A Re-Evaluation of the Pleistocene Hellbender, Cryptobranchus guildayi , and an Overview of Cryptobranchus Remains from Appalachian Caves.

Cryptobranchus guildayi is described as an extinct species of large salamander that is closely related to the hellbender, Cryptobranchus alleganiensis . The validity of this extinct taxon has been questioned, so an expanded osteological sample of modern hellbenders was used for comparative purposes with the C. guildayi fossil material. Based on this analysis, all supposed distinguishing morphological characteristics used to define C. guildayi can be observed in specimens of C. alleganiensis , or are based on misidentifications. Therefore, Cryptobranchus guildayi is considered to be conspecific with C. alleganiensis and taxonomically should be considered a junior synonym of the latter. The reassignment of the C. guildayi specimens to C. alleganiensis and examination of undescribed fossil specimens from the same region expands the prehistoric range of the species to the Potomac River and its tributaries and also extends the age of the species to the Irvingtonian North American land mammal age.