The pygmy salamander (Desmognathus wrighti) is a species of salamander in the family Plethodontidae. It is endemic to the United States in the southern Appalachians in North Carolina and Tennessee. Desmognathus wrighti is a member of the family Plethodontidae and is commonly known as the pygmy salamander. As the name suggest the pygmy salamander is the smallest of the nineteen species in the genus Desmognathus. D. wrighti undergoes direct development and does not have a free-living larval stage. Only two other taxa in Desmognathus, D. aeneus and D. organi, exhibit direct development along with the pygmy salamander. In the genus Desmognathus, body size, habitat preferences, and patterns used by males during courtship are quite variable. D. wrighti courtship is noted by the male biting and seizing its partner in order to provide them with a chemical stimulus. The pygmy salamander can be found in the southern Appalachians of the United States in western North Carolina and eastern Tennessee. Geographical distribution of the Desmognathus wrighti is fragmented and the highest abundance of the species can be found at high elevations in spruce and fir tree forest.
Identification
Desmognathus wrighti has a light belly with a gold-colored iridophore pattern that extends from the abdomen to the anterior of the cloacal vent. The salamander has a rounder snout and the total body length ranges from . The tail is not keeled and the body length is equal to or greater than the tail length. Pygmy salamanders are typically light brown with dark brown pigment on the dorsal side forming an inverted V-shape marking down the back This ‘V’ shape marking is a classic pigmentation marking. The salamander's color can range from brick red to yellow but usually is found as a light brown shade. The light stripe from the eye to the jaw designates the salamanders as a desmognathan. Desmognathus wrighti typically has six vomerine teeth on each side of the mouth along with premaxillary and mandible teeth. The maximum size of males and females has been determined to have no real difference in the species.
General description and taxonomy
Desmognathus wrighti was named and discovered by King in 1936. The pygmy salamander's natural habitat includes temperate forests, intermittent rivers, and freshwater springs. This species small size places it among the smallest salamanders in the world. D. wrighti adult size is in the range of the sizes of the genus Thorius, which are neo-tropical and considered the smallest urodeles in the world. The genus Desmognathus consists of nineteen species which all vary in body size, life history, and habitat. The most basic way of sorting the species in this genus is by body size and distance they are found from streams which they inhabit.
In 2010, there was a taxonomic revision to Desmognathus wrighti. This revision was based on genetic and ecological analyses. This divergence has been reported by DNA sequencing, but further research shows several differences in the body type and ventral pigmentation. An ecological niche analysis was completed on two niches separated by the French Broad River and significant morphological variation was found between the two lineages. Findings show differences in snout-vent length, body condition, and head width, suggesting that there are two distinct and separately evolving lineages in Desmognathus wrighti. The diverging northern lineage, Desmognathus organi, is the new species described by Crespi and Browne in 2010. The revision to the taxonomic Desmognathus wrighti was seen needed for the northern pygmy salamander to reflect the genetic, ecological, and geographical differences in the two different populations located north and south of the French Broad River. The original species Desmognathus wrighti described by King more accurately describes the lineage from the southern part of the French Broad River and the morphological descriptions described on this page. The new species Desmognathus organi, the Northern pygmy salamander, is a sister taxon to D. wrighti. Differences of D. organi from its sister taxon includes a slightly larger body length, wider heads, and the ventral gold iridophore patterns are absent. Also, D. organi is found in higher elevations north of the French Broad River including Tennessee, North Carolina, and Virginia.