Description from Dr. Richard C. Willan: The nudibranch can grow to 65 mm. It is recognised by the network of dark brown lines with yellow spots in between on the central mantle. The body, which is soft and slimy, is elongate. The mantle is completely smooth, and the margins are not wavy. The mantle is raised into a tall, sheath-like branchial pocket. The 10 to 12, very long, simple gills form a circle around the anus. The mantle has an orange marginal band. The foot repeats the colours of the mantle. The rhinophores are orange-red with a white tip. The gills are transparent white with 2 red lines up the outer exes (From Undersea Jewels, page 165).