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4 October 2021 |
Mussel of the Month
The December 2012 Mussel of the Month is Trapezoideus exolescens. Trapezoideus is a genus of only four species from southern and southeastern Asia.
[Since December 2012 when this species was selected as Mussel of the Month, T. exolescens has been moved to the genus Trapezidens. This specimen is now known as Lens misellus. — DLG]
USNM 85893. Siam (type of Unio siamensis Lea).
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The last Mussel of the Month of 2012, Trapezoideus exolescens, is dedicated to Mr. John M. Pfeiffer III in honor of the defense of his master's thesis at the University of Alabama. John has spent the last couple years exploring the phylogenetic relationships of southeast Asian freshwater mussels, and Trapezoideus has figured prominently in his research.
 Trapezoideus is one of the five genera of tropical Asia freshwater mussels reported to have asymmetrical glochidia (Ortmann, 1916; Panha & Eongprakornkeaw, 1995; Deein et al., 2008).The asymmetry of the larva is the result a pronounced flange (appendix, appendage, process, hook, &c. &c.) on only one of the valves. As John explained last summer in an award-winning presentation to the American Malacological Society, these genera are polyphyletic. That is, this odd larval morphology appears to have evolved more than once in the same geographical area. However, there are more interesting twists to this story. Watch this site for updates, and we will let you know when the paper on the subject is published.
Congratulations, John!! |
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To find out more about Trapezoideus and asymmetrical glochidia, check out:
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