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

Plethodon glutinosus - Northern Slimy Salamander

No image for this species.
Taxonomy
Class: Amphibia Order: Caudata Family: Plethodontidae Subfamily: Plethodontinae
Taxonomic Comments: A group of wide-ranging large Plethodon species in the eastern US with a blackish ground color and varying levels of whitish or golden flecking, blotching, and spotting have traditionally been known as 'slimy salamanders' due to glutinous secretions that are produced from the tail. These were originally thought to represent a single wide-ranging species (the Slimy Salamander, Plethodon glutinosus), but were split into 16 species by Highton (Highton 1984, 1989; Highton and MacGregor 1983) and constitute the 'Plethodon glutinosus complex'. One (P. aureolus) was described in 1984 and the other (P. kentucki) was resurrected in 1983. The remainder were described by Highton (1989) and constitute a complex of geographically and genetically variable groups that are difficult to distinguishable from one another based on external phenotypic traits.

Highton (1989) analyzed geographic variation in protein patterns and split these into numerous species using an arbitrary genetic distance to define species. This resulted in a series of parapatric forms that show varying levels of gene exchange in contact zones. Frost and Hillis (1990) objected to splitting P. glutinosus into multiple species based solely on arbitrarily selected genetic distances and cited a variety of perceived problems, including several biases in estimating genetic distances. Data from studies using mitochondrial and nuclear sequence data (Fisher-Reid and Wiens 2011, Wiens et al. 2006) was used to justify keeping Highton's original taxonomy for the group. These studies sometimes relied on sequence data from a single representative individual of each species and did not carefully examine contact zones or examine levels of gene exchange between form, which Hillis (2019) argued is essential for making taxonomic decisions.

Joyce et al. (2019) analyzed multiple specimens from Alabama that represented three members of the P. glutinosus complex (P. glutinosus, P. grobmani, and P. mississippi) and concluded that these represent a single species of slimy salamander (P. glutinosus) rather than three as proposed by Highton (1989). They further argue that similar issues arise when multiple individuals have been used in studies: paraphyly is common place and the validity of several species is questionable (e.g., Smith et al. 2018, Wiens et al. 2006). To complicate matters further, members of the P. glutinosus complex show widespread evidence of historical or present gene exchange with members of the P. jordani complex (Weisrock et al. 2005). Joyce et al. (2019) recommended only recognizing three species within the P. glutinosus complex: P. aureolus, P. kentucki, and P. glutinosus. The latter would be treated as a geographically variable species that contains all of the remaining species that Highton recognized.

The taxonomic status of many members of the Plethodon glutinosus complex is clearly unresolved, and there may never be a complete resolution of the problem given that experts often embrace different taxonomic philosophies when interpreting geographic variation within a group. In addition, there is often widespread discordance in the lines of evidence used to delineate species. North Carolina may have as many as 6 members of the 16 species recognized by Highton, although two are of questionable status. These include P. aureolus, P. chattahoochee, P. chlorobryonis, P. cylindraceus, P. glutinosus and P. teyahalee. Here we continue to include all six of these forms in the North Carolina fauna, with the understanding that the taxonomic status of some may change in the future.

Species Comments:
Identification
Description: This member of the P. glutinosus complex is a large species with large brassy colored dorsal spots and moderately abundant white or yellow spotting along the sides. Adults have a black to dark bluish black ground color, and the venter is grayish black and slightly lighter colored than the dorsum. The tail is rounded in cross-section and slightly longer than the body. The number of costal grooves averages 16. Sexually mature males have prominent circular-shaped mental glands and papillose cloacal lining.

Plethodon glutinosus is largely indistinguishable from many other members of the complex, and is best identified by range. It may possibly coexists with P. teyahalee in extreme southwestern North Carolina. The latter has very small white dorsal spots and reduced lateral white spotting, which will help distinguish it from P. glutinosus. It may also possibly coexists with P. cylindraceus in the northwestern corner of the state, and can be distinguished by the large white dorsal spots on P. cylindraceus versus more brassy spots on P. glutinosus.
Online Photos:    Google   iNaturalist
Observation Methods: The juveniles and adults can be easily observed at night during the warmer months feeding on the forest floor, and can be collected underneath surface objects during the day.
AmphibiaWeb Account
Distribution in North Carolina
Distribution Comments: Plethodon glutinosus ranges from southwestern Connecticut west to southern Illinois and south through West Virginia, western Virginia, Kentucky and Tennessee to eastern Alabama and northwestern and central Georgia (Highton 1989). Populations have been found along the NC-TN border in eastern Tennessee, but (Highton 1989) shows only one record for North Carolina in Cherokee Co. This species also occurs on Parson Bald in the Smokies (Swain Co.), and possibly in Ashe Co., although this record has not been verified by molecular analyses.
Distribution Reference: Highton (1989)
County Map: Clicking on a county returns the records for the species in that county.
GBIF Global Distribution
Key Habitat Requirements
Habitat: Plethodon glutinosus is most characteristically associated with hardwood or mixed pine-hardwood forests and has been found as high as 1500 m (4920') in elevation. Mature hardwood forests with a well-developed leaf-litter layer, loamy soils, and abundant amounts of coarse woody debris often support healthy populations. Large rotting logs are important microhabitats that are used as surface cover and foraging sites by the adults. Individuals are also sometimes found in rock crevices or cave entrances.
See also Habitat Account for General Montane Mesic Forests
Life History and Autecology
Breeding and Courtship: The adults mate during the summer and early fall months. Mating in Virginia and New Jersey has been observed from August through October, and the females appear to produce a clutch of eggs every other year (Petranka 1998). Details of courtship are not documented, but members of the P. glutinosus complex frequently interbreed and presumably have nearly identical courtship behaviors (see the description of the courtship of P. cylindraceus that is likely representative of this species).
Reproductive Mode: After mating, each female lays a globular cluster of eggs that is often suspended from the top of a cavity. Freshly-laid eggs average 3.5-5.5 mm in diameter, are creamy white, and are surrounded by two jelly envelopes (Petranka 1998). The outer envelopes of adjoining eggs tend to stick together and may sometimes fuse partially after oviposition. Females remain with their eggs through hatching, and sometimes stay with the young for a week or two after hatching.

