Amphibians of North Carolina
Scientific Name:
Common Name:
 Family (Alpha):
« »
Plethodontidae Members:
NC Records

Desmognathus orestes - Blue Ridge Dusky Salamander

Taxonomy
Class: Amphibia Order: Caudata Family: Plethodontidae Subfamily: Plethodontinae
Taxonomic Comments: Members of the genus Desmognathus are commonly known as dusky salamanders because of their overall dark brown or dusky ground color. Like many plethodontid salamanders, they have proven to be a taxonomically challenging group that contains several species complexes. Kozak et al. (2005) documented 35 major lineages in the eastern US, even though only 22 species were formally recognized by taxonomists in 2021. This suggests that there are numerous cryptic species that remain to be described. A more recent comprehensive molecular survey of populations in the eastern US by Beamer and Lamb (2020) indicate that at least 45 major lineages or clades are present.

In North Carolina, a group of medium-sized dusky salamanders with rounded, unkeeled tails (D. carolinensis, D. imitator, D. ocoee, and D. orestes) have been treated as members of an informal cryptic species complex known as the D. ochrophaeus complex (Tilley and Mahoney 1996). The members of this group are commonly referred to as mountain dusky salamanders, and were previously treated as a single species (D. ochrophaeus, sensu lato) before being split. The most recent molecular study based on mtDNA sequence data (Beamer and Lamb 2020), as well as previous studies (see Beamer and Lamb 2020), indicate that there are many additional clades within the D. ochrophaeus complex that may represent undescribed cryptic species. In addition, certain forms appear to be more genetically similar to D. fuscus than to other members of the D. ochrophaeus complex. Some of the highlights of this study are that 1) Populations currently referred to as D. carolinensis do not appear to constitute a genetically distinct lineage and instead cluster with 39 populations of D. fuscus, 2) Populations currently referred to as D. ocoee contain several clades that may reflect additional cryptic species; in some cases these clades contain mixtures of populations that are currently referred to as D. ocoee, D. conanti and D. apalachicolae, 3) Populations currently referred to as D. orestes contain three clades, one of which is sister to a clade containing D. ochrophaeus and other clades of D. orestes, and 4) Populations currently referred to as D. imitator constitute a well-defined clade that is not closely related to other members of the D. ochrophaeus complex and should not be treated as a member of that complex. One problematic issue with studies of this sort is that the results based on using different molecular evidence (e.g., mtDNA; nuclear DNA; allelic frequencies) are sometimes discordant, in part due to past or present hybridization that commonly occurs between closely related plethodontid species (see Pyron et al. 2020) as it relates to Desmognathus species). As additional studies emerge, the taxonomic status of D. carolinensis, D. ocoee, and D. orestes as currently recognized will likely change. Here, we continue to recognize these forms until additional studies are completed and formal taxonomic changes are made.
Species Comments:
Identification
Description: D. orestes is indistinguishable based on external coloration, patterning and morphology from Desmognathus carolinensis and D. ocoee. These species have mutually exclusive ranges and are best identified based on the geographic locality of the collection site. All three species are medium-sized Desmognathus with tails that are unkeeled, slightly longer than the body, and typically rounded or oval-shaped in cross-section on the proximal half. The distal half can vary from being rounded to more laterally compressed towards the tip depending on the age and condition of an individual. The toe tips lack cornifications as seen in some of the more aquatic Desmognathus species. The adults vary from about 7-11 cm TL and average slightly longer than the females.

