Pleurobema georgianum
(I. Lea, 1841)
Southern Pigtoe
G1Critically ImperiledGlobal Rank
Critically endangeredIUCN
Very high - highThreat Impact
U.S. Fish & Wildlife Service, https://www.usa.gov/government-works
Identity
Unique IDELEMENT_GLOBAL.2.827840
Element CodeIMBIV35140
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryInvertebrate Animal
IUCNCritically endangered
Endemicendemic to a single nation
KingdomAnimalia
PhylumMollusca
ClassBivalvia
OrderUnionoida
FamilyUnionidae
GenusPleurobema
Synonyms
Pleurobema troschelianum(I. Lea, 1852)
Concept Reference
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.
Taxonomic Comments
It is difficult to differentiate this species from Pleurobema troschelianum and Pleurobema hanleyianum in the field due to similar shell characteristics (Parmalee and Bogan, 1998).
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2023-12-29
Change Date2023-12-29
Edition Date2023-12-29
Edition AuthorsCordeiro, J. (2009); rev. T. Cornelisse (2023)
Threat ImpactVery high - high
Range Extent5000-20,000 square km (about 2000-8000 square miles)
Number of Occurrences6 - 20
Rank Reasons
This species has a limited range and, due to long and short-term population declines and many ongoing threats, it has few viable occurrences.
Range Extent Comments
This species is found in the Coosa River drainage of the Mobile Basin in Alabama, Georgia, and Tennessee (Williams et al. 2008; USFWS 2019; GBIF 2023).
Occurrences Comments
This species is known from 12 occurrences in 9 Coosa River tributaries using a 2 km separation distance and records from 2000-2023 (USFWS 2019; GBIF 2023).
Threat Impact Comments
This species is threatened by sedimentation, nutrient, and chemical pollution from land conversion activities, including agriculture, oil and gas operations, and coal mining, dams and water diversions that change hydrological conditions, host fish distribution, and prevent habitat connectivity and recolonization, and habitat alteration due to climate change, including increased water temperatures and drought (USFWS 2008, 2019).
Ecology & Habitat
Description
The shell is elliptical to oval in outline and somewhat compressed. The posterior slope is smoothly rounded. The pseudocardinal teeth are small but well-developed, and the nacre is white. The periostracum is yellow to yellow-brownh. Growth lines are numerous and may be dark brown. Small specimens may have green spots at the growth lines along the posterior ridge and near the umbo (FWS, 2003).
Habitat
This species is found in riffles, runs, and shoals of medium creeks to large rivers in gravel and sand substrates (Williams et al. 2008; USFWS 2019).
Reproduction
This species is a short-term brooder and females are gravid during spring and early summer (USFWS 2019).
Other Nations (1)
United StatesN1
| Province | Rank | Native |
|---|---|---|
| Alabama | S1 | Yes |
| Georgia | S1 | Yes |
| Tennessee | S1 | Yes |
Threat Assessments
| Threat | Scope | Severity | Timing |
|---|---|---|---|
| 3 - Energy production & mining | Large - restricted | Serious - moderate | — |
| 3.2 - Mining & quarrying | Large - restricted | Serious - moderate | — |
| 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 - restricted | Serious - moderate | High (continuing) |
| 9.3 - Agricultural & forestry effluents | Large - restricted | Serious - moderate | High (continuing) |
| 9.3.2 - Soil erosion, sedimentation | Large - restricted | Serious - moderate | High (continuing) |
| 11 - Climate change & severe weather | Large - restricted | Moderate or 11-30% pop. decline | High (continuing) |
| 11.1 - Habitat shifting & alteration | Large - restricted | Moderate or 11-30% pop. decline | High (continuing) |
Roadless Areas (7)
Alabama (4)
| Area | Forest | Acres |
|---|---|---|
| Blue Mountain | Talladega National Forest | 4,986 |
| Cheaha A | Talladega National Forest | 236 |
| Cheaha B | Talladega National Forest | 741 |
| Oakey Mountain | Talladega National Forest | 6,129 |
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 (25)
- Biological Resources Division, USGS. 1997. Database of museum records of aquatic species. Compiled by J. Williams (USGS-BRD, Gainesville, FL).
