Sohgenia? from Kerama Ids

February 24, 2002
From: Atsushi Ono

Dear Bill,
The animal in the attached photo is very similar to Kato's animal. This is the animal I identified as as Eubranchus sp. 2 in my book but now I think it sacoglossa species. I had thought it was Mourgona sp....

Photo: May 28 2001, Zamami Is. 6m depth in Kerama Ids. 6mm long.

(I collected a specimen of this individual. All the big cerata came off which made it look very similar to Hamatani's painting.)
This is the second individual I have seen.
Atsushi Ono

Ono, A., 2002 (Feb 24) Sohgenia? from Kerama Ids. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Atsushi,
Thanks for this excellent photo. It makes me even more convinced that Hamatani's animal had lost most of its cerata when it was collected, or at least seen by him. Only two genera of the caliphyllids, Cyerce and Sohgenia, have the anus opening on a papillae midway between the eyes and the pericardium. If you look at Hamatani's drawing you can see it labelled '(a)'. If you look at Kato's photo there is a white object in the same position which I assume is the anal papilla. If so this would make his animal either Sohgenia or a Cyerce which has lost most of its cerata. The shape of the cerata, like in your photo, are cylindrical, quite unlike the flattened cerata of Cyerce. On these grounds I think we can be pretty sure that Sohgenia is not naturally 'bald' as in the original description, but has a full set of cerata, in normal circumstances. Of course its anatomy would need to be checked before we could be 100% sure.
Best wishes,
Bill Rudman

Rudman, W.B., 2002 (Feb 24). Comment on Sohgenia? from Kerama Ids by Atsushi Ono. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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