Mussel of the

Page last updated
31 October 2006

Mussel of the Month

The November 2006 Mussel of the Month is Simpsonaias ambigua. Simpsonaias is a monotypic genus unique among the North American assemblage for parasitizing an amphibian rather than a fish.

Simpsonaias ambigua
USNM 122252. Ohio River at Louisville, Kentucky.
(type of Margaritana hildrethiana Lea, 1834)

Almost all freshwater mussels have larvae that are parasitic upon fishes: that is the normal unionoid life cycle. Simpsonaias ambigua, also known as the salamander mussel, uses a mudpuppy (genus Necturus) as its host. While amphibians are generally considered distinct from "fishes" at some level, a mussel infecting the gills of a salamander rather than a fish is really not that big of an ecological shift. Freshwater mussels are notorious for their generalist tendencies in host preference, and it has been hypothesized that they periodically colonize new hosts.


Phylum Mollusca
Class Bivalvia
Subclass Palaeoheterodonta
Order Unionoida

Superfamily Unionoidea Rafinesque, 1230

Family Unionidae s.s.
Subfamily Unioninae s.s.
Tribe Anodontini Rafinesque, 1820

Genus Simpsonaias Frierson, 1914

Species Simpsonaias ambigua (Say, 1825)

For more information about Simpsonaias, check out:
  • Clarke, A.H. 1985. The Tribe Alasmidontini (Unionidae: Anodontinae), Part II: Lasmigona and Simpsonaias. Smithsonian Contributions to Zoology (399). 75 pp.
  • Cummings, K.S. & C.A. Mayer. 1992. Field guide to freshwater mussels of the Midwest. Illinois Natural History Survey Manual 5. 194 pp.
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