Nembrotha livingstonei? from Japan

August 24, 1999
From: Atsushi Ono

Dear Bill,
Thank you very much for ID of Aeolids.

Now, I found a strange Polycerid from Kerama Island [near Okinawa] in Japan.
This individual is similar to Nembrotha lineolata with many slender lines on body. But it is also similar to Nembrotha kubaryana with red line (small red dot) of edge of foot, too. This animal is about 45mm long, I found this 7m depth.
There are N. lineolata and N. kubaryana here.

Is this a hybrid?
Do a hybrid of Opisthobranchs exist?

Atsushi Ono

Ono, A., 1999 (Aug 24) Nembrotha livingstonei? from Japan. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Atsushi,
I think your animal is not a hybrid but probably a colour form of Nembrotha livingstonei. That species in Australia is rather variable in colour and has spots rather than lines. However there are a number of consistent colour characters all the specimens have on common. There is the white cross pattern between the rhinophores and a similar pattern around the gill pocket. And if you compare your photo of the head of the Kerama Island animal with my photo of the head of an Australian animal they are identical.

I am sure some will disagree and I have not seen the radula of your animal, but the radula of orange, green and black animals from Australia have an identical radular morphology. your animal retains the greenish spots at the anterior end of the dorsum, and also down the sides of the body.

Concerning hybridisation. I have seen no evidence of hybridisation. It is a difficult question, because what may look like two species hybridising may be just two colour forms of the same species. We still have a bit to learn about the species of Nembrotha. Look at the messages about Nembrotha rutilans and similar coloured species, and the red-spotted Nembrotha species, to see what I mean.

Best wishes,
Bill Rudman.

Rudman, W.B., 1999 (Aug 24). Comment on Nembrotha livingstonei? from Japan by Atsushi Ono. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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