Plethodon caddoensis - Pope and Pope, 1951
Caddo Mountain Salamander
Other English Common Names: Caddo Mountain salamander
Taxonomic Status: Accepted
Related ITIS Name(s): Plethodon caddoensis Pope and Pope, 1951 (TSN 173652)
Unique Identifier: ELEMENT_GLOBAL.2.100395
Element Code: AAAAD12010
Informal Taxonomy: Animals, Vertebrates - Amphibians - Salamanders
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Amphibia Caudata Plethodontidae Plethodon
Genus Size: D - Medium to large genus (21+ species)
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Concept Reference
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Concept Reference: Frost, D. R. 1985. Amphibian species of the world. A taxonomic and geographical reference. Allen Press, Inc., and The Association of Systematics Collections, Lawrence, Kansas. v + 732 pp.
Concept Reference Code: B85FRO01HQUS
Name Used in Concept Reference: Plethodon caddoensis
Taxonomic Comments: This is a member of the Plethodon ouachitae complex (Petranka 1998). Duncan and Highton (1979) examined electrophoretic variation in this complex and found that P. caddoensis is moderately distinctive from the other forms (Petranka 1998).

Mahoney (2001) used mtDNA data to examine phylogenetic relationships of western and eastern Plethodon and Aneides. She found strong support for eastern Plethodon as a clade, but monophyly of Aneides was only weakly supported in some analyses, though "the monophyly of this clade is not in doubt." Analyses indicated that Plethodon stormi and P. elongatus are clearly sister taxa, and P. dunni and P. vehiculum also are well-supported sister taxa. Plethodon larselli and P. vandykei appear to be closely related, whereas P. neomexicanus did not group with any other lineage. All analyses yielded a paraphyletic Plethodon but constraint analyses did not allow rejection of a monophyletic Plethodon . Mahoney recommended continued recognition of Aneides as a valid genus and adoption of the metataxon designation for Plethodon*, indicating this status with an asterisk. (A metataxon is a group of lineages for which neither monophyly nor paraphyly can be demonstrated.)
Conservation Status
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NatureServe Status

Global Status: G2G3
Global Status Last Reviewed: 04Dec2017
Global Status Last Changed: 04Dec2017
Ranking Methodology Used: Ranked by calculator
Rounded Global Status: G2 - Imperiled
Reasons: Occurs in the Caddo Mountains, Arkansas; locally common in small range; habitat degradation and loss are potential threats, but most known localities occur within the Ouachita National Forest, which affords this species some level of protection.
Nation: United States
National Status: N2 (05Nov1996)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Arkansas (S2)

Other Statuses

IUCN Red List Category: NT - Near threatened

NatureServe Global Conservation Status Factors

Range Extent: 250-1000 square km (about 100-400 square miles)
Range Extent Comments: Occurs in the Caddo Mountains, Ouachita Mountains region, southwestern Arkansas (Conant and Collins 1991, Petranka 1998), 900-2150 ft (274-655 m).

Area of Occupancy: 6-125 4-km2 grid cells
Area of Occupancy Comments:  

Number of Occurrences: 21 - 80
Number of Occurrences Comments: There are four distinct lineages of P. caddoensis in the Caddo Mountain region (Shepard and Burbrink 2011).

Population Size: Unknown

Number of Occurrences with Good Viability/Integrity: Few (4-12)
Percent Area with Good Viability/Integrity: Excellent percentage (>40%) of area with excellent or good viability or ecological integrity Viability/Integrity Comments: Ranges of the four distinct lineages primarily occur within the Ouachita National Forest, and so are mostly protected. A small portion of the southern distribution of their range occurs outside the National Forest, within the valleys along lower elevation streams. This part of their range has largely been converted to pine plantations for paper production.

Overall Threat Impact: High - medium
Overall Threat Impact Comments: Threatened by habitat destruction and fragmentation resulting from silviculture, but primarily only in lower elevation habitat off National Forest land (Kelly Irwin, pers. comm., 2017). Timber management activities and conversion of land to pine plantations most likely reduced suitable habitat for this species (Warriner 2002, Kelly Irwin, pers. comm., 2017). Habitat degradation and loss continue to be potential threats, but most known localities occur within the Ouachita National Forest, which affords this species some level of protection (Warriner 2002, Kelly Irwin, pers. comm., 2017).

