Plectostoma jucundum (Smith, 1893)  

By Smith (1892)

"Testa umbilicata, conica, plus minus rufescens; anfractus 7, apicales laeves, rotundati, caeteri lamellis numerosis tenuibus obliquis in medio subproductis instructi, ultimus contortus, retrorsus, antice solutus; peristoma tenue, anguste reflexum. Alt. 2 1/2 millim., diam. maj. 3, min. 1 1/2. Apertura 1 lata.."

By Vermeulen (1994)

"spire conical with flat sides. Apex slightly oblique or not. Whorls 5 7/8 - 6 1/8, convex; last whorl rounded. Constriction with a parietalis, a longitudinal and a transverse palatalis, a columellaris which continues as a ridge-shaped transverse basalis. Tuba gradually narrowed towards the constriction, rounded below. Radial ribs on the spire moderately to widely spaced (3-5 ribs/0.5 mm on the penultimate whorl), sinuous with a shallowly concave projection half-way, abrading to a sinuous scar, those on the tuba widely spaced (2-3 ribs/0.5 mm half-way), below slightly sinuous and with a shallowly concave projection, abrading to a not or slightly sinuous scar. Spiral striation distinct, rather coarse. Umbilicus open, 0.30-0.35 mm across. Aperture hardly tilted with regard to the coiling axis, circular to elliptic. Peristome distant from the spire, double; outer peristome only slightly spreading beyond the inner, but gradually narrowed towards, and absent along the right side of the aperture, sometimes slightly widened along the upper side; inner peristome slightly protruding from the outer, spreading. Spire: height 2.0-2.3 mm; width 1.4-1.5 mm; index 1.4-1.5. Total width 2.5-2.8 mm. Height aperture 0.5-0.6 mm; width 0.6 mm."