- Bogan, Art (Curator of Aquatic Invertebrates, North Carolina State Museum of Natural Sciences). 1997. Review and annotation of mussel watershed distribution maps for TN. Review requested by Ruth Mathews, TNC. September 1997.
- 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.
- 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.
- 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
- Parmalee, P.W. and A.E. Bogan. 1998. The Freshwater Mussels of Tennessee. University of Tennessee Press: Knoxville, Tennessee. 328 pp.
- 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. Southern Pigtoe Recovery Plan Amendment. Atlanta, Georgia. 11 pp.<br/>
- U.S. Fish and Wildlife Service (USFWS). 1993. Endangered status for eight freshwater mussels and threatened status for three freshwater mussels in the Mobil River drainage. Final rule. Federal Register, 58(60): 14330-14340.
- U.S. Fish and Wildlife Service (USFWS). 1997. Draft Recovery Plan for the Mobile River basin aquatic ecosystem. U.S. Fish and Wildlife Service, Southeast Region, Atlanta, Georgia.
- U.S. Fish and Wildlife Service (USFWS). 2000. Recovery plan for the Mobile River basin aquatic ecosystem. U.S. Fish and Wildlife Service, Southeast Region, Atlanta, Georgia. 128 pp.
- U.S. Fish and Wildlife Service (USFWS). 2003. Candidate assessment and listing priority assignment form- <i>Pleurobema chattanoogaense</i>, <i>Pleurobema hanleyanum</i>, <i>Pleurobema troshelianum</i>. U.S. Fish and Wildlife Service, Jacksonville, Mississippi. 8 pp.
- U.S. Fish and Wildlife Service (USFWS). 2003. Endangered and Threatened Widlife and plants; proposed designation of critical habitat for three threatened mussels and eight endangered mussels in the Mobile River basin; proposed rule. Federal Register, 68(58): 14752-14832.
- 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). 2008. Fine-lined pocketbook (<i>Hamiota </i>(=<i>Lampsilis</i>) <i>altilis</i>), orange-nacre mucket (<i>Hamiota </i>(=<i>Lampsilis</i>) <i>perovalis</i>), Alabama moccasinshell (<i>Medionidus acutissimus</i>) Coosa moccasinshell (<i>Medionidus parvulus</i>), Southern clubshell (<i>Pleurobema decisum</i>), dark pigtoe (<i>Pleurobema furvum</i>), southern pigtoe (<i>Pleurobema georgianum</i>), ovate clubshell (<i>Pleurobema perovatum</i>), triangular kidneyshell (<i>Ptychobranchus greenii</i>), upland combshell (<i>Epioblama metastriata</i>), and southern acornshell (<i>Epioblasma othcaloogensis</i>), 5-Year Review: Summary and Evaluation. Jackson, MS. 37pp.
- U.S. Fish and Wildlife Service (USFWS). 2019a. Finelined Pocketbook (<i>Hamiota</i> (=<i>Lampsilis</i>) <i>altilis</i>), Orangenacre Mucket (<i>Hamiota</i> (=<i>Lampsilis</i>) <i>perovalis</i>), Alabama Moccasinshell (<i>Medionidus acutissimus</i>), Coosa Moccasinshell (<i>Medionidus parvulus</i>), Southern Clubshell (<i>Pleurobema decisum</i>), Dark Pigtoe (<i>Pleurobema furvum</i>), Southern Pigtoe (<i>Pleurobema georgianum</i>), Ovate Clubshell (<i>Pleurobema perovatum</i>, Triangulua Clubshell (<i>Pleurobema greenii</i>), 5-year review: summary and evaluation. U.S. Fish and Wildlife Service, South Atlantic-Gulf Region (Region 2), Alabama Ecological Services Field Office, Daphne, Alabama. 69 pp.
- U.S. Fish and Wildlife Service (USFWS). 2023. Initiation of 5-Year Status Reviews for 67 Southeastern Species. Notice of initiation of reviews; <br/>request for information. Federal Register 88(91): 30324-30328.
- Vaughn, C.C. 2018. Ecosystem services provided by freshwater mussels. Hydrobiologia, 810: 15-27.
- Williams, James D. (Research Biologist, USFWS, Gainsville, Florida). 1997a. Review and annotation of mussel watershed distribution maps. Reviews coordinated by Larry Master (TNC) and Christine O'Brien (USGS-BRD).
- 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.