This species was uncommon at Enewetak Atoll but seems quite rare at Kwajalein. All individuals observed have been on lagoon interisland reefs or pinnacles at depths ranging from about 3 to 12 meters, where they typically live underneath chunks of dead coral. Marshall Islands specimens seem to range in size up to about 28mm. This species is very similar to and possibly the same species as Goniobranchus albopustulosus. If you imagine that the white pustules of G. albopustulosus shrink away, leaving only a pattern of orange dots, they would be virtually identical. The rhinophores, gills, and marginal coloration are all very similar between the two species, and we have observed the two species mating in captivity. We did not, however, find mixed pairs in the wild, even though both species could be found on the same reef. Although neither species is very common, we did find a few pairs, and specimens would always pair with a like kind, as in the third photo below. The odds against that happening by chance would suggest that they could be different, so they are treated as such here.
The photo below is of a small juvenile, and the one below that is a tiny juvenile, measuring only about 5mm.
Created 13 December 2005
Updated 14 August 2015