Tag Archives: Unionidae

Epioblasma metastriata (Conrad)

Upland Combshell (Epioblasma metastriata)

The upland scallop lived in shallow areas including the Black Warrior and Cahaba rivers in Alabama and the Coosa River basin in Alabama, Georgia and Tennessee, USA. 

The shell of the species reached a width of up to 6 cm. 

The last living specimen of this species was collected from the Conasauga River in Georgia in 1988.


syn. Dysnomia metastriata Conrad


Depiction from: ‘T. A. Conrad: Monography of the family Unionidae; or Naiades of Lamarck (freshwater bivalve shells) of North America. Philadelphia, J. Dobson 1836’

(public domain)


edited: 29.07.2012

Alasmidonta wrightiana (Walker)

Ochlockonee Arcmussel (Alasmidonta wrightiana)  

The Ochlockonee Arcmussel was scientifically described in the year 1901.  

The species lived exclusively in the Ochlockonee River in Florida, where it occurred obviously at only two places (Specimens, that were found in the Flint River in the Upson County in Georgia, were later identified as Southern Elktoes (Alasmidonta triangulata (Lea)).).  

The habitat of the mussel was destroyed when in the year 1927 a dam was build to impound the Ochlockonee River for power production, and when the sections of the river, in which the species lived, were inundated thereby.  

The last members of this species were found in the year 1931.  


The former habitat of this species does not exist any more, it has been replaced by today’s Lake Talquin.  


edited: 23.09.2017

Amphinaias couchiana (Lea)

Rio Grande Monkeyface (Amphinaias couchiana)  

The Rio Grande Monkeyface is known, on the one hand, from subfossil remains from the Pecos River drainage in New Mexico, USA, but on the other hand also from live specimens from the Rio Grande in Texas, USA as well as from the Río Conchos in Chihuahua and from the Río Salado in Tamaulipas (both in Mexico).  

The last living specimes of this species have been collected in the year 1898 near Bracketville in the Kinney County in Texas.  


The Rio Grande Monkeyface is very possibly extinct, there exists, however, a vaguely possibility, that a population may still survive at least somewhere in Mexico.


edited: 13.12.2012

Epioblasma haysiana (Lea)

Acornshell (Epioblasma haysiana)

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.


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’



edited: 17.08.2022

Epioblasma lewisii (Walker)

Lewis’ Pearly Mussel (Epioblasma lewisii)

Lewis’ Pearly Mussel, also known as Forkshell, was once widespread over a large area in the Cumberland and Tennessee River systems. 

The species is only known from empty shells, with the exception of a single specimen with preserved soft parts. 

The larvae of the vast majority of the freshwater mussel species live parasitically in the gills of various river fish. However, nothing is usually known about the symbiotic relationships of the extinct species.


syn. Dysnomia lewisi Walker, Plagiola lewisi (Walker), Truncilla lewisi (Walker)


Photo: ‘Bryant Walker: Description of a new species of Truncatilla. The Nautilus 24: 42-44. 1910’

(not in copyright)


edited: 01.03.2024