OKINAWAN
OPISTHOBRANCH OF THE WEEK

Gymnodoris okinawae Baba, 1936 (22mm)

Opisthobranch of the Week Data

Taxonomy:

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


Species Account:

        Gymnodoris okinawae is considered to be common on Okinawa's main island; I've collected nine specimens and have seen numerous others. I have specimens and photographs of quite a few individuals which may be G. okinawae, but in as much as the variation within the species is not well known these additional animals will have to remain as Gymnodoris spp. See also a second page with images of an additional Okinawa-collected specimen as well as a scanned image of Baba's original holotype specimen.

        Baba (1936) described the species based on a single specimen collected from Ishigaki Island (the third largest island in the Ryukyus Archipelago, after Okinawa and Iriomote Islands, located in the East China Sea, approximately 460km Southwest of Okinawa's capitol, Naha.

        The following species description is taken from Baba (1936):

        The living animal is limaciform and measures about 40 mm in length. The head is indistinctly expanded to form a subquadrate veil; the body is swollen at the middle of the body-length, where the branchiae lie, thence gets narrower and ends in an elongated tail. The back passes over into the sides of the body without clear demarcation. The back and lateral sides are sparsely covered with indistinct tubercles. The head is loaded with a pair of small conical rhinophores which are perfoliated and retractile within sheaths. The branchial plumes are rather small, tripinnate, 9 in number, non-retractile, and arranged in a circle round the anal papilla. The foot is linear; the anterior end is obtusely truncated and the hinder end passes off into a pointed tail. The mouth lies in front of the foot and is guarded by a pair of lobe-like oral tentacles.

        The ground-colour of the body is pale yellow; the upper surface is ornamented with spots and short lines of an orange-yellow colour; the perfoliated portions of the rhinophores are tinged with orange-yellow.

        The present species resembles Gymnodoris alba (BERGH) in the form of the teeth, but differs from it in the body-coloration as well as in the formation of the hermaphrodite glands.

Literature Cited:


Page Date: 12 Aug '02
Page Modification Date: 14 Feb '11
Digitally manipulated photo
Copyright © 2011 Robert F. Bolland