Amphibians of North Carolina
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Plethodontidae Members:
NC Records

Plethodon cylindraceus - White-spotted Slimy Salamander

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 is a relatively large member of the P. glutinosus complex that has large white dorsal spots and moderately abundant lateral white spotting. 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. Identification of this species in North Carolina is best achieved using the collection locality.

The White-spotted Slimy Salamander comes into close geographic contact with the Atlantic Coast Slimy Salamander (P. chlorobryonis) from southeastern Virginia to western South Carolina near the boundary between the Piedmont and Coastal Plain. Highton and Peabody (2000) sampled populations along two transects in southeastern Virginia and northeastern North Carolina and found that there is a hybrid zone in both areas. These species can be separated to some extent using size and coloration. In addition to being smaller on average, P. chlorobryonis tends to have small, slightly brassy white dorsal spots and abundant lateral white or yellowish spotting, while P. cylindraceus tends to have larger dorsal spots that are whiter and with only moderately abundant lateral white spots. However, specimens often deviate substantially from these general trends. Beane et al. (2010) noted that the dorsal spotting on North Carolina specimens of P. chlorobryonis is often greatly reduced or missing. Highton (1989) found that Piedmont populations of P. chlorobryonis in South Carolina are substantially larger than those in the Coastal Plain, so size may not always be helpful in identifying specimens collected near the border of the Piedmont and Coastal Plain, particularly if hybrids are present. A comprehensive molecular analysis of the contact zone in North Carolina is needed.
Online Photos:    Google   iNaturalist
Observation Methods: Adults are most easily collected by turning rocks or logs on the ground surface during the day and by searching the forest floor at night during periods of wet weather.
AmphibiaWeb Account
Distribution in North Carolina
Distribution Comments: Based on his genetic analyses of populations, Highton (1989) reported that the range includes the Piedmont and Blue Ridge physiographic provinces of Virginia and North Carolina west to the French Broad River and south to the northern Piedmont of South Carolina. It also occurs in parts of the Valley and Ridge physiographic province in western Virginia and extreme eastern West Virginia and a small area of the Coastal Plain physiographic province of eastern Virginia. Beane et al. (2010) show the range encompassing most of Virginia except for the far western counties and the southeastern corner, and extending into the Coastal Plain of North Carolina.
Distribution Reference: Beane et al. (2010); Highton 1989
County Map: Clicking on a county returns the records for the species in that county.
GBIF Global Distribution
Key Habitat Requirements
Habitat: The White-spotted Slimy Salamander is typically found in mesic hardwoods or mixed pine-hardwoods. Sites with mature stands of trees, a well-developed leaf litter layer, loamy soils, and large cover objects such as rock piles or large rotting logs provide ideal conditions for this species. Populations in the mountains mostly occur from the lower valleys to mid-elevational sites.
See also Habitat Account for General Mesic Hardwood Forests
Life History and Autecology
Breeding and Courtship: Organ (1960) observed courting pairs in Virginia that are presumed to be this species, and the following is a summary of his observations as reported in Petranka (1998).

When a male encounters a female, he places his nasolabial grooves and mental gland in contact with her head, body, or tail. The male then engages in a 'foot dance' in which he raises and lowers his rear limbs either alternately or simultaneously. When raising the limbs simultaneously, the tail is used as a brace to support the body. As the dance proceeds all four limbs are raised and lowered as if the male is marking time. The male then proceeds forward towards the female's head. While moving forward, he repeatedly rubs his nasolabial grooves on the female, then gently grasps her body or tail with his mouth and releases it shortly thereafter.

The male eventually reaches the head of the female, keeping his mental gland over the head and nasolabial grooves. He then pushes his head under her chin and passes beneath. Foot dancing continues throughout these early stages of courtship. The male undulates his tail as it passes under the female's chin, then stops his forward progress. The female straddles the tail and the pair moves forward and engages in a tail-straddle walk. During the tail-straddle walk the male undulates his tail and often flexes his body laterally to slap the snout of the female with his mental gland. The tail-straddle walk is prolonged and may cover a linear distance of > 5 m.

Prior to spermatophore deposition the male stops moving forward and begins rocking his sacral region laterally. The female moves her head laterally in synchrony, but counter to, the direction of movements of the male. The male lowers his vent to the substrate and deposits a spermatophore. He then raises the vent and flexes his tail to one side. The couple then moves forward with the female keeping her chin against the tail base of the male. As the female passes over the spermatophore she picks up the sperm cap with her cloacal lips. The couple usually breaks up shortly thereafter.

