Orthalicus Reses

Orthalicus reses, common name the Stock Island, Florida treesnail, is a species of large tropical air-breathing land snail, a tree snail, a terrestrial pulmonate gastropod mollusk in the family Orthalicidae. It was first described in 1830 by the American naturalist Thomas Say. The holotype, a specimen probably collected in Key West, was subsequently lost. Over a hundred years later, in 1946, the American biologist Henry Augustus Pilsbry redescribed the species using a specimen from Stock Island. Orthalicus reses has two subspecies, O. reses reses and O. reses nosodryas. The validity of these two taxa is still being discussed, but some experts argue that considering them as independent units may be important for management purposes.

The Stockland treesnail has a large conical shell (45 - 55 mm in length) with variable thickness, generally lighter and more translucent than other species of Orthalicus. It is colored white to buff, with weakly developed spiral bands and several flame-like, purple-brown axial stripes. The subspecies O. reses reses and O. reses nosodryas can be distinguished from one another based on the different color patterns of the apical whorl, columella, and parietal callus.

The nominate subspecies Orthalicus reses reses is threatened; it lives on trees in hardwood hammocks habitat in Southern Florida, USA, specifically the Florida Keys.