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Home/Species/ Cumberlandian Combshell

Epioblasma brevidens

(I. Lea, 1831)

Cumberlandian Combshell

G1Critically Imperiled Found in 1 roadless area NatureServe Explorer →
G1Critically ImperiledGlobal Rank
Critically endangeredIUCN
Very highThreat Impact
Cumberlandian combshell (Epioblasma brevidens). Photo by U.S. Fish & Wildlife Service, Public Domain (U.S. Government Work), via ECOS.
U.S. Fish & Wildlife Service, https://www.usa.gov/government-works
Identity
Unique IDELEMENT_GLOBAL.2.115217
Element CodeIMBIV16030
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryInvertebrate Animal
IUCNCritically endangered
Endemicendemic to a single nation
KingdomAnimalia
PhylumMollusca
ClassBivalvia
OrderUnionoida
FamilyUnionidae
GenusEpioblasma
Synonyms
Dysnomia brevidens(I. Lea, 1831)Plagiola brevidens(I. Lea, 1831)
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
This species has been synonymized mistakenly under Obliquaria (Plagiola) interrupta Rafinesque, 1820, by Johnson (1978).
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2023-12-05
Change Date2003-10-28
Edition Date2023-12-04
Edition AuthorsCordeiro, J. (2009); rev. T. Cornelisse (2023)
Threat ImpactVery high
Range Extent5000-200,000 square km (about 2000-80,000 square miles)
Number of Occurrences1 - 20
Rank Reasons
This species has a moderate range but due to long-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 Cumberland River system in Pulaski and McCreary Counties, Kentucky and in Scott County, Tennessee and in the Tennessee River system in Scott and Lee Counties, Virginia, Claiborne and Hancock County, Tennessee, Colbert County, Alabama, and Tishimingo County, Mississippi (USFWS 2004; 2019; GBIF 2023).
Occurrences Comments
This species is known from five stream reaches in 8-11 populations as well as four populations from reintroduction efforts (USFWS 2004; 2019).
Threat Impact Comments
This species is threatened by oil and gas exploration, coal mining, and the heavy metal and chemical pollutants that result from those activities, development, as well as sedimentation due to runoff from development and agriculture, dams or other barriers that alter its habitat, host fish distribution, and prevent habitat connectivity and recolonization, and drought conditions that reduce habitat, elevate water temperature, and reduce dilution of pollutants and sediment runoff (USFWS 2004; 2019).
Ecology & Habitat

Description

Shell subquadangular (female) to subhomboid (male), solid, increasingly inflated with age; anterior end regularly rounded; ventral margin slightly curved; dorsal margins straight (male) to broadly curved (female); beaks elevated, wide, flattened, sculptured with feebly double-looped bars; posterior ridge well-developed, narrowly rounded; posterio-ventral area of female inflated and dilated to accommodate the expanded marsupia, separated from the rest of the shell by anterior and posterior sulci, margin of expansion may be semicircular or sulcate, growth lines in this area serrate, shell margin dentate; periostracum smooth to cloth-like, yellow to tawny brown with narrow green broken rays, rays may be quite numerous and often punctate particularly posteriorly. Two ragged triangular pseudocardinal teeth in left valve, single in right; interdentum short; lateral teeth heavy, short, tend to be curved, double in left valve, single in right; beak cavity shallow; anterior muscle scars confluent, small, deeply impressed; pallial line distinct; nacre white.

Diagnostic Characteristics

The broad, yellowish shell with broken rays and the distinctive marsupial expansion of the female distinguish this species from most other mussels in its range except Ptychobranchus fasciolaris and Epioblasma lenior (Lea, 1842). Male Epioblasma brevidens are broader than P. fasciolarisand females of the latter species do not exhibit the marsupial development of the former. Raying patterns on P. fasciolaris usually are not as developed. E. lenior is a considerably smaller species, has a much lighter shell, tends to be greenish, does not have as developed a marsupial expansion, and is probably extinct.

Habitat

This species is found in medium-sized streams to large rivers on shoals and riffles in coarse sand, gravel, cobble, and boulders (USFWS 2003; 2004).

Reproduction

Glochidia become juvenile mussels after 16 - 45 days of encystment of these fish (Yeager 1986).
Other Nations (1)
United StatesN1
ProvinceRankNative
VirginiaS1Yes
TennesseeS1Yes
KentuckyS1Yes
MississippiS1Yes
AlabamaS1Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentLarge (31-70%)Serious - moderateHigh (continuing)
1.1 - Housing & urban areasLarge (31-70%)Serious - moderateHigh (continuing)
3 - Energy production & miningRestricted (11-30%)Serious or 31-70% pop. declineHigh (continuing)
3.2 - Mining & quarryingRestricted (11-30%)Serious or 31-70% pop. declineHigh (continuing)
7 - Natural system modificationsLarge (31-70%)Serious or 31-70% pop. declineHigh (continuing)
7.2 - Dams & water management/useLarge (31-70%)Serious or 31-70% pop. declineHigh (continuing)
9 - PollutionPervasive - largeSerious or 31-70% pop. declineHigh (continuing)
9.2 - Industrial & military effluentsLarge (31-70%)Serious or 31-70% pop. declineHigh (continuing)
9.3 - Agricultural & forestry effluentsLarge (31-70%)Serious or 31-70% pop. declineHigh (continuing)
9.3.2 - Soil erosion, sedimentationLarge (31-70%)Serious or 31-70% pop. declineHigh (continuing)
11 - Climate change & severe weatherRestricted (11-30%)Serious or 31-70% pop. declineHigh (continuing)
11.2 - DroughtsRestricted (11-30%)Serious or 31-70% pop. declineHigh (continuing)

