Freshwater Molluscan Shells

Backlit image of a shell, Megalonaias nervosa (Rafinesque,1820) the "Washboard", showing growth rings
and corrugated sculpture. Single valve and reflection.


The ambleminae include a number of the most interesting as well as thick-shelled and commercially important species. All North American genera and species of this subfamily, as defined by Burch, are native to waters that drain directly or indirectly into the Gulf of Mexico.

Tritogonia verrucosa (Rafinesque,1820)
"Pistolgrip" Widespread in American Midwest.

Quadrula metanevra (Rafinesque,1820)
"Monkeyface", American Midwest.

Quadrula pustulosa (Lea, 1831)
and detail of hinge teeth. The "Pimpleback"
is widespread in the American Midwest.

Quadrula quadrula (Rafinesque,1820)
"Mapleleaf". Widespread in American Midwest.

Fusconaia ebena (Lea, 1831) "Ebonyshell".   Fusconaia flava (Rafinesque,1820)
"Wabash Pigtoe" and detail of the hinge teeth, below



Amblema plicata (Say, 1817), "Threeridge"
Large-river form. The small-river form is larger
and looks very much like the "Washboard", below.
However, A. plicata is always smooth on the thick
anterior part of the shell, while corrugations on the
washboard often cover the entire shell.

Widespread and extremely variable throughout
the North American midcontinent.


Meglaonaias nervosa (Rafinesque,1820).
"Washboard". Widespread in the larger rivers
of the American Midwest.

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