These are what appear to be Siphopteron sp. 5 on the Sea Slug Forum or Siphopteron sp. 2 in Gosliner et al (2018). The Sea Slug Forum figures show two color forms similar to those below that certainly look like different species, although the Australian reports indicated numerous observations of the different forms mating. One has to wonder by reports of a limited number of specimens with mixed coloration if they indeed are two species that just smell enough alike to try to mate but which are different enough to produce few hybrids. Some DNA work on these would be very interesting. The two specimens from Kwajalein, one of each color form, were found and photographed on 12 April 2015 on a lagoon sandy bottom at about 13m by Peter and Marissa Brown. The Marshall Islands represents a considerable range extension for this species.
What appears to be a third specimen of this Siphopteron was found by the Browns in the same general area as the other two about a month later. The orange color with white spots on this 3-4mm individual ties together the two other color forms pictured above.
Created 17 April 2015
Updated 2 December 2018