Home/Species/ Georgia Pigtoe

Pleurobema hanleyianum

(I. Lea, 1852)

Georgia Pigtoe

G1Critically Imperiled Found in 3 roadless areas NatureServe Explorer →

G1Critically ImperiledGlobal Rank

Critically endangeredIUCN

Very highThreat Impact

Identity

Unique IDELEMENT_GLOBAL.2.116006

Element CodeIMBIV35160

Record TypeSPECIES

ClassificationSpecies

Classification StatusStandard

Name CategoryInvertebrate Animal

IUCNCritically endangered

Endemicendemic to a single nation

KingdomAnimalia

PhylumMollusca

ClassBivalvia

OrderUnionoida

FamilyUnionidae

GenusPleurobema

Synonyms

Pleurobema aldrichianumGoodrich, 1931Pleurobema hanleyanum(I. Lea, 1852)

Concept Reference

Turgeon, D. D., J. F. Quinn, Jr., A. E. Bogan, E. V. Coan, F. G. Hochberg, W. G. Lyons, P. M. Mikkelsen, R. J. Neves, C. F. E. Roper, G. Rosenberg, B. Roth, A. Scheltema, F. G. Thompson, M. Vecchione, and J. D. Williams. 1998. Common and scientific names of aquatic invertebrates from the United States and Canada: Mollusks. 2nd Edition. American Fisheries Society Special Publication 26, Bethesda, Maryland. 526 pp.

Taxonomic Comments

Spelling of the name follows the original publication (Turgeon et al., 1998). It is difficult to differentiate this species from Pleurobema georgianum and Pleurobema trochelianum in the field due to similar shell characteristics (Parmalee and Bogan, 1998), but some morphological features of each are outlined in USFWS (2003). Recent genetic studies were unable to distinguish the painted clubshell from the southern clubshell (listed as endangered), or populations of Georgia pigtoe and Alabama clubshell from southern pigtoe (listed as endangered) (P. Johnson, Tennessee Aquarium, pers. comm. 2002). The uniqueness of the species has been verified morphologically (Williams et al., 2008) and genetically (Campbell et al., 2008).

Conservation Status

Rank Method Rank calculation - Biotics v2

Review Date2024-01-03

Change Date2000-08-30

Edition Date2024-01-03

Edition AuthorsMorrison, M. (2000); rev. J. Cordeiro (2011); rev. T. Cornelisse (2024)

Threat ImpactVery high

Range Extent1000-20,000 square km (about 400-8000 square miles)

Number of Occurrences1 - 5

Rank Reasons

This species has a limited range and due to long and short-term population declines and many ongoing threats, it has a limited number of viable occurrences.

Range Extent Comments

This species occurs in the United States in the Upper Conasauga River in Tennessee and Georgia and in the Little and Big Canoe creeks in Alabama (USFWS 2021).

Occurrences Comments

This species is known from two occurrences, one in the Upper Conasauga River in Tennessee and Georgia and one in the Little and Big Canoe creeks in Alabama (USFWS 2021).

Threat Impact Comments

This species is threatened by sedimentation, nutrient, and chemical pollution from land conversion activities, including development, agriculture, oil and gas operations, and mining, dams and water diversions that change hydrological conditions and prevent habitat connectivity and recolonization, and habitat alteration due to climate change, including increased water temperatures and drought (USFWS 2021).

Ecology & Habitat

Habitat

This species is found in shallow runs and riffles of medium sized rivers with strong to moderate current and coarse sand-gravel-cobble bottoms (USFWS 2010).

