Plethodon

Plethodon is a genus of salamanders in the family Plethodontidae. They are commonly known as woodland salamanders. All members of the genus are endemic to North America (Canada and the United States). They have no aquatic larval stage. In some species, such as the red-backed salamander (Plethodon cinereus). Young hatch in the adult form. Members of Plethodon primarily eat small invertebrates. The earliest known fossils of this genus are from the Hemphillian of Tennessee in the United States.

Taxonomy
Plethodon is part of the family Plethodontidae (lungless salamanders) and the subfamily Plethodontinae. The genus Plethodon can be divided into two subgenera: the nominal subgenus Plethodon, which includes up to 49 eastern species (the bulk of diversity in the genus), and the subgenus Hightonia, which includes 9 species native to the western part of North America.

The eastern Plethodon subgenus can be further categorized into at least three major species groups which genetic analyses confirm to be clades:


 * The Plethodon cinereus group, which contains the ubiquitous red-backed salamander and 9 other small, slender species (P. electromorphus, P. hoffmani, P. hubrichti, P. nettingi, P. richmondi, P. serratus, P. shenandoah, P. sherando, and P. virginia).
 * The Plethodon wehrlei group  is a species complex centered on Wehrle's salamander and at least 4 of its close relatives (P. dixi, P. jacksoni, P. pauleyi, P. punctatus). Some of these species were only formally distinguished from P. wehrlei as recently as 2019.
 * The Plethodon welleri group includes Weller's salamander and the three species of zigzag salamander (P. angusticlavius, P. dorsalis, P. ventralis). Many studies have argued that the wehrlei and welleri groups should be conceived of as one larger clade, the Plethodon wehrlei-welleri group.
 * The Plethodon glutinosus group is the largest species group within Plethodon, with around 30 species and several subordinate species complexes. Many species within this group (including the nominal species) are commonly known as "slimy salamanders", characterized by a large size, robust build and black-and-white coloration. Not all members of the Plethodon glutinosus group are labelled as slimy salamanders, and species delimitation among slimy salamanders and their close relatives is a subject of continued debate.  For example, some studies interpret Plethodon grobmani and Plethodon mississippi to be junior synonyms of Plethodon glutinosus, based on a lack of genetic or anatomical distinctiveness.
 * One difficult-to-classify species is Webster's salamander, which may lie among the wehrlei-welleri group    or the glutinosus group, or outside both groups, depending on the study.

List of species
As of 2024 there are up to 58 species in the genus Plethodon. Most are native to eastern and central North America, with the Appalachian Mountains having the highest diversity. Seven species live along the West Coast, one (P. idahoensis) in the Rocky Mountains of Idaho, and one (P. neomexicanus) in the Jemez Mountains of New Mexico.

All 58 Plethodon species listed in alphabetical order of specific name:

Nota bene: A binomial authority in parentheses indicates that the species was originally described in a genus other than Plethodon.