The Blacksburg salamander (''Plethodon jacksoni'') is a species of

salamander Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All t ...

in the family

Plethodontidae Plethodontidae, or lungless salamanders, are a family of salamanders. With over 500 species, lungless salamanders are by far the largest family of salamanders in terms of their diversity. Most species are native to the Western Hemisphere, from B ...

. It is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the

Southeastern United States The Southeastern United States, also known as the American Southeast or simply the Southeast, is a geographical List of regions in the United States, region of the United States located in the eastern portion of the Southern United States and t ...

, where it is restricted to a portion of the

Appalachian Mountains The Appalachian Mountains, often called the Appalachians, are a mountain range in eastern to northeastern North America. The term "Appalachian" refers to several different regions associated with the mountain range, and its surrounding terrain ...

in southwestern

Virginia Virginia, officially the Commonwealth of Virginia, is a U.S. state, state in the Southeastern United States, Southeastern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States between the East Coast of the United States ...

(and possibly neighboring portions of

North Carolina North Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, South Carolina to the south, Georgia (U.S. stat ...

). Its

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often con ...

refers the town of

Blacksburg, Virginia Blacksburg is an incorporated town in Montgomery County, Virginia, United States, with a population of 44,826 at the 2020 census. Blacksburg and the surrounding county is dominated economically and demographically by the presence of Virginia T ...

, as many specimens were initially found in the vicinity of the town.

Description

''Plethodon jacksoni'' is very similar in appearance to the Wehrle's salamander (''P. wehrlei'') in both proportions and color. It is slender in build, with a rounded head, large eyes, and a short snout. Males can reach up to in total length ( on average), with females up to , on average. Broadly speaking, ''P. jacksoni'' are larger than '' P. dixi'' and smaller than ''P. wehrlei''. Mature males have a prominent

mental gland A mental gland is a part of the body found in many species of amphibians and reptiles. Mental glands produce chemicals that conspecific animals use to communicate. Location The mental glands appear in pairs, one on each side of the head. They a ...

on the chin and swellings above the base of the tail, while females have proportionally longer bodies. The background color is dark bluish gray, with the back as the darkest part of the body. The throat and belly are lighter, though there is little consistency between specimens regarding the distribution of light coloration on the underside. Distinctive white blotches typically occur on the sides and limbs and sometimes encroach onto the belly. Silvery mottling and tiny white flecks may be present on the back and tail. Some individuals, including the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

, have sparse but distinctive reddish-orange spots on the back.

Taxonomy

''Plethodon jacksoni'' was formally described in 1954 based on several specimens collected from

Montgomery County, Virginia Montgomery County is a county located in the Valley and Ridge area of the U.S. state of Virginia. As population in the area increased, Montgomery County was formed in 1777 from Fincastle County, which in turn had been taken from Botetourt Cou ...

. The species was named in honor of Herbert Jackson, a biologist at

Virginia Tech The Virginia Polytechnic Institute and State University, commonly referred to as Virginia Tech (VT), is a Public university, public Land-grant college, land-grant research university with its main campus in Blacksburg, Virginia, United States ...

. Shortly after its initial description, it was considered to be a southern population of ''Plethodon wehrlei''Cochran, D.M. (1961
Type specimens of reptiles and amphibians in the US National Museum
Bulletin of the United States National Museum, 220, 1–291.Highton, R. (1962) Revision of North American salamanders of the genus Plethodon. Bulletin of the Florida State Museum, 6, 235–367. and was lumped into that species for many years. A 2019 study once again recovered ''Plethodon jacksoni'' as a valid species according to the distinctiveness of its

mitochondrial A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used ...

cytochrome b Cytochrome b is a protein found in the membranes of aerobic cells. In eukaryotic mitochondria (inner membrane) and in aerobic prokaryotes, cytochrome b is a component of respiratory chain complex III () — also known as the bc1 complex or ubiq ...

gene. In conjunction, this analysis found ''P. wehrlei'' to be a

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

taxon. This conclusion supports earlier genomic studies published in 2012 and 2018. ''Plethodon jacksoni'' diverged from its closest relatives around 4.6 million years ago according to a 2018 estimate. Not all taxonomic issues within ''P. jacksoni'' were solved during the 2019 study: several other salamander populations were found to lie close to the Montgomery County specimens of ''P. jacksoni'', indicating that its geographic range and genetic diversity may be higher than previously considered. These additional potential populations of ''Plethodon jacksoni'' include the "southern ''wehrlei''" clade (which extends as far south as North Carolina) and "population 29" (from

Roanoke County, Virginia Roanoke County ( ) is a county in the U.S. state of the Commonwealth of Virginia. As of the 2020 census, its population was 96,929. Its county seat is Salem, but the county administrative offices are located in the census-designated place of ...

). It remains to be seen whether this broader notion of the species is natural or paraphyletic.

Habitat and distribution

The natural habitat of ''Plethodon jacksoni'' is

temperate forest A temperate forest is a forest found between the tropical and boreal regions, located in the temperate zone. It is the second largest terrestrial biome, covering 25% of the world's forest area, only behind the boreal forest, which covers about 3 ...

. It can be found sheltering under rocks and logs on dry hillsides during the late winter and early spring. Some members of the species live in caves, even during parts of the year where they are not observed on the surface. ''Plethodon jacksoni'' is most frequently observed in Montgomery County, Virginia, though it has also been reported from Giles, Craig, and possibly Pittsylvania counties. The "southern ''wehrlei''" salamander population, which may be closely related or within ''P. jacksoni'', occurs as far south as northwestern North Carolina ( Stokes and Alleghany counties).

References

{{Taxonbar, from=Q65042721 Plethodon Endemic amphibians of the United States Ecology of the Appalachian Mountains Amphibians described in 1954