- Saraphia tridentata Risso 1826: 84.
Identification. Shell minute, fusiform, thin-shelled. Spire more elongate than Carychium minimum, sides rather convex. Whorls c. 5. Apex bluntly rounded. Suture deep. Periphery rounded. Protoconch smooth. Teleoconch with weak incremental striae initially, regular, colabral striae on last 2 whorls. Aperture subovate; c. 2/5 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, thickened, with a strongly projecting, medial callus on inside. Peristome, viewed from side: prosocline, strongly sinuous; belly of last whorl projecting beyond the plane of peristome. Parietal callus glazed, transparent, inconspicuous. Shell colourless or translucent white; with a silken sheen. Shell height to 2.0 mm (higher than wide).
Animal white with black eyespots. The animal has two conical-cylindrical tentacles; ocular tentacles are absent, and the eyes are located at the base of the tentacles. The narrow foot is not divided into two longitudinal sections as is typical for many marine ellobiids (Watson & Verdcourt 1953) and the anterior is bilobed. The male and female genital openings are separate on the right side, with the male genital pore just in front of the right tentacle and the female genital pore towards the base of the neck.
This species is most like C. minimum, but it is recognized by its greater number of whorls, longer spire, and smoothly curved internal lamella.
Habitat. In BC,C. tridentatum is only known from a city park, where it has been found in leaf litter of an unkempt garden of mature trees and shrubs (Forsyth and Williston 2012).
Geographic range. Native to the Western Palaearctic. In BC, this species is known only from Queen Elizabeth Park, Vancouver (Forsyth and Williston 2012; Weigand et al. 2012).
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. Tridentatum (Latin), three-toothed.
Remarks. The identification of BC specimens was confirmed by molecular analysis (Weigand et al. 2012).
References
Forsyth RG, Williston P (2012) Terrestrial snails from an urban park in Vancouver, British Columbia. The Festivus 44: 77–80.
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
Risso A (1826) Histoire naturelle des principales productions de l’Europe méridionale et pariculièrement de celles des environs de Nice et des Alpes Maritimes. Tome quatière. F.-G. Levrault, Paris, France, viii + 439 pp., 12 pls. pp. https://doi.org/10.5962/bhl.title.58984
Watson H, Verdcourt B (1953) The two British species of Carychium. Journal of Conchology 23: 306–324, pls 9, 10. Weigand AM, Pfenninger M, Jochum A, Klussman-Kolb A (2012) Alpine crossroads or origin of genetic diversity? Comparative phylogeography of two sympatric microgastropod species. PLoS ONE 7: e37089. https://doi.org/10.1371/journal.pone.0037089