Plectostoma hosei (Godwin-Austen, 1890)  

By Godwin-Austen (1890)

"shell pyramidal, very narrowly perforate; sculpture of the upper whorls quite smooth, the free portion of the last being strongly constulate, the ribs near the aperture being in high relief; colour shining ochre; spire conic, flat-sided, apex blunt; suture swallow; whorls 5, flat, the last free, with considerable twist, compressed, producing a keel; aperture circular; peristome widely expanded. Size: major diam. 1.8; alt. axis 1.6 millim."

By Vermeulen (1994)

"Spire conical with about flat sides. Apex slightly oblique. Whorls 4 1/4 - 5 1/4; top whorls convex; last whorl obtusely angular at the periphery, flat to slightly convex above and below. Constriction with a transverse palatalis. Tuba slightly bulging and then abruptly narrrowed towards the constriction, obtusely angular or with an obtuse ridge below. Radial ribs on the spire either entirely absent, or present on the top whorls only, or present on the entire spire, if present rather closely placed to moderately spaced (3-5 ribs/0.5 mm on the penulimate whorl), distinctly sinuous on the lower half of the whorls; but those close to the tuba with a single deep loop on the periphery when the shell is observed in front view; those on the tuba (moderately) spaced (2-4 ribs/0.5 mm half-way), below with short, but deeply trough-shaped projection, abrading to a deeply looped scar. Spiral striation absent. Umbilicus open, 0.20-0.30 mm across. Aperture tilted up to 30 degrees with regard to the coiling axis, its upper margin usually below the level of the apex, sometimes slightly above, about circular. Peristome widely distant from the spire, double; outer peristome somewhat spreading beyond the inner, but gradually narrowed towards, and absent along the right side of the aperture; inner peristome slightly protruding from the outer, widely spreading. Spire: height 1.5-2.2 mm; width 1.1-1.5 mm; index 1.2-1.6. Total width 2.2-3.1 mm. Height and width aperture 0.5-0.8 mm."