OKINAWAN
OPISTHOBRANCH OF THE WEEK

Durvilledoris similaris Rudman, 1986 (10mm)
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:

        I've not personally seen Durvilledoris similaris here in the waters of Okinawa's main island, however Atsushi Ono mentions (pers. comm.) that the above featured animal is one of approximately ten individuals he's seen in the Keramas* and he considers the species to be rare there. Atsushi reports that this animal was found on rock in a reef environment. I've added a second page with an additional animal of Atsushi's from Gahi Island (Keramas).

        Durvilledoris similaris is one of three species of Durvilledoris found to date (April, 2005) in Okinawan waters. The additional two species are:

        The following partial description of Durvilledoris similaris is taken from Rudman (1986):

        Color: The mantle is a pale pinkish-purple colour with a white band around the edge. At the end of the pinkish-purple region, alongside the white border, are diffuse reddish-purple patches which coalesce anteriorly and posteriorly to form an irregular reddish crescent in front of the rhinophores, and another behind the gill pocket.
        A median white line runs from between the rhinophores back to and encircling the gill pocket. In one specimen the upper half of the rhinophore club is orange and the lower half and stalk are translucent white. In the other specimen the rhinophore club is a deeper orange-red, the colour extending almost to the base of the club. The stalk is a pale translucent purple.
        Shape: The mantle is elongately ovate with a relatively narrow mantle overlap. The gills are simple. The mantle glands are clearly visible in preserved specimens forming a closely packed series of glands right around the edge of the mantle. They open at the edge of the mantle and correspond to the white marginal mantle band. The glands are twice as large at the posterior end of the mantle.

Remarks
In colour, this species is almost identical to the colour form of Pectenodoris trilineata with the single median white line only and to Noumea varians, but features of the internal anatomy clearly differentiate the three species.

Etymology:

Literature Cited:


        * Keramas = the Kerama Islands Group, located 30 ~ 40 kilometers west of the Okinawa capitol, Naha.


Page Date: 04 Apr '05
Page Modification Date: 04 Apr '05
Digitally manipulated photo
Copyright © 2005 Robert F. Bolland