Carapace somewhat triangular and thick with grooves, knobs and lumps symmetrically arranged. Rostrum of two horns, wide and flattened with divergent tips. Hooked setae on carapace, seldom used for decoration, but the surface is often encrusted by a growth of bryozoa, hydroids and sponges. Chelipeds large in mature male with numerous blunt knobs on ischium, merus and carpus, in rows on margins and scattered in between. Hand elongate, with sharp dorsal and ventral ridges; fingers slender with gape; dactyl with small teeth distally and 1 large tooth medially. Walking legs short and relatively stout, with short, stiff, club-shaped setae; dactyl about ½ the length of propodus. Abdomen of male narrow with 3 flat knobs per segment; telson smooth and triangular. Eyes small. Antennae short, flat and hidden under rostrum.

Size

Carapace: male 55 x 45 mm, female 41.2 x 30 mm.

Colour

Often masked by encrusting growths. Carapace usually bluish white with blue-tipped, brown granules. A mature male may be deep red, brown or purple-brown. Chelipeds brown with blue or red granules; palm brown to orange; fingers orange red or pink; teeth white. Walking legs irregularly banded with dark and light brown; dactyl reddish; claw yellow. Antennal peduncle striped with light and dark brown, flagella orange. Antennal peduncle white and flagellum red. Eyestalk grey; cornea opalescent pink with black pigment spot.