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Plethodon savannah Highton, 1989
Savannah Slimy Salamander
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G2G3
State Rank: S2?
Element Locations Tracked in Biotics: Yes
SWAP 2015 Species of Greatest Conservation Need (SGCN): Yes
SWAP 2025 Species of Greatest Conservation Need (SGCN): Yes
2025 SGCN Priority Tier: Data Deficient
Element Occurrences (EOs) in Georgia: 17
Habitat Summary for element in Georgia: Hardwood forest, mixed forest
Average sized among the Coastal Plain species of the slimy salamander complex, the Savannah slimy salamander reaches total lengths of 14 cm (5.5 inches). It has a black background with many white spots (some, but few spots may be brassy) scattered on the back, abundant white spotting on its sides and the upper surfaces of its limbs, and a moderate amount of spotting on the cheeks, chin, and sides of the head; its belly possesses few white spots.
Once thought to be a single species (i.e., Plethodon glutinosus), laboratory analysis of protein divergence of slimy salamander populations has identified 16 separate species, collectively now recognized as the “slimy salamander complex.” While these species are genetically differentiated, most Georgia members of the complex are not identifiable through morphological characters or coloration alone. Thus, successful identification (particularly in a field setting) often is dependent on accurate specimen locality data and knowledge of species’ distribution of the complex.
The distribution of P. savannah shares contact zones with four other members of the slimy salamander complex (P. chlorobryonis, P. glutinosus, P. ocmulgee, & P. variolatus), but it is allopatric (ranges do not overlap) and not known to hybridize with other members of this complex.
Ranging directly to the south of the Savannah slimy salamander’s distribution, the venter (under-belly) of the Ocmulgee slimy salamander (P. ocmulgee) is as dark as its dorsum (back) background color; for all other slimy salamander species sharing a range boundary with P. savannah, the venter is at least slightly lighter than the dorsum. The venter of P. savannah possesses few light spots, while venter of the northern slimy salamander (P. glutinosus, ranging to the west) usually lacks spots altogether. The chin of the South Carolina slimy salamander (P. variolatus, ranging to the southeast) is much lighter than its venter. The Atlantic Coast slimy salamander (P. chlorobryonis, ranging to the north) has very small, slightly brassy, white dorsal spots and abundant lateral white or yellow spotting, while the Savannah slimy salamander possesses many scattered white dorsal spots on the dorsum, abundant white spotting on its sides and dorsal surfaces of its legs, and a moderate amount of white spotting on its cheeks, chin, and side of the head.
Members of the slimy salamander complex superficially resemble adult frosted flatwoods salamanders. While adults of these two groups can be found in pine flatwoods (the historical range of Ambystoma cingulatum is thought to overlap with the range of P. savannah in eastern Emanuel, southern Burke, and Jenkins counties), frosted flatwoods salamanders lack a groove between each nostril and the upper lip that is characteristic in slimy salamanders, and they possess a net-like pattern on their backs as opposed to the unconnected, widely scattered light spots on the back and sides of slimy salamanders.
Savannah slimy salamanders inhabit moist forest floor microhabitats of deciduous upland forests, bottomland hardwood forests, swamp forests, and wet pinewoods, emerging at night from subterranean refugia, leaf litter, or other forest floor cover objects such as logs to forage if conditions are sufficiently moist. While they may be found near wetlands, aquatic habitats are not necessary for slimy salamanders nor other members of their genus. Migration of this species from forest ravines into a nearby cave as refugia from drought conditions has been documented for this species.
Slimy salamanders are generalists, feeding on a wide variety of forest floor macroinvertebrates including springtails, pseudoscorpions, spiders, mites, millipedes, centipedes, earthworms, snails, and a multitude of different kinds of insects.
The existence of this species was unknown until its description in 1989 based on observed genetic differences. Pointing to incomplete isolation and introgressive hybridization among some species within the glutinosus complex, some scientists have refused to accept the taxonomic division of the complex or even that the Savannah slimy salamander is differentiated from the Ocmulgee slimy salamander (P. ocmulgee). Ironically the only slimy salamander species bordering the range of P. savannah that can readily be visually differentiated from the Savannah slimy salamander is P. ocmulgee (see Similar Species above). Recent research however, continues to offer support for these taxonomic changes. Although the Ocmulgee slimy salamander is most closely related to the Savannah slimy salamander exhibiting similarities in mitochondrial DNA, differences in nuclear DNA support continued species recognition.
As is characteristic of its genus, Savannah slimy salamanders remain within a terrestrial environment, not requiring bodies of water for reproduction; instead of water bodies, eggs are laid in moist microhabitats (e.g, subsurface cavities) and larvae exhibit direct development terrestrially. As such, the relative availability of moisture on the landscape has greatly shaped evolution of this and related woodland salamanders. Just as topography and elevation have driven speciation through isolation over geologic time in the Southern Appalachian Mountains in the Plethodon jordani complex (P. metcalfi and P. shermani in Georgia), it is thought that slight differences in precipitation patterns across the Piedmont and Coastal Plain (arid climates during the Pliocene, over 3 million years ago, isolated populations in wetter forest habitats), coupled synergistically with differences in surficial geology have similarly acted as a mechanism of isolation creating variable niches related to moisture availability, resulting in speciation.