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Roadless Areas (1)
Idaho (1)
AreaForestAcres
Bear CreekCaribou-Targhee National Forest118,582
References (50)
  1. Ahlstedt, S.A. and J.M. Tuberville. 1997. Quantitative reassessment of the freshwater mussel fauna in the Clinch and Powell rivers, Tennessee and Virginia. Pages 72-97 in K.S. Cummings, A.C. Buchanan, C.A. Mayer, and T.J. Naimo, eds. Conservation and management of freshwater mussels II: initiatives for the future. Proceedings of a UMRCC symposium, 16-18 October 1995, St. Louis, Missouri. Upper Mississippi River Conservation Committee, Rock Island, Illinois.
  2. Anthony, J.L. and J.A. Downing. 2001. Exploitation trajectory of a declining fauna: a century of freshwater mussel fisheries in North America. Canadian Journal of Fisheries and Aquatic Sciences, 58: 2071-2090.
  3. Baker, F.C. 1928b. The freshwater Mollusca of Wisconsin: Part II. Pelecypoda. Bulletin of the Wisconsin Geological and Natural History Survey, University of Wisconsin, 70(2): 1-495.
  4. Barr, W.C., S.A. Ahlstedt, G.D. Hickman, and D.M. Hill. 1993-1994. Cumberlandian mollusk conservation program. Activity 8: Analysis of macrofauna factors. Walkerana 7(17/18):159-224.
  5. Biological Resources Division, USGS. 1997. Database of museum records of aquatic species. Compiled by J. Williams (USGS-BRD, Gainesville, FL).
  6. 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.
  7. Cicerello, Ronald R. (Kentucky State Nature Preserves). 1997b. Review and annotation of mussel watershed distribution maps. Review requested by Ruth Mathews, TNC. September 1997.
  8. 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
  9. Global Biodiversity Information Facility (GBIF). 2023. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2023).
  10. Gordon, M.E. and J.B. Layzer. 1989. Mussels (Bivalvia: Unionoidea) of the Cumberland River review of life histories and ecological relationships. U.S. Fish and Wildlife Service Biological Report, 89(15): 1-99.
  11. 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.
  12. Hanlon, S.D., M.A. Petty, and R.J. Neves. 2009. Status of native freshwater mussels in Copper Creek, Virginia. Southeastern Naturalist 8(1):1-18.
  13. Hill, D.M. 1986. Cumberlandian mollusk conservation program, activity 3: identification of fish hosts. Office of Natural Resources and Economic Development, Tennessee Valley Authority, Knoxville, Tennessee. 55 pp.
  14. Howard, A. D. 1915. Some exceptional cases of breeding among the Unionidae. The Nautilus 29:4-11.
  15. Hubbs, D. 2002. Monitoring and management of endangered mussels. 2001-02 Annual Report Project 7365, Tennessee Wildlife Resources Agency, Nashville, Tennessee. 3 pp.
  16. Isom, B.G., P. Yokley, Jr., and C.H. Gooch. 1973. Mussels of Elk River Basin in Alabama and Tennessee- 1965-1967. American Midland Naturalist 89(2):437-442.
  17. James, M.R. 1987. Ecology of the freshwater mussel <i>Hyridella menziesi</i> in a small oliogotrophic lake. Archives of Hydrobiology 108:337-348.
  18. Jenkinson, J.J. and S.A. Ahlsedt. 1988a. Quantitative reassessment of the freshwater mussel fauna in the Clinch River, Tennessee and Virginia. Tennessee Valley Authority, Knoxville, Tennessee. 28 pp.
  19. Jenkinson, J.J. and S.A. Ahlstedt. 1988b. Quantitative reassessment of the freshwater mussel fauna in the Powell River, TN and VA. Tennessee Valley Authority, Knoxville, Tennessee. 28 pp.
  20. Johnson, R.I. 1978. Systematics and zoogeography of <i>Plagiola </i>(= <i>Dysnomia </i>= <i>Epioblasma</i>), an almost extinct genus of freshwater mussels (Bivalvia: Unionidae) from middle North America. Bulletin of the Museum of Comparative Zoology, 148(6): 239-320.
  21. Johnson, R.I. and H.B. Baker. 1973. Types of Unionacea (Mollusca:Bivalvia) in the Academy of Natural Sciences of Philadelphia. Proceedings of the Academy of Natural Sciences of Philadelphia, 125: 146-186.
  22. Jones, R.L., W.T. Slack, and P.D. Hartfield. 2005. The freshwater mussels (Mollusca: Bivalvia: Unionidae) of Mississippi. Southeastern Naturalist, 4(1): 77-92.
  23. 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.
  24. Lopez, G.R. and I.J. Holopainen. 1987. Interstitial suspension-feeding by <i>Pisidium </i>spp. (Pisidiiae: Bivalvia): a new guild in lentic benthos? American Malacological Bulletin, 5: 21-29.
  25. Major, Smoot (Tennessee Division of Natural Heritage). 1997. Review and annotation of fish and mussel watershed distribution maps. Review requested by Ruth Mathews, TNC on 19 August 1997.
