Page 86 - The Freshwater Mussels of Oklahoma

Partial Synonymy:
Symphynota complanata (Barnes, 1823), Simpson 1914; Isely 1925
Lasmigona complanata (Barnes, 1823), Murray and Leonard 1962; Valentine and
Stansbery 1971; Branson 1983; Oesch 1984; Clarke 1985; Turgeon and
Others 1988; Vidrine 1993; Howells and others 1996
Description:
“Shell large, solid, irregularly elliptical, obovate or subrhomboid, inequilateral,
compressed; beaks low, decidedly flattened, their sculpture consisting of coarse, doubly-
looped, subnodulous ridges with radiating raised threads behind; post-dorsal part of the
young shell produced into a high, often angular wing, which is truncated behind making
the outline at this period of growth somewhat triangular; as the shell becomes old this
wing breaks off and is worn away; posterior ridge low, sometimes double and ending
behind in a biangulation on the median line; base rounded, full behind the middle; surface
with rude growth lines, often somewhat plicate on the posterior slope; epidermis dark
green in young shells, blackened in old ones, scarcely shining; left valve with two strong,
uneven pseudocardinals, the hinder generally divided sometimes somewhat ^-shaped;
right valve with one or two pseudocardinals, which are frequently split up and imperfect;
laterals very much blurred in both valves; muscle scars large; nacre white, thickened in
front, with a wide border outside the pallial line” (Simpson 1914, p 490-491).
Hosts for Glochidia:
Banded Killifish, Carp, Green Sunfish, Largemouth Bass, Orangespotted Sunfish,
White Crappie (Watters, 1994).

Table 13. Summary of L. complanata shell characters.

Maximum
H/L Range* Mean H/L* Length W/L Range Mean H/L
Location N (%) (%) (mm) (%) (%)
Arkansas River Drainage
Neosho River (and 14 69.8-92.1 77.3 172 21.9-28.0 25.4
Fort Gibson Lake)
Verdigris River 18 70.3-95.2 80.9 156 19.4-31.0 25.2
Caney River 12 61.7-92.6 79.5 165 21.8-34.2 27.3
Illinois River 3 71.2-78.8 74.2 151 26.0-31.8 29.3
Red River Drainage
Lake Texoma 11 72.5-92.7 83.1 160 21.1-29.8 25.4
East Cache Creek 1 75.0 - 136 26.5 -
Blue River 4 73.0-82.8 77.4 126 27.0-31.2 29.6
Muddy BoggyRiver 3 66.1-88.8 77.4 128 29.9-35.2 32.6
*The wing structure of this species is extremely variable, ranging from extremely well developed to almost
non-existent. The wing is very easily eroded or broken.

General Distribution:
Found throughout much of eastern United States and Canada except for the
Atlantic and Gulf coastal areas.

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