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Terrestrial Gastropods of the Columbia Basin, British Columbia

Family Helicidae Rafinesque, 1815 Genus Cepaea Held, 1837 Cepaea nemoralis (Linnaeus, 1758): Grovesnail Description: Shell large (width to 25 mm), heliciform; opaque, not very glossy; brightly coloured, brown, orange or yellow, with 1-5 blackish or dark brown spiral bands that may be coalesced or absent; spire moderately elevated; whorls 4.5-5.25, convex; periphery rounded; suture deep; last whorl strongly descending at the lip; protoconch smooth; teleoconch with axial striae and wrinkles; aperture wider than high, and without denticles within; columella slightly thickened and usually dark coloured; basal lip thickened, rather straight and not evenly curved into the outer and columellar lips; outer lip moderately thickened and a slightly recurved; umbilicus absent in adults. Juveniles in which the columellar lip is still poorly formed are narrowly umbilicate. Variation in the colour of the shell is remarkable with the number of bands varying from zero to five, but three-banded individuals appear to be most common. Banding is influenced both by genetics and environmental conditions (Brussard 1975; Clarke et al. 1978). The body of this snail is cream coloured/pale brown, becoming darker towards the head and on the tentacles. Similar Species: The locally introduced snail Helix aspersa Linnaeus, 1758 is larger, with a more rounded aperture and with a different colour pattern consisting of pale axial streaks over top of darker spiral bands. The native, coastal snail, Monadenia fidelis (J.E. Gray, 1838) is also banded, but larger and with a distinctly open umbilicus. Habitat: Gardens and parks in urban areas. On and under plants and sometimes up trees, well off the ground.  Biology: C. nemoralis breeds in the spring and summer, the eggs hatch in two or three weeks and the young grow to adult size the subsequent year (Ellis 1969). In Britain, this snail takes three years to reach adult size (Williamson 1979). Range: Central and western Europe. Introduced to North America, presumably with plants (Pilsbry 1936; Hanna 1966). Distribution: Introduced to southern Vancouver Island, Greater Vancouver, the Fraser Valley, the Okanagan (Westbank) (Forsyth in press) and the Columbia Basin. Name: Genus name meaning "an onion". Species name meaning "sylvan". Records: Nelson (ca. 49o30'N, 117o17'W) (RBCM 999-278-001). View the map.

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