Pennsylvania Land Snails
Mesomphix inornatus (Say, 1821)
Common name: Plain button
The plain button is one of the larger snails commonly found in leaf litter in the forests of western Pennsylvania, sometimes near logs or rocks. To call this snail “plain” is a bit misleading—the somewhat glossy shell is a rather pretty pale yellow, pale green or gold, giving away its location to searchers.
The shell of the plain button is heliciform, 7-12mm in diameter and 8-10mm tall (Pilsbry, 1946). It has a thin lip, like others of its family, and a tiny “pinhole” umbilicus. Under magnification the shell is seen to be covered with neat rows of minute papillae. These papillae can be used to separate this species from a close congener, the smooth button (Mesomphix perlaevis Pilsbry, 1900), which has a coarser microsculpture with grooved ridges (click here for an image of the microsculpture). The soft body of the animal is very dark above and gray beneath.
The plain button appears to tolerate a variety of leaf litter habitats, as it is often found in oak litter, which is relatively acidic. It tends to be smaller in the northern part of its range (Pilsbry, 1946), which runs from Kentucky to New England (Hubricht, 1985).
Ken Hotopp, 10/8/05
Development of this site was supported by the generous contributions of Pennsylvanians to the Wild Resource Conservation Fund.