Re: Cuthona gymnota? from Cork, Ireland

June 20, 2006
From: Marina Ossokine

Concerning message #16843:

Dear Bill and Jamie,
In my humble opinion, these animals aren't Cuthona gymnota (please let me call it so). In Arcachon Basin C. gymnota is a very common species in early spring when there is plenty of Tubularia everywhere. Jamie's animals don't look like my specimens for the following reasons :

- Jamie's animals are twice the largest size of C. gymnota
- the usual colour of C. gymnota is pale red / brown. I have never seen animals with so bright red colour by far
- the egg-mass of C. gymnota is very different from the one in Jamie's photo.

Please, see attached here the photos of an adult C. gymnota with the characteristic egg-mass. As you can see it, the curved packets of eggs are inside one single envelope. Also, I'm adding here a SEM photo of the radula showing the distinctive recessed median cusp characteristic of this species.

Locality: 'Hortense', Cap Ferret, Arcachon Basin, 4-5m , France, Atlantic Ocean, February 2005 & 2006 , fields of Tubularia. Length: animal : 12mm / eggs : 5mm + 3mm . Photographer: Marina Poddubetskaia Ossokine.

As for Jamie's animals, from the general shape and the related egg-mass, I think it is a Flabellina, but I couldn't suggest you the species. In Arcachon, another red Flabellina feeds on Tubularia - F. lineata, but it doesn't fit that species either.

Best wishes,
Nembro website

Poddubetskaia Ossokine, M., 2006 (Jun 20) Re: Cuthona gymnota? from Cork, Ireland. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Marina,
I agree that it looks like a Flabellina, that's why my Cuthona gymnota identification was tentative. Thanks for the photos of the radula and egg mass. It's funny how I misinterpreted Bernard's description of the egg mass. I envisaged his curved packets of eggs being arranged end to end like a string of sausages.

Interestingly this egg 'package' looks very similar to that in an earlier photo from XiKun Song [message #14556] of the egg mass of Pseudobornella orientalis which also lives on Tubularia. If Song had not mentioned he had seen Pseudobornella laying these eggs, I would have wondered whether there was a similar species of Cuthona in the Taiwan Straits.

Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Jun 20). Comment on Re: Cuthona gymnota? from Cork, Ireland by Marina Ossokine. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


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