Review of the Graptemys pulchra group (Reptilia: Testudines: Emydidae), with descriptions of two new species

Abstract

The Graptemys pulchra species group, which includes G. puichra sensu lato and G. barbouri, is defined by the combination of large female size, extreme sexual dimorphism, head pattern with large interorbital and postorbital blotches, enlarged heads and hypertrophied jaws in females, presence of salient vertebral spines, and possibly, a diploid chromosome number of 52 . Graptemys ernsti, n. sp. is described from the Pensacola Bay drainage, Florida and Alabama, and Graptemys gibbonsi, n. sp. from the Pascagoula River and Pearl River drainages, Mississippi and Louisiana. A speciation hy= pothesis for the group, based on successive isolation and contact of drainages due to sea level changes, agrees with data for freshwater fishes of the region.