Page 50 - The Freshwater Mussels of Oklahoma

Partial Synonymy:
Unio gibbosus Barnes, 1823, Simpson 1914; Isely 1925
Elliptio dilatatus (Rafinesque, 1820), Murray and Leonard 1962; Branson 1983
Elliptio dilatata (Rafinesque, 1820), Johnson 1980; Oesch 1984; Turgeon and
Others 1988; Vidrine 1993
Description:
“Shell elongated, generally solid, rarely inflated, sometimes subcompressed,
decidedly inequilateral, usually a little higher in front and often arcuate, especially in an
adult state; beaks not much elevated above the curved dorsal line, generally
subcompressed, turned a little forward over a well-developed lunule, their sculpture a
number of strong, often rude, subcorrugated, longitudinal bars, which are sometimes
slightly doubly looped; posterior ridge well developed, subangular or rounded, curved
and placed close to the dorsal line, rarely double and ending behind in a point of
biangulation at or near the base of the shell; surface with uneven growth lines, sometimes
concentrically sculptured; epidermis dull, greenish or yellowish-brown in young shells,
darker when old, often faintly rayed in young specimens; left valve with two rather small,
stumpy or subcompressed pseudocardinals; right valve with one, having occasionally a
vestigial tooth in front of and behind it; laterals club-shaped, one in the right valve which
is sometimes double and two in the left; beak cavities exceedingly shallow; dorsal scars
immediately under the hinge; muscle scars deep; pallial line impressed, crenate; nacre
deep purple, salmon, straw-colored or white, obliquely ribbed” (Simpson 1914, p 597).
Hosts for Glochidia:
Black Crappie, White Crappie, Flathead Catfish, Gizzard Shad, Sauger, Yellow
Perch (Watters, 1994).
Comments:
Uncommon in Oklahoma.

Table 6. Summary of E. dilatata shell characters.
Maximum
Mean H/L H/L Range Length Mean W/L W/L Range
Location N (%) (%) (mm) (%) (%)
Arkansas River Drainage
Illinois River 3 48.6 46.2-52.0 93 26.7 25.3-28.0

General Distribution:
This species occurs throughout most of the eastern United States except the
Atlantic coastal region.
Oklahoma Distribution:
Found only in the Neosho and Illinois River systems. Live specimens are
uncommon.

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