March 20, 2001
From: Bernard Picton
In C. gymnota the rhinophores and oral tentacles don't have white surface pigment and are colourless or tinged with orange. The rhinophore and oral tentacle pigmenation in these species is usually a reliable character in my experience. I still use Catriona for this species as it seems different to the other British species of Cuthona in a number of ways and has a distinctive radula.
UPPER: Skomer Is., S. Wales. - June 1976
LOWER: Streymoy, Faeroe Is. - July 1980 - more brightly pigmented than normal for the British Isles.
firstname.lastname@example.orgPicton, B., 2001 (Mar 20) Photos of Cuthona gymnota. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3998
These small aeolids seem to cause problems with identification worldwide. I suspect part of the problem is the subleties and complexities of their colour patterns, which are difficult to describe in words. Hopefully the more colour photos we can publish, the greater the chance of clarifiying the differences.
Concerning Catriona, I agree that we probably have not heard the final word on the genera in this group. Unfortunately we had got to the point where every slight difference was being elevated to generic status which didn't help either. In my experience, the C. gymnota - type radula, in which the central cusp is set back from the other cusps, seems to occur amongst species which seem to be feeding on the hydroid tisue in the 'roots' or stolons of the hydroid colony rather than the polyps. I haven't any rigorous experimental evidence to support that, but some cuthonids seem to be found nestling in the basal parts of the colonies rather than up near the polyps. Have you noticed any such difference?
Re: Cuthona gymnota? from Cork, Ireland
From: Marina Ossokine, June 20, 2006
Cuthona gymnota? from Cork, Ireland
From: Jamie Malone, June 16, 2006
Cuthona gymnota from Maine, USA
From: Alan Shepard, September 2, 2003
Re: Photos of Cuthona gymnota
From: Bernard Picton, March 23, 2001
Cuthona gymnota from the Netherlands
From: Peter H. van Bragt , September 26, 2000