Adult specimens can be found by turning coarse woody debris on the forest floor during the day and by searching the forest floor at night.
This salamander has one of the smallest ranges of the slimy salamander complex and is one of only two members of this complex that are endemic to a single State (the much wider ranging P. ocmulgee as well as P. savannah, both endemic to Georgia). The Savannah slimy salamander is known through genetic examination of specimens from only from Burke, Jefferson, and Richmond counties, but based on cursory physical examination of specimens, its range is suspected to include all or portions of Columbia, Emanuel, Glascock, Hancock, McDuffie, Warren, and Washington counties. The eastern extent of the species’ range is the Savannah River which apparently has functioned as a barrier to gene flow. The combined extent of the ranges of P. ocmulgee and P. savannah correspond to an area in Georgia that receives the lowest average annual rainfall of anywhere in the State; undoubtedly, this relationship has created a particular niche driving speciation, however the precise mechanism of isolation between these two most closely related species, perhaps more recently on the geologic time scale, remains to be determined (see Life History above).
Development of forest habitat to uses incompatible with this species ecological needs, remains the greatest threat. The type locality for this species within Richmond County, for instance, was destroyed by a housing development.
| Threat 1 | Threat 2 | Threat 3 | |
|---|---|---|---|
| General Threat | Residential & commercial development | Energy production & mining | Agriculture & aquaculture |
| Specific Threat | Housing & urban areas | Renewable energy | Annual & perennial non-timber crops |
Largely because of the species’ endemism, small range, general lack of current survey data, and uncertainty as to the long-term protection of any populations on conservations lands, the Savannah slimy salamander was added to the list of High Priority Species within the 2015 revision of Georgia’s Wildlife Action Plan. Results of surveys of a limited portion of the range (a population in Richmond County) in 1979, 1988, and again in 1995 under similar conditions and similar effort were suggestive of a precipitous decline of the species. Further survey effort may very well prove this to be a relatively common species with a stable conservation status.
Slimy salamanders have been documented from Ft. Gordon, Hamburg State Park, Magnolia Spring State Park, McDuffie Public Fishing Area & Hatchery, Georgia Power's Plant Vogtle, and Yuchi WMA. Surveys should be conducted in areas within the presumed species distribution including Di-lane, Phinizy Swamp, Spirit Creek Forest, Mead Farm, Alexander, Big Dukes Pond, and Ohoopee Dunes wildlife management areas, as well as several out holdings of the Piedmont and Savannah national wildlife refuges, and US Army Corps of Engineers lands bordering Clarks Hill Lake, all of which have the potential of harboring the species. Further concerted survey effort and laboratory work for the species throughout its presumed range over several years is suggested to determine the full extent of the species distribution, abundance, conservation status, and needed management actions.
Beamer, D. A. and M. J. Lannoo. 2005. Plethodon savannah Highton, 1989 (Savannah slimy salamander). Pp. 837-838, In: M. Lannoo, ed. Amphibian Declines: The Conservation Status of United States Species. University of California Press, Berkeley. 1094pp.
Highton, R., A. P. Hastings, C. Palmer, R. Watts, C. A. Hass. M. Culver, and S. J. Arnold. 2012. Concurrent speciation in the eastern woodland salamanders (Genus Plethodon): DNA sequences of the complete albumin nuclear and partial mitochondrial 12s genes. Molecular Phylogenetics and Evolution 63: 278-290.
Highton, R. 1995. Speciation in eastern North American salamanders of the genus Plethodon. Annual Review of Ecology and Systematics 26: 579-600.
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Humphries, R. L. 1956. An unusual aggregation of Plethodon glutinosus and remarks on its subspecific status. Copeia 1956(2): 122-123.
Smith, W. H., J. A. Wooten, and C. D. Camp. 2018. Genetic divergence correlates with the contemporary landscape in populations of Slimy Salamander (Plethodon glutinosus species complex) across the lower Piedmont and Coastal Plain of the southeastern United States. Canadian Journal of Zoology 96(11): 1244-1254.
Wiens, J. J., T. N. Engstrom, and P. T. Chippindale. 2006. Rapid diversification, incomplete isolation, and the "speciation clock" in North American salamanders (genus Plethodon): testing the hybrid swarm hypothesis of rapid radiation. Evolution 60(12): 2585-2603.
Wooten, J. A., C. D. Camp, J. R. Combs, E. Dulka, A. Reist, and D. M. Walker. 2013. Re-evaluating niche conservatism versus divergence in the Woodland Salamander genus Plethodon: a case study of the parapatric members of the Plethodon glutinosus species complex. Canadian Journal of Zoology 91: 883–892.
Thomas M. Floyd
T. Floyd, March 2019: original account