The seepage salamander (Desmognathus aeneus) is a small, terrestrial species of salamander in the family Plethodontidae. It is endemic to the United States. They are found in small areas of Tennessee, North Carolina, Georgia, and Alabama. Its natural habitats are temperate forests, intermittent rivers, and freshwater springs. It gets its name from the seepages around which it lives. It is very similar in its appearance and life history to the pygmy salamander (Desmognathus wrighti). These two species differ greatly from the other Desmognathus species. They are the smallest salamanders in the genus, measuring only in length. They are also the only two terrestrial, direct-developing Desmognathus species. However, the two species are not often seen to coexist, differing in distribution by elevation; although there are exceptions. The seepage salamander is currently listed as Near Threatened, with its numbers declining in most of states in which it is found. It is threatened by habitat loss, with logging having a major effect.
Description
The seepage salamander is a very small and slender salamander, ranging from . The adults possess vomerine teeth. The tail is terete and rounded. The seepage salamander has a pale dorsal stripe, with a wide, wavy to almost straight shape, and ranging in color from yellow or tan to reddish brown. The stripe is sometimes flecked with a darker pigment. A mid-dorsal, dark line is also seen and is continuous with a Y-shaped mark on the head. There is a dark brown band on the sides, fading towards the belly. The underbelly is pale and is mottled with brown and white, but it may also be plain, with no other coloration.
The seepage salamander is easily confused with the Pygmy Salamander (Desmognathus wrighti). These two species overlap in a small area of southern North Carolina. D. wrighti and D. aeneus are the smallest species in the genus Desmognathus and are the only terrestrial direct-developers, lacking a free-swimming larval stage. They both have vomerine teeth, and similar tail length to total body length ratios; however, they have different patterns and coloration. Seepage salamanders have a smoother top of the head. The mental glands are also shaped differently in the males. The pygmy salamander has a large, U-shaped mental gland while the seepage salamander's is small and kidney shaped.
General description and taxonomy
The seepage salamander is part of the genus Desmognathus and the family Plethodontidae. Like all other plethodontids, the seepage salamander is lungless and respires through its skin and the lining of its mouth. They also have a naso-labial groove and a relatively immoveable lower jaw which allows them to force their way under objects. As with all species in Desmognathus, they have a pale line running diagonally from the eye to the angle of the jaw. This line may be hard to see in older, darker adults. Their hind legs are larger and stouter than the forelegs. Their body is short and stout and they are good jumpers, often used as an escape.
According to the phylogenetic tree, the seepage salamander branched deep within the tree of the Desmognathus species. D. aeneus is a sister group to all species of Desmognathus except D. wrighti, which is an outgroup. D. aeneus and D. wrighti have distinct character differences from the rest of the Desmognathus species. They are the smallest species, direct-developers, and the most terrestrial, with all other species being semi-aquatic or aquatic. Since these two species branch the earliest, evolution has moved toward larger body size, lengthened larval periods, and more aquatic habitats within Desmognathus.
Geographic distribution
Seepage salamanders get their name from the seepages where they are often found. However, they are also found near streams and under leaf litter, leaf mold, and rotten logs. They are a terrestrial species.
Seepage salamanders are distributed in southeast Tennessee, southwest North Carolina, northern Georgia, and central to northern Alabama. They are found in Monroe and Polk counties in Tennessee; Fannin, Pickens, Towns, and Union counties in Georgia; Oconee County in South Carolina; and Cherokee, Clay, Graham, Macon, and Swain counties in North Carolina. In Alabama, they can be found in Calhoun, Clay, Cleburne, and Tallapoosa counties. They also might be found in Cherokee, Chilton, Etowah, Hale, and Tuscaloosa counties in Alabama, but may be extirpated from these locales.