October 17, 2001
From: Anne DuPont
Can you confirm that this is Tritoniopsis frydis? The photo was taken on August 22, 2001 in 35 feet of water on a night dive, off Pompano Beach, Florida, USA. The critter was about 1/2 inch long and was found on a purple rope sponge. We have done several night dives at this site, and we only find them at night, and only on this type of sponge, and most of them were smaller than this one.
firstname.lastname@example.orgDuPont, A., 2001 (Oct 17) Tritonia bayeri from Florida. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/5481
Although it looks superficially like Tritoniopsis frydis there are a few features which make me pretty sure it is Tritonia bayeri. Firstly the translucent clear body with its very obvious reticulate network of opaque white are characteristic of T. bayeri and the relatively small gills are quite different from the position in Tritoniopsis where the gills are usually much more extended and 'bushy'. The most important difference is the shape and number of the papillae on the edge of the oral veil. Tritoniopsis frydis has numerous papillae along the edge, alternating between large and small. In Tritonia bayeri there are only four relatively long and large papillae as can be clearly seen in your photo.
One difference between your photo and Marcus's original description is that they describe a long papillae, similar in size and shape to those on the oral veil, originating from the edge of the rhinophore sheath. I can't see any sign of it in yoru photo or for that matter in Barry Lipman's earlier photo. Perhaps the Marcus's misinterpreted a shadow in the photograph they used to draw the animal. I am not sure, but it a charcter worth checking in other specimens.
Interestingly both species were described from animals found in the Florida region. The animal you have photographed T. bayeri on is not a sponge, but rather a gorgonian octocoral, in which the polyps are retracted. Tritoniids feed on a variety of soft corals and Marcus & Marcus report this species from a soft coral "... Briareum asbestinum (Pallas), feeding after the manner of Cyphoma .. " and a gorgonian "on Pseudopterogorgia".
Thanks for the interesting record, and when you find some, I am still interested in some photos of Tritoniopsis frydis.