Page 53 - The Freshwater Mussels of Oklahoma

Partial Synonymy:
Fusconaia rubiginosa (Lea, 1829), Isely 1925
Fusconaia flava (Rafinesque, 1820), Murray and Leonard 1962; Valentine and
Stansbery 1972; Johnson 1980; Branson 1982; Oesch 1984; Turgeon and
Others 1988; Vidrine 1993; Howells and others 1996
Description:
“Shell quadrate to triangular; dorsal line short, straight only at the hinge; sharply
angled posteriorly; ventral line straight, anterior end with a straight face dorsally, gently
rounded ventrally; posterior end sharply truncated above, sharply rounded below. A
broad, shallow sulcus anterior to the posterior ridge; shell is strong and heavy even in
small shells; in old shells the valves usually become quite thick in the anterior half; size
to 9.5cm; moderately inflated, posterior ridge prominent, sometimes sharply angled
dorsally, often flattening ventrally and causing a double angle on the postero-ventral
margin. Beaks broad, raised above the hinge line, inequipartite; beak sculpture consists
of three to five faint concentric bars that become sharp-angled on the posterior slope and
may form slight tubercles there. Growth lines often prominent, forming raised concentric
ridges which are dark-stained at rest periods. Epidermis yellow-brown in young,
becoming chestnut brown to black when old; small valves may have faint green rays on
the umbones.
Left valve has two dissimilar pseudocardinal teeth; the anterior one is narrow and
elongate, the posterior one heavy and triangular, both are rough and serrated; the two
lateral teeth are short and straight. Right valve has one heavy, serrate pseudocardinal

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