Land Snails

Photo(s): Views of a Triodopsis fallax shell © Dan Dourson.

Click photo(s) to enlarge.

Triodopsis fallax (Say, 1825)

Family: Polygyridae
Common name: Mimic Threetooth

Identification
Width: 11-13 mm
Height: 7-9 mm
Whorls: 5+

The narrow umbilicus of Triodopsis fallax may have a dome-like or cone-shaped spire, and is covered in tiny papillae (Pilsbry, 1940). The aperture has three distinct lobes separated by two obtuse angles on either side of the basal lip. The parietal tooth, slightly boomerang-shaped as seen from below, protrudes towards the bluff-shaped tooth on the outer lip. The narrow, blunt basal tooth rises abruptly from its base.

Ecology
This snail prefers open habitats. It typically inhabits clearings, meadows, and the verges of roads and railroad tracks (Hubricht, 1985).

Taxonomy
Previous names for T. fallax include: Helix fallax, H. introferens, Polygyra fallax, Triodopsis introferens, and T. i. var. minor.
Triodopsis fallax affinis or Triodopsis affinis is a designation given to an apparent hybrid between this species and T. alabamensis (Hubricht, 1954; 1985), and is a name no longer formally recognized.

Distribution
Triodopsis fallax is a snail of the Ridge-and-Valley. It primarily occupies the eastern portion of the Middle Atlantic, from Pennsylvania in the north to Georgia in the south.

NatureServe Global Rank: G5
NatureServe State Rank: S4

 

Meegan Winslow, Ken Hotopp 10/2012

Range Map