As of 2022, our one observation of courtship was by Tom Ward who observed a pair courting on 10 October.
Reproductive Mode: The females nest underground in cavities or rocky recesses. The eggs are presumably laid in a globular mass, with the females brooding them through hatching.
Terrestrial Life History: Juveniles and adults are active on the ground surface during the warmer months of the year. They remain beneath surface cover or in underground burrows during the day, but emerged at night when conditions are favorable to feed on the forest floor. Surface activity is curtailed during periods of dry weather that causes the leaf litter to dry.

This species is an opportunistic predator that takes a wide array of prey. Food items in 58 adults examined by Pope (1950) from Johnston County, Tennessee included collembolans, homopterans, hemipterans, lepidopterans, dipterans, coleopterans, hymenopterans, phalangids, pseudoscorpions, spiders, mites, millipedes, centipedes, earthworms, and snails. Ants and beetles constituted most of the bulk of specimens from Augusta County, Virginia (Davidson 1956). Other prey included snails, isopods, earthworms, centipedes, millipedes, arachnids, phalangids, pseudoscorpions, and miscellaneous insects.

Wells and Wells (1976) found that juveniles in a population in east-central North Carolina remained beneath their home logs during the first year of life. Adults moved significantly greater distances between captures than juveniles, but adult females and males did not differ significantly in the average distance moved. Although the maximum distance moved between captures was 92 m, most adults move < 9 m. The most distant moves were made by juveniles shortly after becoming sexually mature.

A related study examined the spacing patterns of P. cylindraceus that dwelled beneath logs (Petranka 1998, Wells 1980). In most cases a single salamander was found under a log on a given day. However, captures of 417 different individuals under 78 logs over a 3-year period indicate that some logs are used by up to several dozen salamanders. When two or more individuals were found beneath the same log, males were associated with other males less frequently than expected by chance. Males and females also were together more frequently than expected by chance, but females did not appear to avoid other females. Juveniles associated with males, females, and other juveniles equally. These data suggest that females and juveniles show little tendency to avoid logs with occupants. The underrepresentation of male-male groupings and overrepresentation of male-female groupings may reflect the fact that males defend home logs from other males, or that males actively search logs until they find females. During summer droughts groups of 10-25 animals could be found under large logs (Wells and Wells 1976). In some cases the animals piled on top of one another, a behavior that presumably functions to reduce dehydration.
General Ecology
Adverse Environmental Impacts
Status in North Carolina
NHP State Rank: S5
Global Rank: G5
Environmental Threats: This and other species of large eastern Plethodon reach their highest densities in mature hardwood forests and are sensitive to intensive timber harvest practices such as clearcutting. Deforestation and the conversion of hardwoods to pine monocultures has reduced or eliminated many Plethodon populations in eastern North America, including P. cylindraceus. Although data are largely lacking, populations on the Piedmont have undoubtedly suffered major historical losses due to urbanization, deforestation, the construction of roadways and other infrastructure, and the conversion of hardwoods to agricultural fields and pine forests that are harvested on short rotation cycles. Highton (2003) found evidence of declines in all 14 P. cylindraceus populations that he sampled during the past four decades. At 13 sites the number of specimens collected during surveys conducted during the 1990s were fewer than half of those obtained during earlier time periods.
Status Comments: This species has undoubtedly suffered major declines since European colonization due to the loss and fragmentation of deciduous forests in the Piedmont associated with agriculture, urbanization, and clearcutting. Populations in the mountains are more protected and appear to be more secure. This species is still common and locally abundant in many areas where mature forest stands are present.
Stewardship: This and other woodland salamanders do best in mature hardwood forests that have rich soils, well-developed leaf litter layers, substantial amounts of logs and other coarse woody debris, and a well-developed canopy.

Photo Gallery for Plethodon cylindraceus - White-spotted Slimy Salamander

16 photos are shown.

Recorded by: B. Bockhahn, J. Thomson
Buncombe Co.		Recorded by: Andrew W. Jones
Polk Co.
Recorded by: Andrew W. Jones
Polk Co.		Recorded by: B. Bockhahn, J. Thomson
Buncombe Co.
Recorded by: tom ward
Buncombe Co.		Recorded by: B. Davis
Burke Co.
Recorded by: A. Pharr
Gaston Co.		Recorded by: L. Knepp
Surry Co.
Recorded by: L. Osteen
Orange Co.		Recorded by: tom ward
Buncombe Co.
Comment: A courting pair on October 10, 2020.
Recorded by: tom ward
Buncombe Co.
Comment: A courting pair in a tail-straddle walk on October 10, 2020. 		Recorded by: Morgan Freese
Wake Co.
Recorded by: Owen McConnell
Orange Co.		Recorded by: Steve Hall and Harry LeGrand
Granville Co.
Recorded by: Steve Hall and Harry LeGrand
Granville Co.		Recorded by: Rob Van Epps
Mecklenburg Co.