Known only from Okinawa in the Ryukyu Islands, Japan.
Upper: Seragaki Tombs, Okinawa, Japan. Photo: R.F. Bolland. Lower: SEM of radula showing lateral teeth on right side (CASIZ 070256). Scale bar = 19 µm. [Photos from Gosliner, 2004 with permission].
The animal is relatively elongate and there is a well-developed, mantle edge bearing seven elongate papillae along each side. The two anterior-most papillae on each side are situated in front of the rhinophores and are anteriorly directed. There are also two papillae in the dorsal midline between the gills and the rhinophores. There are four or five simple gills. The rhinophores are elongate, similar in length to the lateral papillae. The anterior corners of the foot are extended into a pair of elongate tentacular processes. The oral tentacles are broadly triangular and extend beyond the lateral margins of the foot.
The animal is uniformly translucent purple and there is an irregular network of thin darker purple lines on the dorsal surface. Darker purple pigment is also present on the gill lamellae. The rhinophore stalks are darker purple while the clubs are a translucent reddish colour. The largest reported living animals are 10-12 mm in length.
Reported to feed on ctenostome bryozoan Amathia sp (see Rudman, 2004).
Gosliner, T. M. (2004) Phylogenetic Systematics of Okenia, Sakishimaia, Hopkinsiella and Hopkinsia (Nudibranchia: Goniodorididae) with descriptions of new species from the tropical Indo-Pacific. Proceedings of the California Academy of Sciences, 55: 125-161
Rudman, W.B. (2004) Further species of the opisthobranch genus Okenia (Nudibranchia: Goniodorididae) from the Indo-West Pacific. Zootaxa, 695: 1-70.
Rudman, W.B., 2004 (December 21) Okenia purpureolineata Gosliner, 2004. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/okenpurp