OKINAWAN
OPISTHOBRANCH OF THE WEEK

Gymnodoris nigricolor Baba, 1960 (photo only, size not recorded)
The gymnodorid is attached near the insertion of the first dorsal fin of the goby.

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 nigricolor is considered to be uncommon and very seasonal here (during a typical year the animals are first seen between January and about mid-June; reappearing about the middle of December). I've collected more than fifty individuals since the initial specimen was collected on 3 February, 1990 (the first was seen on 7 May, 1989, with its host goby). It should be noted that although fifty plus animals have been collected, many of these were collected along with their goby hosts and the search for these has been "labor intensive" to say the least. On some dives I've spent over 180min in the upper six meters searching for these elusive little gymnodorids. Admittedly, I've been more interested in the gymnodorid/goby associations than I have with the individual dorids themselves, and have therefore allowed quite a few of the observed unattached gymnodorids go uncollected.

        I've added an additional page, showing a mating pair, one individual laying an egg rosette, and another animal showing the relatively high profile of both the rhinophores and gills.

        Baba (1960) described the species from a single 4mm animal collected from Misaki, Sagami Bay, Japan, in November of 1956. He reported that it was found in 2 meters on bottom mud. Baba (1960) in describing the morphology of the species points out, in part, that it is:

        Very distinct in colouring and in the shape of the radular teeth. Length 4mm. Body smooth. Gills small, consisting of 9 plumes arranged in a semicircle open behind. Back and sole uniformly bluish black; rhinophores and gills also bluish black.

Literature Cited:


Page Date: 20 Nov '00
Page Modification Date: 14 Feb '11
Digitally manipulated photo
Copyright © 2011 Robert F. Bolland