Polycera sp. 2.
Kerama Is, near Okinawa, Japan, 3-8m. 4.5 to 5mm long, June 1999. PHOTO: Atsushi Ono.
See Atsushi Ono's message below.
July 7, 1999
From: Atsushi Ono
I found this Polycerid at 3 to 8m depth at Kerama Is. June 1999. One was attached to Bryozoa. Its size was 4.5 to 5mm. Any ideas as to the identification?
firstname.lastname@example.orgOno, A., 1999 (Jul 7) Another polycerid from Kerama Island, Japan. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1026
I think this is different from the orange species you just sent photos even though they both have white speckling on the body and a yellow band around the posterior end of the foot. The main reason is the much larger rhinophores in this brown animal, which in my experience suggests that the animal is a juvenile. Often in juveniles the rhinophores are proportionally larger than in adults. However I could be quite wrong so it will be interesting for you to keep a lookout to see if the brown on also lays eggs, and if so, are they the same as the orange one.
These small polycerids are often quite variable in colour so it would also be worth seeing just how variable the colour pattern is in this and the orange species. Unfortunately I can't help with a name at present.