Desmognathus marmoratus ( Moore, 1899 )

Pyron, R. Alexander & Beamer, David A., 2023, A systematic revision of the Shovel-nosed Salamander (Plethodontidae: Desmognathus marmoratus), with re-description of the related D. aureatus and D. intermedius, Zootaxa 5270 (2), pp. 262-280 : 270-273

Desmognathus marmoratus ( Moore, 1899)

Leurognathus marmorata Moore, 1899

Syntypes and Type Locality: Moore (1899) ’s description was explicitly based on both a male and female syntype along with an additional female specimen which was skeletonized for illustration. These were taken from “a large clear rocky pool beneath a waterfall of a stream on the south flank of Grandfather Mt., N. C., and at an elevation of about 3,500 feet.” A site matching this description is found at Green Mountain Creek Falls (36.114308, -81.778430; 1182m) on U.S. Hwy 221 near Blowing Rock (NC: Watauga), which we suggest is the type locality. The male syntype was deposited by Moore in 1916 at the Academy of Natural Sciences of Philadelphia as ANSP 19610. The two females (the alcoholic syntype and the skeleton) were said by Dunn (1917) to have been examined by himself at the University of Pennsylvania, presumably still in the collection of Moore, who was still a professor there at the time. Fowler and Dunn (1917) listed ANSP 19610 as a paratype, while Malnate (1971) listed it as the holotype. It is neither, but rather a syntype as per the original publication. We here designate it as the lectotype of Leurognathus marmorata Moore, 1899 to remove any ambiguity. This renders the second, female syntype a paralectotype. This specimen is of unknown disposition; it was originally in the P.J. Moore collection at the University of Pennsylvania, but inquiries to the university and the ANSP yielded no information. The female skeleton is also not known to exist but is not part of the type series and carries no name-bearing function.

Description: After Moore (1899) and Martof (1956), a large (SVL = ~ 30–75mm), highly aquatic, fin-tailed salamander with slit-like internal nares; an indistinct dorsal color pattern consisting of a dark-brown background color and numerous mottled markings lacking light-colored centers; darker or grey venter; adult males lacking vomerine teeth, females with very few; large, prominent eyes; and snout usually not darker than the remainder of body ( Fig. 5 , 6 ). Can putatively be differentiated from the other two described shovel-nosed species based on the original characters given in the other accounts below, though these have not been re-assessed based on modern understandings of species limits and are of unknown diagnostic utility. Based on our size-corrected linear morphometric analyses, this species can be distinguished from Desmognathus aureatus and D. intermedius by a shorter head (SG in original measurements = 4.3–16.4mm) and from D. intermedius by a shorter trunk (AG in original measurements = 9.3–41.7mm). Of the 10 specimens observed in West Virginia, 8 were adults and the largest (a gravid female) was only ~ 60mm SVL, suggesting that this population may represent a dwarf race since the median SVL of 45 metamorphosed individuals sampled from southern populations is ~ 62mm. Ironically, little is known about the natural history of this species despite it being the earliest-described species as most studies have focused on D. aureatus and D. intermedius . Pope (1924) found a clutch of 28 eggs on 6 August 1924, and Bishop (1924) sampled females in October with 26–34 ovarian eggs. Previous reports suggest that larvae typically metamorphose between 26–33mm SVL (see Camp and Tilley in Lannoo 2005 and references therein).

Range: In high-gradient mountain streams of the Appalachians, on the Blue Ridge northeast of the Pigeon River to southwestern Virginia. Populations are known from the South Fork Holston, Watauga, and Nolichucky (Upper Tennessee) and Upper Broad and Upper Catawba (Santee) River drainages. Also known from a handful of riffle zones along a 2–3km stretch of Glade Creek near Beckley, Raleigh County, West Virginia in the Lower New (Kanawha) River drainage. We are confident that this species is absent from several other similar creeks in the New River Gorge in which we exerted similar sampling effort ( Fig. 2 ). In contrast, other nearby streams with apparently similar geological and hydrological characteristics may harbor populations of this species. This population is widely (~120 airline km) disjunct from the nearest known populations in the Upper Tennessee drainage in southwestern Virginia (Smyth and Washington Counties). Elevational range ~ 450–1600m (see Fig. 1 for localities).

Habitat: Occurs almost exclusively in the rocky riffle zones of a fast-flowing, high-gradient mountain stream of the “typical” character associated with other Shovel-nosed Salamanders farther south in the Appalachian Mountains ( Martof 1962).

