E-Fauna BC: Electronic Atlas of the Wildlife of British Columbia

Allogona ptychophora A.D. Brown, 1870)
Idaho Forestsnail
Family: Polygyridae
Species account author: Robert Forsyth.
Photo of species

© Robert Forsyth  Email the photographer   (Photo ID #303)

E-Fauna BC Static Map
Distribution of Allogona ptychophora in British Columbia
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Species Information


The shell is most similar to that of Allogona townsendiana but smaller, with fewer malleations and more regular colabral riblets. In some, a weak callus or low, poorly developed denticle is occasionally present on the parietal.


Large, heliciform, light brown or yellow-brown, with lighter coloured irregular but ribs; periostracum never hairy; lip thickened and expanded, white; aperture without denticles, except very occasionally with a low parietal denticle or callus.


Carney (1966) noted that in Montana, and as seen along the Elk River in B.C. (Forsyth 2004), most snails position their shells with the apex directed downward during the winter hibernation. Carney found that mortality was greater when the shell was not positioned in this fashion and speculated that this orientation of the shell might be important for over-wintering survival.


Interior Cedar-Hemlock forests; mesic wooded areas generally.


Global Distribution

Western North America, from BC and Montana, west of the Continental Divide, south through Idaho, to Washington east of the Columbia River, and northeast Oregon (Pilsbry 1940). This species occurs east of the range of Allogona townsendiana, except for down the lower part of the Columbia River, where both have been found together (Pilsbry 1940).

BC Distribution

Throughout the southern Kootenay, Columbia, and Elk river drainages; north as far as the vicinity of Revelstoke, Salmon Arm, and Salmon Arm and Shuswap Lake (Forsyth 2004; map data). Not on the coast and Vancouver Island [map data incorrect].


Montane Cordillera.



Genus derived from the Greek "allos" meaning "other" or "different" + "gona", "genitalia"; the gender is feminine. Species epithet from the Greek, "ptychos", “fold” + "phoro", "to bear" or “carry”.

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
NativeS4YellowNot Listed
BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Additional Range and Status Information Links

Additional Photo Sources

General References

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: 2024-04-12 2:11:47 PM]
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