Pygmy salamander

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King Pygmy salamander
Pygmy salamander Desmognathus wrighti.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Urodela
Family: Plethodontidae
Subfamily: Plethodontinae
Genus: Desmognathus
Species:
D. wrighti
Binomial name
Desmognathus wrighti
King, 1936

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. [2] 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. [3] 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. [4] 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. [5]

Contents

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 35–44 mm (1.4–1.7 in). 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. [5] The maximum size of males and females has been determined to have no real difference in the species. [3]

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. [5] 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. [3] 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. [5]

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. [5] 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. [5]

Geographical distribution

Desmognathus wrighti has a very fragmented geographical distribution. The species is found in the Southern Appalachian Mountains of North Carolina and Tennessee south of the French Broad River. In Tennessee, D. wrighti inhabits the Great Smoky Mountains National Park in Blount, Cocke, and Sevier counties. The species is also found in the Cherokee National Forest in Monroe County. In North Carolina, the pygmy salamander is only documented in Graham County along the Tennessee border. [6] The highest abundance of pygmy salamanders is found at higher elevations ranging from 1600 to 2082 meters. The distribution of the salamander primarily lies adjacent to areas of red spruce ( Picea rubens ) and Fraser's fir ( Abies fraseri ) forests at these high elevations. However, pygmy salamanders populations can be found at lower elevations from 950 to 1400 meters, but the highest densities occur at the higher elevations. [7] Desmognathus wrighti populations appear to have stayed fragmented for some time due to their restriction to high elevation. The lower elevation populations of the pygmy salamanders documented exhibit little gene flow. This low gene flow reflects their preference for higher elevation and possible competition with other Appalachian salamanders. [6] In its known geographical locations the pygmy salamander can primarily be found in moist depressions such as under logs and rocks along streams, in damp leaf litter, and in mossy areas. [3]

Ecology

Desmognathus wrighti is typically a light brown color with a dorsal pigmentation pattern of inverted V's in a darker brown. The salamander ranges from 35 mm to 55 mm and rarely exceeds 50 mm making it the smallest salamander in the genus Desmognathus. Pygmy salamanders are typically found at higher elevations. Adult salamanders are active at night and have been found up to one meter above the ground in vegetation. [5] The pygmy salamander is the most terrestrial species of its genus. It lives in depressions in moss and leaf litter on the forest floors and is most often found in spruce-fir forests of high elevation. The salamander goes to seepages and stream banks for egg-laying in summer and early autumn. [8]

Life history and behavior

D. wrighti courtship differs from other members of Desmognathus in the phenology of oviposition which is in late summer into autumn. Males reach sexual maturity by their second or third year while females reach their sexual maturity by their third year. [3] Males normally have two testes lobes but this number can increase with body size. In courtship males use their vomerine teeth to bite the female which in turn allows pheromone secretion to enter directly into the female circulation. [5] D. wrighti and D. aeneus are the only two desmognathine salamanders that exhibit the courtship that which the male bite and seizes its partner before behaviors exhibited to accomplish sperm transfer. The male approaches the female quickly, bites, and tugs as he begins to undulate his tail. The female in return turns towards the male and places her chin on his laterally undulating tail so that they rotate in full circle. Typically in courtship behavior a Plethodontidae characteristic tail-straddling walk follows. In the tail-straddling walk, the male release the female and slides his head under her chin, then her forelimbs straddle the male's tail and the pair then move forward. [4] The male then deposits a spermatophore on the ground which is followed by the female picking up a sperm cap with her cloacal lips as she moves forward undulating her pelvic area. [9]

Desmognathus wrighti females have an average clutch size of 8 to 9 eggs which are suspended by a single attachment stalk and develop between 4 and 25 oocytes. Females lay eggs in banks of streams in areas of saturated gravel. The females also typically remain close to their egg mass and coil their bodies around the mass. Eggs change from spheroid shape to ovoids when hatching conditions occur. The embryo then thrusts itself against the capsule and rotates within the egg until it escapes from the egg fluid. [9] D. wrighti hatchlings are not larvae and have gills in late embryonic stages. At hatching the ventral side is unpigmented and the characteristic ‘V’ pigmentation is found on the dorsal side. The characteristic stripe from the eye to the jaw is also present in late embryo and hatching stages. [9]

Conservation

Desmognathus wrighti was assess in 2004 as being of least concern on the IUCN Red List of Threatened Species, in light of the species having a wide distribution, a large population, and being unlikely to decline fast enough to be placed in a more threaten category. Threats to the pygmy salamander include deforestation of spruce-fir forest. Acid rain is also a threat at the high elevation that can destroy the spruce-fir trees in the pygmy salamander's natural habitat. [1]

Related Research Articles

<span class="mw-page-title-main">Plethodontidae</span> Family of amphibians

Plethodontidae, or lungless salamanders, are a family of salamanders. Most species are native to the Western Hemisphere, from British Columbia to Brazil, although a few species are found in Sardinia, mainland Europe south of the Alps, and South Korea. In terms of number of species, they are by far the largest group of salamanders.

