HerpIndiana

Northern Dusky Salamander (Desmognathus fuscus)

Adult from Wayne County

Description

Morphology: 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 and while adults are darker and many become melanistic with age. Ventral coloration is light gray to cream-colored.

Size: This species can grow to around 3-5in total length (Conant and Collins 1998, 447).

Larvae:.

Eggs: 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).

Similar Species: 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 the state.

Distribution

Dusky Salamanders are found primarily in the bluegrass natural region of southeastern Indiana where seeps and springs are prevalent, but there are a number of populations further west in the highland rim region and along the Ohio River.

Activity

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.

Breeding Season: This salamander is a summer breeder, with eggs being deposited sometime during June or July. Eggs hatch sometime in late summer or fall(Minton 2001, 73). The larvae transform quite soon after hatching (Minton 2001, 73).

Taxonomy

The Northern Dusky Salamander (Desmognathus fuscus) has no subspecies. The Northern Dusky Salamander belongs to the genus Desmognathus and is in the family Plethodontidae which is represented in Indiana by 11 different species.

Natural History

Habitat: This is truly a species of springs and seeps. Sometimes they can be found in creeks, but generally only those that have springs or seeps flowing into them and often they are in springs, but absent from the creek only meters away. 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.

Feeding: This species feeds on small terrestrial, diurnally active invertebrates (Minton 2001, 74).

Breeding: This salamander deposits eggs in and around spring seepage areas, usually in moist or muddy areas. Actualy 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.

Conservation: 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, the future of the salamander seems secure at the time being.