Opisthobranch of the Week Data
Gymnodoris citrina is considered to be common in Okinawa's main island as well as in the Kerama Islands Group (Atsushi Ono reports seeing hundreds there, pers. comm.), which are located 30 ~ 40 kilometers west of the Okinawa capitol, Naha. I've collected twenty-seven specimens from Okinawa's main island and many others have been seen but not collected. I've added A second page illustrating some additional individuals, including a photograph by Atsushi Ono of G. citrina feeding on opisthobranch ova.
The following species description of G. citrina, based on Hong Kong material, is taken from Rudman & Darvell (1999):
Remarks. The animal is translucent white or straw coloured with small orange spots all over. Each spot is raised on a short pointed papilla. The rounded mantle ridge around the head lend is fringed with these papillae. The rhinophore is translucent white, straw coloured or tending to olive green and usually the club is tipped with orange. The gills form a semi-circle or complete circle. They are quite large and straw coloured and sometimes there is an orange line on the outer edge of each gill axis. Some specimens are much more heavily pigmented with orange, with large orange spots, the head almost completely orange and the gills and rhinophore club translucent orange.
Scott Johnson (2000) in a posting to the Sea Slug Forum has a remarkable series of photographs of G. citrina showing cannibalism as well as G. citrina feeding on the eggs of G. striata. Additionally, Scott's photos show both the yellow and white forms of G. citrina.