Most females presumably nest underground in natural cavities, but a few have been found elsewhere, including in a decaying stump in West Virginia and in a cave in northern Alabama where over a dozen clutches were found between 15-28 September (Highton 1962b). Estimates of clutch size based on counts of large ovarian eggs are generally higher than counts of eggs in nests. Reported values for ovarian eggs include a mean of 17 (13-25) for Pennsylvania specimens, a mean of 26 (16-34) for Maryland specimens (Highton 1962b), a mean of 25 for southeastern Kentucky specimens (Bush 1959), a mean of 23 (17-33) for Virginia specimens (Pope and Pope 1949), and a range of 17-38 ova for New York specimens (Bishop 1941a). In Maryland and Pennsylvania populations, clutch size is positively correlated with female SVL (Semlitsch 1980b).

Seasonal patterns of vitellogenesis and nesting records indicate that females in eastern Kentucky, Maryland, Pennsylvania, Virginia, and other northern populations oviposit in late spring or early summer (Bush 1959, Highton 1962b). Eggs have been found in early July in Pennsylvania (Hudson 1954), and in early June in West Virginia and Indiana (Fowler 1940, Minton 1972). The eggs require 2-3 months to develop to the hatching stages. Hatchlings were found from 3 November-10 December in a north Alabama cave (Highton 1962b), and during the second week of October in Indiana. We currently have no information on the reproductive biology of this species in North Carolina.
Aquatic Life History: The Northern Slimy Salamander is a fully terrestrial species that lacks an aquatic larval stage.
Terrestrial Life History: During the warmer months of the year the juveniles and adults emerge from daytime retreats with the onset of darkness and forage on the forest floor. Surface activity is curtained during periods of hot, dry weather. Green and Pauley (1987) noted that individuals at low-elevation sites In West Virginia are inactive during the summer, while those at high elevations are active throughout the summer. It is uncertain to what extent reduced summer activity occurs in other areas of the range (Petranka 1998).

The Northern Slimy Salamander appears to be an opportunistic, generalist feeder (Petranka 1998). Food items in adults from western Virginia included collembolans, homopterans, hemipterans, lepidopterans, dipterans, coleopterans, hymenopterans, phalangids, pseudoscorpions, spiders, mites, millipedes, centipedes, earthworms, and snails (Pope 1950), while a series of Pennsylvania specimens had earthworms, snails, spiders, millipedes and insects in their guts (Surface 1913). Ants and beetles were important prey in specimens from New York and Virginia, but many other prey were taken including other insects, isopods, earthworms, centipedes, millipedes, spiders, pseudoscorpions, slugs, and snails (Davidson 1956, Hamilton 1932).

Studies indicate that individuals begin maturing sexually 3-4 years after hatching and reproduce for the first time the following year. Males mature sexually at 45-52 mm SVL in a western Virginia population, and females between 58-65 mm SVL. Individuals in Maryland and Pennsylvania populations are mature at 53-70 mm SVL, with males reaching sexual maturity at smaller sizes than females. Individuals in southern Illinois appear to mature after 3 years when 47-58 mm SVL (Highton 1962b, Petranka 1998).
General Ecology
Population Ecology: This and many other members of the P. glutinosus complex will aggressively defend territories from conspecifics (Petranka 1998, Thurow 1976), and this likely sets an upper limit on population size in many populations. Semlitsch (1980b) estimated the average densities of Maryland and Pennsylvania populations in optimal habitats to be 0.52-0.81 salamanders/m2 using mark-recapture estimates.
Community Ecology: These and other woodland salamanders are important members of many forest communities and probably play important roles in structuring invertebrate communities inhabiting the forest floor. The Northern Slimy Salamander frequently coexists locally with an array of other salamanders that feed on insects and other small invertebrates, but detailed studies of competition among community members are largely lacking.
Adverse Environmental Impacts
Status in North Carolina
NHP State Rank: SU
Global Rank: G5
Status in North Carolina: W4
Environmental Threats: This and other species of large eastern Plethodon reach their highest densities in mature hardwood forests. Deforestation, urbanization, and the conversion of hardwood forests to agricultural fields and pine monocultures has reduced or eliminated many Plethodon populations in eastern North America.