- Helix pulchella O.F. Müller 1774 in 1773–1774: 30.
- Vallonia excentrica Sterki in Pilsbry 1893 in 1892–1893: 249, pl. 32 figs 6–9.
Identification. Shell depressed. Spire low but elevated. Whorls c. 3–3½, convex. Periphery medial. Suture deep. Last whorl not or scarcely descending at adult aperture. Protoconch smooth. Teleoconch without lamellar riblets but with incremental striae and wrinkles. Aperture rounded, width and height about equal, edentulous. Lip abruptly expanded, heavily thickened within. Umbilicus c. ⅓ of shell width. Shell silken; thin, translucent, whitish or almost clear; thickened lip brilliant white and opaque. Shell to 2.5 mm (wider than high).
Animal white, with black eye spots.
Comparisons. This species differs from all other Vallonia species in BC in lacking well-formed colabral ribs. In strongly ribbed species, when these ribs are worn off, care must be taken not to mistake them for V. pulchella.
Habitat. In BC, this species lives in gardens, in lawns, and on waste ground, under rocks, wood, debris, and vegetation. Snails are often associated concrete structures such as culverts and sidewalks, or under rocks, wood, and debris. Vallonia excentrica appears to occur only in anthropogenic habitats in BC, which is the basis for thinking that it is introduced.
Geographic range. In BC, generally widespread. Grass (1967a) reported V. pulchella from BC for the first time, and Forsyth (2004b) thought it (along with the synonymous V. excentrica) to be introduced. It occurs across southern Canada east to Newfoundland. It is also present in Europe and introduced to many places worldwide.
Etymology. Vallonia: named after either for the Roman goddess of valleys, Vallonia (Pilsbry 1948), or perhaps after the town of Vallon, Ardèche, south-central France (Kennard & Woodward 1926); the gender is feminine. Pulchella: diminutive of pulcher (Latin), lovely.
Remarks. Vallonia excentrica was, until recently, considered to be a separate species. Nekola et al. (2025) analyzed mtDNA and nDNA sequences and found that many of the morphological characters used to differentiate purported species of Vallonia are rather remarkably variable. Included among these characters is the development of the final portion of the last whorl. In the past V. excentrica was differentiated from V. pulchella by its more gradual expansion (vs sudden expansion at nearly a right angle in V. pulchella—e.g. Pilsbry 1948; Gerber 1996; Forsyth 2004).
References
- Forsyth RG (2004) Land Snails of British Columbia. Royal BC Museum, Victoria, BC, Canada, iv, 188 pp.
- Grass AL (1967) On Vallonia pulchella. Pacific Northwest Shell News 7: 43–44.
- 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
- Müller OF (1774) Vermium terrestrivm et fluviatilium, seu animalium infusorium, helminthicorum, et testaceorum, non marinorum, succincta historia. Volumen alterum: testacea. Heineck & Faber, Havniæ & Lipsiæ, xxxvi + 214 + [x] pp. https://doi.org/10.5962/bhl.title.46299
- Nekola JC, Gerber J, Horsáková V, Líznarová E, Kafimola S, Mikulášková E, Nováková M, Horsák M (2025) Taxonomic deception via obvious traits: oversplitting in European Vallonia Risso, 1826 (Mollusca: Gastropoda: Valloniidae). Zoologica Scripta 55: 37–51. https://doi.org/10.1111/zsc.70024
- Pilsbry HA (1892–1893) Helicidæ, Vol. VI. Manual of Conchology, Structural and Systematic with Illustrations of the Species Second Series: Pulmonata 8: 1–314, pls 1–58. https://www.biodiversitylibrary.org/page/1287448