Short-term Trend: Relatively Stable (<=10% change)
Short-term Trend Comments: Core population trends of the four lineages trends considered stable throughout most of their ranges.  One site (Albert Pike) in the Caddo Mountains offer some rough comparisons over time. Highton (2005) found an average of 5.3 P. caddoensis per person based on 3 visits in 1975-76. Then, an average of 2.0 P. caddoensis per person based on 1 visit in 1996. Shepard (2006) found an average of 3.0 P. caddoensis per person based on one visit to this same site in 2006. Search times were usually about 1 hr for Highton (2005) and about 20 min for Shepard (2006, unpublished data).

Long-term Trend: Unknown
Long-term Trend Comments: Probably decline from historical numbers due to timber operations (pine plantations), especially in the lower elevation parts of their range. Extent of timber harvesting impacts on their populations is not known (Kelly Irwin, pers comm. 2017).

Intrinsic Vulnerability: Moderately vulnerable

Environmental Specificity: Very narrow to narrow.

Other NatureServe Conservation Status Information

Inventory Needs: Survey to determine population sizes and trends. Search for more localities with breeding populations.

Protection Needs: Protect buffers around streams in lower elevation habitat off National Forest lands. Avoid higher elevation conversion of forest land to timber plantations.

Distribution
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Global Range: (250-1000 square km (about 100-400 square miles)) Occurs in the Caddo Mountains, Ouachita Mountains region, southwestern Arkansas (Conant and Collins 1991, Petranka 1998), 900-2150 ft (274-655 m).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: endemic to a single state or province

U.S. & Canada State/Province Distribution
United States AR

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted. For information on how to obtain shapefiles of species ranges see our Species Mapping pages at www.natureserve.org/conservation-tools/data-maps-tools.

Range Map Compilers: IUCN, Conservation International, NatureServe, and collaborators, 2004


U.S. Distribution by County Help
State County Name (FIPS Code)
AR Garland (05051), Howard (05061), Montgomery (05097), Pike (05109), Polk (05113)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
08 Ouachita Headwaters (08040101)+, Upper Ouachita (08040102)+, Little Missouri (08040103)+
11 Mountain Fork (11140108)+, Lower Little (11140109)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A small lungless salamander.
Diagnostic Characteristics: Differs from PLETHODON OUACHITAE in lacking chestnut pigment (though some may have small amounts of red on the dorsum). Differs from PLETHODON GLUTINOSUS complex in having less prominent whitish spots and a dark throat (Robison and Allen 1995).
Reproduction Comments: Terrestrial breeder. Eggs are laid mainly in June. Young hatch in late summer and fall (Petranka 1998). Females probably reproduce biennially (Taylor et al. 1990).
Non-Migrant: Y
Locally Migrant: N
Long Distance Migrant: N
Terrestrial Habitat(s): Bare rock/talus/scree, Forest - Mixed, Woodland - Mixed
Subterranean Habitat(s): Subterrestrial
Special Habitat Factors: Burrowing in or using soil, Fallen log/debris
Habitat Comments: "Locally abundant in or near talus slopes or other rocky sites, particularly on north-facing slopes that support mature, mesic forests" (Petranka 1998). Moves into underground retreats under shaded talus or in abandoned mine shafts during hot, dry weather (Petranka 1998). Large numbers have been found in abandoned mines on rock walls near water in summer (Saugey et al. 1985). Has been found in second-growth, mixed deciduous woods with some pine (Pope 1964). Eggs clusters have been found in mine shafts (Heath et al. 1986).
Adult Food Habits: Invertivore
Immature Food Habits: Invertivore
Food Comments: Eats small terrestrial invertebrates.
Adult Phenology: Nocturnal
Immature Phenology: Nocturnal
Phenology Comments: Active on the ground surface in spring and fall, especially on rainy nights (Spotila 1972).
Length: 11 centimeters
Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: Plethodon caddoensis is a forest-dwelling, terrestrial, lungless salamander endemic to the Caddo Mountain region of the Ouachita Mountains of Arkansas (Duncan and Highton 1979; Shepard and Burbrink 2011). There are four geographically distinct genetic lineages of P. caddoensis, each of which associates with high-elevation areas within particular stream drainages (Shepard and Burbrink 2011). Population trends of all four lineages are considered stable; their ranges primarily occur within the Ouachita National Forest, and so are mostly protected. A small portion of the southern distribution of P. caddoensis extends into lower elevations outside the Ouachita National Forest, in riparian areas along rivers and streams (Shepard and Burbrink 2011). These lower-elevation areas largely have been converted to pine plantations for paper production.

