almost straight to distinctly curved projection abrading to a deeply looped scar. Spiral striarion present. Umbilicus open, 0.25-0.30 mm across. Aperture tilted 30-45 degrees with regard to the coiling axis, its upper margin slightly below the level of the apex, sometimes slightly above it, circular. Peristome distant from spire, double; outer peristome moderately to widely spreading beyond the inner all around, but gradually narrowed towards the right side of the aperture and soemtimes (almost) absent there; inner peristome slightly to moderately protruding from the outer, (widely) spreading. Spire: height 1.8-2.2 mm; width 1.3-1.5 mm; index 1.3-1.5. Total width 2.6-3.1 mm. height aperture 0.7-0.8 mm; width 0.7-0.9 mm."