OKINAWAN
OPISTHOBRANCH OF THE WEEK

Protaeolidiella atra Baba, 1955 (size unrecorded)

Opisthobranch of the Week Data

Taxonomy:

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


Species Account:

        Protaeolidiella atra is considered to be uncommon on Okinawa; although I've collected only six specimens since the first animal was found in March of 1991, others have been seen but not collected.

        P. atra is extremely well camouflaged on its prey hydroid colony, the single row of white-tipped cerata mimicking the scattered white polyps of Solanderia (Rudman, 1990). In the case of four of the six collected specimens from Okinawa, my attention was brought to the animals presence by the brightly colored egg-masses found coiled around a branch of the hydroid prey, Solanderia sp. Upon closer inspection the adult animal was discovered. An image of a 18mm specimen collected from 14m, shows a nearby egg mass on the Solanderia hydroid. Baba (1992) reports the Solanderia sp. to be S. secunda in Japan while Rudman (1990) finds the host to be S. fusca in the South Pacific.

        P. atra is an unusually shaped aeolid, having reduced cerata and the presence of a relatively narrow shape. Rudman (1990, 1999) believes this has possibly occurred so as to allow the animal to be better camouflaged on its prey hydroid colonies.

Literature Cited:


Copyright © 1999 Robert F. Bolland
Digitally manipulated photo