Opisthobranch of the Week Data
The above featured animal, Goniodoris sp. 3, was photographed and collected by Atsushi Ono from the waters of Gahi Island in the Kerama Islands, one of a series of islands in the Kerama Islands Group, which are located 30 ~ 40 kilometers west of the Okinawa Capitol, Naha. This featured animal was found by Atsushi during September of 1999 in 5m of water from an area of rock and coral rubble. I've not personally seen Goniodoris sp. 3 in the waters of Okinawa's main island and Atsushi reports (pers. comm.) collecting two specimens as well as seeing several others from the Kerama Islands.
There are several images of Goniodoris sp. 3 found on Bill Rudman's Sea Slug Forum; there is also an excellent image of this Goniodoris on Yukinobu Adachi's Marine Photography page (an image of a 6mm animal photographed at Sunabe, from Okinawa's main island).
Marshall & Willan (1999) have a photograph of what would appear to be the same animal (as Goniodoris cf. violacea, p. 67, Fig. 110). I've taken the following description of external morphology and color from Marshall & Willan (1999) based on their collection of a single adult Heron Island specimen:
This is a very small plump dorid nudibranch that cannot retract the gills into a pocket beneath the mantle. The mantle, which is smooth, has a distinct brim separating it from the foot. The tail is long and rounded and there is no keel. The lamellate nonretractile rhinophores are large. The five gills are small.
The body and foot are uniformly opaque white. There is a faint yellowish brown line around the margin of the foot. The oral tentacles are speckled with brownish orange. The rhinophores have a translucent white stalk and opaque white clavus. The rhinophoral lamellae are often speckled with brown and the apex is also brown. The gills are uniformly opaque white.
Goniodoris cf. violacea is the only white species in the genus on Heron Reef. The long, smooth tail and small gills also serve as guides to identification. According to Risbec (1928), the original specimen of G. violacea from New Caledonia was pale purplish red with white speckles and a large translucent patch where the heart was located and the brim was darker violet than the remainder of the mantle. An anatomical investigation needs to be undertaken to decide whether our specimen is really G. violacea or not.
Goniodoris cf violacea probably feeds on compound ascidians. The spawn is unknown.
In addition to the above featured animal the following Goniodoris spp. have been previously featured on the Okinawa Slug Site: