Apalone
Apalone is a genus of turtles in the family Trionychidae. The three species of Apalone are native to freshwater habitats in North America; they are the only living softshell turtles from the Americas.
Geographic range
Most Apalone species are restricted to the United States, though the range of the spiny softshell, A. spinifera, extends into southern Canada and northern Mexico.Fossil evidence suggests that Apalone may have reached as far south as Costa Rica during the Pliocene.
Taxonomy
Apalone is a fairly new classification, resurrected by Meylan in 1987, assigned to North American species of the genus Trionyx. They are still listed as Trionyx in some texts.Molecular phylogenetic studies generally suggest that Apalone is most closely related to the highly endangered Asian genus Rafetus, with the two genera most likely diverging during the Late Eocene. The ancestral Apalone most likely crossed from Asia into North America via Beringia, taking advantage of the warm climate during the Eocene.
Species
The following three species are recognized as being valid.- Apalone ferox – Florida softshell turtle - South Carolina, Georgia, Florida, and Alabama
- Apalone mutica – smooth softshell turtle - United States, east of the Rocky Mountains
- Apalone spinifera – spiny softshell turtle - Canada, most of the United States, and northeastern Mexico.
Fossil taxa
One definitive fossil species is also known, A. amorense Valdes, Bourque & Vitek, 2017 from the late Miocene of Florida.In addition, two other potential fossil species, generally placed in "Trionyx" sensu lato, may belong to Apalone: Apalone latus from the Campanian-aged Dinosaur Park Formation of Alberta, Canada and Apalone leucopotamica from the late Eocene-aged Cypress Hills Formation of Saskatchewan. These two species are much older than any other remains assigned to Apalone, and even predate the presumed divergence of the genus based on molecular phylogenies. However, none of these have been rigorously tested, and the placement of these genera within Apalone may just be a result of homoplasy.