Abstract

Plethodon yonahlossee is a particularly large woodland salamander with many distinct characteristics. The species is a member of the family Plethodontidae which is characterized by being lungless and reproductive direct development. Plethodon yonahlossee was first described in 1917 by E.R Dunn on a collection site on Grandfather Mountain in North Carolina. The common as well as the specific name are of Indian origin and means “trail of the bear” and are derived from Yonahlossee Road which is Northeast of Linville North Carolina where the specimen was first described.

General Description

Plethodon yonahlossee is a large Southern Appalachian woodland salamander typically differentiated by its large size and its distinctive rust colored dorsum. As with all other members of the genus Plethodon yonahlossee are lungless, direct developers meaning there is no larval stage; instead the young hatch into miniature adults; and fully metamorphosed adult individuals are characterized by a nasolabial groove that aids in chemoreception. The yonahlossee’s back has a black base color and is covered by reddish-brown to red blotches depending on age. Typically juveniles are more spotted while in older individuals the reddish blotches come together to form a wide band spanning the length of it’s back. The sides of the body are covered with grey to white blotching, and the dorsal part of the head is all black. The belly and throat are both pigmented but sometimes have a similar blotched pattern as the back. . Plethodon yonahlossee is the largest member of the family Plethodontidae in North America. Females are significantly larger than males. The typical adult length is between 11 and 22 centimeters. Typically the yonahlossee has 15 to 16 costal grooves.

Distribution

Plethodon yonahlossee can be found in the Southern Blue Ridge Mountains of Northern Tennessee, western North Carolina, and small portions of southwest Virginia. Specifically they have been located in Avery, Yancey, and Rutherford counties in North Carolina; Limestone Cove in Unicoi County Tennessee, and Whitetop Mountain Virginia. They are found in a variety of upland wooded habitats. They tend to be located in deciduous forests at high elevations between 437 and 1,737 meters, but tend to be more altitudinally restricted compared to other members of Plethodontidae. They are also commonly found in damp, shaded areas around wooded hillsides and ravines where rock slides are covered with mosses and ferns; areas with old windfalls; and grassy areas near woodlands. A unique population only found in Rutherford county North Carolina occurs near Bat Cave and is often found in rock crevices but is sometimes recognized as a separate species characterized by different coloration and limb morphology- Plethodon longicrus. These bat cave variants may have red of the dorsum prominent, patchy, or even lacking and their sides are dark with light spots. The coloration of the bat cave variant is much darker than the common Plethodon yonahlossee and some scientists still consider them to be a separate species. Furthermore, the variant does not reach sexual maturity like Plethodon yonahlossee but matures according to size. Males must reach greater than 65 mm and females must be greater than 61 mm before being considered mature.

During the day they are they take cover under rotting logs, rocks, or in burrows on the forest floor which are under logs; although it is argued whether or not they create these burrows or just reopen partly eradicated passages. They prefer areas of old windfalls that have shed most of their bark and logs greater than twenty five centimeters in diameter with no more than five to fifteen centimeters of the log below the surface and a thick layer of leaf litter at the interface between the log and the ground. They can also be found active on humid or rainy nights, even crossing the roads in suitable habitat.

Behavior and Ecology

Little is known about the reproduction habits of this species. Reproduction does take place terrestrially and eggs are deposited in underground cavities where scientists assume that like other members of the genus the female guards the eggs until they hatch. Spermatogenesis most likely occurs after the emergence from hibernation. It is assumed that courtship occurs in early August as this is the time pairs of salamanders have been found under a single cover object and males have noticeably enlarged mental glands. Females then lay their eggs in late August or early September. Clutch size is dependent on the size of the female, but typically ranges from 19 to 27.

Sexual maturity is thought to be approximately three years of age. Also, a definitive feature of maturity is the length of the mental glands which in males is approximately 56 millimeters whereas in females it is more like 60 to 66 millimeters depending again on the size of the female.

Both adults and juveniles emerge at night to forage. Juveniles have been found to be most active one hour after sunset where adults peak one to two hours later. Each stage is carnivorous and eats small insects and invertebrates including mites, spiders, millipedes, centipedes, and earthworms.
Predators are thought to include snakes, birds, and small mammals. To escape predation Plethodon yonahlossee produces secretions from the tail that is noxious to birds and other mammals. Also after initial contact they become immobile making them harder to detect which may increase survival with visual predators.

In laboratory settings Yonahlossee salamanders demonstrated aggressive defense of their territories. Like most species in the genus they exhibit vertical underground migration and move underground during the cold winter months.

Conservation

According to the IUCN red list of endangered species Plethodon yonahlossee is listed as of least concern in 2004 and is warranted because they occur in an area of extensive, suitable habitat which appears to not be under any substantial threat with an assumed large population and unlikely to be declining fast enough to be eligible for listing in a more threatened category.

Plethodon yonahlossee among other terrestrial salamanders have been reported to have no change in abundance in single or several locales over many years. Concurrently, others are viewing the same species over the entire range and are reporting that many populations have been lost to habitat destruction which includes urban sprawl and increased forestry practices. Clearly there is a possibility for one species to be locally abundant and stable populations and yet still be declining throughout the range. Salamander habitat is mainly due to outright destruction, fragmentation, forestry practice, and pollution.