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3 January 2007 |
Mussel of the Month
The January 2007 Mussel of the Month is Ligumia recta. Ligumia is a widespread genus of three species inhabiting much of eastern North America.
MNHN Lamarck Collection. Lake Erie. Michaud! (type of Unio recta Lamarck, 1819)
Ligumia species are recognized by their elongate shells and distinctive mantle elaborations. Simimlar to other lampsiline freshwater mussels, the posterior mantle ventral to the incurrent aperture is adorned with a series of papillae. These have been hypothesized to carry out various functions, including brood aeration and host fish attraction. The picture below shows the marsupium of Ligumia recta and the papillae along the edge of the mantle (photograph by Chris Barnhart from the Unio Gallary).
 In North America, the Lampsilini (the tribe of freshwater mussels with special brooding morphologies and mantle elaborations) is the most diverse clade. Looking only at the Nearctic fauna, it would be easy to get the impression that those lampsiline characteristics are typical of the Unionidae. However, from a global perspective, the lampsilines are better regarded as a bizarre, derived group. Most freshwater mussel species — within the Unionidae and, indeed, the whole order Unionoida — lack any kind of specialized marsupium or mantle elaborations. At least, as far as has been observed to-date...
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Classification:
Phylum Mollusca
Class Bivalvia
Subclass Palaeoheterodonta
Order Unionoida
Superfamily UNIONOIDEA Rafinesque, 1820
Family UNIONIDAE s.s.
Subfamily AMBLEMINAE Rafinesque, 1820
Tribe Lampsilini von Ihering, 1901
Genus Ligumia Swainson, 1840
Species Ligumia recta (Lamarck, 1819)
For more information about Ligumia and lampsiline reproductive characters, check out:
- Lydeard, C., M. Mulvey & G.M. Davis. 1996. Molecular systematics and evolution of reproductive traits of North American freshwater unionacean mussels (Mollusca: Bivalvia) as inferred from 16S rRNA gene sequences. Philosophical Transactions of the Royal Society, London B 351: 1593-1603.
- Graf, D.L. & D. Ó Foighil. 2000. The evolution of brooding characters among the freshwater pearly mussels (Mollusca: Bivalvia: Unionoidea) of North America. Journal of Molluscan Studies 66: 157-170.
- Zanatta, D.T. & R.W. Murphy. 2006. Evolution of active host-attraction strategies in the freshwater mussel tribe Lampsilini (Bivalvia: Unionidae). Molecular Phylogenetcs and Evolution 41: 195-208.
- Chris Barnhart's Unio Gallery.
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