• Mississippi National River and Recreation Area


    National River & Recreation Area Minnesota

Purple Wartyback

(Cyclonaias tuberculata) Rafinesque, 1820
A Purple Wartyback mussel
K.S. Cummings, Illinois Natural History Survey
Other Common Names:
Purple Pimpleback; Wartyback; Missouri mapleleaf; Deerhorn.
Medium to large rivers in gravel or mixed sand and gravel.
Up to 5 inches (12.7 cm).
Outer Shell Color:
The outside shell color is brown or black.
Inner Shell Color:
Usually deep purple, or occasionally white with a purple tint.
Shell Thickness:
Moderately thick and heavy.
Shell Outline:
The entire shell outline is shaped like a circle, except for a flattened extension of the shell directly off of one side of the point where the two shell halves join. This extension has a straight edge, shaping this one "corner" of the shell somewhat like a square.
Shell Surface:
Rough: many small pimple-like bumps scattered over three-quarters of the outer shell surface. The surface without bumps is always located along the outer surface following the shell edge that is opposite from the squared-off "corner" of the shell. The bumps may form into small ridges along the squared-off outer surface of the shell. Entire shell surface may look either flattened or somewhat bulged-out. Looking at the inner shell, there is a deep depression: it forms a visible bulge on the outer shell surface (called the beak). This beak is covered in wavy lines, which look as though a fine-toothed comb were dragged in a wavy motion over the beak's outer surface.
Scientific Description:
Brown or black, heavy shell. Subrectangular, totally tuberculate. Beak sculpture extends onto disc. Incurrent papillae aborescent. Excurrent aperture entire (fused), lacking papillae.
Similar Looking Mussels:
Host Fish:
Black Bullhead, Yellow Bullhead, Channel Catfish, Flathead Catfish
Widespread but uncommon in most of the Midwest.
Minnesota State Listing:
Federal Listing:

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