OKINAWAN
OPISTHOBRANCH OF THE WEEK

Thorunna florens (Baba, 1949) 15mm
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:

        Thorunna florens is considered to be rare on Okinawa's main island as I have seen and collected five individuals. I've added a second page with photos of the five collected animals as well as a scanned image of a painting as seen in Baba's 1949 publication. The above featured animal was photographed, but not collected, from the SE Area 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. This featured animal was found and photographed on a rock of a shallow coral reef by Atsushi Ono during March of 1998 in 5m of water. Atsushi's photograph is used here with his kind permission. It should be noted that Atsushi considers the species to be rare in the Kerama Islands as he has seen approximately five individuals (pers. comm.).

        Thorunna florens was originally described from Japan by Baba (1949) as Glossodoris florens; Baba's description was based on a single specimen from shallow water of Sagami Bay in July of 1939. Baba (1988) later reports additional anatomical information based on additional collected specimens. The following is taken from Baba's original description (1949, pp. 53 & 143-144):

        Length about 15 mm. Back smooth. Coloration of the back very complicated and beautiful. The region in front of the rhinophores faintly rosy red, the same colour continued behind as a median longitudinal band from between the rhinophores to the anterior base of the branchiae. With 2 conspicuous stripes on either side from behind the rhinophores to just the back of the branchiae, the inner stripe opaque white and edging the mid-dorsal rosy red band, the outer one chrome-yellow. There is a continuous row of purple-shaded spots, arrange inside the whitish mantle-edge, and the space between this and the above-said chrome-yellow stripes, is covered with a narrow band of faint green. In front of the rhinophores a transverse arc of chrome-yellow. Tip of foot with a row of purple-shaded spots. The rhinophores and the branchial plumes, orange-coloured. Radula formula 30 X 23-25.0.23-25. All the lateral teeth (including the 1st) tall and more or less spatula-shaped, their apex usually bifid, very rarely trifid.

        Thorunna florens is one of six described species of Thorunna known from Okinawan waters. The six species are:

Literature Cited:


Page Date: 23 Sep '02
Page Modification Date: 19 Nov '07
Digitally manipulated photo
Copyright © 2007 Robert F. Bolland