Gray, 1856
Cooter turtles
Recognition
The seven species of freshwater basking turtles in the genus Pseudemys are restricted to North America, and are most closely related to the genera Chrysemys, Deirochelys, Graptemys, Malaclemys, and Trachemys, with which Pseudemys forms a complex. It has at times been included in the genus Chrysemys (McDowell, 1964; Zug, 1966; Weaver and Rose, 1967; Ernst and Barbour, 1972; Gaffney, 1979b), but evidence indicates that it should be considered a separate genus (Seidel and Smith, 1986). The genus has recently been revised by Seidel and his coworkers (Seidel, 1994, 1995; Seidel and Dreslik, 1996; Seidel and Ernst, 1996), but there are alternate views regarding the arrangement of its species and subspecies (Obst, 1985a; Ernst et al., 1994; Jackson, 1995).
Species of Pseudemys have oval, elongated, moderately domed carapaces with a serrated posterior rim, and, at least in juveniles, a medial keel. The neurals are six sided and shortest anteriorly. There is a tendency for old males, and sometimes females, to become melanistic, and females are usually larger than males. The plastron is hingeless, with short to moderately long axillary and inguinal buttresses. The entoplastron lies anterior to the humero-pectoral seam. The skull is moderate in size with a complete temporal arch, and the orbito-nasal foramen is much larger than the posterior palatine foramen. Contact occurs between the lower parietal process and palatine. Triturating surfaces are broad; that of the upper jaw bears a medial tuberculate ridge. The upper jaw may or may not be medially notched, and if notched may bear cusplike projections. There are four phalanges in the 5th toe; the toes are webbed.
Species identification
Jump to the key: Page 343: Genus Pseudemys