|Scientific Name:||Elliptio crassidens|
|Species Authority:||Lamarck, 1819|
|Taxonomic Notes:||Clench and Turner (1956) considered E. crassidens incrassatus (Lea, 1840) to be distinct from E. crassidens crassidens. All subsequent authors have synonomyzed incrassatus with crassidens.
A list of synonyms for this species can be found on The MUSSEL project web site (Graf and Cummings 2011).
|Red List Category & Criteria:||Least Concern ver 3.1|
|Reviewer/s:||Böhm, M. & Collen, B.|
|Contributor/s:||Dyer, E., Soulsby, A.-M., Whitton, F., McGuinness, S., De Silva, R., Milligan, H.T., Kasthala, G., Thorley, J., Herdson, R., McMillan, K. & Collins, A.|
Elliptio crassidens has been assessed as Least Concern due to its large distribution and absence of any major threat process. Further research and monitoring of Elliptio crassidens should be undertaken as it is possible that localised threats will continue to become more widespread in the future, causing significant declines in the global population of this species.
|Range Description:||In the United States, this species is wide-ranging in the Midwest, eastern and some southern states with its southeastern distribution ending in the Escambia and Apalachicola River drainages in the Florida panhandle (Parmalee and Bogan 1998). This species occurs in Alabama, Florida, Georgia, Illinois, Indiana, Kentucky, Louisiana, Minnesota, Mississippi, Missouri, Ohio, Tennessee, Virginia, West Virginia and Wisconsin. It is presumed extirpated in Oklahoma and is possibly also extirpated in Pennsylvania and Iowa (NatureServe 2009). In Canada, this species is known from Quebec and Ontario (NatureServe 2009).|
Native:Canada (Ontario, Québec); United States (Alabama, Florida, Georgia, Illinois, Indiana, Iowa - Possibly Extinct, Kentucky, Louisiana, Minnesota, Mississippi, Missouri, Ohio, Oklahoma - Possibly Extinct, Pennsylvania - Possibly Extinct, Tennessee, Virginia, West Virginia, Wisconsin)
|Range Map:||Click here to open the map viewer and explore range.|
This species is considered stable in the Apalachicola/Chattahoochee/Flint River Basin (ACF basin) (Brim Box and Williams 2000) and southern portions of its range. The species is widespread but relatively rare in the Midwest; locally abundant in some parts of the Ohio and White rivers of Illinois and Indiana; endangered in Missouri, Ohio, and Wisconsin; and threatened in Illinois and Minnesota (Cummings and Mayer 1992). Locally this species has been extirpated from the Minnesota River and likely the Mississippi River in Minnesota (Sietman 2003) as well as parts of northern Illinois.
The most recent AFS mussel evaluation (Williams et al. in press) will list this species as Vulnerable, changed from currently stable (K.Cummings pers. comm. 2011). Abundance estimates for Canadian populations are not known.
|Habitat and Ecology:||
This species inhabits muddy sand, sand, and rocky substrates in moderate currents, and is also an inhabitant of channels (Heard 1979). When surveying the ACF Basin, Brim Box and Williams (2000) found the species to be most common in large creeks to rivers with moderate to swift currents primarily on sand and limestone or rock substrates.
The primary host fish for this species is the Skipjack Herring (Alosa chrysochloris) (Missouri Department of Conservation 2000).
|Major Threat(s):||This species is threatened on a local scale by siltation, mining, headcutting, damming and agriculture run-off (Bogan 1993, Brim Box and Mossa 1999, NatureServe 2009), but these factors are not considered a major threat to the species over its entire range. This species has been found to be intolerant to drought conditions (Golladay et al. 2002).|
This species has been given a NatureServe Global Heritage Status Rank of G5 - secure (NatureServe 2009), and was assigned an American Fisheries Society Status of Currently Stable (NatureServe 2009). On a global scale, it is unknown whether any occurrences of this species are appropriately protected and managed (NatureServe 2009). In places the species' distribution coincides with protected areas, and there are many local and state action plans in place.
Further research and monitoring of Elliptio crassidens should be undertaken due to the recent AFS mussel evaluation (Williams et al. in press) elevating the threat status to Vulnerable. Localised threats and further population declines must be monitored in order to elevate this species' threat category in the future.
Bogan, A.E. 1993. Freshwater Bivalve Extinctions (Mollusca: Unionoida): A Search for Causes. American Zoologist 33(6): 599-609.
Brim Box, J. and Mossa, J. 1999. Sediment, Land Use, and Freshwater Mussels: Prospects and Problems. Journal of the North American Benthological Society 18(1): 99-117.
Brim Box, J. and Williams, J.D. 2000. Unionid mollusks of the Apalachicola Basin in Alabama, Florida, and Georgia. Alabama Museum of Natural History Bulletin 21: 1-143.
Clench, W.J. and Turner, R.D. 1956. Freshwater mollusks of Alabama, Georgia, and Florida from the Escambia to the Suwanee River. Bulletin of the Florida State Museum Biological Sciences 1(3): 97-239.
Cummings, K.S. and Mayer, C.A. 1992. Field guide to freshwater mussels of the Midwest. Illinois Natural History Survey Manual 5, Illinois.
Golladay, S.W., Gagnon, P., Kearns, M., Battle, J.M. and Hicks, D.W. 2002. Changes in Mussel Assemblage Composition in the Lower Flint River Basin from 1999 to 2001: An Assessment of the Impacts of 2000 Drought. Project Report 50. Georgia Department of Natural Resources Environmental Protection Division Georgia Geologic Survey, Atlanta.
Graf, D.L. and Cummings, K.S. 2007. Review of the systematics and global diversity of freshwater mussel species (Bivalvia: Unionoida). Journal of Molluscan Studies 73: 291-314.
Graf, D.L. and Cummings, K.S. 2011. The MUSSEL Project Database: MUSSELp. Available at: www.mussel-project.net. (Accessed: 18/08/2011).
Heard, W.H. 1979. Identification Manual of the Freshwater Clams of Florida. State of Florida Department of Environmental Regulation.
IUCN. 2011. IUCN Red List of Threatened Species (ver. 2011.2). Available at: http://www.iucnredlist.org. (Accessed: 10 November 2011).
Johnson, R.I. 1970. The systematics and zoogeography of the Unionidae (Mollusca: Bivalvia) of the southern Atlantic slope region. Bulletin of the Museum of Comparative Zoology, Harvard University 140(6): 263-449.
Missouri Department of Conservation. 2000. Elephant-ear Mussel - Elliptio crassidens. Best Management Practices. Missouri Department of Conservation, Missouri.
NatureServe. 2009. NatureServe Explore: An online encyclopaedia of life [web application]. Version 7.1. Arlington, Virginia Available at: http://www.natureserve.org/explorer/.
Parmalee P.W. and Bogan A.E. 1998. The Freshwater Mussels of Tennessee. University of Tennessee Press, Knoxville Tennessee.
Sietman, B.E. 2003. Field guide to the freshwater mussels of Minnesota. Minnesota Department of Natural Resources, St. Paul, Minnesota.
Williams, J.D., Warren, M.L.Jr., Cummings, K.S., Harris, J.L. and Neves, R.J. in press. Conservation status of freshwater mussels of North America and Mexico.
|Citation:||Cummings, K. 2011. Elliptio crassidens. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 19 April 2014.|
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