- Carychium minimum O.F. Müller 1773 (1773–1774): 125.
- Other synonyms in older European literature.
Identification. Shell obese-fusiform. Spire elongate, with strongly convex sides. Apex bluntly pointed. Whorls c. 4, convex. Sutures rather well indented. Protoconch smooth. Teleoconch with weak incremental striae initially, regular, colabral striae on last two whorls. Aperture subovate; 1 parietal lamella, continuing internally around columella in a smooth, not undulating curve; 1 smaller lamella at base of columella. Adult lip expanded, a little recurved, thickened on inner side, especially medially on palatal lip. Belly of the last whorl projected beyond the plane of peristome. Chink-like “false umbilicus” against base of last whorl. Shell translucent, colourless when fresh, opaque, and white when dead. Shell to 1.9 mm high (higher than wide).
The animal’s body in unpigmented, white, with black eye spots behind the single pair of cylindrical tentacles (Adam 1960; Roth 1982).
Comparison. Among Carychium species in BC, this species is recognized by its faintly striate, stouter shell, having fewer whorls and a greatly thickened palatal lip which bears a prominent medial denticle. The aperture is relatively larger portion of the shell height than in the other Carychium species in BC. The internal lamella is regularly spiral, which is not the case inC. tridentatum.
Habitat. This species lives in permanently wet habitats. In BC, in occurs in dead vegetation and under driftwood and logs along the tidal shoreline of the Fraser River, and it was found under flowerpots and other objects in a well-watered garden centre on Vancouver Island (Forsyth 2004b). It should be expected in wet areas of gardens, such as found in the tree-fern garden in Golden Gate Park, San Francisco, California (Roth 1982). At Ithaca, New York, populations were in a seep near a lake and in the riparian zone of a creek (Weigand & Jochum 2010).
In Europe, typical habitats of C. minimum include edges of swamps and in wet woods, floodplain meadows, and dune slacks (Germain 1931; Kerney 1999), and this species occurs at elevations up to 1,000 m in the Alpes (Germain 1931). Geographic range. Native to the Western Palaearctic. Introduced to BC, this species was first found in a nursery in Cobble Hill, Vancouver Island (Forsyth 2004b). Only later, was it discovered living naturalised along the Fraser River estuary in Richmond (Forsyth 2015). It is expected that this species occurs more generally in suitably wet habitats in BC. Elsewhere in Canada,C. minimum has been introduced to Ontario (Grand River, Brant County; Port Whitby, Durham Region) and New Brunswick (Mactaquac Lake, a broadening of the Saint John River) (Forsyth 2015; unpublished data); it has also been reported from California (Roth 1982), New York (Forsyth 2015; Weigand & Jochum 2016); Massachusetts (Clapp 1912; Winslow 1922), and Pennsylvania (Pearce and Payne 2011). It is likely more widely occurring in North American than presently known
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. Minimum (Latin), least or smallest.
Remarks. In much of the older European literature, C. minimum and C. tridentatum were not distinguished from each other, or with the latter treated as a variety of the former; Watson & Verdcourt (1953) reviewed the history the use of these names. However, in the recent literature, these taxa have generally been treated as separate species, and this has been confirmed DNA barcoding by Weigand et al. (2010).
In another study, Weigand et al. (2012) investigated the population structure of C. minimum and found in Europe four distinct, genetically isolated phylogenetic units which are likely explained by refugial areas during glacial periods; a population in eastern North America was found to belong to the Central–Western Europe clade.
References
- Adam W (1960) Mollusques. Tome 1, mollusques terrestres et dulcicoles. Institut Royal des Sciences Naturelles de Belgique, Bruxelles, 402 pp., 4 pls.
- Clapp W (1912) Carychium minimum Mull. The Nautilus 26: 24.
- Forsyth RG (2004) Land Snails of British Columbia. Royal BC Museum, Victoria, BC, Canada, iv, 188 pp.
- Forsyth RG (2015) First record of Carychium minimum Müller, 1774 in New Brunswick, Canada (Mollusca: Gastropoda: Ellobioidea). Check List 11: 1511. https://doi.org/10.15560/11.1.1511
- Germain L (1931) Faune de France 22. Mollusques terrestres et fluviatiles (deuxième partie). Paul Lechavalier, Paris, France, 479-897, i-xiv, pls 1-26 pp.
- 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
- Kerney M (1999) Atlas of the land and freshwater molluscs of Britain and Ireland. Harley Books, Colchester, United Kingdom, 264 pp.
- 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
- Pearce TA, Payne SL (2011) European Carychium land snails in Pennsylvania. Tentacle 19: 13.
- Roth B (1982) European land mollusks in the San Francisco Bay area, California: Carychium minimum Müller and the Arion hortensis complex. The Veliger 24: 342–344.
- Watson H, Verdcourt B (1953) The two British species of Carychium. Journal of Conchology 23: 306–324, pls 9, 10.
- Weigand AM, Jochum A, Pfenninger M, Steinke D, Klussman-Kolb A (2010) A new approach to an old conundrum—DNA barcoding sheds new light on phenotypic plasticity and morphological stasis in microsnails (Gastropoda, Pulmonata, Carychiidae). Molecular Ecology 11: 255–265. https://doi.org/10.1111/j.1755-0998.2010.02937.x
- Weigand AM, Jochum A (2016) Mollusca, Gastropoda, Ellobioidea, Carychium minimum O.F. Müller, 1774: filling gaps. New population record for the State of New York, Northeastern United States. Check List 6: 517–518. https://doi.org/10.15560/6.4.517
- Winslow ML (1922) Notes on the internal lamellae of Carychium. Occasional Papers of the Museum of Zoology, University of Michigan 128: 1–17.