Ceratosoma amoenum (Cheeseman, 1886)
This beautiful dorid nudibranch is a temperate (cold water) species from the southern shores of Australia.
This species looks much more like a species of Hypselodoris than a Ceratosoma, but its internal anatomy, especially the reproductive system and radular morphology show that it belongs to the genus Ceratosoma. It's main difference from other members of the genus is that it lacks the large recurved dorsal horn present in most.
The Sea Slug Forum reports that - "Ceratosoma amoenum also shows considerable color variation through-out its range. In Western Australia the orange spots are very small and numerous and the reddish purple spots form a submarginal band around the edge of the mantle. Moving east, the reddish purple spots become more numerous and widespread over the mantle and the orange spots become larger. In New Zealand the orange spots are very large and the purple markings are often absent."
Specimens may reach 35 mm in length and lay a spiral coil egg mass that may differ in color from pink to orange.
Dave Cowdery is a retired biomedical engineer and Divemaster at Byron Bay Australia. He has over 5000 logged dives. He is a keen participant in trips organised by Graham Abbott at Diving4Images and has dived the tropics extensively from Cocos Keeling Islands east to Niue. 3 Camera equipment used Nikon D300 in Ikelite Housing with twin 125 substrobes and a 60mm Nikon macro lens.
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