Etymology: The specific epithet is a Latin singular adjective in the nominative case meaning “marbled,” in reference to the dorsal color-pattern.

Standard English Names: Moore’s Triton ( Brimley 1907), Moore’s Salamander ( Bishop 1943), Northern Shovel-nosed Salamander ( Schmidt 1953), Shovelnose Salamander ( Collins et al. 1978). We suggest that “Northern Shovel-nosed Salamander” is most appropriate.

Conservation: The re-described concept of this species occupies a smaller range than the previous, more inclusive definition but is nevertheless widespread and abundant at numerous historical localities. Consequently, we suggest that it retain its “LC—Least Concern” status on the IUCN Red List based on the known information (see Maes et al. 2015). Special attention should be paid to the isolated population in the New River Gorge of West Virginia.

Notes: First assigned to Desmognathus by Titus and Larson (1996) after the unpublished results of Titus (1992) and the informal suggestion of Bernardo (1994). Genetic variation in the widespread former concept of this species was first reported by Voss et al. (1995) and expanded by Jackson (2005), Kozak et al. (2005), and Jones et al. (2006), who confirmed the existence of multiple species-level taxa based on phylogenetic analysis of mitochondrial and nuclear DNA. This echoed earlier morphological work ( Pope 1928; Martof 1956), though Martof (1962) had later downplayed the significance of this phenotypic variation.

Accordingly, we offer revised accounts of the other known species of shovel-nosed salamander. These occur in two distantly related clades, Nantahala ( Desmognathus aureatus ) and Pisgah ( D. intermedius ). Beamer and Lamb (2020) and Pyron et al. (2020, 2022c) sampled the type locality of Leurognathus m. aureata Martof, 1956 and populations geographically proximate (5.5 airline km) to the type locality of L. m. roborata Martof, 1956, confirming their inclusion in marmoratus B. Acting as the First Reviser (Article 24.2.1), Raffaëlli (2013) had previously selected the former as the senior subjective synonym when the two taxa are considered conspecific. Consequently, this lineage should be referred to as Desmognathus aureatus ( Martof, 1956) and include D. roboratus ( Martof, 1956) in synonymy.

Figures

FIGURE 1. Map of genetic, specimen-vouchered, and literature localities for the three species of Shovel-nosed Salamanders, from our collections (RAP and DAB) and Martof (1956), Jackson (2005), Kozak et al. (2005), Wooten and Rissler (2011), Beamer and Lamb (2020), and Pyron et al. (2022c). Type localities are indicated with inverted triangles, and the site indicated in grey is a dubious locality reported by Wooten and Rissler (2011). Our extensive fieldwork at this and numerous other sites in the headwaters of the New (Kanawha) River yielded no specimens. State abbreviations are GA—Georgia, SC—South Carolina, NC—North Carolina, TN—Tennessee, VA—Virginia, and WV—West Virginia.

FIGURE 2. Map of the Lower New River drainage (HUC8:05050004) in West Virginia (WV) showing surveyed localities from our recent fieldwork (2020–2022), highlighting sites containing Desmognathus kanawha, D. marmoratus, no aquatic Desmognathus, and likely candidates for future surveys. Each area was searched for at least 1 person/hour, netting the effluent of disturbed riffle zones adequate to detect Shovel-nosed Salamanders.The New (Kanawha) River is indicated in dark blue, with tributaries in gray. In addition to Piney Creek which we consider a likely site (?), numerous additional creeks and streams in the region remain to be evaluated. Watershed data are projected at 1:24,000 from the National Hydrography Dataset (https://www. usgs.gov/national-hydrography/national-hydrography-dataset), accessed 7 November 2022. Literature record (lit.) from Wooten and Rissler (2011).

FIGURE 5. An adult Desmognathus marmoratus from Laurel Creek (VA: Smyth). Note the indistinctiveness of the dorsal color pattern. Photo courtesy of T.W. Pierson (KSU).

FIGURE 6. An adult Desmognathus marmoratus from Hickory Creek (NC: Henderson), from the isolated population (marmoratus G) in Hickory Nut Gorge. This phylogeographic sublineage of D. marmoratus contains significant genomic ancestry from D. intermedius and potentially other Pisgah-clade species (Pyron et al. 2022c). Photo courtesy of M.A. Seldes (UGA).