Amphibians of North Carolina
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Plethodontidae Members:
NC Records

Plethodon ventralis - Southern Zigzag Salamander

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Taxonomy
Class: Amphibia Order: Caudata Family: Plethodontidae Subfamily: Plethodontinae
Taxonomic Comments: Populations of a wide-ranging and geographically variable small Plethodon that occurs in the eastern US were traditionally treated as a single species, the Zigzag Salamander (P. dorsalis). Molecular analyses subsequently revealed several deep evolutionary lineages within this species (Highton 1997, Larson and Highton 1978), and the most distinctive lineages are currently recognized as four species. These include P. angusticlavius in the Ozark mountains, P. dorsalis (sensu stricto) in southern Illinois, Indiana, northern Kentucky, and western and central Tennessee, P. ventralis in southeastern Kentucky, southwestern Virginia, eastern Tennessee, western North Carolina, northwestern Georgia, northern Alabama, and northeastern Mississippi, and P. websteri in scattered locations from the Piedmont of western South Carolina to Louisiana. We consider the first three species to comprise the P. dorsalis complex, while P. websteri is so distantly related to the other three (Feist et al. 2019) that is is not included despite being morphologically similar. Of these, only the Southern Zigzag Salamander (P. ventralis) occurs in North Carolina.
Species Comments:
Identification
Description: The Southern Zigzag Salamander is a small Plethodon that is about the same size and shape as the Eastern Red-backed Salamander (P. cinereus). Most adults range in size from around 65-100 mm TL. The tail of adults comprises about half of the body length and there are usually 18 costal grooves. Two color morphs occur in some populations, particularly in the southern portion of the range (Highton 1997, Petranka 1998). The striped morph has a wavy yellowish brown to orangish red dorsal stripe that extends from the head to the tail tip. The dorsal stripe is wavy anteriorly, but more straight-edged towards the tail. The unstriped or dark morph lacks the dorsal stripe and is grayish-black above, but often has a suffusion of orange or red near the insertion of the limbs. The belly of both morphs is mottled with small black, white, gray and reddish-orange blotches, and the sides and back often have silvery white to brassy flecks that can produce a frosted appearance, particularly on the unstriped morph. Intermediates between these two color phases are common in many populations, with the dorsal stripe becoming obscure before reaching the tail. Most populations from throughout the range only consist of the unstriped morph (Highton 1997), and this appears to be the case for North Carolina populations. North Carolina specimens can be distinguished from unstriped morphs of P. cinereus by the presence of an orangish wash near the insertion of the limbs and in having relatively longer limbs. Sexually active males have swollen tissue around the nasolabial grooves and a small, oval-shaped mental gland on the chin.
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Observation Methods: Individuals are most easily found by turning logs, bark, and other surface covers during periods of warm weather during the fall through early spring months.
AmphibiaWeb Account
Distribution in North Carolina
Distribution Comments: Populations of the Southern Zigzag Salamander have been found in southeastern Kentucky, southwestern Virginia, eastern and east-central Tennessee, western North Carolina, extreme northwestern Georgia, northern Alabama and extreme northeastern Mississippi. This species hybridizes with P. dorsalis in Kentucky to form a relatively wide hybrid zone. In North Carolina, only a few scattered populations have been found in Yancey, Madison, Buncombe, and Henderson counties. All but one of the records are from the French Broad River Basin. The Henderson Co. record is historical and questionable due to the fact that the exact locality was not reported. These specimens could have been collected in southern Buncombe Co.
Distribution Reference: Highton (1997)
County Map: Clicking on a county returns the records for the species in that county.
GBIF Global Distribution
Key Habitat Requirements
Habitat: Most members of the P. dorsalis complex are strongly associated with rocky habitats and are abundant in limestone regions where caves, talus, or rock crevices provide easy access to underground passageways (Petranka 1998). Populations in North Carolina are not as strongly associated with caves or talus slopes, and are often found on rich, lower-elevational slopes and ravines, some of which have substantial cliff formations.
See also Habitat Account for General Montane Mesic Forests
Life History and Autecology
Breeding and Courtship: Most aspects of the natural history of this species are undocumented, but studies of closely related populations of P. dorsalis to the northwest suggest that mating occurs from late fall through spring (Petranka 1998). There are no published accounts of courtship behavior.
Reproductive Mode: The reproductive ecology of this species is undocumented, but is presumably very similar to populations of P. dorsalis in Kentucky and Indiana. Females in this region oviposit shortly after moving to underground retreats in late spring or early summer, then resurface in September and October after the embryos have hatched. Populations in North Carolina follow a similar seasonal trends, with the adults moving into underground retreats during the summer months.
Terrestrial Life History: The terrestrial life history is poorly documented. In North Carolina, the juveniles and adults are active on the ground surface during the cooler months of autumn through spring. They presumably feed on small invertebrates that reside in leaf litter and beneath cover objects.
General Ecology
Adverse Environmental Impacts
Habitat Loss: Most known populations in North Carolina occur at relatively low elevations in the French Broad River Valley. Some populations may have been lost historically in this region due to the widespread loss of forested habitats as land was cleared in the valleys and valley slopes for cattle grazing, agricultural crops such as tobacco, and urban development. Wade et al. (2021) found that populations were less likely to occur at sites in eastern Tennessee where invasive plants were common.
Habitat Fragmentation: Wade et al. (2021) determined population occupancy in a fragmented landscape in the Knoxville, Tennessee area and found that the likelihood of finding a local population at a site was not affected by the forest patch size that was present. This suggests that populations in this region are not strongly affected by forest fragmentation. It is not certain if the same applies to western North Carolina populations since limestone formations are usually not present locally that allow easy access to underground retreats.
Status in North Carolina
NHP State Rank: S2
Global Rank: G4
Status in North Carolina: SC
Environmental Threats: Most of the known populations in North Carolina occur at relatively low elevations in the French Broad River Valley. They tend to be geographically isolated from one another and could potentially be adversely affected by future land clearing and urban development in the region.