Desmognathus organi Crespi, Browne & Rissler, 2010
Northern Pygmy Salamander
|Species Description: Crespi EJ, Browne RA, Rissler LJ 2010 Taxonomic revision of Desmognathus wrighti (Caudata: Plethodontidae). Herpetologica 66:283-295.|
© 2015 Will Lattea (1 of 14)
DESCRIPTION:Desmognathus organi is a small yet robust bodied salamander belonging to the terrestrial Plethodontid family. The snout to vent length on average measures 40 to 60 millimeters. There are 14 intercostal grooves and when the limbs are adpressed along the body towards each other, they are separated by three coastal folds. This species has a relatively wide oval head and long, rounded tail relative to its small size. Adults within this species have four toes on their forelimbs and five toes on their hindlimbs. They have six vomerine teeth (Crespi et al. 2010).
Desmognathus organi occupies drier, colder environmental conditions and is more robust and heavier compared to its sister taxon D. wrighti, which occurs south of the French Broad River. Unlike D. wrighti, which features complete speckled iridophores, D. organi have incomplete or absent iridophore formation on the abdomen (Crespi et al. 2010). In literature prior to Crespi et al. (2010), D. organi can be distinguished from D. wrighti by the location of the specimen.
Desmognathus organi have bronze to dark brown dorsal coloration, darker brown intervertebral costal grooves, and light underside with typically some gold iridophores present on the abdominal musculature between the forelimbs to the anterior tip of the cloacal vent (Crespi et al. 2010).
Females have a more rounded snout than males and tend to be lighter in color but larger, heavier, and more robust. Individuals may vary in iridophore presence ranging from a few golden speckling on the abdomen to none. Some individuals may have a lighter brown, wavy dorsal strip that runs along the ventral dorsal area to the tip of the tail (Crespi et al. 2010).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: United States
U.S. state distribution from AmphibiaWeb's database: North Carolina, Tennessee, Virginia
Life History, Abundance, Activity, and Special Behaviors
Desmognathus organi like its sister species D. wrighti, is typically associated with wet forest floors during warmer months. While a rare species overall, D. organi is most common under small cover-objects such as logs, bark, rocks, or moss. These habitats allow them to avoid predation and interspecific competition (Rossell et al. 2018).
Microarthropods such as oribatids and collembolans make up a large portion of D. organi's diet, hence their association with moss carpets, round wood, and leaf litter (Bruce 2019). Foraging occurs mainly at night due to increased moisture and decreased visibility to predators. During colder months, they relocate to overwinter in springs and seepages near stream headwaters (Bruce 2019, Organ 1961).
When exposed to or touched by a predator, D. organi will flip over onto its back and become immobile (Harrison 2000).
Reproduction occurs in late summer when larger populations congregate in more aquatic environments where females nest and oviposition occurs (Organ 1961). During courtship, males grasp and hold females with their jaw, rhythmically tugging back and away while undulating his tail. The female turns towards the male and places her chin on his tail, forming a circle - this process can happen two or more times per encounter. After releasing the female, the male slides his head under the female's body and moves forward in a tail-straddle walk as he deposits his spermatophore, which is taken up by the female’s cloaca (Verrell 1999).
The spermatophore is 2.5 mm tall, slender, "glass-like", and flares at the base. The sperm cap is a thin milk-white sheath at the tip of a slender stalk (Organ 1961). The number of testes in males increase with body size with up to nine testes being recorded (Crespi et al. 2010).
Females guard their clusters of 3 to 8 eggs, which are attached to small rocks in cavities in mud or gravel in seepages and headwater streams (Organ 1961).
Hatchlings show direct development, lacking a larval stage with embryos completely absorbing their gills prior to hatching - a unique feature to Desmognathus species (Organ 1961). Sexual maturation is reached in 2 - 3 years (Bruce 2019).
