Freshwater Mussels Pacific Northwest - State Water Resources ...

Winged floaters inhabit sloughs of the lower Columbia River. photo: Allan SmithWinged FloaterAnodonta nuttalliana Lea, 1838DescriptionSize: Up to 4.25 inches. Smaller than other western Anodonta.Shape: Elliptical or ovate; L:H ratio usually 1.5 or less. Dorsal posterior margincompressed and raised into a high prominent wing. Wing less conspicuousin some individuals. Valves slightly inflated, though compressed in someindividuals. Valves very thin.Beaks: Flattened, usually not raised above the hinge line. Beak sculpture withup to 20 irregular single or double-looped concentric ridges.Periostracum: Yellowish-green, yellowish-brown, or brown. Growth linessometimes prominent.Hinge Teeth: NoneNacre: White or bluish.DistributionThe winged floater is the least common western Anodonta, confined to California,Oregon, Washington, and southern British Columbia. There wereseveral historical records for Utah. Unfortunately, historical data are difficultto assess because people often included this species under other species names.For example, specimens with a low dorsal wing can be nearly indistinguish-26Freshwater Mussels of the Pacific Northwest