Opisthobranch of the Week Data
Spurilla major is considered to be uncommon in Okinawan waters; I've not personally seen this attractive aeolid in waters of Okinawa's main island and Atsushi Ono reports the above featured animal is one of four which he has seen in the Keramas* (per. com.). The animal was collected by Atsushi in January of 1999 from a rope-supported buoy within the confines of a Zamami Island bay. Atsushi has furnished an image of a second individual, also from the Kerama Islands, showing the blue subapical band and yellow tip seen in the cerata of some specimens. Also, on the Slug Forum there is a blue pigmented animal from New South Wales which is similar to this second image by Ono; the Forum animal is quite similar to a species of Phyllodesmium. The major difference in external appearance between Phyllodesmium and Spurilla is the presence of papillae on the rhinophores of Spurilla, whereas in Phyllodesmium they are smooth. Both of the "Ono specimens" exhibit whitish patches of pigment over both cerata and body as well as showing the papillate rhinophores quite well.
Baba (1937, pp. 335-336) described a subspecies from Tomioka, Japan, Baeolidia major amakusana, which Rudman (2000) feels is a synonym of Spurilla major.
* Keramas = the Kerama Islands Group, located 30 ~ 40 kilometers west of the Okinawa capitol, Naha.