- Carychium exiguum var. occidentalis [sic] Pilsbry 1891a: 109, without gender agreement; with gender corrected: occidentale.
- Carychium magnificum Hanna 1923: 51, fig. 1.
Identification. Shell minute, fusiform, thin-shelled. Spire elongate, sides rather straight. Whorls c. 5. Apex bluntly rounded. Suture deep. Periphery rounded. Protoconch smooth. Teleoconch smoothish, with weak colabral striae. Aperture subovate; c. ⅓ of shell height, with 1 larger parietal lamella that continues internally around columella in a smooth curve, 1 weakly formed lamella at base of columella that may be lacking. Lip expanded, edge thin, seldom with a low, medial callus on inside. Peristome, viewed from side: prosocline, not strongly sinuous; belly of last whorl not projecting beyond the plane of peristome. Parietal callus glazed, transparent, inconspicuous. Shell colourless or translucent white; with a silken sheen. Shell 2.0–2.7 mm high (higher than wide).
Animal white with black eyespots.
This is the largest Carychium species in BC, further distinguished by its clearly tapering spire, weakly sculptured shell, and thin, but expanded, palatal lip.
Habitat. This species occurs in relatively undisturbed deciduous and mixed lowland forests at and below 80 m elevation. Bigleaf Maples (Acer macrophyllum Pursch) are usually present. It is found mostly in deep-litter areas, in hollows, near seeps, and in riparian zones that are perpetually moist but not overly wet. Colonies are scattered and patchy in their distribution.
Geographic range. BC, south to northern California where it occurs in the coastal counties of Del Norte, Humboldt, and Mendocino (Roth and Sadeghian 2003); east through northern Washington and possibly in the Idaho Panhandle (Frest and Johannes 2001).
In BC, C. occidentale occurs along the coast from at least the northern end of Vancouver Island south. It is expected for wet areas of the south-eastern interior, although not found there in the extensive surveys by Ovaska et al. (2020). Union Bay, Vancouver Island (Hanna 1923), is the type locality of C. magnificum, a synonym of C. occidentale (Pilsbry 1948).
Etymology. Carychium, from the Greek karyx, a herald, signifying the ancient use of a shell as a trumpet (Kennard & Woodward 1926); the gender is neuter. Occidentale (Latin), western.
Remarks. Carychium occidentale was first described as new by Pilsbry (1891a) from Portland, Oregon, the only locality from which he had seen this species. In the original description, Pilsbry wrongly spelled the species occidentalis, a mismatch of the gender with that of the genus.
In 1916, G Dalla Hanna (1923) briefly visited Vancouver Island where he collected land snails. Among those found at Union Bay were specimens of Carychium which he described as C. magnificum on account of their impressively large size. Hanna thought that his C. magnificum was a larger species, different from C. occidentale, although “undoubtedly closest related” (Hanna 1923: 52). Shortly thereafter, Pilsbry commented that it is “larger than one of the type lot of C. occidentale, and appears to resemble that in shape and internal lamellæ” (Pilsbry 1923: 141), but Hanna’s C. magnificum was soon subjugated to the synonymy of the earlier C. occidentale.
Early records of C. exiguum from Vancouver Island (e.g. Taylor 1889), which pre-date Pilsbry’s description of C. occidentale, are almost certainly this species.
References
- Hanna GD (1923) A new species of Carychium from Vancouver Island, British Columbia. Proceedings of the California Academy of Sciences (Series IV) 12: 51–53.
- Roth B, Sadeghian PS (2003) Checklist of the land snails and slugs of California. Santa Barbara Museum of Natural History Contributions in Science 3: 1–81.
- Frest TJ, Johannes EJ (2001 “2000”) An annotated checklist of Idaho land and freshwater mollusks. Journal of the Idaho Academy of Science 36: 1–51.
- Kennard AS, Woodward BB (1926) Synonymy of the British non-marine Mollusca (Recent and post-Tertiary). British Museum (Natural History), London, United Kingdom, xxiv + 447 pp. https://doi.org/10.5962/bhl.title.8325
- Taylor GW (1889) The land shells of Vancouver Island. The Ottawa Naturalist 3: 84–94.
- Pilsbry HA (1923) A new species of Carychium from Vancouver Island. The Nautilus 36: 141.
- 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. https://doi.org/10.22621/cfn.v133i3.2287
- Pilsbry HA (1891) Forms of American Carychium. The Nautilus 4: 109–110.