Another Melibe from Turkey

Dear Baki,
Thanks for the photo of this swimming Melibe. I am sure this is the same species as the one reported by Thompson & Crampton (1984) in large populations from Greece. It is certainly an immigrant from the Red Sea / Indian Ocean. The problem is giving it a name. As I said in reply to Peter Van Bragt's message, the problem is the lack of information we have on variation within populations. Species of Melibe have no radula and they are rather uniformly coloured with drab brown and opaque white, so the two most useful characters in nudibranch identification are not available to us.

Differences which have been used are shape of cerata, degree of development of gills and papillae, and colour. While some species, such as Melibe leonina and Melibe rosea are very distinctive, separating many species is very difficult. Until more studies are done on populations of these animals so we better understand how they change shape and colour as they grow from juveniles to adults, I think out identifcations will involve a considerable amount guesswork.
Best wishes,
Bill Rudman