Page 38 - The Freshwater Mussels of Oklahoma

Partial Synonymy:
Arcidens confragosus (Say, 1829)
Description:
“Shell rhomboid, inflated, subsolid, or solid, slightly inequilateral; beaks
high and full, their sculpture consisting of irregular, doubly-looped ridges, the
bases of the loops being developed into strong, pinched-up nodules, which extend
out on to the disk of the shell; in front of and behind the loops there are a number
of radiating, wavy, subnodulous lirae or small ridges; from the anterior row of
knobs extending backwards and downwards there is a series of strong folds and
these are crossed by wrinkled, radiating, sometimes zigzagged, threads; the
posterior slope has radial, wrinkled sculpture, while the anterior base has usually
merely concentric striae; posterior ridge rather high; post-dorsal region almost
winged; epidermis brownish-green with dark bands, sometimes clouded; left
valve with an arched, somewhat elongated tooth under the beak, which often
curves upward; in front of this there is a compressed tooth; right valve with a
strong, subcompressed tooth in front of the beak; at the beak the hinge plate is cut
away for the reception of the tooth in the left valve; laterals reduced to blurred,
uneven vestiges; beak cavities deep; muscle scars shallow; nacre bluish-white,
dull, often with uneven radial sculpture, with a wide prismatic border” (Simpson,
1914, p. 475-476).
Comments:
Only recently confirmed in Oklahoma.
General Distribution:
Mississippi drainage and Gulf of Mexico rivers west into Texas.

Oklahoma Distribution:

Map 7. Distribution of A. confragosus in Oklahoma.

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