Mussel of the

Page last updated
5 January 2015

Mussel of the Month

The January 2015 Mussel of the Month is Toxolasma lividum. Toxolasma is a genus of eight species found in eastern North America, from the Great Lakes south to the Gulf of Mexico.

Toxolasma lividum
USNM 85312. [Wabash River,] New Harmony, Indiana
(male & female specimens of Unio glans Lea, 1831 from the Lea Collection).

The freshwater mussel genus Toxolasma is distinctive for its small adult size — generally less than an inch. At that size, the shells are fully sexually dimorphic in the typical lampsiline style. Good, interesting stuff.

Recent UWSP graduate Charlie Jordan at the College of Letters and Sciences Undergraduate Research Symposium last spring.Toxolasma lividum does not occur in Wisconsin, but T. parvus does. In fact, T. parvus was described from the Dairy State. Recent UWSP graduate Charlie Jordan had been working on the distributions of freshwater mussels like Toxolasma parvus in Wisconsin. Last spring, he and Madalyn Zimbric (now at the University of Michigan) presented a poster on patterns of freshwater mussel species richness in Wisconsin at the UWSP College of Letters and Sciences Undergraduate Research Symposium. Their poster, "A Biodiversity Informatics Assessment of Wisconsin Freshwater Mussels" will form the basis of a future publication on the subject.

And, speaking of the freshwater mussels of the North America, it seems that we have a new book chapter. Our previous bivalve chapter from Thorp & Covich's invertebrate zoology book (Cummings & Graf, 2009) has been recycled into Thorp & Covich's general freshwater invertebrates book (Cummings & Graf, 2014). We were surprised, too.


Phylum Mollusca
Class Bivalvia
Subclass Palaeoheterodonta
Order Unionoida

Family UNIONIDAE Rafinesque, 1820
Subfamily AMBLEMINAE Rafinesque, 1820
Tribe LAMPSILINI Ihering, 1901

Genus Toxolasma Rafinesque, 1831

Species Toxolasma lividium Rafinesque, 1831
(+ Unio glans Lea, 1831)

To find out more about Toxolasma and other Nearctic mussels, check out:
  • Cummings, K.S. D.L. Graf. 2009. Mollusca: Bivalvia. [in] J.H. Thorp & A.P. Covich (eds.). Ecology and Classification of North American Freshwater Invertebrates, 3rd edition. Academic Press-Elsevier, New York. pp. 309-384.
  • Cummings, K.S. D.L. Graf. 2014. Mollusca: Bivalvia. [in] J.Thorp & D.C. Rogers (eds.). Ecology and General Biology: Thorp & Covich’s Freshwater Invertebrates. Academic Press-Elsevier, New York. pp. 423-506.
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