Other Nations (1)

United StatesN1

Province	Rank	Native
Alabama	SX	Yes
Georgia	S1	Yes
Tennessee	S1	Yes

Threat Assessments

Threat	Scope	Severity	Timing
7 - Natural system modifications	Large (31-70%)	Serious or 31-70% pop. decline	High (continuing)
7.2 - Dams & water management/use	Large (31-70%)	Serious or 31-70% pop. decline	High (continuing)
9 - Pollution	Large (31-70%)	Serious - moderate	High (continuing)
9.1 - Domestic & urban waste water	Restricted (11-30%)	Moderate or 11-30% pop. decline	High (continuing)
9.2 - Industrial & military effluents	Large - restricted	Serious - moderate	High (continuing)
9.3 - Agricultural & forestry effluents	Large - restricted	Serious - moderate	High (continuing)
11 - Climate change & severe weather	Large (31-70%)	Moderate or 11-30% pop. decline	High (continuing)
11.1 - Habitat shifting & alteration	Large (31-70%)	Moderate or 11-30% pop. decline	High (continuing)

Roadless Areas (3)

Georgia (3)

Area	Forest	Acres
Foster Branch	Chattahoochee National Forest	171
Ken Mountain	Chattahoochee National Forest	527
Pink Knob	Chattahoochee National Forest	12,127

References (31)

