Taxonomy
Class: AmphibiaOrder: CaudataFamily: PlethodontidaeSubfamily: 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. 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). oconee group. These include two new species (D. adatsihi ; D. balsameus ) and one resurrected species (D. perlapsus ). Four of the five species in the D. oconee complex occur in western North Carolina and are best identified using their geographic ranges (see distribution map above).Species Comments:
Identification
Description: Desmognathus balsameus is a medium-sized Desmognathus (approximately 19–47 mm SVL; n = 22) with a tail that is round in cross section along its length and shorter than the body (up to approximately 90% of the SVL; Pyron and Beamer, 2022a). Desmognathus santeetlah is the only species in its range that it might be confused with, but the latter is more aquatic and has keeling on the dorsal surface of the tail. Desmognathus balsameus exhibits a wide range of color patterning, with most individuals possessing a partially or mostly complete dorsal stripe with wavy or undulating edges. The patches are formed from the irregular invasion of melanophore patches between the remnants of paired larval spots, and are typically brownish, yellowish, or reddish against a darker lateral ground color (Pyron and Beamer, 2022a). Individuals darken with age, with individuals as small as 33 mm SVL sometimes having dark brown to blackish coloration that obscures the dorsal pattern. This species lacks cornified, dark toe tips as seen in most of the more aquatic Desmognathus species. ocoee complex typically average slightly larger than females and are more likely to be melanistic. 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 of members of the ocoee complex 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 4-6 pairs of alternating light spots along the dorsum. Online Photos: Google iNaturalist Observation Methods: Individuals are easy to collect by searching beneath cover objects along stream margins, under rocks and debris in the stream proper, or in the adjoining woods. They are most easily observed at night when they actively forage and seek mates on the forest floor. AmphibiaWeb Account
Distribution in North Carolina
Distribution Comments: Desmognathus balsameus is a narrow southern Appalachian endemic that is restricted to the Great Balsam Mountains of western North Carolina southeast of Balsam Gap. It is a high-elevation species that is found above ca. 3280’ in elevation. This species is currently known only from Haywood, Jackson, and Transylvania counties (see distribution map above), but can be locally abundant in headwater streams and seepages. Desmognathus balsameus will likely be adversely affected by future climate change that results in a the warming of higher elevation peaks in the Blue Ridge. 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. ocoee complex that occur in western North Carolina are associated with montane forests 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. Desmognathus balsameus can be found from the lower valleys to the highest peaks in the the Great Balsam Mountains.Biotic Relationships: This and other members of the D. ocoee complex are palatable to predators and are undoubtedly preyed upon by aquatic predators such as crayfishes, as well as woodland birds, small snakes, large salamanders, and small mammals such as shrews that live in stream, streamside, and forest-floor habitats in mesic forests. The Spring Salamander (Gyrinophilus porphyriticus ), members of the Black-bellied Salamander complex, and the Seal Salamander (D. monticola ) feed on members of the D. ochrophaeus and D. ocoee species complex (Bruce 1979, Coker 1931, Formanowicz and Brodie 1993, Hairston 1986, Petranka 1998, Whiteman and Wissinger 1991) and undoubtedly feed on D. balsameus as well.
