Opisthobranch of the Week Data
Noumea purpurea is considered to be rare on Okinawa as I have seen and collected a total of ten individuals since the initial specimen was found during a daytime SCUBA excursion on 9 May, 1987. The featured animal above was found crawling in the open on a vertical rock wall covered with cnidarians, bryozoans, poriferans, and others. All ten of the animals were found at Horseshoe Cliffs. The species was described by Baba (1949), based on four specimens, collected from shallow water at Hayama, Sagami Bay, Japan, between August & September of 1940.
Noumea purpurea is very similar appearing to both Durvilledoris pusilla and N. varians. N. purpurea is one of a group of similarly colored species of chromodorids having a pink or purple background color and a single longitudinal white line which Rudman (1986) calls the "Noumea purpurea colour group". D. pusilla differs from N. purpurea by its two pairs of purple lobes which extend uniformly to the lateral margins of the notum. N. varians has a rose-violet body, several median opaque white spots and a yellow emarginated line on the notum. I've added an additional image of N. purpurea, which is more typical of N. purpurea specimens found on Okinawa, with a single elongated median white stripe. The separated median stripe in the featured animal above is a variation, which is very similar to one of several illustrated by Rudman (1986, fig 2a, p. 314).