Freshwater Mussels Pacific Northwest - The Xerces Society
Freshwater Mussels Pacific Northwest - The Xerces Society
Freshwater Mussels Pacific Northwest - The Xerces Society
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Identification<br />
Field Guide<br />
<strong>The</strong> purpose of these descriptions is to help the user identify adult mussel<br />
shells or live animals to genus. Descriptions, photographs, and illustrations<br />
are provided in the species, clade, and family accounts that follow.<br />
Outline of shell triangular or round. Beak inflated and centrally located along<br />
dorsal edge. Well-developed concentric sculpture lines, absent on other genera<br />
(introduced)...Asian clam, Corbicula (page 40)<br />
Very small (0.08 to 0.60 inches long). Adult shell round, oval or quadrate,<br />
fragile, with one or two cardinal teeth in one valve. Shell sculpture, if present,<br />
very fine with no color pattern...Fingernail clams, Sphaeriidae (page 40)<br />
Well-developed pseudocardinal teeth. Ventral margin slightly concave. Nacre<br />
purple on fresh specimens. Arborescent papillae surrounding the incurrent<br />
opening...western pearlshell, Margaritifera (page 31)<br />
Distinct heavy ridge running at an angle from beak to posterior ventral surface.<br />
Shell thick, heavy, sturdy. Divided, purplish incurrent aperture papillae...western<br />
ridged mussel, Gonidea (page 36)<br />
Pseudocardinal and lateral teeth and heavy ridge absent. Shell thin, light, and<br />
fragile. Single, whitish incurrent aperture papillae...Floaters, Anodonta (page<br />
17)<br />
<strong>Freshwater</strong> <strong>Mussels</strong> of the <strong>Pacific</strong> <strong>Northwest</strong> 15
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