Cymadusa compta is a small, tube-building gammaridean amphipod of family Ampithoidae. Its most distinguishing feature is its large, ovate, encapsulated and red-tinted eyes which occupy most of the head lobe. The coxal plates are deep and sparingly setose along their lower margins, with the fifth coxal plate being the deepest. There are two pairs of antennae and two pairs of moderately robust gnathopods. The appendages and antennae all bear setae (Bousfield 1973).The tubiculous structures C. compta builds and occupies have been described as web-like nests by Marsh (1973).