Description

Adult Morphology:

Desmognathus valentinei is a dusky salamander found in the eastern Gulf Coastal Plain of the United States. Adults have a snout-vent length of 42 to 72 mm in males and 42 to 62 mm in females. The total length is complicated due to the partial regeneration of tails. The head is wider at the jaw musculature than long and the eyes are located high up on the dorsal side of the head. A groove runs horizontally from the back of the eye along the side of the head down to the prominent gular fold. In the holotype, there are 14 costal grooves. When the limbs are adpressed to the body they are separated by six costal grooves. The tail is laterally compressed into a blade-like shape with a fleshy fin rising up along the middle of it. The forelimbs are relatively small with 4 non-webbed digits each. The hindlimbs are slightly larger than the forelimbs and have 5 non-webbed digits each (Means et. al 2017).

Larval Morphology:

Larvae hatch out with filamentous gills, small limbs, a shallow dorsal tail, and a slender body shape. The snout-vent length ranges from 11.36 to 12.73 mm. Rows of dots along the larvae’s bodies mark the lateral line organs and run along the body dorsolaterally and ventrolaterally. The gills have rather long rami for a Desmognathus and the three gill pairs have varying amounts of fimbriae on them. A range of 5 to 7 fimbriae are found on the first gill, 8 to 16 found on the second, and the most being found on the third gill with 11 to 17 fimbriae (Means et. al 2017).

DIAGNOSIS:

Desmognathus valentinei can be distinguished from other Desmognathus species through the following traits. Desmognathus valentinei has a characteristic laterally compressed tail that forms a blade-like shape, whereas other Desmognathus species have rounder or more triagonal tails with narrow points at the end. Desmognathus valentinei have a larger body size than D. conanti, which has a snout-vent length of around 48 mm, but a smaller body size than D. brimleyorum, which has a snout-vent length of over 70 mm. The focal species' dorsal markings are less crisp compared to more defined pairs of colorful dorsal markings on most other Desmognathus. Lighter ventrolateral coloration in D. valentinei distinguishes from D. auriculatus, which is darker and more uniformly colored. Lighter portholes lacking red also distinguish D. valentinei from D auriculatus. Lastly, bright coloration ranging from reddish-brown to lighter orange can often be seen on the anterior half of the tail in D. valentinei, which is distinct from other Desmognathus (Means et. al 2017).

COLORATION:

In life, there is a medium gray coloration on the dorsolateral surface with dense splotches of black coloration from the hind limbs to the front of the head. Down the dorsum runs a thin dark line with dark splotches around it. The lateral surfaces are medium gray as more of the dark splotches thin out, leaving a lighter coloration. Along the lateral surfaces are rows of lighter colored “portholes” that can be light orange or tan. These portholes are arrange with one per costal fold along each side. A lighter cheek pattern common to most Desmognathus is found angling downwards and back from behind the eye. The color of the pattern is the same as the portholes, as well as a dorsal stripe that begins at the base of the tail and ends about halfway down it. The sides of the tail is a light gray similar to that of the sides of the body and there are fewer pronounced portholes on the dorsolateral side. The tail also has ventrolateral portholes that are more pronounced than those above them. The limbs are all colored similarly to the darker splotched dorsal coloration. The underside is a light gray with small uniform light blotches (Means et. al 2017).

In preserved specimens the coloration is very similar to that in life. The main differences are that the dark splotches become more faded and any orange or red coloration fades to a lighter shade. All other coloration remains mostly the same after preservation (Means et. al 2017).

VARIATION:

Some variation is found in individuals depending on where they are located, age, and sex. Darker individuals are found in southeastern Mississippi and lighter individuals are found west of the Pearl River (Valentine 1963). This variation is thought to be due to the differences in color of the substrate the individuals live in and by number of the melanophores. Juveniles vary from mature adults by retaining some larval coloration, including reddish brown splotches along the side with a brighter orange running dorsally along the back. This leftover color variation from the larval state gives way to adult coloration as individuals mature, leaving a much more uniform coloration behind. Sexual dimorphism is present in the species. Mature males are generally larger than mature females and have a mental gland under their chin that females do not have. The vent opening is also proportionally longer in males, is ringed with a dark coloration, and has papillose cloacal lips. The snout is proportionally longer in males and the head is proportionally larger. The males also appear to have larger “jowls” than females due to larger quadrato-pectoralis muscles. The teeth are longer, more pointed, and monocuspate in males, which are used during courtship to scratch at the female’s skin. In females, a light yellow coloration can be seen through the undersurface anterior to the hind limbs, which mark the presence of enlarged ova (Means et. al 2017).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: United States

U.S. state distribution from AmphibiaWeb's database: Louisiana, Mississippi

View distribution map in BerkeleyMapper.

