Caribbean Costasiella ocellifera from Okinawa?

November 22, 2006
From: Atsushi Ono

Dear Bill:

In Okinawa, I found this individual which looks very much like Costasiella ocellifera. There might not have been problem if this individual had been found in the Caribbean Sea! To my regret,because egg ribbon is not found , the development type is uncertain. This individual was growing on Avrainvillea lacerata var. robustior between branches of Porites (Synaraea) rus of 9m in depth.

Locality: Kerama Is. Okinawa, 9m, Japan, East China Sea, July 2006. Length: 4mm. Photographer: Atsushi Ono.

Atsushi Ono

Atsushi Ono, 2006 (Nov 22) Caribbean Costasiella ocellifera from Okinawa?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Atsushi,
This is indeed an interesting find. As you suggest, A. ocellifera is known only from the Caribbean so if this is the same species, then its discovery in Okinawa suggests that it may have been transported by shipping. Is it A. ocellifera? The only external difference I can see is that the small black spots found in Caribbean animals seem to have been replaced by orange-brown spots on the body and sole of the foot. This shift from black to orange pigment seems to be quite a common occurrence in opisthobranchs, so my feeling is that this is indeed A. ocellifera.

Comments from experts would be very welcome.

Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Nov 22). Comment on Caribbean Costasiella ocellifera from Okinawa? by Atsushi Ono. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


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