The Acornshell aka. Acorn Pearly Mussel was described in 1834; this species inhabited the drainages of the Cumberland- and the Tennessee Rivers in Alabama, Kentucky, Tennessee and Virginia, USA.

The species died out due to habitat destruction and pollution; the last known individuals died in the 1970s due to exposure to domestic sewage.

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Photo from: ‘Paolo G. Albano; Barbara Bongiovanni; Pamela D’Occhio; Bruno Sabelli: Natural history museums as repositories of endangered diversity: the case of the United States Unionida in the Museo di Zoologia dell’Università di Bologna. Zoosystematics and Evolution 90(2): 105-111. 2014’

https://creativecommons.org/licenses/by/4.0/

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edited: 17.08.2022