Desmognathus valentinei is found in the coastal plains of the southeastern United States; more specifically, they are found in Alabama, Mississippi, and Louisiana. The species’ habitat can be described as muddy, lowland swamps with pale or tan substrates that closely match the skin color of the species. In undisturbed habitats, the vegetation is typical of low-lying wetlands in the eastern United States, such as swamp black gum (Nyssa biflora) and swamp laurel oak (Quercus laurifolia). Although there is no listed elevation range for D. valentinei, we can presume that their habitat is not high in elevation since they are lowland swamps and many of the individuals were found in bottomland drainages for watersheds (Means et. al 2017).

Life History, Abundance, Activity, and Special Behaviors
In gravid females, the enlarged ova can be seen as a light yellow coloration through the ventrum anterior to the hind limbs (Means et. al 2017).

Courtship behaviors consists of a “waltz” like dance that is also present in at least one other lineage of Desmognathus. The dance lasts an average of 2.5 minutes and as long as 7 minutes in some instances (Lamb 2017).

Observations of a female along with her newly-hatched offspring on muddy earth indicate that D. valentiniei oviposits on land rather than in water. Hatchlings undergo indirect rather than direct development. One gravid female was brought into captivity and laid two clutches of 31 and 27 eggs. All 31 eggs of the first clutch and 9 of the second clutch hatched between 56 - 59 and 46 days, respectively. The 31 larvae all reached adulthood in captivity and metamorphosed between 70 - 90 days after hatching (Lamb 2017, Means et al. 2017).

One unusual behavior present in D. valentinei is dermatophagy, which was observed in a courtship trial between a female D. valentinei and a male D. conanti. The courtship did not progress into copulation, however the female appeared to consume a slough of dead skin on her tail. Although there is no conclusive explanation to this shedding behavior in females, it is speculates that it could be induced if males cause skin abrasions during courtship or if reproduction makes individuals vulnerable to skin pathogens. In general, amphibians may eat their skin as a means to recovering valuable nutrients and removing evidence of their presence to predators. Skin shedding and dermatophagy likely has no relation to courtship (Lamb 2019).

Trends and Threats
As of 2021, D. valentinei has not been assessed by the IUCN Red List of Threatened Species.

Comments

PHYLOGENETIC RELATIONSHIPS:

Although D. valentinei was originally lumped in with D. auriculatus, genetic analyses of two mitochondrial genes (COx I and CytB) and one nuclear gene (RAG-1) found that D. valentinei was more closely related to D. conanti than it was to D. auriculatus. Bayesian analysis of the mitochondrial genes resulted in a polytomy consisting of D. brimleyorum, D. conanti and D. valentinei. Parsimony based haplotype analysis on RAG-1 showed that D. valentinei does not share any alleles with D. auriculatus or D. conanti, but the latter two, while also not sharing any alleles, have fewer mutation steps between alleles than either with D. valentinei (Means et. al 2017).

ETYMOLOGY: :

The species epithet, “valentinei”, is derived from the name of the researcher who first described them: Barry Valentine. Valentine distinguished D. valentinei from other species in the Desmognathus genus that are found in the southeastern United States, including D. auriculatus (Means et. al 2017).

References

Lamb, J. Y. (2019). “Skin sloughing and sperm cap loss during courtship in Dusky Salamanders (genus Desmognathus).” Issue 18(3), 2019. Southeastern Naturalist, 18(3). [link]

Lamb, J.Y. (2017) “Sexual isolation between two sympatric Desmognathus in the Gulf Coastal Plain.” Copeia, 105(2), 261-268 [link]

Means, D. B., Lamb, J. Y., Bernardo, J. (2017). “A new species of dusky salamander (Amphibia: Plethodontidae: Desmognathus) from the Eastern Gulf Coastal Plain of the United States and a redescription of D. auriculatus.” Zootaxa, 4263(3), 467-506. [link]

Valentine, B. (1963). “The salamander genus Desmognathus in Mississippi.” Copeia, 1963(1), 130-139. [link]

Species Account Citation: AmphibiaWeb 2021 Desmognathus valentinei: Valentine's Southern Dusky Salamander <https://amphibiaweb.org/species/8617> University of California, Berkeley, CA, USA. Accessed Dec 26, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 26 Dec 2024.

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