OKINAWAN
OPISTHOBRANCH OF THE WEEK

Platydoris sanguinea Bergh, 1905 (25mm & 20mm)
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:

        Platydoris sanguinea is considered to be very rare in Okinawan waters; only three individuals have been seen by Atsushi (per. comm.) and RFB has seen none directly off Okinawa's main island. The above pair of featured animals were photographed, and collected, from 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 on the underside of a rock by Atsushi Ono during July of 1999 in 5m of water. Atsushi's photograph is used here with his kind permission.

        Dorgan, Valdes and Gosliner (2002) point out that the type specimen has been lost, but Mike Miller, featuring Platydoris sanguinea (from Bali) on his Slug Site in December of last year, has a scan of a line drawing taken from Berg's original description. Both Mike's and Atsushi's photos are excellent matches to the Berg line drawing. In addition, Mike also has a photo showing the yellowish egg ribbon of the species. Also, Marshall & Willan (1999) have a photograph of an additional similar appearing animal (as Platydoris sp. 2, fig. 145, p. 225).

        The following description of Platydoris sanguinea is taken from the description of external morphology from Dorgan, Valdes and Gosliner (2002):

External Morphology. The body shape is flat and wide. The dorsum is covered with small caryophyllidia. The branchial sheath has six branchial lobes, with the anterior and posterior ones being larger than the others. The gill is composed of six tripinnate branchial leaves. The perfoliate rhinophores always have 22 lamellae. The colour of the dorsum is dark red or orange-red with a few white spots. The rhinophores are also red with white spots and the branchial leaves are white. The gill is far less ramified than in other species studied. The pigment around the outer edge of the mantle is slightly darker red. The ventral notum is scattered with very small, dark spots.

        As of late-March, 2003, the following four described species of Platydoris are known from Okinawan waters:

Etymology:

Literature Cited:


Page Date: 24 Mar '03
Page Modification Date: 31 Mar '03
Digitally manipulated photo
Copyright © 2003 Robert F. Bolland