Desmognathus perlapsus Neill, 1950

Pyron, R. Alexander & Beamer, David A., 2022, Systematics of the Ocoee Salamander (Plethodontidae: Desmognathus ocoee), with description of two new species from the southern Blue Ridge Mountains, Zootaxa 5190 (2), pp. 207-240 : 226-230

Desmognathus perlapsus Neill, 1950

Holotype: ERA-WTN 14150 ( Fig. 2 ), collected 4 August 1950 by Wilfred T. Neill, type locality on a “rocky outcropping on the western wall of Tallulah Gorge, near the town of Tallulah Falls, Rabun County, Georgia.” The locality described is southeast of Tallulah Falls in Habersham County (Huheey in Valentine 1964), approximate coordinates 34.730, -83.385. Type specimen not known to exist; Neill (1950) included a note that it was to be deposited in the FLMNH, but it was not listed by Christman in Gilbert (1974) or among the current holdings. Because the identity of the taxon is not in dispute, a neotype is not warranted.

Paratypes: ERA-WTN 14151–66, from the type collection. Not known to exist .

Description: After Neill (1950) and Valentine (1961), a robustly proportioned salamander with a round tail (or weakly keeled on the distal portion), four pairs of dorsal spots, and a well-defined color-pattern with wide black margins around the larval spots, white flecking on the upper surfaces, and whitish mottling on the sides and venter, putatively diagnosable from Desmognathus ocoee by larger adult body size (~ 22–56mm SVL; n = 77), a longer and wider head, shorter limbs, vomerine teeth present in adult males, long slender parasphenoid tooth-patches, lessdefined dorsal color-pattern, and 4 vs. 5–6 pairs of spots between the axilla and groin. However, Valentine (1961) questioned the diagnostic utility of these characters; for instance, many specimens have 5–6 pairs of larval spots, and the size ranges overlap substantially. Additional work is needed to establish the morphometric description of this taxon. Some populations in the Cowee Mountains and Highlands Plateau also occasionally exhibit red, orange, or yellow cheek patches ( Brimley 1928; Huheey 1966a; Labanick 1983), differentiating them from all lineages other than D. ocoee E and D. imitator . Specimens from the southern part of the range in the Piedmont and adjacent Coastal Plain of Alabama and Georgia are typically considerably more melanic with an overall dark coloring and obscured pattern of paired larval spots, often with a partial keel on the tail.

Distribution: Based on expanded genetic sampling, this species ranges from the Alarka and Cowee Mountains in western North Carolina between the Tuckasegee and Little Tennessee Rivers, the western headwater mountain streams of the Savannah River drainage in northwestern South Carolina, northeastern Georgia, and adjacent North Carolina, and the Chattahoochee River drainage in the Piedmont of Georgia and Alabama to the Fall Line and Uchee Creek (AL: Russell) in the adjacent Coastal Plain ( Fig. 4 ).

Etymology: From the perfect passive participle of the Latin perlabor for “slipping” or “gliding through” as an adjective in the nominative singular, in reference to the lithe nature of the species when active in rock crevices, or in hand once captured. Previous common names include Tallulah Salamander ( Schmidt 1953) and Cliffside Salamander (Conant et al. 1956). Neither is particularly appropriate; we suggest “Chattooga Dusky Salamander.”

Notes: Comprises the ocoee C/D lineage defined by Kozak et al. (2005), Beamer & Lamb (2020), and Pyron et al. (2020, 2022c). Synonymized with Desmognathus ocoee by Valentine (1961) and resurrected here with an expanded geographic range. Voluminous data on the biology of this species exist under the name D. ocoee but will need to be carefully disambiguated by reference to the originating populations; see extensive bibliographies in Valentine (1964) and Camp & Tilley (2005).

The fifth and final species corresponds to a slight restriction of Valentine (1961) ’s concept of D. ocoee (see Valentine 1964), including five geographically distinct genetic population segments. These are the ocoee E–H lineages of Kozak et al. (2005), along with the apalachicolae A2 populations from the southernmost Blue Ridge first identified by Beamer & Lamb (2008) and named by Pyron et al. (2022c). The ocoee H lineage occupies a restricted portion of the southern Cumberland Plateau in Tennessee; the G lineage ranges along an extensive portion of Sand Mountain/ Walden Ridge in northeastern Alabama, northwestern Georgia, and central Tennessee (genetically identified as D. ocoee by Anderson & Tilley 2003); and the F lineage occurs in the Unicoi Mountains and adjacent ridges in eastern Tennessee and extreme western North Carolina. Together, these form a single genetic unit, the ocoee F/G/H lineage ( Beamer & Lamb 2020; Pyron et al. 2020, 2022c). The ocoee E lineage occurs in the Nantahala Mountains of western North Carolina and northern Georgia, and the apalachicolae A2 lineage occupies the southern terminus of the Blue Ridge escarpment in north-central Georgia. These three groups are parapatric and replace each other geographically in the mountains of Georgia, North Carolina, and Tennessee, while also exhibiting admixture across their contact zones. Therefore, we conservatively treat them as a single species with at least three major phylogeographic lineages. Phylogenetic estimates suggest that D. apalachicolae is nested within this species, though population-genetic analyses indicate that it is genealogically exclusive, and the nested topological position may be an artifact of the complex history of diversification and reticulation in the group ( Chan et al. 2020; Dolinay et al. 2021). Given its geographic and genetic distinctiveness, we treat D. apalachicolae as distinct from apalachicolae A2, which we consider part of D. ocoee . We re-describe D. ocoee here as:

Figures

FIGURE 2. Illustrated holotype (ERA-WTN 14150) of Desmognathus perlapsus Neill, 1950 from a “rocky outcropping on the western wall of Tallulah Gorge, near the town of Tallulah Falls, Rabun [actually Habersham] County, Georgia.” The specimen, an adult male 38.6mm SVL, is not currently known to exist but may be in the FLMNH. Reprinted from the original description.

FIGURE 4. Map of the five species considered by our taxonomy from genetically verified recent localities (RAP collection; Anderson & Tilley 2003; Beamer & Lamb 2020; Karlin & Guttman 1986; Kozak et al. 2005; Means et al. 2017; Pyron et al. 2022c; Tilley 2000; Tilley et al. 1978, 2008; Tilley & Mahoney 1996). We include apalachicolae A2 and ocoee E within our concept of D. ocoee, for which the nominotypical lineage is ocoee F/G/H. Note that some individuals from these populations are admixed between one or more species, and hybrid zones exist between phylogeographic lineages within D. ocoee and D. perlapsus, primarily at the geographic margins where each adjacent lineage contacts its neighbor. Type localities are indicated with triangles, the population of unknown affinity from Horse Cove (GA: Gilmer; Fig. 21) is indicated with a gray dot, and the potential Cohutta populations are indicated with a “?.”