Amphibians of North Carolina
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NC Records

Desmognathus aeneus - Seepage 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. Pyron et al. (2020) built upon this data set and incorporated information on nuclear DNA. They suggest that as many as 49 lineages might exists that qualify as candidate species. Although some of the currently recognized Desmognathus species are well supported by both data sets, many are not and likely represent species complexes. Discordance between mtDNA and nuclear DNA analyses are problematic and likely reflect widespread gene flow and reticulate evolution among many Desmognathus lineages.

Populations that are currently recognized as D. aeneus are also problematic. These vary geographically, and those near the southern extent of the range in Alabama were originally described as a separate species, D. chermocki (Bishop and Valentine 1950). Beamer and Lamb (2020) noted that the phylogeographic structure within D. aeneus is complex and that the more genetically divergent populations do not occur at the southern extent of the range. The authors hope to address this and the taxonomic status of regional groups in a future publication. Here, we continue to treat D. aeneus as a single, geographically variable species until these studies are completed.
Species Comments:
Identification
Description: The Seepage Salamander is a tiny, slender Desmognathus that has a yellow to reddish brown dorsal stripe that is bordered laterally by a dark band. The dorsal stripe can be either straight or wavy. Specimens often have a light porthole or patch on the dorsal surface of each thigh and a Y-shaped mark immediately behind the eyes that may continue as a faint mid-dorsal stripe or line of dots down the back (Petranka 1998). A faint herringbone pattern is often evident on the back. The venter is mottled and light colored, and the top of the head is smooth rather than being rugose as in D. wrighti. The tail is round in cross-section and comprises slightly more than half of the body length, and the toes lack cornifications. Adults vary from around 38-57 mm TL and have 13-14 costal grooves.

The hatchlings are about 6-7 mm SVL and have proportionately shorter tails and larger heads than the adults. The juveniles resemble the adults but are more brightly colored. Adult males have a small bean-shaped mental gland on the chin (Petranka 1998).
Online Photos:    Google
Observation Methods: Individuals are most easily collected by searching through leaf litter or beneath moss mats near seepages and streams. In the southern Appalachians, individuals can occasionally be found foraging on the ground surface at night, but far less frequently than other species such as D. ocoee.
AmphibiaWeb Account
Distribution in North Carolina
Distribution Comments: The Seepage Salamander is patchily distributed in deciduous and mixed deciduous forests across its range. Populations have been found in extreme southeastern Tennessee, southwestern North Carolina, extreme northwestern South Carolina, and northeastern and north-central Georgia. From there, the range extends southwestward in a narrow band to central Alabama. This species is most common in the Blue Ridge where local populations are found next to streams or seepages. Possible disjunct populations occur in the Coastal Plain (Fall Line Hills) of west-central Alabama and the Piedmont (Talladega Uplands) of east-central Alabama (Graham et al. 2012). Populations in North Carolina are restricted to the southwestern counties. Although scattered populations are present throughout the range, individuals can be locally abundant (Harrison 2005).

Distribution Reference: Petranka (1998); Graham et al. (2012)
County Map: Clicking on a county returns the records for the species in that county.
Key Habitat Requirements
Habitat: Seepage salamanders are most frequently encountered in mesic hardwood forests in and around seeps, small streams, or moss-covered rock faces. The juveniles and adults are most commonly found in moist leaf litter or moss mats in the immediate vicinity of small streams and seepages, and to a lesser extent in clumps of wet vegetation or beneath logs (Beane et al. 2010, Bruce 2019, Graham et al. 2012, Petranka 1998). The larval stage is essentially lacking (see below), and populations are not dependent on flowing water to complete their life cycle. However, females frequently nest in moss mats or wet litter in or near the margins of seepages or streams, and local populations are generally affiliated with these habitats. In North Carolina, this species has been found in moist areas along streams, along the banks of seepages, and adjacent to bogs or in swamp forest-bog complexes where they reside in moss mats, wet leaf litter, and rotting logs (Bruce 2019). During the warmer summer months, the juveniles and adults are usually found within 20 meters of stream margins and tend to avoid areas immediately adjacent to stream edges.
See also Habitat Account for Montane Mesic Forests with Seepages/Headwater Streams
Life History and Autecology
Breeding and Courtship: Published information on the mating season of D. aeneus is not available. Like many Desmognathus, this species probably mates in both the autumn and spring (Petranka 1998). Unlike some Desmognathus species, the females breed annually (Harrison 1967).

