Length 88 mm, height 85 mm, breadth 12 mm. Shell thick, solid, fan-shaped. Anterior ear bigger than the posterior. Surface with 9─10 broad and round radial ribs overridden by slender, strong, scaly radial riblets. Some of principal ribs with spaced, round knobs on the left valve. No knob presents on the right valve, but pronounced steps. Externally reddish in color with pale spots. Interior pale purplish centrally but orangy marginally. Ventral margins wavy and well fit to each other.
Distribution:
North Carolina to Florida, Texas, Bermuda to Central Atlantic, and off Suriname. Sublittoral.
Remarks:
East Pacific congener, L. subnodosus, has a similar appearance but lacks of knobs unlike this species.