Mussel of the

Page last updated
1 June 2023

Mussel of the Month

The August 2005 Mussel of the Month is Amphinaias pustulosa. Amphinaias is widespread in the Interior and Gulf Coastal basins of eastern North America.

[Since August 2005 when we selected this species as Mussel of the Month, the whole genus Amphinaias has been transferred to the genus Cyclonaias. Then, it was all moved to Pustulosa. This species is now known as Pustulosa pustulosa. — DLG, 1 June 2023]

Amphinaias pustulosa
INHS 23355. Embarras River, Cumberland Co., Illinois.
Cummings et al., 20 July 1999!

Members of the genus Amphinaias have generally been treated as part of Quadrula. However, a recent molecular phylogenetic analysis by Jeanne Serb et al. has demonstrated the monophyly of several traditionally recognized subtaxa within Quadrula; given the conchological distinctiveness along those groups, we have decided to treat them as genera.


Phylum Mollusca
Class Bivalvia
Subclass Palaeoheterodonta
Order Unionoida

Superfamily Unionoidea Rafinesque, 1820

Family Unionidae s.s.
Subfamily Ambleminae Rafinesque, 1820
Tribe Quadrulini von Ihering, 1901

Genus Amphinaias Crosse & Fischer, 1894

Species Amphinaias pustulosa (Lea, 1831)

For more information about Amphinaias and its phylogenetic position, check out:
  • Serb, J.M., J.E. Buhay, C. Lydeard. 2003. Molecular systematics of the North American freshwater bivalve genus Quadrula (Unionidae: Ambleminae) based on mitochondrial ND1 sequences. Molecular Phylogenetics and Evolution 28: 1-11.
  • Graf, D.L. 2002. Molecular phylogenetic analysis of two problematic freshwater mussel genera (Unio and Gonidea) and a re-evaluation of the classification of Nearctic Unionidae (Bivalvia: Palaeoheterodonta: Unionoida). Journal of Molluscan Studies 68: 65-71.
NSF icon MUSSEL icon
"Making the world a better place, one mollusk at a time."