This crab is distinguished from other Charybdis species by a spine on the posterior margin of the carpus of the fifth leg. The frontal region has six prominent teeth, two inner orbitals and four blunt submedial teeth. The color is dark green, except for a light purple area on the upper, inner surface of the palm and dark purple on the dorsal surfaces of the distal four segments of the walking and swimming legs. The carapace has pale green or whitish areas on the frontal, hepatic, and epibranchial regions. The fingers of the chelipeds are dark purple.