Polygyridae


Polygyridae is a family of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Helicoidea.
The Polygyridae make up a significant proportion of the land snail fauna of eastern North America, and are also found in western North America, northern Central America, and are present on some Caribbean islands. The definitive reference to the group is Henry Pilsbry's 1940 monograph.

Anatomy

This snail family is distinguished from other gastropods on the basis of several anatomical features: They have no dart apparatus, the muscles which allow the eyes and pharynx to be retracted are united into a single band, and the jaws are ribbed.
In this family, the number of haploid chromosomes lies between 26 and 35.

Taxonomy

According to the Taxonomy of the Gastropoda this family consists of the following subfamilies and tribes:
This family is defined by an absent diverticulum and absent stimulatory organ. The two subfamilies, Polygyrinae and Triodopsinae, are distinguished on the basis of reproductive anatomy. As some species in the subfamily Polygirinae show a penial appendage. This family is monophyletic.
Pilsbry uses the generic names Allogona, Ashmunella, Giffordius, Mesodon, Polygyra, Praticolella, Stenotrema, Trilobopsis, Triodopsis, and Vespericola. The remaining names listed here have either been elevated from Pilsbry's subgenera since 1940, or newly created.
Subfamily Polygyrinae:
Shells of species within the Polygyrinae
Subfamily Triodopsinae:
Shells of species within the Triodopsinae