Upper: Seragaki, 180 ft (55 m), Okinawa, Japan, Pacific, 8 August, 2001, mixed coral rubble and sand with numerous thallophytes. Length: 2~5mm. Photographer: R. F. Bolland. Lower: Fig. 6, dorsal view of C. vegae from Ichikawa, 1993.
The most distinctive feature of this species appears to be the bright blue, or white spot on the upper side of each ceras. The spot is sometimes surrounded by a dark green ring. Ther can be a similar mark behind the eyes in the dorsal midline, but this can lack the ring, and be reddish in colour. A reddish subapical band can also be present on the cerata. It grows to about 10 mm and is found on the green algae Avrainvillea.
It is very possible that this is synonymous with the Caribbean species C. ocellifera. See comments in attached messages.
Ichikawa, M. (1993) Saccoglossa Opisthobranchia) from the Ryukyu Islands. Publications of the Seto Marine Biological Laboratory, 36: 119-139.
Rudman, W.B., 2006 (November 28) Costasiella vegae Ichikawa, 1993. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/costvega
Costasiella vegae from New Caledonia
From: jean-François Hervé, September 21, 2007
Costasiella ocellifera? from Okinawa
From: Robert F. Bolland, November 29, 2006
Caribbean Costasiella ocellifera from Okinawa?
From: Atsushi Ono, November 22, 2006