The dorsal patterning of this and other members of the complex is highly variable and ranges from straight-edged stripes to wavy blotches. These vary markedly in coloration, but are commonly greenish gray, light brown, rusty red, yellowish brown or bright red. The venter is light colored in young animals, but becomes light gray to grayish black with age. Juveniles and young adults tend to have relatively bright coloration that darkens with age. Older adults in high elevation populations are usually melanistic and are often dark gray to brownish gray with reduced dorsal patterning. Males in local populations average from 10-20% larger than females and are more likely to be melanistic (Petranka 1998). Relative to females, the males have well developed premaxillary teeth and large jaw musculature. They also possess small mental glands and have a mouth line that appears sinuate when viewed from the side. The hatchlings vary from about 13-18 mm TL and have prominent yolk reserves. The larvae have rounded snouts, very small whitish gills, and a series of 5-6 pairs of alternating spots along the dorsum. These may be absent or very faint in individuals that develop straight dorsolateral lines as adults (Petranka 1998).
Technical Reference: Tilley and Mahoney (1996)
Online Photos:    Google   iNaturalist
AmphibiaWeb Account
Distribution in North Carolina
Distribution Comments: Desmognathus orestes is confined to mountainous, forested habitats in the Blue Ridge Physiographic Province from Mount Rogers and vicinity in southwestern Virginia southwestward to somewhere between Linville Falls and McKinney Gap in Burke and Mitchell counties, North Carolina. Farther west, the species extends to the headwaters of Toms Creek and Clark Creek about 1.5 km northeast of Iron Mountain Gap on the North Carolina-Tennessee border in Avery and Carter counties (Tilley and Mahoney 1996).
County Map: Clicking on a county returns the records for the species in that county.
GBIF Global Distribution
Key Habitat Requirements
Habitat: This and other members of the D. ochrophaeus complex that occur in western North Carolina are associated with montane hardwoods with cool, clear-flowing headwater streams and seepages (Petranka 1998). They also inhabit wet rock faces. Brooding females and overwintering juveniles and adults congregate in aquatic habitats, but non-brooding individuals move away from aquatic habitats and live on the forest floor during the warmer months of the year. At sites where mesic conditions prevail, they can be found far from water. At lower elevations, individuals tend to remain in the immediate vicinity of seeps and streams (Beane et al. 2010, Petranka 1998).

See also Habitat Account for Montane Mesic Forests with Seepages/Headwater Streams
Life History and Autecology
Breeding and Courtship: The adults mate during the spring, late-summer, and autumn, and the females reproduce annually in most populations (Organ 1961a). When courting and mating, paired adults engage in a stereotypic tail straddle walk (Petranka, 1998). A male that encounters a female normally initiates courtship by rubbing his head over all portions of the female's head. This behavior is interspersed with head lifting in which the male repeatedly lifts and lowers the female's head. The female eventually places her head on the dorsal surface of the base of the male's tail, at which point the male may curve his body backwards towards the female's neck or dorsum and snaps his head backwards with a rapid movement of the body. In addition to rapid snapping, the male may slowly pull his depressed chin across the female's dorsum. The male may also snap and pull when positioned alongside a female (Uzendoski and Verrell 1993). This behavior acts to scratch the female's skin and transfer mental gland secretions into the female's circulatory system (Houck 1986). The female often moves away from the male, and the male pursues and continues to stimulate her.

The pair next engages in a tail-straddle walk in which the male laterally undulates his tail and slides under the female's head until her chin rests on the dorsal base of the tail. The male moves forward in a straight line while undulating his tail laterally, and the female follows as she straddles his tail. Eventually the male deposits a spermatophore, then leads the female forwards about one body length and swings his tail from underneath the female and holds it to one side. The female responds by picking up the sperm cap in her cloaca (Uzendoski and Verrell 1993). The pair splits apart within a few minutes after courtship is completed.

Desmognathus orestes often coexists with other Desmognathus species, but will rarely attempt to court members of other species. Males typically ignore females of the opposite species from the point of initial contact. Differences in female chemical cues may be the primary reason for the lack of responsiveness exhibited by males.
Reproductive Mode: Females deposit grape-like clusters of eggs in hollowed depressions beneath logs, rocks, leaf litter, or moss mats in wet microhabitats such as springs, seeps, and small streams. Each egg has a short gelatinous stalk and is attached to a common base to form a cluster (Martof and Rose 1963). The nests are usually constructed at or slightly above the water surface and females remain with their clutches until the embryos hatch. Although poorly documented, most females presumably oviposit May-July and most embryos hatch in late summer or early fall after an incubation period of about two months (Petranka, 1998). The mean clutch sizes of two North Carolina populations was 14 and 16 mature ova (Martof and Rose, 1963). Clutch size is positively correlated with female body size in this and most other Desmognathus species (Martof and Rose, 1963; Tilley, 1968).
Aquatic Life History: The larvae live in seepages, wet rock-faces, rivulets, and the sluggish portions of small streams where they feed on small invertebrates. Organ (1961a) collected metamorphs in April and May in Virginia, and estimated a 8-9 month larval period for offspring hatching from eggs laid the previous June. Tilley and Tinkle (1968) and Tilley (1973b) questioned this interpretation since some of the metamorphs may have been from winter-brooding females.
Terrestrial Life History: Males and females in southwestern Virginia become sexually mature in the autumn when 3.5 years and 4.5 years old (Organ, 1961a). Females first reproduce the following year when about 5 years old. Age-specific survivorship of males decreases with age, and brooding females have higher mortality rates than immature females -- a fact that may reflect the costs of parental care. As with most plethodontid salamanders in the eastern US, this species is nocturnally active. Individuals generally remain beneath cover during the day, although a small percent of animals may be active outside of cover on very overcast days. Except during periods of dry weather, they emerge at night and actively move about in search of prey or mates. Individuals can often be spotted climbing ferns or other low-lying ground cover at night. Adults and juveniles congregate in seepages or underground retreats during the late-fall and winter months and disperse from winter retreats to surrounding forests during the spring warm-up (Organ 1961a, b). The females migrate short distances to aquatic or semiaquatic sites such as seeps and headwater streams to lay and brood their eggs, and the young disperse from these sites into the surrounding forest.
General Ecology
Community Ecology: Desmognathus orestes often coexists with members of the Black-bellied Salamander complex (D. kanawha; D. mavrokoilius), D. monticola, and D. organi. These form a series of species whose preferred habitats range from aquatic to fully terrestrial (Hairston 1949, Organ 1961a). Desmognathus fuscus is also present in some communities and occupies a position between that of D. monticola and D. orestes. Ecological interactions of D. orestes with these forms have not been investigated, but studies of interactions between members of the D. ocoee species complex, D. monticola, and members of the Black-bellied Salamander complex suggest that D. orestes may be a common food resource and source of competition between the latter two species (Hairston 1980c, 1986). All of the Desmognathus species are generalist predators that mostly subsist on insects and other invertebrates, so competition for food may occur among members of stream and streamside salamander communities. Members of the D. ochrophaeus complex and D. ocoee complex have been implicated as being mimics of several other species of salamanders including members of the Eurycea bislineata complex, Plethodon cinereus, P. nettingi, and P. welleri (Brodie 1981, Brodie and Howard 1973). Virtually all of the common color morphs of this species complex have at one time or another been interpreted as being mimics of other salamanders (Petranka, 1998).
Adverse Environmental Impacts
Status in North Carolina
NHP State Rank: S3S4
Global Rank: G4
Environmental Threats: Local populations of members of the mountain dusky salamander complex are often severely depressed after clearcutting, and low elevation populations may take many decades to recover following intensive timbering (Petranka et al. 1994). Leaving untimbered forest buffers along headwater streams and seepages will greatly reduce the impact of timbering on these and other stream-breeding salamanders.
Status Comments: Desmognathus orestes is a common species at moderate to higher elevations in western North Carolina and is in minimal need of protection.

Photo Gallery for Desmognathus orestes - Blue Ridge Dusky Salamander

5 photos are shown.

Recorded by: B. Bockhahn
Ashe Co.		Recorded by: B. Bockhahn
Mitchell Co.
Recorded by: Max Ramey, Eric Johnson
Watauga Co.		Recorded by: Steve Hall and Bo Sullivan
Ashe Co.
Recorded by: Steve Hall and Bo Sullivan
Ashe Co.