E-Fauna BC: Electronic Atlas of the Wildlife of British Columbia

Diagnosis

Among species of pupilloids in BC, Lauria cylindracea is most similar to species of Pupilla, but differing by the presence of apertural denticles at all stages of growth. In adults, the angular denticle is connected to the palatal lip near the suture by a callus.

Shell

Small (maximum mature height: 4.1 mm); growth determinate; subcylindrical to subovate; subtranslucent. Whorls: ca 6; spire whorls convex. Spire: elongate; sides slightly convex; apex bluntly rounded. Suture: indented. Last whorl: not descending to the peristome; constriction of whorl behind the baso-palatal lip almost non-existent; no apparent crest. Periphery: rounded, medial on last whorl. Protoconch: ca 1½ whorls, smooth. Teleoconch sculpture: fine, irregular incremental striae. Periostracum: simple, cuticular; frequently worn. Umbilicus: small; partially occluded by the columellar lip. Aperture: subovate. Peristome: incomplete. Apertural dentition: 1 prominent, &plusm; tubercular denticle, generally connected to the lip with a callus; sometimes 1 columellar and 1 subcolumellar denticle; juveniles with columellar and parietal folds and several small, flat, transverse lamellae inside the whorl. Palatal and baso-columellar lip: expanded into a broad, flat face; palatal lip often strongly thickened and almost dentate. Peristome, viewed from side: prosocline. Parietal callus: glazed, transparent. Colour (periostracum): brown or grey-brown, &plusm; shining; grey when periostracum worn away; lip and apertural dentition white.

Animal

Dark blue-grey to grey, becoming paler on the sides and sole of the foot (Reeve 1863, Barker 1999). Tail of crawling animals short and not extending behind the shell (Barker 1999). Anatomy Reproductive anatomy is described and figured by Steenberg (1925) and Barker (1999), both of whom also studied and illustrated other organ systems. Aphally is unknown in this species, in contrast to many other species within the Orthurethra.