Desmognathus adatsihi, Pyron & Beamer, 2022

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 : 215-225

Desmognathus adatsihi sp. nov.

Holotype: USNM 596065 ( RAP0892 ; Figs. 5–8 ), collected 14August 2019 by RAP and T. W. Pierson on Cataloochee Balsam in Great Smoky Mountains National Park ( NC: Swain; Fig. 9 ), ~ 1650m ASL.

Paratypes: USNM 596063–4 ( RAP0890–1 ; Figs. 6–8 , 10 , 11 ), same collection as the holotype . NCSM 108356 ( RAP0909 ), collected 15 August 2019 by RAP and T. W. Pierson on Rough Ridge ( NC: Haywood; 35.543, -83.156), ~ 1610m ASL .

Diagnosis: Several phenotypic characters exhibit varying combinations of states which are purported to be diagnostic and differentiate D. adatsihi from related or similar taxa. This species is a small (~ 23–50mm SVL; n = 15), primarily terrestrial mountain dusky salamander with a tail shorter than the body (up to ~90% SVL) that is round in cross section along its length. It is differentiated from D. santeetlah by the lack of any keeling on the dorsal surface of the tail (vs. presence thereof). It is sometimes differentiated from D. imitator by a morph with the prominent remnants of paired yellowish, reddish, or orangish dorsal spots connected by a wash of lighter pigments on a lighter ground color ( Figs. 6–8 , 11 ; vs. more distinct and separated spots on a darker ground color in some D. imitator ), or in uniformly dark older specimens, a lack of red cheek patches ( Fig. 12a ; vs. the presence of such coloration in some uniformly dark D. imitator ). Many individuals can be uniquely diagnosed by the presence of an exceptionally straight and unadorned dorsal stripe of brownish or yellowish color ( Figs. 5–8 , 13a ), a characteristic most common in Smokies populations. This trait is never observed in D. imitator , other D. ocoee lineages, or D. santeetlah , which if exhibiting dorsal color pattern, all typically possess paired spots with varying degrees of intercalated melanophore pigmentation, sometimes yielding relatively unadorned stripes with irregular edges. Some individuals from the paratype locality exhibit yellowish dorsal stripes with irregular edges and indistinct black patterning on the mid-dorsal line ( Fig. 13b ), an arrangement almost never observed in D. apalachicolae and very rarely in any other D. ocoee lineages. Very rarely, other color patterns include characteristic erythristic or xanthic morphs that have never been observed in other species ( Figs. 6–8 , 10 , 14a ) and appear to be uniquely diagnostic when present.

Distribution: In the Great Smoky Mountains of Tennessee and North Carolina and the Plott Balsam Mountains of North Carolina at high elevations. All genetically verified samples illustrated here ( Fig. 4 ) originated> 1500m ASL. Tilley et al. (1978) tentatively suggested ~ 1200m ASL as the approximate lower limit for this species and reported Starkey Gap as the westernmost limit of its range. An informal transect sampling several points at the paratype locality along the western slope of Rough Ridge below Strawberry Knob (NC: Haywood) revealed only D. imitator at ~ 1340m, ~ 1460m, and ~ 1490m, and only D. adatsihi at ~ 1540m, ~ 1570m, and ~ 1610–1630m; previous surveys from near this locality (Mashie Stomp Creek) also found only D. imitator at ~ 1350m ( Tilley 2000).

Etymology: From a Tsalagi (Cherokee) word (in syllabary:) that translates in a rough sense to “the mother of all,” in reference to the matrilineal inheritance of the mitochondrion, which has an unusual hybrid ancestry in this species along with ocoee B–D. Name is a non-Latin singular noun used in apposition. We suggest the common names “Cherokee” or “Great Smokies” Mountain Dusky Salamander.

Notes: Comprises the ocoee A lineage first tentatively identified by Tilley et al. (1978) and defined by Kozak et al. (2005), Beamer & Lamb (2020), and Pyron et al. (2020, 2022c). Little is known of the biology of this species. Like many other mountain duskies, it is highly terrestrial and appears to spend most of its adult life on the forest floor significant distances away from any permanent flowing water. Some populations from the Smokies were briefly described by Huheey (1966b) and Dodd (2004). An aberrant, possibly leucistic morph has been observed at the paratype locality ( Fig. 15 ).

