Is this aglajid a Philinopsis cyanea?

October 19, 2005
From: Nico Michiels

Dear Bill,

Here are two pictures of a sea slug that I found in 2 m on sand in the Rock Islands of Palau. It is 1.2 cm long and has no clear markings, except for a velvet bluish shine and thin white margins on the front of the head and around the ventral part of the tail lobes. The caudal tip of the head shield is pointed upwards very much as in many Philinopsis. Although P. cyanea seems a good guess, the two animals I found were identical in size (small for a P. cyanea ) and colouration, had no blue margins along the parapods, but are definitely sexually mature as they mated in the lab.

Locality: Rock Islands, Republic of Palau. Pacific Ocean / Phillipine Sea.
Depth: 2 m. Length: 1.2 cm. 10 August 2005. White sand, with high "worm hills" Photographer: Nico Michiels

The pictures show the same individual, but have been taken under very different light conditions to make sure that all features are visible.

Your comments are very much appreciated.
Best wishes,

Michiels, NK, 2005 (Oct 19) Is this aglajid a Philinopsis cyanea?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Nico,
Sorry this has taken a while to comment on, but I have been flooded with messages in the last couple of months. In colour, this has similarities to Chelidonura sp. 1 but obviously the body shape is quite different. It may be a species of Philinopsis, but the large notch on the posterior shield is larger than I would expect in this genus, and the posterior end of the head shield seems to taper to a rounded central tip, rather than having a central crest. I am pretty sure it's not Philinopis cyanea.

I think we would need to examine its anatomy to decide its genus as a first step. In the meantime I'll call it Aglajid sp. 10

Best wishes,
Bill Rudman

Rudman, W.B., 2005 (Oct 19). Comment on Is this aglajid a Philinopsis cyanea? by Nico Michiels. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Aglajid sp. 10