Melibe japonica? from Japan

Dear Jason,
I think this is a species which has never before been illustrated. I am pretty sure it is Melibe japonica which was described by Charles Eliot (1913) from a preserved specimen. He described the colour as "transparent yellowish white, with a strong reddish tinge in parts" but I suspect that refers to its preserved state. Baba, (1949) states that living specimens, which he identifies with Melibe japonica, are 'not common' on the Pacific coast of Japan.

He describes it as "colossal, often attaining over 50cm in length, and with a strikingly large hood and expanded foot". I can't see the rhinophores in your photos but Baba describes the 'rhinophore sheaths as small' which may explain my difficulty. Baba also describes the body colour as pinkish with the hood margin and various tubercles as deeper reddish. He also describes blunt tubercles on the oral hood, sides of body and cerata. The only difference I can see is that both Baba and Eliot describe bushy or dendritic papillae irregularly arranged down the midline of the body between the cerata. I can't see these in your photos but it is possible that a series of fuzzy reddish bumps I can see in one of your full size photos are retracted papillae. So I would be grateful if you could check any other photos you have to see if you can see papillae on the back, or a clearer shot of the centre of the back, between the cerata, so I can see if there is any sign of retracted papillae. I would also be grateful if you could let me know when you photographed this animal.

It is a very interesting find. Perhaps Terry Gosliner can give us his views on it
Best wishes
Bill Rudman