March 16, 2009
From: Vishal J. Bhave.
From its morphology it looks like Phidiana anulifera but I need further help.
It was found a rockpool, at lowtide. The rockpool was full of small rocks and it was found under one in a shadowed area of pool. Some rocks were encrusted with hydroids and wall of rockpool was full of hydroids, bryozoans, some small molluscs and sponges.
Locality: Black sea, Mandvi, Ratnagiri, 0.5 feet, Maharashtra, India, Arabian Sea / Indian ocean, 08 February 2009, Rock pool, rocky substratum, Intertidal,. Length: 4-5 mm. Photographer: Vishal Bhave.
Bhave, J.V., 2009 (Mar 16) Phidiana anulifera from Ratnagiri, India. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22326
This is a very interesting find. Your animal certainly looks like Phidiana anulifera except that the body is opaque white while in other examples the body is translucent clear with a scattering of opaque white spots. However I suspect your animals represent a colour variation in which the white spots merge to form a continuous white background. Not many aeolids have been described from India so I am pretty sure there is not an old name lurking around for this species. However it would not surprise me if Phidiana semidecora (Pease, 1860) which was first described from Hawaii, and Phidiana bourailli (Risbec, 1928), first described from New Caledonia, turned out to be synonyms of P. anulifera.
The egg ribbon behind the animal in your photos could well belong to this animal. If an aeolid finds a large hydroid colony it will stay there until all polyps are eaten. Often you will find one or more of its egg ribbons nearby.