Amphibians of North Carolina
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NC Records

Aneides caryaensis - Hickory Nut Gorge Green Salamander


Taxonomy
Class: Amphibia Order: Caudata Family: Plethodontidae Subfamily: Plethodontinae Other Common Name(s): Hickory Nut Gorge Green Salamander
Taxonomic Comments: Populations of a crevice-dwelling greenish salamander with a flattened body, long legs, and squared toe tips have traditionally been treated as a single species, the Green Salamander (Aneides aeneus). Suspicions were raised that a cryptic species complex might exists within this group when researchers examined morphological variation in chromosomes and documented substantial geographic variation among populations (Morescalchi 1975, Sessions and Kezer 1987; however, see Patton et al. 2019). Patton et al. (2019) conducted a comprehensive molecular analysis of populations from throughout the range and delineated four major evolutionary lineages. These include 1) a narrowly endemic group in the Hickory Nut Gorge of western North Carolina, 2) an adjoining group in the Blue Ridge Escarpment of North Carolina, northwestern South Carolina, and northeastern Georgia, 3) a northern Appalachian group that ranges from Maryland, Pennsylvania and West Virginia southwestward through eastern Kentucky to the Cumberland Plateau of central Tennessee, and 4) a southern Appalachian group that adjoins the latter group and ranges from central Tennessee to northwestern Georgia, northern Alabama, and northeastern Mississippi. Analyses of mtDNA indicate that these lineages are ancient, with the Hickory Nut Gorge lineage originating about 12 million years ago, and the youngest lineages originating about 5 million years ago. The authors recognized the Hickory Nut Gorge lineage as a separate species (A. caryaensis) based on molecular and morphological data. The remaining three groups were treated as evolutionarily significant units until the contact zone between the northern Appalachian and southern Appalachian group in Tennessee can be more thoroughly evaluated. These are treated here as A. aeneus (sensu stricto), with the understanding that all three lineages in this group may eventually be recognized as separate species.
Species Comments: Aneides caryaensis is a very rare micro-endemic species that is known from fewer than 25 localities in North Carolina despite extensive searching (Patton et al. 2019). It is an endangered species that should never be collected.
Identification
Description: The Hickory Nut Gorge Green Salamander is very similar to the Green Salamander (A. aeneus) and is best identified in the field by locality and color patterning. The dorsum of the body, tail, and limbs has a dark brownish-black ground color that is overlain with lichen-like patches of bright green to yellowish-green pigment. The lowermost sides and venter have a light grayish yellow ground color with a loose suffusion of punctate melanophores. These are less dense on the venter, especially near the midline, so that the venter appears much lighter than other surfaces (Patton et al. 2019). This species exhibits several morphological adaptations for living in rock crevices, including a flattened body, proportionately long legs, and expanded, squared, toe tips. Three adult males examined by Patton et al. (2019) were 48.5, 52.4, and 58.4 mm, while four adult females were 52.8, 57.8, 58.9, and 59.8 mm. Sexually-active males have a mental gland that is often yellowish orange, enlarged jaw muscles, and elongated premaxillary and maxillary teeth that penetrate the upper lip. Mature females also have somewhat enlarged jaw muscles and protruding teeth, so these traits are not always reliable for sexing individuals in the field.

Patton et al. (2019) noted that the lower sides of A. caryaensis have a light grayish yellow ground color and do not have dark pigment as seen in A. aeneus. In addition, the lichen-like patches on the dorsum are reduced in size relative to those of typical A. aeneus. Hickory Nut Gorge Green Salamander is a micro-endemic species that is separated from the nearest known A. aeneus populations to the west by about 25 km. Thus, locality alone should be sufficient to identify specimens of both species.
Online Photos:    Google
AmphibiaWeb Account
Distribution in North Carolina
Distribution Comments: This species is a very narrow endemic that is known only from the Hickory Nut Gorge in portions of Buncombe, Henderson, Polk, and Rutherford counties.
Distribution Reference: Patton et al. (2019)
County Map: Clicking on a county returns the records for the species in that county.
Key Habitat Requirements
Habitat: Williams et al. (2020) conducted a multiyear survey of A. aeneus and A. caryaensis in North Carolina and made only 12 observations of adult A. caryaensis, versus several hundred of A. aeneus. Because of its rarity, much of the habitat requirements of A. caryaensis will likely need to be inferred from studies of nearby A. aeneus in North Carolina.

A. caryaensis appears to use the same habitats as A. aeneus in North Carolina (Williams et al. 2020). Individuals nest and overwinter in cliff faces and rock outcrops that are typically found in well-shaded habitats in relatively mature hardwood forests. Optimal rocky habitats have crevices that are moist but not dripping wet, that are relatively clear of soil, debris, or plants, and that are deep enough to allow animals to retreat during unfavorable conditions such as during seasonal droughts, heat waves, or winter freezes. The nest rocks that are used in North Carolina by A. aeneus often have specialized brood chambers that are higher above the ground and shorter in length, which presumably facilitates the ability of females to defend their nests and provide microclimate stability (Rossell et al. 2019).

The rock outcrops that are used by A. caryaensis are small and patchily distributed. Individuals likely disperse between local outcrops during the summer months through forested landscapes as seen in A. aeneus (Williams et al. 2020), but the use of forest habitats by A. caryaensis is largely undocumented. Conservation managers should consider both rock outcrops and surrounding mature hardwood forests as essential habitats for this species.
See also Habitat Account for Montane Mesic Rock Faces and Crevices
Life History and Autecology
Breeding and Courtship: The courtship behavior of this species is undocumented, but is presumably similar to that of A. aeneus.
Reproductive Mode: Most aspects of the reproductive biology of this species are undocumented. Each female lays a small cluster of eggs that are suspended by several mucus strands to the roof of a nesting cavity. Although undocumented, females presumably lay their eggs in June or July and guard them through hatching.
Terrestrial Life History: Almost all aspects of the terrestrial ecology are unreported. Non-nesting individuals probably use forest habitats away from rock formations during the summer months as seen in A. aeneus in South Carolina (Waldron and Humphries 2005), but this has yet to be documented. Other aspects of the life history such growth rates, age at sexual maturity, diet, survivorship and life expectancy are undocumented.
General Ecology
Adverse Environmental Impacts
Habitat Loss: The extent to which this species has declined historically is poorly documented. The construction of Lake Lure -- along with development along the lake shore that followed -- may have eliminated many local populations.
Status in North Carolina
NHP State Rank: S1
Global Rank: G1
Status in North Carolina: E
Populations: Local rock outcrops with suitable crevice habitat appear to support very small populations. Patton et al. (2019) noted that surveys often yield only 1-3 animals on a given site visit. In addition, genetic analysis indicate that local populations are experiencing high levels of inbreeding, a clear signature of small population sizes. High levels of inbreeding can have detrimental effects on populations, including a decrease in fecundity that can in turn lead to lower population sizes and even more inbreeding. This positive feedback loop can potentially lead to the extinction of local populations.
Environmental Threats: Fewer than 25 populations of A. caryaensis are known, and most consist of small, seemingly isolated populations of very small size. The known populations are threatened by the loss and fragmentation of forest habitats associated with increases in tourism in the region, real estate development, and transportation and energy infrastructure within the Hickory Nut Gorge (Patton et al. 2019).

Photo Gallery for Aneides caryaensis - Hickory Nut Gorge Green Salamander

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Recorded by: Todd Pierson
Rutherford Co.
Recorded by: B. Bockhahn, K. Kittelberger
Rutherford Co.
Recorded by: B. Bockhahn, K. Kittelberger
Rutherford Co.