Land Snails

Photo: Aperture view of Triodopsis obsoleta © Bill Frank.

Click photo to enlarge.

Triodopsis obsoleta (Pilsbry, 1894)

Family: Polygyridae
Common name: Nubbin Threetooth

Identification
Width: 10-13 mm
Height: 6-8 mm
Whorls: 4.5-6.0

This small coastal threetooth has a depressed heliciform shell with three barriers in the aperture, like many of its genus, though those three teeth are small and weak – “obsolete.” The open umbilicus of Triodopsis obsoleta is narrow and shallow. Pilsbry (1940) describes this animal only in relation to T. hopetonensis.

Ecology
As currently designated, Triodopsis obsoleta lives on the Coastal plain of the Middle Atlantic. It can be found on low, wet ground, especially in swamps and urban areas (Hubricht 1985).

Taxonomy
Triodopsis obsoleta, like T. messana, is another close relative of T. fallax whose taxonomy is not firmly established. Synonyms for T. obsoleta include: Polygyra fallax obsoleta, P. hopetonensis obsoleta, Triodopsis fallax obsoleta, T. hopetonensis chincoteagensis, T. h. obsoleta, and T. palustris.

Distribution
This species is only known from the Atlantic coasts of Maryland, Virginia and North Carolina. In Virginia it is found in the central and southeastern coast.

Conservation
NatureServe Global Rank: G4
NatureServe State Rank: S3

 

Ken Hotopp, Meegan Winslow 11/2012

Range Map (click to enlarge)