Life History and Autecology
Breeding and Courtship: The courtship behavior of members of the D. ocoee complex appear to be identical. The breeding season is also similar other than constraints due to local climatic conditions associated with different elevations in the Blue Ridge Mountains. The adults mate during the warmer months of the year in spring, late-summer, and autumn, and the females reproduce annually in most populations (Forester 1977, Huheey and Brandon 1973, Martof and Rose 1963). Courtship involves a stereotypic tail straddle walk, but detailed descriptions of courtship behavior are not available. The basic sequence of events involves a period of persuasion that is followed by a tail straddle walk and spermatophore deposition. The male may repeatedly snap or pull his chin across the female's dorsum, which scratches the female's skin and transfers mental gland secretions into the female's circulatory system (Houck 1986). Mental gland secretions act to enhance the sexual responsiveness of females to males (Houck and Reagan 1990). D. ocoee complex, females often court several times per year and are capable of long-term sperm storage. As such, sperm competition likely occurs among males (Petranka 1998). When two males are near a female, the larger will often chase the smaller one away prior to mating. Each male normally deposits only one spermatophore per night, even when experimentally presented with multiple partners (Verrell 1988a). In addition, females are not responsive to males for 2-4 days after successful insemination. This corresponds to a time when the female's cloaca is physically blocked by the sperm cap (Verrell 1988b, 1991). Reproductive Mode: The nesting biology of members of the D. ocoee complex -- as well as D. carolinensis and D. orestes -- appear to be very similar or identical. Some of the studies that reported on the nesting biology prior to the splitting of D. ochrophaeus (sensu lato) and D. ocoee (sensu lato) into multiple species (see above) are confounded because they involved two or more species (e.g., Martof and Rose, 1963). The following provides a general summary of the nesting biology of this group of closely related species, with references to specific species where possible. Although few specifics are known about the nesting biology of D. balsameus , it is presumably very similar to the general account that is present below. D. perlapsus collected by Bruce (1990) in western North Carolina contained from 8-23 eggs and averaged 14. The modal clutch sizes for two populations of D. ocoee (sensu stricto) studied by Bernardo (1994) were 12 and 16 eggs, while Tilley (1972) reported clutches of 10-19 eggs (mean = 14 eggs) for D. perlapsus and 13-24 (mean = 18) for D. carolinensis on Mt. Mitchell. Clutch size is positively correlated with female body size in this and most other Desmognathus species and increases with elevation (Petranka 1998). D. perlapsus (and presumably other members of the D. ocoee complex) will lunge at and bite certain intruders, and their aggression towards intruders increases during the brooding season as their investment in parental care increases (Forester 1983). Clutches at or near hatching have been found from August to late September. The estimated incubation periods for North Carolina populations of D. perlapsus were 57-74 days (Forester 1977) and 50-60 days (Tilley 1972), and 52-69 days for D. carolinensis on Mt. Mitchell (Tilley 1972). Embryonic survivorship from early developmental stages to hatching is near 80% in clutches examined by Tilley (1972). Aquatic Life History: We currently lack information on the larval life history and ecology of D. balsameus , but they are presumably very similar to those of other members of the D. ocoee species complex. Fully developed embryos of other members typically hatch in North Carolina in August through September. The larvae subsist on small invertebrates and the larval period last less than one year. Bruce (1989) reported that the larvae of D. perlapsus metamorphose in May and June of the following year when 11-15 mm SVL. Beachy (1995) grew larvae of D. ocoee in the laboratory at temperatures that resembled those in natural streams and found that the larval period typically lasted around 9-10 months. His experimental manipulation of food levels and water temperatures indicate that both can affect larval growth and development rates. Terrestrial Life History: Members of the D. ocoee and D. ochrophaeus complexes have very similar terrestrial life histories. Although the terrestrial ecology of D. balsameus is poorly documented, it presumably is very similar to that of other members of the mountain dusky salamander complexes. A general summary of the terrestrial life history of these species follows. D. perlapsus that were studied by Tilley (1977, 1980) grew about 5-7 mm per year SVL until age 4-5, then slowly declined thereafter. The pattern was similar for females, except that their growth rates begin to decline after reaching 3-4 years of age. Individuals in western North Carolina and extreme southeastern Tennessee often become sexually mature when < 30 mm SVL (Petranka 1998). Bruce (1990) found that both sexes of D. perlapsus reach sexual maturity in a stream population when 3-years old, and that females first oviposit when 4-years old. In general, the age and size at first reproduction, maximum adult size, mean clutch size, and adult survivorship tend to increase with elevation (Tilley 1977, 1980).
General Ecology
Adverse Environmental Impacts
Status in North Carolina
NHP State Rank: [S2S3]Global Rank: GNRStatus in North Carolina: [W]Status Comments: Desmognathus balsameus is restricted to the Great Balsam Mountains of western North Carolina southeast of Balsam Gap. It occurs at elevations above approximately 1000 m (3281’) and primarily in Haywood, Jackson, and Transylvania counties (see distribution map above). North Carolina populations could be adversely affected by future climate change, and the ongoing excessive atmospheric deposition of reactive nitrogen that can impair ecosystem functions and local biodiversity (Walker et al., 2023).
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