OKINAWAN
OPISTHOBRANCH OF THE WEEK

Gymnodoris striata (Eliot, 1908) 35mm
Photo by Atsushi Ono

Opisthobranch of the Week Data

Taxonomy:

Frequency on Okinawa:
Collection Data:
[brackets indicate range for all Okinawa-collected specimens of the species]


Species Account:

        Rudman & Darvell (1990) report the following concerning Gymnodoris striata:

Remarks.
        This species is characterized by its pattern of bright orange lines on a white or yellowish background. One line runs around each edge of the mantle, from the head, to just behind the gills where it folds under on each side to run forward midway between the mantle edge and the edge of the foot, which is bordered in orange. The gills are edged with orange, and the rhinophore club is also orange. Although Johnson and Boucher (1983) report a specimen 55 mm long alive, the largest Hong Kong specimen has a preserved length of 11 mm.
        Specimens from Japan and Hong Kong lack further orange lines on the dorsum but have an orange crescent-shaped transverse bar just in front of the gills. A specimen from Western Australia is similarly coloured (Coleman 1981). All other known specimens from the Indo-West Pacific, including specimens from Hainan Is., China, have more longitudinal orange lines on the dorsum and lack the transverse crescent. It is possible that there are two species but no obvious differences have been found in the anatomy or radular morphology.
Geographic Distribution.
        It has a wide Indo-West Pacific distribution. Originally described from the Red Sea, it has been reported from Japan, China, Eniwetok Atoll, Fiji, New Caledonia and northern Australia.

        Scott Johnson (1999) reports and features photographs in the Sea Slug Forum on the feeding behavior in Gymnodoris striata at Eniwetok Atoll. Scott's images show several different individual G. striata eating the common Placobranchus sacoglossan.

        Gymnodoris striata is currently unknown from the waters of Okinawa's main island and Atsushi Ono reports (pers. comm.) seeing only two animal in the Keramas (the above 35mm animal as well as an approximate 25mm individual). The above featured animal was found and photographed from 3 meters on mixed sand and coral rubble by Atsushi in September of 1998 from Zamami Island, Kerama Islands Group, located 30 ~ 40 kilometers west of the Okinawa capitol, Naha. Atsushi has kindly furnished the above image and is used here with his permission.

        In addition to the above G. striata, there are to date the following eight described species of Gymnodoris, known from Okinawan waters:

        In addition, there are several species of Gymnodoris in the Keramas, not yet found associated w/ Okinawa's main island. I also have a quite a few undescribed species of Gymnodoris as well as quite a few indeterminate Gymnodoris species.

Literature Cited:


Page Date: 08 Jul '02
Page Modification Date: 01 Feb '15
Digitally manipulated photo
Copyright © 2015 Robert F. Bolland