Phidiana salaamica from Kerama Island

Dear Atsushi,
As I thought when I first saw your book, I am as sure as I can be without dissecting an animal, that your photos are of Phidiana salaamica which I found a few times in Dar es Salaam, 20 years ago, and have never seen or heard of since!

The cerata in Phidiana salaamica are very distinctive. In front of the pericardium the cerata are arranged in 4 or 5 slightly sloping rows. Behind the pericardium the ceratal are arranged in pairs of sloping rows, or at the posterior end, a few single rows. The most distinctive feature is that the innermost ceras in the posterior row of each ceratal cluster, is very elongate, and sits coiled over the dorsum. When the aeolid is threatened or disturbed, these enrolled cerata quickly unroll and become stiff and erect. All other cerata stand out horizontally. Another animals with similar behaviour is Moridilla brockii.

In specimens from Dar es Salaam the digestive gland was an apricot yellow and the end of the gland in each ceras, below the cnidosac, was capped with reddish-purple. This purplish cap can be seen in the photos from Kerama Island as well.

This is an interesting find and suggests this species has a wide Indo-West Pacific distribution. The shape and arrangement of the cerata, and the similar colour pattern, strongly suggest that these animals from Kerama Island are Phidiana salaamica.

Bill Rudman.