Leptodea leptodon
| Scale shell | |
|---|---|
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Bivalvia |
| Order: | Unionoida |
| Family: | Unionidae |
| Tribe: | Lampsilini |
| Genus: | Leptodea |
| Species: | L. leptodon |
| Binomial name | |
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Leptodea leptodon Rafinesque, 1820 |
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The scale shell or scaleshell (Leptodea leptodon) is a species of freshwater mussel in the family Unionidae, the river mussels. This aquatic bivalve mollusk has disappeared from much of its historical range. It is endemic to the United States, where it is now present in four or fewer states; it is only found with any regularity in Missouri. It is a federally listed endangered species of the United States.
This mussel is generally up to 10 centimeters long but old individuals may reach 12 centimeters. The shell is very thin and translucent in parts, and is yellowish, greenish, or brownish in color. The nacre is very iridescent and is blue or purple in color with a pinkish or copper tinge. The species is sexually dimorphic, with males having a pointed posterior end and females having a ruffled end.
This mussel had a historical distribution in 56 rivers in 13 states throughout the Mississippi River drainage: Alabama, Arkansas, Illinois, Indiana, Iowa, Kentucky, Minnesota, Missouri, Ohio, Oklahoma, South Dakota, Tennessee, and Wisconsin. While it had a widespread distribution, it was considered rare throughout its range. Today it is considered extirpated from nine of these states, with scattered occurrences remaining in Missouri, South Dakota, Arkansas, and Oklahoma. It has been seen in 18 rivers in the last 25 years. The largest known populations, which are very small and isolated, are in the Meramec, Bourbeuse, and Gasconade Rivers of Missouri.
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Wikipedia