The third species accounted for here is the ocoee B lineage, the second member of the Balsam clade of Pyron et al. (2022c). This taxon is distributed throughout the Great Balsam Mountains of western North Carolina, southeast of Balsam Gap. It shares hybridized non-lineal mitochondrial ancestry with Desmognathus adatsihi and ocoee C/D but is otherwise genealogically exclusive and exhibits no apparent admixture with any other lineage. Consequently, we recognize it here as:

Figures

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 “?.”

FIGURE 5. Holotype (USNM 596065/RAP0892) of Desmognathus adatsihifrom Cataloochee Balsam, Great Smoky Mountains (NC: Swain) in life, photo courtesy of T.W. Pierson (KSU). This solidly striped morph is most commonly representative of Smokies populations and is distinguishable from D. imitator by the straight and well-defined borders of the uniformly colored dorsal stripe.

FIGURE 6. Paratypes (USNM 596063–4/RAP0890–1; a, b) and holotype (USNM 596065/RAP0892, c) of Desmognathus adatsihi from Cataloochee Balsam, Great Smoky Mountains (NC: Swain) isolated in life. Photos courtesy of T.W. Pierson; specimens not to scale.

FIGURE 7. Paratypes (USNM 596063–4/RAP0890–1; a,b) and holotype (USNM 596065/RAP0892, c) of Desmognathus adatsihi from Cataloochee Balsam, Great Smoky Mountains (NC: Swain) in dorsal view in preservative, approximately to scale with tick marks in mm. Photos by RAP.

FIGURE 8. Paratypes (USNM 596063–4/RAP0890–1; a,b) and holotype (USNM 596065/RAP0892, c) of Desmognathus adatsihi from Cataloochee Balsam, Great Smoky Mountains (NC: Swain) in ventral view in preservative, approximately to scale with tick marks in mm. Photos by RAP. Dorsal pattern of erythristic morph (a) shows significant intrusion onto ventral surfaces, compared to the relatively immaculate spotted and striped morphs (b, c).

FIGURE 9. The type locality of Desmognathus adatsihi on Cataloochee Balsam, Great Smoky Mountains National Park (NC: Swain), ~1650m ASL. The habitat is classic “spruce-fir” forest. The type series were captured under rocks and logs in the foreground. Photo courtesy of T.W. Pierson.

FIGURE 10. Paratype (USNM 596063/RAP0890) of Desmognathus adatsihi from Cataloochee Balsam (NC: Swain) in life, photo courtesy of T.W. Pierson. This brilliantly colored erythristic morph and its xanthic counterpart are infrequently observed, primarily on Cataloochee Balsam near the type locality, but also very rarely on Clingmans Dome in the Smokies (Fig. 14a) and Waterrock Knob in the Plott Balsams (S. G. Tilley, pers. comm.). A similar specimen from near the type locality was mislabeled as D. imitator by Dodd (2004).

FIGURE 11. Paratype (USNM 596064/RAP0891) of Desmognathus adatsihi from Cataloochee Balsam (NC: Swain) in life, photo courtesy of T. W. Pierson. This partially spotted morph is the only color pattern that is likely to be confused with D. imitator, but the spots are more contiguous, particularly towards the tail, with an overall lighter ground color (see Tilley 2000).

FIGURE 12. Comparison of large, darkened adult males (based on elongated snouts and peramorphic jaw musculature) of Desmognathus adatsihi (a: RAP2816; Rough Ridge, NC: Haywood) and D. balsameus (b: RAP2827; Bear Pen Gap, NC: Jackson; Fig. 16a) in life, showing the similar overall melanic coloration taken on with age. Photos courtesy of M.A. Seldes (UGA).

FIGURE 13. Photographs of two adult Desmognathus adatsihi (a: RAP2818; b: RAP2820) in life, from the paratype locality on Rough Ridge (NC: Haywood). Photos courtesy of M.A. Seldes.

FIGURE 14. Comparison of small adult Desmognathus adatsihi (a: not collected; Clingmans Dome, TN: Sevier/NC: Swain) and exceptionally large (54mm SVL) adult D. balsameus (b: RAP2831; Lost Knob, NC: Jackson) in life, showing the dramatic possible differences in body form and coloration. Photos courtesy of M.A. Seldes.

FIGURE 15. An aberrant specimen (RAP0908) of Desmognathus adatsihi from Rough Ridge (NC: Haywood) in life on isolated (a) and natural (b) backgrounds. In contrast to the regularly encountered erythristic and xanthic morphs, we hypothesize this individual to be a singular mutant, probably leucistic, rather than a form which occurs with any frequency in the population. Photos courtesy of T.W. Pierson.