Although we rarely found this species along other reefs around Oahu, during the mid 70s to mid 80s, it was common only at Magic Island. There we could always see specimens, often many of them. This species is apparently distributed widely in the Indo-West Pacific, but judging from photo posts on the web, aside from Hawaii it is common only in the Marshall Islands. Interestingly, those from the Marshalls and from other parts of the Indo-Pacific (e.g., Guam, the Tuamotus, New Caledonia lower photo (upper is G. setoensis), the Maldives, Madagascar) all have their orange marginal bands studded with small opaque white granular spots that appear to be embedded on or just within the surface of the skin. Such spots are lacking in all our photos below as well as in nearly all other images of Hawaiian specimens we have seen, with a few very minor exceptions (e.g., one with just a few dots on the Seaslugs of Hawaii site and one again with just a few dots on the MarinelifePhotography site). See the discussion in the section on Marshall Islands' Goniobranchus decorus on differentiating G. decorus from the similar G. setoensis, a species that is not found in Hawaii.
Created 20 April 2009
Updated 31 October 2021