Opisthostoma sulcatum Vermeulen, 1994

Morphology: 

By Vermeulen (1994)

"spire cylindrical. Apex distinctly oblique. Whorl 3 1/8 - 3 3/8, convex; last whorl rounded. Constriction with a transverse palatalis. Tuba touching the spire over its entire length, close to the constriction with a distinct swelling without radial ribs, bordered by a depression on both sides; the swelling with a deep semi-circular furrow opening to the right side if the shell is observed in front view; tuba rounded below. Radial ribs not sinuous, on the spire moderately spaced (4-6 ribs/0.5 mm on the penultimate whorl), those on the tuba often slightly wider spaced (4 ribs/0.5 mm half-way the tuba). Spiral striation present. Umbilicus usually entirely covered by the tuba. Aperture hardly tilted with regard to the coiling axis, its upper margin usually slightly above the level of the apex, circular to slightly elliptic. Peristome double, outer peristome spreading beyond the inner but rather abruptly narrowed towards, and absent along the (lower) right side of the aperture; inner peristome distinctly protruding from the outer, somewhat spreading. Spire: height 0.9-1.0 mm and width 0.7-0.9 mm; index 1.1-1.3. Total width about 1.1-1.3 mm. Height aperture 0.3-0.4 mm; width 0.35-0.40 mm."

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith