Dermatobranchus sp. 4.
See Bob Bolland's message below.Authorship details
Rudman, W.B., 1999 (December 12) Dermatobranchus sp. 4. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/dermsp4
December 14, 1999
From: Robert F. Bolland
Enclosed is a scan of an unknown Dermatobranchus from Okinawa.
RFB # 3529-B, from Horseshoe Cliffs, Okinawa at 43m on 13 December 1996. T.L. 40mm
Found feeding on the alcyonacean coral in the photo.
The animal would appear to fit Baba's redescription of Dermatobranchus striatellus (1976) [the original description in Baba, 1949]; however the black notal blotches on the Okinawa specimen don't fit. Is this a color variation or is it perhaps an undescribed species?
All the best,
firstname.lastname@example.orgBolland, R.F., 1999 (Dec 14) Okinawa Dermatobranchus. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1601
There seem to be many undescribed species of Dermatobranchus often with very subtle differences in external colour pattern but major differences in radular morphology. I therefore am not willing to hazard a guess in answering your question without looking at the internal anatomy.
It's nice to get a photo of another species feeding on a softcoral. The species I have seen on similar softcorals are usually about half the size of your species