Among the largest terrestrial salamanders, reaching up to 20 cm in length. Stout-bodied animals with broad heads and small eyes. Adults have a dark brown to grayish black dorsal color overlain with numerous, large, irregular, dirty brown to brownish yellow spots or vertical streaks. The belly is marked with irregular pale yellow blotches on a darker background. Aquatic larvae are olive-green, with large heads and long feathery gills. Gilled adults are rare but can occur in some permanent water bodies.
 
First described by Green (1825). Eastern populations (those east of the Appalachian Mountains and the Apalachicola River Basin) are divergent from western populations and may constitute a distinct species (Church et al. 2003).