Epioblasma haysiana (I. Lea, 1834)
Acorn pearly mussel, Acornshell
Taxonomy & Nomenclature
Synonyms: Unio haysianus I. Lea, 1834 (basionym); Dysnomia (Penita) haysiana (I. Lea, 1834); Dysnomia (Scalenilla) haysiana (I. Lea, 1834); Dysnomia haysiana (I. Lea, 1834); Margarita (Unio) haysianus (I. Lea, 1834); Margarita (Unio) sowerbianus (I. Lea, 1834); Margaron (Unio) haysianus (I. Lea, 1834); Margaron (Unio) sowerbianus (I. Lea, 1834); Plagiola (Pilea) haysiana (I. Lea, 1834); Plagiola haysiana (I. Lea, 1834); Truncilla (Scalenaria) haysiana (I. Lea, 1834); Truncilla (Scalenilla) haysiana (I. Lea, 1834); Truncilla haysiana (I. Lea, 1834); Unio sowerbianus I. Lea, 1834
See Graf & Cummings (2025) for a more complete taxonomic history.
Conservation Status
Extinct (Stansberry, 1976; Bogan, 2000b; NatureServe, 2014, 2025; Graf & Cummings, 2021, 2025)
Last record: mid-to late 1800s (Alabama) (Williams et al., 2008); 1970's (Cumberland and Tennessee Rivers) (NatureServe, 2014, 2025)
IUCN RedList status: Extinct
The last known population of the Acorn pearly mussel (Epioblasma haysiana) is believed to have been driven extinct by sewage waste contamination of its habitat (Bogan, 2000b; NatureServe, 2011).
Distribution & Habitat
Alabama, Kentucky, Tennessee and Virginia, USA
Biology & Ecology
Hypodigm
8 specimens are in the Illinois Natural History Survey mollusc collection:
INHS 1555
INHS 20279
INHS 20280
INHS 20281
INHS 20282
INHS 20283
INHS 20284
INHS 20285
Media
References
Original scientific description:
Lea, I. (1834). Observations on the naïades; and descriptions of new species of that, and other families. Transactions of the American Philosophical Society. (NS) 5: 23-119, pls 1-19. [August or September 1834]
Other references:
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Bogan, Arthur E. (1993). Freshwater bivalve extinctions (Mollusca: Unionoida): A search for causes. American Zoologist 33(6): 599-609. https://doi.org/10.1093/icb/33.6.599
Bogan, Arthur E. (2000a). Epioblasma haysiana. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. (http://www.iucnredlist.org). Downloaded on 22 April 2012.
Bogan, Arthur E. (Mollusc Specialist Group). (2000b). Epioblasma haysiana. The IUCN Red List of Threatened Species 2000: e.T7872A12859991. https://dx.doi.org/10.2305/IUCN.UK.2000.RLTS.T7872A12859991.en. Accessed on 01 July 2022.
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http://naturalsciences.org/sites/default/files/files/documents/research-collections/Bogan_TN_Endangered_Mollusks.pdf
https://extinctanimals.proboards.com/thread/10362/epioblasma-haysiana-acorn-pearly-mussel
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