Pondhorn
Uniomerus tetralasmus (Say, 1831) |
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Pondhorn |
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| Uniomerus tetralasmus, INHS 7807. Mississippi River, Perry County, Missouri. Length: 4.0 inches (10.2 cm).
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| Other common names Horn shell.
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| Key characters Relatively thin, smooth, elongate shell, light to dark
brown, pointed, and rayless. Posterior slope with a short ridge formed by two
shallow grooves on either side.
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| Similar species Yellow sandshell, giant floater, cracking pearlymussel,
cylindrical papershell, creeper.
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| Description Shell relatively thin, elongate, and compressed to
moderately inflated. Anterior end rounded, posterior end bluntly or sharply
pointed. Dorsal margin straight, ventral margin straight, rarely curved. Umbos
low, approximately even with the hinge line. Beak sculpture of four or five
concentric ridges. Two shallow grooves present on the posterior slope, giving
rise to a short ridge. Surface smooth and shiny in small shells, becoming
rougher and dull in older individuals. Periostracum greenish or yellowish brown
in young individuals, adults dark brown to black and rayless. Length to 5
inches (12.7 cm). Pseudocardinal teeth small and thin; two in the left valve, one in the right. Lateral teeth relatively thin, short, and straight to slightly curved. Beak cavity shallow. Nacre white, occasionally with a tinge of salmon.
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| Habitat Ponds, small creeks, and the headwaters of larger streams in
mud or sand. (This mussel can withstand periods of desiccation and is often
present in areas where few other mussels are found.)
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Status Widespread but generally uncommon. May be abundant in its
preferred habitat. Threatened in Ohio.
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