Mussel of the

Page last updated
1 October 2003

Mussel of the Month

The October 2003 Mussel of the Month is Unio pictorum. U. pictorum is the type species of the genus Unio, which in turn is the type genus of the family Unionidae and the whole order Unionoida!

Unio pictorum
UMMZ 9320. Birmingham, England.

For a long time, the classification of Unio was in a state of confusion— both in the sense of which species properly belong to Unio and where that genus goes in the family-level classification of freshwater mussels. Much of the 20th century was spent organizing the Unionoida into new genera, so that helped fix the first problem. The correct position of Unio was addressed in a recent paper by Dan Graf.


Phylum Mollusca
Class Bivalvia
Subclass Palaeoheterodonta
Order Unionoida

Superfamily Unionoidea Rafinesque, 1820

Family Unionidae s.s.
Subfamily Unioninae s.s.
Tribe Unionini

Genus Unio Philipsson in Retzius, 1788

Species Unio pictorum (Linnaeus, 1758)

For more info on the classification of the widespread and common genus Unio:
  • 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.
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