Page 228 - The Freshwater Mussels of Oklahoma

Partial Synonymy:
Proptera alata (Say,1817), Branson 1973; Branson, 1984
Lampsilis alata (Say), Isely 1925
Description:
“Shell large, elongate, laterally compressed and somewhat rectangular, thin in
young shells to moderately thick in older individuals. Anterior end rounded, posterior
end bluntly squared or truncated. Umbos flattened and only slightly elevated above the
hinge line. Beak sculpture of three or four concentric ridges, visible only in small shells.
Large wing present posterior to the umbos. Shell smooth, dark green or brown,
becoming black in old individuals. Young shells typically marked with dark green rays
that become fainter with age. Length to 8 inches (20.3 cm).
Pseudocardinal teeth small, roughened, thin and divergent; two in the left valve,
two in the right. Lateral teeth long, thin, and straight to slightly curved. Beak cavity
shallow. Nacre usually purple or pinkish purple, rarely white; highly iridescent”
(Cummings and Mayer, 1992).
Comments:
A species generally found to the north and east of Oklahoma. Specimens of P.
purpuratus from the northeastern part of Oklahoma often have higher wings and are more
“alate” than typical P. purpuratus but because of the inflation of the shell and the
continuous range of the species through the area, I do not feel that any specimens can be
assigned to P. alatus.

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