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Washboard - photo by Bob Gress


Megalonais nervosa

The Washboard is the largest species of mussel found in Kansas.  Its shell may be over 280 mm (11 inches) in length.  It prefers the main channels of larger rivers, although it may be found in smaller rivers and streams also.  Areas with slower current and muddy to coarse gravel bottoms are preferred, and it may be found up to 50 feet deep.

Its name comes from the numerous small V-shaped ridges on the thick, relatively flat and somewhat rectangular shell.  It also has several long ridges on the posterior half of the shell, a feature it shares with the Threeridge (Amblema plicata), but the latter have smoother shells otherwise.  The Washboard also has prominent double-looped ridges on the beak while the Threeridge has little or no visible beak sculpture as an adult.

washboard teeth
Hingeline of the washboard - Photo by Jim Mason

The pseudocardinal teeth are massive and the anterior adductor muscle scar is very prominent.  There is a wide interdentum area.

This is a bradytictic species, forming embryos in fall and releasing the glochidia in late winter/early spring.  It uses a wide variety of fish species as hosts for its glochidia including various catfish and sunfish, American eel, freshwater drum, gizzard shad and longnose gar.

The Washboard is a species that is sought after in other states as a source of cultured pearl nuclei.  It is not legal for harvest in Kansas.

RANGE AND STATUS IN KANSAS:  The Washboard is known only from the Neosho, Marais des Cygnes and Verdigris rivers in the southeastern part of the state..  For more information and a distribution map, see the species entry in the Mussel BedS.I.N.C (Species in need of conservation)

RANGE AND STATUS IN NORTH AMERICA:  The heart of the Washboard's range is the Mississippi Valley.  It ranges west to the eastern edge of the Great Plains from the lower Rio Grande valley to Manitoba.  It is found east to western Pennsylvania and Mississippi.  STABLE

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