Current threats include timber production, off-road vehicle use, and climate change. Historically, P. caddoensis populations were probably reduced significantly due to logging and conversion of hardwood forest to pine plantations, but habitat degradation and loss due to timber production today is primarily limited to lower elevations within their range and outside National Forest boundaries (Kelly Irwin and Don Shepard, pers. comm., 2017). Off-road vehicle use, especially that occurring off trail, remains a threat, but is relatively localized. Given these lungless salamanders are adapted to specific climatic conditions, they may be especially vulnerable to decreased relative humidity with climate change (Shepard and Burbrink 2011).

Management needs: 1) conduct controlled burns; 2) eliminate timber harvest along high-elevation ridgelines and slopes, especially those north-facing; 3) reduce/eliminate all-terrain vehicle use within species? range, in particular off road use; 4) set aside wilderness areas where species occurs to ensure long-term survival; 5) maintain and protect riparian buffers around streams in lower-elevation habitat both within and outside of National Forest lands; 6) prohibit further conversion of hardwood forest lands to pine plantations. 
There is much need for population-level data on the different lineages of P. caddoensis to make better, more informed management decisions. Some specific research needs are: 1) establish long-term study plots to monitor population status and trends over time, and understand how populations may be impacted by climate change; 2) conduct genomic analyses to determine if the four lineages identified by Shepard and Burbrink (2011) are distinct species and delineate their geographic ranges and contact zones; 3) conduct genomic analyses to understand gene flow along elevational gradients, within and between mountains, and within and between stream drainages to determine geographic patterns of population connectivity/isolation and potential dispersal corridors; 4) conduct population surveys and occupancy modeling to determine the environmental factors and habitat characteristics that the species requires across its range; 5) couple population surveys and habitat assessments with genomic analyses to determine effects of landscape variables (e.g., land use, fire history) on dispersal, population structure, and abundance; and 6) conduct rigorous population studies and comparisons of low-elevation populations impacted by pine plantations and high-elevation populations located on National Forest land to determine the riparian buffer zone width needed to maintain healthy populations.

(above informed by Don Shepard and Kelly Irwin, pers comm., 2017)
 

Management Requirements: "Hardwood buffers left around the margins of talus would help maintain viable populations...by providing leaf litter and shading" (Petranka 1998).
Biological Research Needs: There is much need for population-level data on the different lineages of P. caddoensis to make better, more informed management decisions. Some specific research needs are: 1) establish long-term study plots to monitor population status and trends over time, and understand how populations may be impacted by climate change; 2) conduct genomic analyses to determine if the four lineages identified by Shepard and Burbrink (2011) are distinct species and delineate their geographic ranges and contact zones; 3) conduct genomic analyses to understand gene flow along elevational gradients, within and between mountains, and within and between stream drainages to determine geographic patterns of population connectivity/isolation and potential dispersal corridors; 4) conduct population surveys and occupancy modeling to determine the environmental factors and habitat characteristics that the species requires across its range; 5) couple population surveys and habitat assessments with genomic analyses to determine effects of landscape variables (e.g., land use, fire history) on dispersal, population structure, and abundance; and 6) conduct rigorous population studies and comparisons of low-elevation populations impacted by pine plantations and high-elevation populations located on National Forest land to determine the riparian buffer zone width needed to maintain healthy populations.

(above informed by Don Shepard and Kelly Irwin, pers comm., 2017)

Population/Occurrence Delineation
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Group Name: Terrestrial Plethodontid Salamanders

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals (including eggs) in or near appropriate habitat where the species is presumed to be established and breeding.
Separation Barriers: Busy highway, especially with high traffic volume at night; major river or lake; other totally inappropriate habitat that the salamanders cannot traverse.
Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 3 km
Separation Justification: These salamanders rarely successfully cross roadways that have heavy traffic volume at night, when most movements occur. Rivers and lakes pose formidable impediments to movement and generally function as barriers, with the effect increasing with river and lake size. Treatment of these as barriers or unsuitable habitat is a subjective determination.

