We originally conisdered this to be Platydoris sanguinea, originally described by Bergh (1905) from Indonesia. The identification was not certain, because the figure in Bergh's (1905) original description shows an animal more uniformly reddish brown with an orange margin, and it is quite a bit larger with a length of 90mm (reproduction at bottom). However, these smaller ones from the Marshalls and elsewhere seemed the closest thing to them until the discovery of a specimen that nearly exactly matches the original description from Kosrae in the Caroline Islands. The species on this page is relatively rare in the Marshalls, known from perhaps a dozen specimens from Kwajalein Atoll. Three of these are pictured below. The 17mm specimen in the first photo below was found at a depth of 13 meters on the seaward reef, in a small cave at night on 26 November 1994. The rest were living in lagoon patches of Halimeda algae at depth of about 9-15m.
The photos below show a 37mm specimen found in a lagoon Halimeda patch on 8 September 2008.
The specimen below was found under a rock on a Kwajalein Atoll lagoon reef at about 7m on 8 February 2009.
Here is a view of the underside of the 37mm specimen.
Here is the drawing of the real Platydoris sanguinea from Bergh's (1905).
Created 15 December 2006
Updated 3 February 2016