OKINAWAN
OPISTHOBRANCH OF THE WEEK

Hoplodoris bifurcata (Baba, 1993) 50mm

Opisthobranch of the Week Data

Taxonomy:

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


Species Account:

        Hoplodoris bifurcata is considered to be rare on Okinawa as I've collected a total of seven individuals (an additional animal was photographed but was neither measured for size nor collected). The above featured animal was collected near the end of a mid-day SCUBA excursion from five feet of water in a reef edge depression (spur & ridge formations amid a live stony coral reef), from beneath coral rubble.

        Hoplodoris bifurcata was originally described (as Carminodoris bifurcata) by Baba (1993) based on nine specimens from several locations found in the waters off mainland Japan.

        The following description of the external morphology of H. bifurcata is taken from Fahey & Gosliner, 2003:

EXTERNAL MORPHOLOGY.- The living animals range from 30-32 mm in length. The body is oval, flat and the notum is covered with large, round and tapered tubercles. The tubercles are mostly rounded on the dorsal median, becoming progressively more tapered around the median. The tubercles closest to the mantle edge are much smaller than the others. The coloration of the living animal is complex, and variegated. The ground color is light to medium gray, with mottled shades of darker grays and reddish-browns scattered over the mantle. There is a central dorsum, red-brown band of color, with all tubercles having the same coloration. On the tubercles towards the mantle edge, there is a white ring at the base followed by a red-brown or tan ring, and a white tip on some tubercles. Sprinkled randomly among the tubercles are tiny, dark brown or black spots. The long, tapered rhinophores have a light tan, short stalk with a darker tan, long lamellar portion (approximately 20 lamellae) that angles posteriorly and terminates with a white tip. The six posteriorly projecting gill leaves are tripinnate and feathery and the anterior leaves are light tan with whitish flecks of color, while the posterior leaves are red-brown. The rhinophore and gill sheaths are moderately tall and have tuberculate, irregular edges.
        The ventral side of some preserved specimens has retained only a few randomly sprinkled dark spots. The long, pointed oral tentacles have not retained any color, and the foot is anteriorly notched.

        I've added a second page showing three additional specimens of H. bifurcata, including a 23mm animal from 220ft, collected from Okinawa's main island.

Etymology:

Literature Cited:


Page Date: 17 Nov '03
Page Modification Date: 17 Nov '03
Digitally manipulated photo
Copyright © 2003 Robert F. Bolland