Desmognathus valtos, Pyron & Beamer, 2022

Pyron, R. Alexander & Beamer, David A., 2022, Allocation of Salamandra auriculata Holbrook, 1838, with a new species of swamp-dwelling dusky salamander (Plethodontidae: Desmognathus) from the Atlantic Coastal Plain, Zootaxa 5188 (6), pp. 587-595 : 590-593

Desmognathus valtos sp. nov.

D. auriculatus Holbrook, 1838 (part: see Means 1999; most historical concepts of D. auriculatus included populations from GA, SC, and NC)

Holotype: MNHN 2021.0131 ( RAP0955 ; Fig. 2 ), collected 30 August 2019 by DAB at Otter Creek ( NC: Craven; 34.968, -76.958; 4m ASL).

Paratypes: NCSM 108360–1 ( RAP 2289 & 2293), collected 22 April 2022 by RAP at the type locality ( Fig. 3 ). BMNH 2021.7566 , GSU 26900, & GMNH 52996 ( RAP1646 & 1648–9), collected 9 January 2021 by RAP, DAB, and Dirk J. Stevenson at Holbrook Pond (GA: Liberty; 31.914, -81.554; 7m ASL). AMNH A-193889 ( RAP2294 ; Fig. 4 ), collected 22 April 2022 by RAP at Jasons Branch ( NC: Carteret; 34.768, -76.943; 6m ASL) .

Etymology: The specific epithet is a non-Latin noun used in apposition, from the Greek váltos (βάλτος) for “swamp,” in reference to the primary habitat of the species. We suggest the common name “ Carolina Swamp Dusky Salamander. ”

Diagnosis: In comparison with the re-description of Desmognathus auriculatus ( Holbrook, 1838) by Means et al. (2017), D. valtos is a moderately-sized Dusky Salamander (17.2–62.4mm SVL for transformed specimens), typically with a dark greenish-grey ground color and orangish wash on the dorsal surfaces ( Fig. 2 ). Smaller individuals often have visible remnants of orangish or reddish paired larval spots on the dorsum; differentiation between dorsal and lateral color pattern is typically absent in D. auriculatus , and larval patterning is usually obscured by darkening in even the smallest specimens. Differs significantly in overall size and shape from D. auriculatus , the greatest difference being proportionally longer torsos (longer AG). Tail is thick, girthy, and long, up to 106% SVL, typically less keeled than D. auriculatus , but still flattened at the terminus. Dorsal surface of tail typically exhibits a yellowish or orangish stripe with indistinct margins even in larger individuals ( Fig. 2–5 ); such stripes are usually less colorful and prominent in D. auriculatus , particularly older specimens. Ventrolateral porthole markings with whitish, yellowish, orangish, or reddish pigment may occur in up to three rows (see Pyron et al. 2022b and references therein), but these are generally less prominent than in D. auriculatus . Ventral color pattern is typically relatively bright and granular, consisting of interspersed flecking of darkened melanophores, lighter xanthophores, and whitish speckling, while in D. auriculatus , “the belly is unmistakably black but may be densely peppered with small whitish or silvery speckling (Fig. 14c)” ( Means et al. 2017).

Notes: Little is known about reproduction, larval morphology, or ecological interactions; a few notes were given by Robertson & Tyson (1950) in comparison to D. “ fuscus ” (potentially representing multiple distinct species) and D. brimleyorum . Sexual dimorphism has not been characterized, but adult males appear to exhibit peramorphic hypertrophied jaw musculature as in most other Desmognathus . Ontogenetic change in color pattern is minimal; a 17mm juvenile ( Fig. 6 ) was mostly transformed with barely any gill nubs visible, and a less colorful but essentially adult pattern. That specimen exhibited substantial metachrosis (primarily dorsal lightening) ~24 hours after capture, but this was not observed in adults.

Figures

FIGURE 2. Holotype (MNHN 2021.0131/RAP0955) of Desmognathus valtos. Specimen is an adult (53.1mm SVL), possibly a female based on apparent lack of mental gland and lack of peramorphic or hypertrophied jaw musculature. The holotype exhibits the diagnostic greenish-grey ground color with a reddish-orange dorsal wash, orangish stripe with indistinct margins on the dorsal surface of the tail, yellowish or orangish portholes on the lateral surfaces in three rows, and granular ventral color-pattern with clusters of xanthophores and melanophores interspersed with white flecks and speckles.

FIGURE 3. Paratype (NCSM 108360/RAP2289) of Desmognathus valtos. Specimen is a juvenile or small adult (32.1 mm SVL) showing the same diagnostic features as the holotype, with more prominent dorsal color-pattern and lateral white flecking that is characteristic of younger individuals.

FIGURE 4. Paratype (AMNH A-193889/RAP2294) of Desmognathus valtos. Specimen is a small adult (41.2 mm SVL) showing the same diagnostic features as the holotype, with more prominent dorsal color-pattern and lateral white flecking or speckling that is characteristic of younger individuals, with the latter extending noticeably onto the dorsal surfaces.

FIGURE 6. Comparative specimen (AMNH A-193890/RAP2297) of Desmognathus valtos. Specimen is transformed juvenile (17.2 mm SVL) with remnants of gill nubs, showing general approximation of the adult color pattern. This specimen exhibited substantial metachrosis after capture and rapid fading in preservative; in life, it exhibited more prominent differentiation of lateral, dorsal, and ventral surfaces and a bolder stripe on the dorsal surface of the tail.