Adults of this species are a robust brown to black plethodontid with enlarged jaw muscles and muscular rear legs. There is a distinct light line running from the eye to the posterior end of the jaw in all species in this genus that can quickly distinguish it from other species. Dorsal coloration is extremely variable and individuals can be light orange-brown to dark brown with faint to profuse and irregular mottling. Younger individuals tend to have more noticeable patterns while adults are darker and many become melanistic with age. Ventral coloration is light gray to cream-colored. This species can grow to around 3-5 in total length.
Females lay their eggs under debris (logs, leaf litter, rocks, etc.) in small clusters near springs and seeps. The eggs are usually in two clusters of around 12 each. (Minton 2001, 73). Desmognathus larvae are small (~10mm SVL at hatching) and aquatic. They have a more rounded head than Eurycea larvae and frequently have greatly reduced and non-vascularized gills. Larvae have a series of 5-6 pairs of spots or diamonds on the dorsum.
This species can be distinguished from all other Plethodontids by the light line running from the eye to the back of the jaw that all Desmognathus species exhibit. The muscular legs, robust body form, and large jaw muscles are also unique to this species in Indiana.
Ecology and Conservation
This is a very aquatic salamander and is rarely found away from water. While they can be found throughout small creeks, they are most heavily concentrated in seepages and springs at the edge of the water. Much of their habitat in Indiana consists of rocky gorges or rocky upland hills, but further west in the state, they can be found in more lowland seep habitat. They can be found in both gravelly, rocky springs and mud seeps, although muddy seeps seem to be somewhat favored. On rainy spring nights, they can be observed actively foraging in woodlands near their springs and seeps. Northern Dusky Salamanders are common around permanent seeps and springs all months of the year and can be found in nearby creeks and further from water during rainy weather. Even when temperatures are down around freezing, this salamander can be turned up under cover along flowing springs. Like most salamanders, Desmognathus feed upon a variety of small invertebrates.
When breeding, this salamander deposits eggs in and around spring seepage areas, usually in moist or muddy areas. They can be laid directly onto the ground, but they are frequently suspended and attached to the surface of a rock or log. Actual breeding involves an elaborate courtship routine and usually takes place in spring or fall (Minton 2001, 73). In Jefferson County, during August, I found a female curled around her eggs under a log along a small seepage creek on a sandy substrate. I have also observed a recently hatched nest in Clark County during September where the newly hatched larvae were laying on top and around the female. This salamander is a summer breeder, with eggs being deposited sometime during June or July. Eggs hatch sometime in late summer or fall.
This species seems to be locally abundant and in many parts of southeastern Indiana more widespread. With many of the seepage creeks and springs that this species utilizes being in rocky gorges and ravines that are virtually useless for agriculture and impossible to log, the future of the salamander seems secure at the time being.
The Northern Dusky Salamander is found in springs and headwater streams throughout the northeastern United States. They occur from Indiana south to Tennessee and east into South Carolina, northward all the way up into Maine with an isolated population in Michigan. Northern Dusky Salamanders are found primarily in the bluegrass natural region of southeastern Indiana where seeps and springs are prevalent, but there are scattered populations further west in the highland rim region and along the Ohio River.
The Northern Dusky Salamander (Desmognathus fuscus) has no recognized subspecies but is part of the larger Desmognathus fuscus species complex. These salamanders belong to the family Plethodontidae, which is the world's most diverse family of salamanders.
Conant, R. and J. T . Collins. 1998. Reptiles and Amphibians of Eastern and Central North America. Third Edition, Expanded. Houghton Mifflin, New York, NY.
Hoffman, A., M. Lodato, and T. Pierson 2014. Desmognathus fuscus. Northern Dusky Salamander. Geographic distribution (Floyd County). Herpetological Review 45:86.
Minton, S. A. Jr. 2001. Amphibians and Reptiles of Indiana. Indiana Academy of Science, Indianapolis, IN.
Petranka, J. W. 1998. Salamanders of the United States and Canada. Smithsonian Institute Press, Washington D.C.