Shell disc-shaped; spire moderately raised; brown, with growth lines but no spiral lines; animal blackish with a dull orange spot visible through the shell.
Animal
Black throughout; when the animal is fully retracted, a dull orange spot on the mantle shows through the shell. It is best be seen through the shell behind the apertural lip, between the suture and the periphery.
Anatomy
The development of the genitalia is variable with both euphallic individuals (with fully developed genital organs) and hemiphallic ones (with small, degenerate male genitalia) present (Watson 1934, Pilsbry 1946, Jordaens et al. 1998).
Similar Species
Two species of Zonitoides, Zonitoides nitidus (Müller, 1774) and Z. arboreus (Say, 1817), occur in Canada (and BC). Sometimes, material in collections are confused because shells are often difficult to identify with certainty. Zonitoides nitidus grows to a slightly larger size, has a somewhat higher spire, and lacks the exceedingly fine and very weak spiral striae of Zonitoides arboreus. However, a better way to distinguish species is by the body pigmentation. Zonitoides nitidus (as its name suggests) has an entirely blackish body; that of Z. arboreus is lighter along the sides of the foot. There is also a spot, not present in the other species, that is sometimes described as “dull orange” and can be seen through the shell a little ways back from the aperture, especially in retracted animals. Take a look a the snail in the upper left of photo # 37371 in the photo gallery and you might make out this orangish spot.
Biology
Reproduction is thought to be mostly by self-fertilization (Jordaens et al. 1998).
Habitat
A calciphile. In some places (and in BC), restricted to very wet ground such as marshes and along the edges of waterbodies (Forsyth 2004). However elsewhere, in Ontario, the species occurs in mesic forest habitats and is often particularly abundant at anthropogenic sites. Snails live under dead wood, logs, rocks, leaf litter, and vegetation.
Distribution
Global range
Europe, North Africa, northern Asia, Iceland and most of North America; introduced to Australia and Madeira (Pilsbry 1946).
BC range
Known from suitable habitats in the Lower Fraser Valley, on Vancouver Island, and in the Okanagan. Apparently it is absent in central or northern areas of the province (Forsyth 2004). Pilsbry (1946) speculated that this species could be introduced along the west coast, and he could be correct.
BC Ministry of Environment:BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.
Additional Notes
This is a small species of air-breathing land snail (Wikipedia 2009) that occupies wet calcareous habitats (it is a calciphile), including "marshes and wet areas along the edges of rivers, sloughs, lakes and ponds, where it lives under wood, rocks and vegetation (Forsyth 2004). It is an omnivorous species that eats vegetation and gastropod eggs (Forsyth 2004). It is considered carnivorous (Rondelaud 1975).
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2021. E-Fauna BC:
Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab
for Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
2026-06-07 12:39:47 PM]
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