Opisthobranch of the Week Data
Noumea flava is considered to be rare on the main island of Okinawa in as much as I've collected only a single 4mm (notum) specimen. The above featured animal is one which was photographed in the waters of Gahi Island, one of a series of islands in the Kerama Islands Group, which are located 30 ~ 40 kilometers west of the Okinawa capitol, Naha. The featured animal was photographed by Atsushi Ono during October of 1999, from dead coral in 25m of water. Atsushi's photograph is used here with his kind permission and he considers the species to be rare in the Kerama Islands; Atsushi reports (per. comm.) seeing only two individuals in the Keramas, and specimens were not collected.
I've included a very poor photo of the single collected specimen from Okinawa's main island. The animal was collected from ten feet of water on 3 May, 1996 and it's the only one I've found here to date.
The following species description of Noumea flava is taken from Rudman (1986):
Color: The whole of the animal, including the gills and rhinophores, is bright yellow. There is a thin bright red or orange-red line right at the end of the mantle. This line widens at fairly regular intervals to give a pattern of spaced semicircular spots around the mantle edge.
Shape: The mantle is ovate with a semi-permanent fold about midway along each side giving the animal the appearance of having a thin 'waist'. The body is relatively high and the mantle overlap is relatively narrow. The gills are simple and arranged in a circle around the anus. In the preserved specimen, a few large ovate opaque mantle glands were visible arranged in a submarginal band.
Noumea flava is part of a group of yellow Noumea which includes N. flava, N. crocea, N. sulphurea, N. closei and the yellow form of N. haliclona. See Bill Rudman's presentation on the Sea Slug Forum for a description of these yellow-colored Noumea species (the Noumea flava Colour Group). Of the above six species of described yellow Noumea, three are currently known from Okinawan waters:
Noumea flava is but one of ten species currently confirmed as being found in Okinawa waters. The ten Noumea species found here to date are: