Page 93 - The Freshwater Mussels of Oklahoma

Partial Synonymy:
Lampsilis gracilis (Barnes, 1823), Simpson 1914; Isely 1925
Leptodea fragilis (Rafinesque, 1820), Isely 1925; Murray and Leonard 1962;
Valentine and Stansbery 1971; Johnson 1980; Branson 1984; Oesch 1984;
Turgeon and others 1988; Vidrine 1993; Watters 1995; Howells and
others 1996
Description:
“Shell large, thin, obovate, subcompressed to subinflated, with generally low
compressed beaks having very feeble sculpture, which shows a tendency to be doubly
looped; posterior ridge almost wanting, there being two or sometimes three radial raised
lines on the posterior slope; there is a moderately developed posterior wing, which is
broken away in adult specimens showing the long ligament, and in front of the hinge the
young shell is angular; surface rather smooth, with faint, irregular growth lines, greenish-
yellow or pale smoky-brownish, sometimes feebly rayed, often rayless, the posterior
slope dark green and generally rayed; left valve with two feeble, compressed
pseudocardinals and two remote, often imperfect, laterals; right valve with one
pseudocardinal and one truncate lateral; beak cavities shallow, showing a row of ill-
developed muscle scars running in the direction of the retractor muscle scar; adductor
scars large, faint, the anterior irregular; nacre faint purplish and bluish. Generally the
male and female are much alike, the former is sometimes a little rhomboid and again it
ends in a wide, rounded point about on the median line. The female shell is a little fuller
and more rounded on the post-basal region, and sometimes has a well-developed
marsupial swelling” (Simpson 1914, p 181-182).
Hosts for Glochidia:
Freshwater Drum (Watters, 1994).
Comments:
Often one of the few species able to inhabit unstable substrates.

Table 15. Summary of L. fragilis shell characters.

Mean Maximum Mean
H/L Range H/L Length W/L Range H/L
Location N % % (mm) % % Remarks
Arkansas River System
Arkansas River 16 59.7-70.5 65.1 144 27.8-36.4 33.2 10 with rays
Chickaskia River 10 58.5-66.7 63.3 147 31.4-37.2 33.0 4 with rays
Verdigris River 15 56.4-69.2 62.5 139 29.4-37.4 34.0 6 with rays
Caney River 25 57.4-69.3 62.6 120 28.6-37.8 32.7 18 with rays
Neosho River 17 58.6-68.1 63.7 139 30.0-35.2 32.7 11 with rays
Spring River 3 63.8-69.4 67.1 105 31.4-37.5 34.0
Illinois River 5 62.5-67.0 64.4 131 32.1-37.5 34.3 1 with rays
Poteau River 6 61.9-64.8 63.3 120 31.7-38.9 35.0 1 with rays
Deep Fork River 3 60.0-64.2 62.3 110 30.7-38.2 33.5
Red River System
Cow Creek 7 59.5-65.5 62.7 121 26.9-39.1 34.9
East Cache Creek 6 58.4-66.4 62.3 126 31.0-35.8 33.7 1 with rays
Washita River 33 55.0-72.4 62.0 149 32.1-41.2 36.3 6 with rays
Bitter Creek 8 58.3-68.0 63.2 119 30.0-40.0 35.0 3 with rays
Wildhorse Creek 4 64.6-69.3 66.4 127 34.5-38.4 36.2
Lake Texoma 10 56.7-69.4 63.9 113 26.7-38.9 32.5 1 with rays

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