Trends and Threats
Relation to Humans
Possible reasons for amphibian decline
General habitat alteration and loss
PHYLOGENETIC RELATIONSHIPS:Desmognathus organi was split from D. wrighti in 2010 due to differences in genetics, morphology, ecology, life history, and behavior, which can be attributed to D. organi’s adaptation to colder, high elevation forests relative to D. wrighti’s warmer, lower elevation forest habitat (Crespi et al. 2003, Crespi et al. 2010, Bruce 2019). Phylogeographical analysis done in Crespi et al. (2003) demonstrated a clear genetic difference between populations of then D. wrighti, while Crespi et al. (2010) demonstrated physiological and ecological differences between populations separated by the French Broad River.
Desmognathus is derived from Greek – “Desmos”, meaning “ligament”, and “gnathos”, meaning “jaw”. This refers to jaw morphology unique to Desmognathus salamanders (Virginia Herpetological Society).
The species epithet, “organi” stems from James Organ’s surname, who first described D. organi’s life history in 1961 (Crespi et al. 2010). At the time D. organi and D. wrighti were not considered separate species, but Organ’s study location only coincides with D. organi’s range and habitat.
Bruce, R.C. (2019). “Life history evolution in Plethodontid salamanders and the evolutionary ecology of direct development in dusky salamanders (Desmognathus).” Herpetological Review, 50(4), 673-682.
Crespi, E. J., Browne, R. A., Rissler, L. J. (2010). “Taxonomic revision of Desmognathus wrighti (Caudata: Plethodontidae).” Herpetologica, 66(3), 283-295. [link]
Crespi, E. J., Rissler, L. J., Browne, R. A. (2003). “Testing Pleistocene refugia theory: phylogeographical analysis of Desmognathus wrighti, a high‐elevation salamander in the southern Appalachians.” Molecular Ecology, 12(4), 969-984. [link]
Harrison, J.R., III (2000). ''Desmognathus wrighti.'' Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles, 704.1-704.7.
Organ, J. A. (1961). “Life history of the pygmy salamander, Desmognathus wright, in Virginia”. The American Midland Naturalist, 66(2), 384-390.
Rossell, C.R., Haas, I.C., Williams, L.A., Patch, S.C. (2018). “Comparison of relative abundance and microhabitat of Desmognathus organi (northern pygmy salamander) and Desmognathus wrighti (southern pygmy salamander) in North Carolina.” Southeastern Naturalist, 17(1). 141-154. [link]
USFS (2014). “Potential Species of Conservation Concern for the Nantahala and Pisgah NFs Plan Revision Including Botanical and Animal Species.” United States Department of Agriculture. [link]
Verrell, 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(1), 105-111. [link]
Virginia Herpetological Society “Pygmy Salamander, Desmognathus organi.” Accessed February 11, 2021 from http://www.virginiaherpetologicalsociety.com/amphibians/salamanders/pygmy-salamander/pygmy_salamander.php. [link]
Originally submitted by: Cari Daly, Kaj Jakobsen, Star Ghanaat (2021-08-20)
Description by: Cari Daly, Kaj Jakobsen, Star Ghanaat (updated 2021-08-20)
Distribution by: Cari Daly, Kaj Jakobsen, Star Ghanaat (updated 2021-08-20)
Life history by: Cari Daly, Kaj Jakobsen, Star Ghanaat (updated 2021-08-20)
Trends and threats by: Cari Daly, Kaj Jakobsen, Star Ghanaat (updated 2021-08-20)
Relation to humans by: Cari Daly, Kaj Jakobsen, Star Ghanaat (updated 2021-08-20)
Comments by: Cari Daly, Kaj Jakobsen, Star Ghanaat (updated 2021-08-20)
Edited by: Ann T. Chang (2021-08-20)
Species Account Citation: AmphibiaWeb 2021 Desmognathus organi: Northern Pygmy Salamander <https://amphibiaweb.org/species/7527> University of California, Berkeley, CA, USA. Accessed Mar 27, 2023.
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Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 27 Mar 2023.
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