The Seepage Salamander has a biting phase during courtship that substitutes for the pulling, snapping, and butterfly motions that are used by most Desmognathus species (Promislow 1987, Petranka 1998). The male initially approaches a female and touches his snout to her body or rubs his chin on her back. He then usually bites the female near the midbody or proximal part of the tail and maintains a hold that can lasts for several hours. Biting and struggling by the female creates a wound that allows mental gland secretions to enter the circulatory system of the female. Struggling by the female diminishes during the first 30 minutes, at which point she becomes quiescent. The male eventually releases the female and undulates his tail. The female maintains her head on his tail and follows him in a tail straddle walk which may last 0.5-2.0 hours. Near the termination of the tail-straddle walk, the male undulates his tail from side to side then deposits a spermatophore. The female continues forward with her chin on the distal part of the tail until her cloaca lines up with the spermatophore. The female then picks up the sperm mass into her cloaca. If the female is unsuccessful in picking up the sperm mass, a second spermatophore may be deposited.
Reproductive Mode: The females usually nest in or beneath clumps of mosses near seepages or streams, but may also lay their eggs beneath logs, in moist leaf litter, and in root mats (Bruce 2019, Harrison 1967, 2005, Jones 1982, Marks and Collazo 1998, Mount 1975). They sometimes aggregate in seepages where as many as 12 nests have been located in close proximity to one another (Petranka 1998). All of the egg masses found by Marks and Collazo (1998) in the Nantahala Mountains were accompanied by brooding females and were under moss mats that were growing on rotting logs in seepages or small streams.

The creamy white eggs have short pedicels that are wrapped around each other to form a grape-like cluster, and the females remain with their eggs until the embryos hatch (Bishop and Valentine 1950, Brown and Bishop 1948). The average diameters of freshly-laid ova vary among local populations from 1.9-2.7 mm, while the entire egg capsule varies from 2.4-3.0 mm in diameter (Petranka 1998).

Geographic variation in average clutch size is slight and ranges from 11-14 eggs. The number of mature ova in 34 females from the southern Appalachians ranged from 6-17, averaged 12, and was positively correlated with SVL (Harrison 1967), while the mean size of 27 clutches that were found in the field varied from 6-18 and averaged 11. Bruce (2019) found nests with 3-14 eggs in the Nantahala Mountains in North Carolina.

Females lay their eggs from April through June in Georgia, Tennessee and North Carolina (Harrison 1967, Jones 1982, Marks and Collazo 1998) and as early as February in western Alabama (Valentine 1963c). Brooding females have been found in Alabama during the spring and from July-October (Mount 1975), but females in North Carolina typically nest during the spring and early summer (Bruce 2019). Marks and Collazo (1998) found 59 egg clutches with brooding females in the Nantahala Mountains in late May and June that varied from early to late-stages of development. Hatching occurs from late May to early August in Georgia and North Carolina populations (Harrison 1967), and as early as late June in Tennessee (Jones 1982). The incubation period lasts about 6-9 weeks (Petranka 1998).
Aquatic Life History: The Seepage Salamander lacks a true feeding larval stage as seen in most other dusky salamanders. The gills are either resorbed just before hatching, or are lost a few days or weeks after hatching (Harrison 1967). As such, populations are not dependent on running water to complete the larval stage and this species is best treated as being fully terrestrial (Harrison 2005). Hatchling larvae from Alabama were 10.2-12 mm TL and transformed when 11.5-14 mm TL (Valentine 1963).
Terrestrial Life History: The juveniles and adults live in moist leaf litter or moss mats during the warmer months of the year where they subsist on small invertebrates. They appear to be opportunistic generalists and consume a wide variety of prey (Petranka 1998). Food items that were documented by Donovan and Folkerts (1972) in Alabama and Georgia specimens included isopods, amphipods, mites, spiders, myriopods, earthworms, terrestrial snails, nematodes, shed salamander skins, numerous insects, and a conspecific. Tiny mites and collembolans are the dietary staple of seepage salamanders in a Tennessee population (Jones 1982). Other prey include nematodes, snails, isopods, various insects, millipedes, centipedes, spiders, and pseudoscorpions. Individuals appear to forage mostly beneath litter and are less likely to emerge at night to forage on the ground surface compared to conspecifics such as D. ocoee (Hairston 1987; Petranka 1998).

