Striatura exigua

Striatura (Pseudohyalina) exigua (Stimpson, 1851)
Ribbed Striate

  • Helix annulata Case 1847: 101, figs 1–3, non Helix annulata G. B. Sowerby I, 1841.
  • Helix exigua Stimpson 1851: 175.
Striatura exigua, Prince Edward Island.

Identification. Shell subdiscoid, with very low, domed spire. Suture deep. Whorls ca 3½, last often rather descending in large adults. Periphery rounded, medial. Width of last whorl ca 2× penultimate whorl. Aperture subrotund, edentulous. Lip thin, simple. Protoconch with close, strong spiral threads. Teleoconch with widely spaced colabral thin-edged riblets, with spiral threads between, including on base. Umbilicus ca … of shell width. Shell thin, pale corneous. Width to … mm (wider than high).

Animal pale and said to be slightly greenish (Baker 1928).

Habitat. In forests; in leaf litter and under woody debris.

Global range. Eastern North America: Manitoba and east in Canada; in the USA from Maine, southwest to Virginia, and west to Michigan (Hubricht 1985).

Canadian range. Manitoba to Ontario (over much of the province, north nearly to James Bay; Oughton 1948); Quebec, the Maritime Provinces, and the Island of Newfoundland.

Etymology. Latin exiguus, small.

Remarks. This species was first described as Helix annulata by Case (1847), but that name is a homonym of Helix annulata G. B. Sowerby I, 1841, now Pachysphaera annulata (family Camaenidae), from the Philippines. Although frequently dated from 1850, Stimpson’s description of Helix exigua was published in 1851 (Runhoff 1980).