Compared to larger ambystomatid salamanders, the movements of plethodontids are poorly documented, but it is clear that home ranges tend to be very small (e.g., Marvin 2001), on the order of a few meters to a few dozen meters in diameter. For example, Welsh and Lind (1992) found that over six months, 66% of Plethodon elongatus males and 80% of females recaptured were in the same 7.5 x 7.5 m grid, and the maximum distance moved was 36.2 m. D. Clayton (pers. comm 1998) estimated that average home ranges may be as small as one square meter. Yet, on occasion, dispersing plethodontids likely travel at least several hundred meters. The separation distance for unsuitable habitat reflects the nominal minimum value of 1 km. The separation distance for suitable habitat reflects the limited movements of these salamanders, tempered by their tendency to occur throughout patches of suitable habitat and the likely low probability that two locations separated by a gap of less than a few kilometers of suitable habitat would represent independent occurrences over the long term.

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): .1 km
Date: 10Sep2004
Author: Hammerson, G.
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 04Dec2017
NatureServe Conservation Status Factors Author: Rev. A.D. Davidson and D.B. Shepard (2017); Jefferson, J., and G. Hammerson;
Management Information Edition Date: 12Jan2018
Management Information Edition Author: A.D. Davidson and D.B. Shepard (2018)
Element Ecology & Life History Edition Date: 10Nov2000
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Behler, J. L., and F. W. King. 1979. The Audubon Society field guide to North American reptiles and amphibians. Alfred A. Knopf, New York. 719 pp.

  • Blackburn, L., P. Nanjappa, and M. J. Lannoo. 2001. An Atlas of the Distribution of U.S. Amphibians. Copyright, Ball State University, Muncie, Indiana, USA.

  • Blair, A. P. 1957. A comparison of living PLETHODON OUACHITAE and P. CADDOENSIS. Copeia 1957:47-48.

  • Conant, R. and J. T. Collins. 1991. A field guide to reptiles and amphibians: eastern and central North America. Third edition. Houghton Mifflin Co., Boston, Massachusetts. 450 pp.

  • Dowling, H. G. 1956. Geographic relations of Ozarkian amphibians and reptiles. Southwestern Naturalist 1:174-189.

  • Dowling, H. G. 1957. A review of the amphibians and reptiles of Arkansas. Occasional Papers University of Arkansas Museum (3):1-51.

  • Duncan, R., and R. Highton. 1979. Genetic relationships of the eastern large PLETHODON of the Ouachita Mountains. Copeia 1979:95-110.

  • Frost, D. R. 1985. Amphibian species of the world. A taxonomic and geographical reference. Allen Press, Inc., and The Association of Systematics Collections, Lawrence, Kansas. v + 732 pp.

  • Heath, D. R., D. A. Saugey, and G. A. Heidt. 1986. Abandoned mine fauna of the Ouachita Mountains, Arkansas: vertebrate taxa. Proceedings of the Arkansas Academy of Sciences 40:33-36.

  • Highton, R. 1962. Revision of North American salamanders of the genus PLETHODON. Bulletin of the Florida State Museum 6:235-367.

  • Mahoney, M. J. 2001. Molecular systematics of Plethodon and Aneides (Caudata: Plethodontini): phylogenetic analysis of an old and rapid radiation. Molecular Phylogenetics and Evolution 18:174-188.

  • Petranka, J. W. 1998. Salamanders of the United States and Canada. Smithsonian Institution Press, Washington, D.C.

  • Pope, C. H., and S. H. Pope. 1951. A study of the salamander Plethodon ouachitae and the description of an allied form. Bull. Chicago Acad. Sci. 9:129-152.

  • Pope, C.H. 1964. Plethodon caddoensis. Catalogue of American Amphibians and Reptiles. 14:1.

  • Robison, H.W. and R.T. Allen. 1995. Only in Arkansas: A Study of the Endemic Plants and Animals of the State. University of Arkansas Press, Fayetteville, Arkansas.

  • Saugey, D. A., G. A. Height, and D. R. Heath. 1985. Summer use of abandoned mines by the Caddo Mountain salamander, PLETHODON CADDOENSIS (Plethodontidae), in Arkansas. Southwestern Naturalist 30:318-9.

  • Spotila, J. R. 1972. Role of temperature and water in the ecology of lungless salamanders. Ecological Monographs 42:95-125.

  • Taylor, C. L., R. F. Wilkinson, Jr., and C. L. Peterson. 1990. Reproductive patterns of five plethodontid salamanders from the Ouachita Mountains. Southwestern Naturalist 35:468-472.

  • Trauth, S. E., H. W. Robison, and M. V. Plummer. 2004. The amphibians and reptiles of Arkansas. University of Arkansas Press.

  • Warriner, M. D. 2002. Arkansas Natural Heritage Commission, Rare Amphibian Fact Sheet, Caddo Mountain Salamander - Plethodon caddoensis.

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