  26. McGregor, S.W. and J.T. Garner. 2004. Changes in the freshwater mussel (Bivalvia: Unionidae) fauna of the Bear Creek system of northwest Alabama and northeast Mississippi. American Malacological Bulletin, 18(1/2): 61-70.
  27. 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.
  28. MolluscaBase eds. 2024. MolluscaBase. Accessed at https://www.molluscabase.org
  29. 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.
  30. Parmalee, P.W. and A.E. Bogan. 1998. The Freshwater Mussels of Tennessee. University of Tennessee Press: Knoxville, Tennessee. 328 pp.
  31. 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.
  32. Strayer, D. L. 1999. Use of flow refuges by unionid mussels in rivers. Journal of the North American Benthological Society 18(4):468-476.
  33. Strayer, D. L., and J. Ralley. 1993. Microhabitat use by an assemblage of stream-dwelling unionaceans (Bivalvia) including two rare species of <i>Alasmidonta</i>. Journal of the North American Benthological Society 12(3):247-258.
  34. 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.
  35. U.S. Fish and Wildlife Service (USFWS). 1997. Determination of Endangered Status for the Cumberland Elktoe, Oyster Mussel, Cumberlandian Combshell, Purple Bean, and Rough Rabbitsfoot. Final rule. Federal Register, 62(7): 1647-1658.
  36. U.S. Fish and Wildlife Service (USFWS). 1998. Cumberland elktoe (<i>Alasmidontaq atropurpurea</i>), oyster mussel (<i>Epioblasma capsaeformis</i>), Cumberlandian combshell (<i>Epioblasma brevidens</i>), purple bean (<i>Villosa perpurpurea</i>), and rough rabbitsfoot (<i>Quadrula cylindrica strigillata</i>): Technical Draft Recovery Plan. U.S. Fish and Wildlife Service: Asheville, North Carolina. 119 pp.
  37. U.S. Fish and Wildlife Service (USFWS). 2001. Endangered and Threatened Wildlife and Plants; establishment of nonessential experimental population status for 16 freshwater mussels and 1 freshwater snail (Anthony's Riversnail) in the free-flowing reach of the Tennessee River below the Wilson Dam, Colbert and Lauderdale Counties, Alabama. Federal Register, 66(115): 32250-32264.
  38. U.S. Fish and Wildlife Service (USFWS). 2003. Endangered and Threatened Widlife and plants; proposed designation of critical habitat for five threatened mussels in the Tennessee and Cumberland River basins; proposed rule. Federal Register, 68(106): 33234-33282
  39. U.S. Fish and Wildlife Service (USFWS). 2004a. Recovery plan for Cumberland elktoe, oyster mussel, Cumberlandian combshell, purple bean, and rough rabbitsfoot. U.S. Fish and Wildlife Service, Atlanta, Georgia. 168 pp.
  40. U.S. Fish and Wildlife Service (USFWS). 2004b. Endangered and Threatened wildlife and plants; designation of critical habitat for five endangered mussels in the Tennessee and Cumberland River basins; final rule. Federal Register 69(168): 53135-53180.
  41. U.S. Fish and Wildlife Service (USFWS). 2006. Endangered and threatened wildlife and plants; establishment of nonessential experimental population status for 15 freshwater mussels, 1 freshwater snail, and 5 fishes in the lower French Broad River and in the lower Holston River, Tennessee; Proposed Rule. Federal Register, 71(113): 34195-34230.
  42. U.S. Fish and Wildlife Service (USFWS). 2007. Cumberlandian Combshell <i>Epioblasma brevidens</i>, five year review: summary and evaluation. U.S. Fish and Wildlife Service Southeast Region Tennessee Ecological Services Field Office Cookeville, Tennessee. 31 pp.
  43. U.S. Fish and Wildlife Service (USFWS). 2019. Cumberlandian Combshell <i>Epioblasma brevidens</i>, five year review: summary and evaluation. U.S. Fish and Wildlife Service Southeast Region Tennessee Ecological Services Field Office Cookeville, Tennessee. 31 pp.
  44. 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.
  45. Watters, G. T. 1992. Unionids, fishes, and the species-area curve. Journal of Biogeography 19:481-490.
  46. Wells, S.M., R.M. Pyle, and N.M. Collins. 1983. The IUCN Invertebrate Red Data Book. IUCN, Gland, Switzerland. 632 pp.
  47. 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.
  48. 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.
  49. 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.
  50. Yeager, B.L. and C.F. Saylor. 1995. Fish hosts for four species of freshwater mussels (Pelecypoda: Unionidae) in the Upper Tennessee River drainage. American Midland Naturalist, 133(1): 1-6.