Hatchlings in many areas become sexually mature in 2 years after reaching 18-19 mm SVL (Harrison 1967). Many females, however, may not breed until nearly 3-years old. Males studied by Hining and Bruce (2005) in North Carolina became sexually mature when 2-3 years old, while females appeared to first oviposit when three years old.

General Ecology
Population Ecology: Local populations are strongly affiliated with seepages and small headwater streams and are patchily distributed across the landscape where suitable habitats for nesting and foraging are present. We have much to learn about population connectivity and population organization at different spatial scales.
Community Ecology: The Seepage Salamander usually coexists with a variety of other streamside salamanders, including other Desmognathus species. Ecological interactions with these species is poorly documented, but both competition and predator-prey interactions are likely. Their reliance on leaf litter as foraging sites may be a way to avoid surface-active predators such as larger salamanders or even large invertebrates such as spiders.
Adverse Environmental Impacts
Habitat Loss: Numerous local populations of this species have been lost historically since European colonization in association with the widespread destruction and degradation of deciduous forests in the eastern US. Continued habitat loss or degradation from the conversion of deciduous forest to agricultural land, home building sites, and managed pine forests will likely results in additional populations being lost in the future. Small wetlands such as seepages receive little or no legal protection, which makes populations more vulnerable to human losses.
Habitat Fragmentation: Forest fragmentation can not only directly eliminate critical habitat for this species, but also generate edge effects that can degrade terrestrial habitat. This and other plethodontid salamanders rely on their moist skin as a respiratory organ to obtain oxygen. Forests that adjoin pastures, agricultural fields, roadways or clearcuts tend to be hotter and drier along their margins relative to interior regions. These edge effects can extend 30 meters or more into a forest and often result in reduced salamander numbers along forest margins (e.g., Crawford and Semlitsch 2007, Demaynadier and Hunter 1998, Semlitsch et al. 2006).
Status in North Carolina
NHP State Rank: S3
Global Rank: G3G4
Status in North Carolina: W2
Populations: Local populations of the Seepage Salamander are centered around seepages and small woodland streams that provide nesting and foraging sites. Suitable habitats are patchily distributed across the landscape and the extent to which local populations are connected via occasional dispersal between sites is largely unknown.
Environmental Threats: Populations are strongly associated with seepages and headwater streams in forested habitats and in all likelihood are vulnerable to intensive management practices such as clearcutting that eliminates leaf litter and shading and causes significant edge effects. Whenever possible, forest buffers of 30-50 meters or more should be left around seepages and headwater streams in areas scheduled for timbering since these are the major breeding sites of this and many other salamander species. The conversion of streamside forests to pastures, agricultural fields, and homesites would create major barriers to dispersal between local populations and likely increase the risk of local populations being extirpated.
Status Comments: The status of populations in North Carolina are poorly known due to the lack of long-term monitoring of populations. Populations in national forests presumably receive more protection than those on private lands due to management policies that leave forest buffers along streams.
Stewardship: Woodland seepages and small headwater streams often lack predatory fishes and are important habitats for this and many other salamanders. Much like D. aeneus, many of these species forage in the surrounding forest during the summer months. Populations of the Seepage Salamander and many stream-breeding salamanders are best maintained by leaving forest buffers of 50 m or more along stream and seepage margins, and by minimizing excess sedimentation from upstream sites.

Photo Gallery for Desmognathus aeneus - Seepage Salamander

2 photos are shown.

Recorded by: Todd Pierson
Macon Co.
Recorded by: Steve Hall, Haven Wiley, Dee Stuckey, UNC Vertebrate Field Biology Class
Macon Co.