Striatura pugetensis

Striatura (Pseudohyalina) pugetensis (Dall, 1895)
Northwest Striate

  • Patulastra? (Punctum?) pugetensis Dall 1895: 130.
  • Radiodiscus hubrichti Branson 1975: 47, fig. 1a–c.

Identification. Shell subdiscoid, with very low, domed spire. Suture deep. Whorls ca 3½, last slightly descending in 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 colabral thin-edged riblets, with spiral threads between, including on base. Umbilicus ca ¼ of shell width. Width to 1.8 mm (wider than high). Shell thin, pale corneous.

Animal translucent white, with head and tentacles grey and a small black spot over the lung.

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

Global range. Alaska south to Isla Guadalupe, Baja California, Mexico (Pilsbry 1927, Smith et al. 1990); east to Glacier National Park, north-western Montana (Berry 1919). Said to occur in Kauai, Hawaiian Islands (Baker 1941) but see ‘Remarks’.

Canadian range. British Columbia: along the whole coast; southern interior, including the Kootenays where it is known from a few, scattered records (Ovaska et al. 2020) and the North Thompson river valley (Forsyth 2001).

Etymology. Named after Puget Sound or its region.

Remarks. This species was first described as new by Dall (1895) from material collected at Seattle, Washington by the amateur conchologist P. B. Randolph. Berry (1919) first recognized this species as a Striatura, and Baker (1928) later placed the species in the subgenus Pseudohyalina. While specimens from northwest Montana were said by Berry (1919: 492) to be “larger and flatter and coarser in appearance, slightly approaching in some respects the giant southern meridionalis Pilsbry and Ferriss [1906]”, Pilsbry (1946) considered these to be typical of S. pugetensis. Specimens from Kauai were identified by Baker (1941) as S. pugetensis, but his figured specimen (pl. 60, figs 1–3) shows a shell with a higher spire and slightly different form than British Columbia material, and one suspects that it is not the same species. Radiodiscus hubrichti Branson, 1975, which was described from the Olympic Peninsula, was recognized by Solem (1977a, b) as a synonym of Striatura pugetensis.


References

  • Baker HB (1928) Minute American Zonitidae. Proceedings of the Academy of Natural Sciences of Philadelphia 80: 1–44, pls. 1–8.
  • Baker HB (1941) Zonitid snails from Pacific Islands, parts 3 and 4. 3. Genera other than Microcystinae. 4. Distribution and indexes. Bernice P Bishop Museum, Bulletin 166: 203–370, pl. 43–65.
  • Berry SS (1919) Mollusca of Glacier National Park, Montana. Proceedings of the Academy of Natural Sciences of Philadelphia 1919: 195–205, pls 9–10.
  • Branson BA (1975) Radiodiscus hubrichti (Pulmonata: Endodontidae) new species from the Olympic Peninsula, Washington. The Nautilus 89: 47–48.
  • Dall WH (1895) New species of land shells from Puget Sound. The Nautilus 8: 129–130.
  • Forsyth RG (2001) A note on the distribution of Striatura pugetensis in British Columbia. The Festivus 33: 57–58.
  • Ovaska K, Sopuck L, Heron J (2020 “2019”) Surveys for terrestrial gastropods in the Kootenay region of British Columbia, with new records and range extensions. The Canadian Field-Naturalist 133: 221–234.
  • Pilsbry HA (1927) Expedition to Guadalupe Island, Mexico, in 1922. Land and freshwater mollusks. Proceedings of the California Academy of Sciences (Series 4) 16: 159–203, pls 6–12.
  • Pilsbry HA (1946) Land Mollusca of North America (north of Mexico), 2(1). The Academy of Natural Sciences of Philadelphia, Monographs 3: frontis., i–vi, 1–520.
  • Smith AG, Miller WB, Christensen CC, Roth B (1990) Land Mollusca of Baja California, Mexico. Proceedings of the California Academy of Sciences 47: 95–158.
  • Solem A (1977a) Radiodiscus hubrichti Branson, 1975, a synonym of Striatura pugetensis (Dall, 1895) (Pulmonata: Zonitidae). The Nautilus 91: 146–148.
  • Solem A (1977b) Shell microsculpture in Striatura, Punctum, Radiodiscus, and Planogyra (Pulmonata). The Nautilus 91: 149–155.