Gosliner & Fahey, 2008
Known only from Bali, Indonesia.
Upper: CASIZ 172855, Tulamben, Bali, Indonesia, 5 mm. Photo: T. Gosliner. Lower: CASIZ 172855. Radular morphology. Scale =3 µm. [From Gosliner & Fahey, 2008 Fig 2C].
The background colour of the body is a translucent bright blue, but this is largely obscured by large symmetrically arranged patches of opaque cream-yellow on the foot, sides of body and the dorsum.. There is also a thin dark brown line running back from the inside edge of each rhinophore pocket before angling out to the mantle edge just in front of the gills and running around the mantle edge to join the corresponding line on the other side. The gills and rhinophores are a dull translucent brown.
The extra-rhinophoral appendages and extra-branchial appendages are a translucent cream-yellow. The extra-rhinophoral appendages are relatively short and curved, looking fairly normal for the genus, but the extra-branchial appendages are said by Gosliner & Fahey to be shaped like "flattened shields". Unfortunately they give no drawing of these structures and I can't make out any detail in their photo [see above] so I am not sure how they differ from other species. The two known specimens were 5 and 7 mm in length.
Gosliner, T.M. & Fahey, S.H. (2008) Systematics of Trapania (Mollusca: Nudibranchia: Goniodorididae) with descriptions of 16 new species Systematics and Biodiversity, 6 (1): 53-98
Rudman, W.B., 2008 (March 10) Trapania caerulea Gosliner & Fahey, 2008. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/trapcaer