Planogyra clappi

Planogyra clappi (Pilsbry, 1898)
Western Flat-coil

  • Punctum clappi Pilsbry 1898: 133.
Planogyra clappi; Moresby Island, Haida Gwaii, BC; width 1.85 mm (RGF 04.018.5406).

Identification. Shell subdiscoidal. Spire nearly flat. Whorls few, ca 3½. Suture deep. Periphery rounded. Aperture almost round. Lip thin, simple. Umbilicus ca ¼ of shell width. Protoconch indistinctly, microscopically granular. Teleoconch sculpture prominent, erect, fragile, colabral periostracal ribs (but sometimes eroded off), ca 35 on last whorl; microscopic spiral striae, especially on base; microscopic incremental striae. Shell with a silky sheen, brown. Width to 2.2 mm (wider than high).

Animal translucent white; head and ocular tentacles grey.

Planogyra asteriscus from Eastern and Atlantic Canada and the Maritimes has a slightly broader umbilicus (ca ⅓ of shell width), somewhat fewer, more strongly erect colabral riblets (ca 18–30 on last whorl).

Habitat. Rich, moist forests, especially in cedar woods. In leaf litter.

Global range. Alaska and south to California; east to Idaho.

Canadian range. British Columbia: along coast, Haida Gwaii to Vancouver Island and mainland, and also in the wet southern interior mountains.

Etymology. Named for Dr George Hubbard Clapp (1858–1949), an American conchologist.