<span class="mw-page-title-main">Texas blind salamander</span> Species of amphibian

The Texas blind salamander is a rare and endangered cave-dwelling troglobite amphibian native to San Marcos, Hays County, Texas, specifically the San Marcos Pool of the Edwards Aquifer. This species resembles the olm, another stygofaunal salamander from Europe. Unlike the olm, this amphibian's body is not as elongated, and also has less reduced digits on its limbs.

<span class="mw-page-title-main">Seepage salamander</span> Species of amphibian

The seepage salamander is a small, terrestrial species of salamander in the family Plethodontidae. It is endemic to the United States. They are found in small areas of Tennessee, North Carolina, Georgia, and Alabama. Its natural habitats are temperate forests, intermittent rivers, and freshwater springs. It gets its name from the seepages around which it lives. It is very similar in its appearance and life history to the pygmy salamander. These two species differ greatly from the other Desmognathus species. They are the smallest salamanders in the genus, measuring only 3–5 cm (1–2 in) in length. They are also the only two terrestrial, direct-developing Desmognathus species. However, the two species are not often seen to coexist, differing in distribution by elevation; although there are exceptions. The seepage salamander is currently listed as Near Threatened, with its numbers declining in most of states in which it is found. It is threatened by habitat loss, with logging having a major effect.

<i>Desmognathus fuscus</i> Species of amphibian

Desmognathus fuscus is a species of amphibian in the family Plethodontidae. The species is commonly called the dusky salamander or northern dusky salamander to distinguish it from populations in the southern United States which form several distinct species, the southern dusky salamanders. The northern dusky salamander is the most widespread representative of its genus in Canada. It can be found in eastern North America from extreme eastern Canada in New Brunswick south to South Carolina. The size of the species' total population is unknown, but is assumed to easily exceed 100,000. The species' habitat differs somewhat geographically; dusky salamanders in the northern part of the range prefer rocky woodland streams, seepages, and springs, while those in the south favor floodplains, sloughs, and muddy places along upland streams. They are most common where water is running or trickling. They hide under various objects, such as leaves or rocks, either in or near water. Alternatively, they may enter burrows for protection. The dusky salamander lays its eggs close to water under moss or rocks, in logs, or in stream-bank cavities. The larval stage which follows is normally aquatic.

<span class="mw-page-title-main">Imitator salamander</span> Species of amphibian

The imitator salamander is a species of salamander in the family Plethodontidae. It is endemic to the Appalachian Mountains in the Eastern United States.

<span class="mw-page-title-main">Shovelnose salamander</span> Species of amphibian

The shovelnose salamander is a species of salamander in the family Plethodontidae. It is endemic to the United States.

<span class="mw-page-title-main">Ocoee salamander</span> Species of amphibian

The ocoee salamander is a species of salamander in the family Plethodontidae. This salamander has a variety of colors and patterns, and got its name from Tennessee state wildflower. Its natural habitats are temperate forests, rivers, intermittent rivers, freshwater springs and wet rocks in mountainous areas of the Southeastern United States. It was first described by Nicholls in 1949. They are territorial and feed on small invertebrates. It is widely distributed in the southeastern United States and is listed as "Least Concern" by the International Union for Conservation of Nature.

<span class="mw-page-title-main">Blackbelly salamander</span> Species of amphibian

The blackbelly salamander is a species of salamander in the family Plethodontidae. It is endemic to the United States. Its natural habitats are rivers, intermittent rivers, and freshwater springs. It is threatened by habitat loss.

The black mountain salamander is a species of salamander in the family Plethodontidae.

<span class="mw-page-title-main">Northern two-lined salamander</span> Species of amphibian

The northern two-lined salamander is a species of salamander in the family Plethodontidae found in Canada and the United States. Its natural habitats are temperate forests, temperate shrubland, rivers, intermittent rivers, freshwater marshes, freshwater springs, arable land, and urban areas. It is more water-oriented than the related northern redback salamander, and can often be found in and around water such as rain puddles, streams, swamps, and damp stream beds, whereas the northern redback tends to be found in damp ground, but usually not near open water.

<span class="mw-page-title-main">Spring salamander</span> Species of amphibian

The spring salamander is a species of salamander in the family Plethodontidae. It is found in Canada and the United States. The genus, Gyrinophilus, means "tadpole lover" and refers to the long period of time it spends as a gilled larva before maturing. The specific epithet, porphyriticus, is Latin from Greek, meaning the color of porphyry, a purple stone, and this salamander has also been called the purple salamander.

<span class="mw-page-title-main">Red-cheeked salamander</span> Species of amphibian

The red-cheeked salamander, also known as the Jordan's salamander, Jordan's redcheek salamander, or Appalachian woodland salamander, is a species of salamander in the family Plethodontidae. It is endemic to the Appalachian Mountains in the eastern United States.

