Flat-spired Three-toothed Snail

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Flat-spired Three-toothed Snail

Triodopsis platysayoides

ListedJuly 3, 1978
FamilyPolygyridae (Land Snail)
DescriptionLight or reddish-brown five whorled snail with oblique banding.
HabitatDeciduous and mixed-pine deciduous forest.
ReproductionLays a clutch of three to five eggs.
ThreatsRestricted distribution, habitat disturbance.
RangeWest Virginia


The flat-spired three-toothed snail, Triodopsis platysayoides, has a thin, flattened, five-whorled shell, 1.2 in (3 cm) in diameter and up to 0.4 in (1.1 cm) thick. The shell is light brown to light reddish brown with oblique banding. The aperture is oblique with a narrow white lip. A thick, white conical tooth is present on the inner wall of the shell. This species was first classified as Polygra platysayoides.


This snail feeds mainly on lichens on rock surfaces and in leaf litter and will occasionally feed on other snails. Densities must be sustained at less than four snails per square foot to prevent cannibalism. These snails breed in captivity in temperatures between 41 and 59°F (5 and 15°C). In damp, cool weather, snails venture out into the deep, shaded litter at the base of cobbles and boulders. In dry, hot weather they retreat into the crevices of exposed sandstone boulders. Predators are thought to be shrews and beetles.

Little is known about the reproductive characteristics of this species, but it is thought that individuals live for two years and breed before dying. Egg laying of clutches of three to five eggs probably occurs in May and June.


These snails live mostly in a deep, moist layer of leaf litter among sandstone boulders along the rim of the Cheat River gorge in a mixed pine and deciduous forest. Habitat elevation ranges between 1,800 and 2,000 ft (540 and 600 m).


This species is extremely rare and probably never ranged much outside of Monongalia County, West Virginia. The genus Triodopsis is relatively widespread in the eastern United States where 28 species are known. Closely related species are T. complanata in Kentucky and T. tennesseensis in Kentucky, Tennessee, West Virginia, Virginia, and North Carolina. The flat-spired three-toothed snail inhabits an area below the summit of Cooper's Rock adjacent to Cheat River Canyon in Monongalia County. Most of the habitat falls within the Cooper's Rock Recreational Area which is part of Cooper's Rock State Forest. Research in the early 1970s placed the population at between 300-500 individuals. More recent studies suggest that the population may number closer to 1,000.


Cooper's Rock Recreational Area and State Forest attracts more than 450,000 visitors annually. Facilities and concessions on top of Cooper's Rock draw heavy traffic to the summit. Foot traffic not only crushes the snails but also destroys the leaf litter in which they live. This project was funded by the U.S. Fish and Wildlife Service through the Ohio River Valley Ecosystem program and the West Virginia Nongame Wildlife Fund.

Conservation and Recovery

Because so little is known about this species, the recovery strategy will depend on the results of ongoing research to determine distribution, reproduction, and habitat requirements. In the meantime, state park personnel have limited access to the population site by fencing and rerouting hiking trails. If disturbance can be minimized, the snail population will probably stabilize. Construction was completed recently on a "snail fence" at Cooper's Rock State Forest in Monongalia County, West Virginia. The purpose of the fence is not to keep snails in, but to reroute human foot traffic in the area containing the largest known population of this threatened species.


U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
300 Westgate Center Drive
Hadley, Massachusetts 01035-9589
Telephone: (413) 253-8200
Fax: (413) 253-8308


Brooks, S. T. 1933. "Polygra platysayoides, a New Species from West Virginia." Nautilus 46: 54

Hubricht, L. 1972. "Endangered Land Snails of the Eastern United States." Sterkiana 45: 33.

MacMillan, G. K. 1949. "Land Snails of West Virginia." Annals of the Carnegie Museum 31: 89-239.

U.S. Fish and Wildlife Service. 3 July 1978. "Determination that Seven Eastern U. S. Land Snails are Endangered or Threatened Species." Federal Register 43 (128): 28932-28935.

U.S. Fish and Wildlife Service. 1983. "The Flat-Spired, Three-Toothed Snail Recovery Plan." U.S. Fish and Wildlife Service, Newton Corner, Massachusetts.