Campbell, David (University of Alabama). 2004. Personal communication with Jay Cordeiro (NatureServe) about the distribution of freshwater mussels in Georgia and Alabama in February 2004.
Campbell, D.C., P.D. Johnson, J.D. Williams, A.K. Rindsberg, J.M. Serb, K.K. Small, and C. Lydeard. 2008. DNA barcoding: Identificatio of 'extinct' freshwater mussel species using DNA barcoging. Molecular Ecology Resources, 8: 711-724.
Freshwater Mollusk Conservation Society (FMCS). 2023. The 2023 checklist of freshwater bivalves (Mollusca: Bivalvia: Unionida) of the United States and Canada. Considered and approved by the Bivalve Names Subcommittee October 2023. Online: https://molluskconservation.org/MServices_Names-Bivalves.html
Graf, D.L. and K.S. Cummings. 2021. A 'big data' approach to global freshwater mussel diversity (Bivalvia: Unionoida), with an updated checklist of genera and species. Journal of Molluscan Studies 87(1):1-36.
Howard, A. D. 1915. Some exceptional cases of breeding among the Unionidae. The Nautilus 29:4-11.
Johnson, P.D., C. St. Aubin, and S.A. Ahlstedt. 2005. Freshwater mussel survey results for the Cherokee and Chattahoochee districts of the United States Forest Service in Tennessee and Georgia. Report to the U.S. Fish and Wildlife Service, Daphne, Alabama. 32 pp.
Lefevre, G. and W. T. Curtis. 1912. Studies on the reproduction and artificial propagation of fresh-water mussels. Bulletin of the Bureau of Fisheries 30:102-201.
Mirarchi, R.E., et al. 2004a. Alabama Wildlife. Volume One: A Checklist of Vertebrates and Selected Invertebrates: Aquatic Mollusks, Fishes, Amphibians, Reptiles, Birds, and Mammals. University of Alabama Press: Tuscaloosa, Alabama. 209 pp.
Mirarchi, R.E., J.T. Garner, M.F. Mettee, and P.E. O'Neil. 2004b. Alabama wildlife. Volume 2. Imperiled aquatic mollusks and fishes. University of Alabama Press, Tuscaloosa, Alabama. xii + 255 pp.
MolluscaBase eds. 2024. MolluscaBase. Accessed at https://www.molluscabase.org
Moyle, P., and J. Bacon. 1969. Distribution and abundance of molluscs in a fresh water environment. Journal of the Minnesota Academy of Science 35(2/3):82-85.
Parmalee, P.W. and A.E. Bogan. 1998. The Freshwater Mussels of Tennessee. University of Tennessee Press: Knoxville, Tennessee. 328 pp.
Strayer, D. 1983. The effects of surface geology and stream size on freshwater mussel (Bivalvia, Unionidae) distribution in southeastern Michigan, U.S.A. Freshwater Biology 13:253-264.
Strayer, D. L. 1999. Use of flow refuges by unionid mussels in rivers. Journal of the North American Benthological Society 18(4):468-476.
Strayer, D. L., and J. Ralley. 1993. Microhabitat use by an assemblage of stream-dwelling unionaceans (Bivalvia) including two rare species of Alasmidonta. Journal of the North American Benthological Society 12(3):247-258.
Turgeon, D. D., J. F. Quinn, Jr., A. E. Bogan, E. V. Coan, F. G. Hochberg, W. G. Lyons, P. M. Mikkelsen, R. J. Neves, C. F. E. Roper, G. Rosenberg, B. Roth, A. Scheltema, F. G. Thompson, M. Vecchione, and J. D. Williams. 1998. Common and scientific names of aquatic invertebrates from the United States and Canada: Mollusks. 2nd Edition. American Fisheries Society Special Publication 26, Bethesda, Maryland. 526 pp.
United States Fish and Wildlife Service (USFWS). 2019. Recovery Plan Amendment for the endangered Georgia pigtoe (Pleurobema hanleyianum). Atlanta, Georgia. 7 pp.
U.S. Fish and Wildlife Service (USFWS). 1999. Candidate and listing priority assignment forms.
U.S. Fish and Wildlife Service (USFWS). 2003. Candidate assessment and listing priority assignment form- Pleurobema chattanoogaense, Pleurobema hanleyanum, Pleurobema troshelianum. U.S. Fish and Wildlife Service, Jacksonville, Mississippi. 8 pp.
U.S. Fish and Wildlife Service (USFWS). 2004. Endangered and Threatened Widlife and plants; designation of critical habitat for three threatened mussels and eight endangered mussels in the Mobile River basin; final rule. Federal Register, 69(126): 40083-40171.
U.S. Fish and Wildlife Service (USFWS). 2009. Endangered and threatened wildlife and plants; proposed endangered status for the Georgia pigtoe mussel, interrupted rocksnail, and rough hornsnail with Critical Habitat. Federal Register 74(123):31114-31151.
U.S. Fish and Wildlife Service (USFWS). 2010. Endangered and threatened wildlife and plants; determination of endangered status for the Georgia pigtoe mussel, interrupted rocksnail, and rough hornsnail and designation of critical habitat. Federal Register 75(211):67512-67550.
U.S. Fish and Wildlife Service (USFWS). 2014. Recovery Plan for the Georgia pigtoe mussel, Interrupted rocksnail, and Rough hornsnail. Atlanta, Georgia. 55 pp.
U.S. Fish and Wildlife Service (USFWS). 2021. Georgia pigtoe (Pleurobema hanleyianum), 5-year review: summary and evaluation. U.S. Fish and Wildlife Service, Alabama Ecological Services Field Office, Daphne, Alabama. 24 pp.
Van der Schalie, H. 1938. The naiad fauna of the Huron River in southeastern Michigan. Miscellaneous Publication of the Museum of Zoology, University of Michigan 40:7-78.
Vaughn, C.C. 2018. Ecosystem services provided by freshwater mussels. Hydrobiologia, 810: 15-27.
Watters, G. T. 1992. Unionids, fishes, and the species-area curve. Journal of Biogeography 19:481-490.
Williams, J.D., A.E. Bogan, and J.T. Garner. 2008. Freshwater Mussels of Alabama & the Mobile Basin in Georgia, Mississippi & Tennessee. University of Alabama Press: Tuscaloosa, Alabama. 908 pp.
Williams, J. D., A. E. Bogan, R. S. Butler, K. S. Cummings, J. T. Garner, J. L. Harris, N. A. Johnson, and G. T. Watters. 2017. A revised list of the freshwater mussels (Mollusca: Bivalvia: Unionida) of the United States and Canada. Freshwater Mollusk Biology and Conservation 20:33-58.
Williams, J.D. and M.H. Hughes. 1998. Freshwater mussels of selected reaches of the main channel rivers in the Coosa drainage of Georgia. U.S. Geological report to U.S. Army Corps of Engineers, Mobile District, Alabama. 21 pp.
Williams, J. D., M. L. Warren, Jr., K. S. Cummings, J. L. Harris, and R. J. Neves. 1993. Conservation status of freshwater mussels of the United States and Canada. Fisheries 18(9):6-22.

Pleurobema hanleyianum

Habitat

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