<span class="mw-page-title-main">Northern gray-cheeked salamander</span> Species of amphibian

The northern gray-cheeked salamander is a species of salamander in the family Plethodontidae and endemic to the Blue Ridge Mountains and Appalachian Mountains in the eastern United States. It is closely related to the Red-cheeked salamander and the Red-legged salamander. Its natural habitat is temperate forests. It is found under moss, rocks, logs, and bark in cool, moist forests above 2500 feet. Especially found in spruce-fir forests. The Gray-cheeked Salamander commonly eats millipedes, earthworms, crane flies, spiders, and centipedes and less commonly eats ants, mites, and springtails. They eat spiders, moths, flies, beetles, bees, and snails. The male and female perform a courtship, where the male nudges the female with his snout, does a foot dance, then circles under the female and the two then walk together. Like other salamanders, they do not migrate or aggregate during breeding season. It is threatened by habitat loss.

<span class="mw-page-title-main">Weller's salamander</span> Species of amphibian

Weller's salamander is a species of salamander in the family Plethodontidae. This species in endemic to the southeastern mountain range of the United States. It is mainly found in North Carolina near Grandfather Mountain. The salamanders have a unique metallic spotting which distinguishes them from other Plethodon species and other salamanders in the area. They mainly inhabit cool forests with rocky areas.

<span class="mw-page-title-main">Yonahlossee salamander</span> Species of amphibian

The Yonahlossee salamander is a particularly large woodland salamander from the southern Appalachian Mountains in the United States. The species is a member of the family Plethodontidae, which is characterized by being lungless and reproductive direct development. P. yonahlossee was first described in 1917 by E.R Dunn on a collection site on Grandfather Mountain in North Carolina. The common and specific name is of Native American origin, meaning “trail of the bear”. It is derived from Yonahlossee Road northeast of Linville, where the specimen was first described.

<span class="mw-page-title-main">Many-lined salamander</span> Species of amphibian

The many-lined salamander is a species of salamander in the family Plethodontidae. It is the only species of the monotypic genus Stereochilus. It is endemic to the United States.

<span class="mw-page-title-main">Green salamander</span> Species of amphibian

The green salamander is a species of lungless salamander in the family Plethodontidae. It and the Hickory Nut Gorge green salamander are the only currently-described members of the genus Aneides that inhabit any areas in the eastern half of United States. Rarely seen in the field, the green salamander is an extremely habitat-specific species that is seldom found away from its preferred surroundings: moist, shaded rock crevices.

<span class="mw-page-title-main">Northern pygmy salamander</span> Species of amphibian

The northern pygmy salamander is a terrestrial species of salamander in the family Plethodontidae and genus Desmognathus. Along with the southern pygmy and the seepage salamander, these are some of the smallest salamander species in North America and can be found in higher elevations in the southern Appalachians.

References

  1. 1 2 Geoffrey Hammerson (2004). "Desmognathus wrighti". IUCN Red List of Threatened Species . 2004: e.T59259A11907504. doi: 10.2305/IUCN.UK.2004.RLTS.T59259A11907504.en . Retrieved 16 November 2021.
  2. ↑ Frost, Darrel R. (2015). "Desmognathus wrighti King, 1936". Amphibian Species of the World: an Online Reference. Version 6.0. American Museum of Natural History. Retrieved 10 November 2015.
  3. 1 2 3 4 5 Hining, K. J. and R. C. Bruce. 2005. Population structure and life history attributes of syntopic populations of the salamanders Desmognathus aeneus and Desmognathus wrighti (Amphibia: Plethodontidae). Southeastern Naturalist, 4(4): 679-688
  4. 1 2 Verrel, P. 1999. Bracketing the extremes: courtship behaviour of the smallest- and largest-bodied species in the salamander genus Desmognathus (Plethodontidae: Desmognathinae). Journal of Zoology, 247: 105-111.
  5. 1 2 3 4 5 6 7 8 Crespi, E. J., R. A. Robert, and L. J. Rissler. 2010. Taxonomic Revision of Desmognathus wrighti (Caudata: Plethodontidae). Herpetologica, 66(3): 283-295.
  6. 1 2 Reynolds, R. G., M. L. Niemiller, and S. A. Pasachnik. 2011. Occurrence of pygmy salamanders (Desmognathus wrighti) in Monroe County, Tennessee. Journal of the Tennessee Academy of Science, 86(2): 53-55.
  7. ↑ Crespi, E. J., L. J. Rissler, and R. A. Browne. 2003. Testing Pleistocene refugia theory: phylogeographical analysis of Desmognathus wrighti, a high-elevation salamander in the southern Appalachians. Molecular Ecology, 12(4): 969-984.
  8. ↑ Bruce, R. C. 1977. The pygmy salamander, Desmognathus wrighti (Amphibia, Urodela, Plethodontidae), in the Cowee Mountains, North Carolina. Journal of Herpetology, 11(2): 246-247.
  9. 1 2 3 Organ, J. A. 1961. Life History of the Pigmy Salamander, Desmognathus wrighti, in Virginia. The University of Notre Dame. American Midland Naturalist, 66(2): 384-390.
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