Chromodoris sphoni from Galapagos Ids

Dear Angel,
This is Chromodoris sphoni, which has been reported from the Galapagos Ids and along the east Pacific coast of central America to Mexico. It is very similar in colour to Chromodoris ruzafai, Ortea, Bacallado and Valdes, 1992, which as you say is known only from the Galapagos Ids at present.

Unfortunately I don't have photos of C. ruzafai for you to compare, but like C. sphoni it has a dark reddish purple region on the mantle with scattered yellow spots. In C. ruzafai the size and shape of the purple region is quite variable, while in C. sphoni it is usually cross-shaped, as in your photos. One other difference is that while C. sphoni has a series of blue, yellow and purple concentric bands around the mantle edge, the rest of the mantle in C. ruzafai is white. The rhinophores in C. ruzafai are deep red with a white tip, while in C. sphoni they are white with a reddish band around the upper half of the rhinophore club. These two species belong to a group of similarly coloured species in the eastern Pacific much like the red-spotted group in southeastern Australia.

I am interested in your record of feeding. I assume you mean Psammocinia [Thorectidae, Dictyoceratida] not Psammochinia. A sponge of this genus is the preferred food of Hypselodoris bennetti from southeastern Australia. Is the sponge the dark purplish patch in the lower right corner of the lower photo?

• Ortea, J.A., Bacallado, J.J. & Valdes, A. (1992) Resultados cientificos del Proyecto Galapagos: Patrimonio de la humanidad. No.1. Chromodorididae (Mollusca: Nudibranchia). Resultados cientificos del Proyecto Galapagos, TFMC 1:, 31-70. (Figs 1-20, Pls 1,2)

Best wishes
Bill Rudman