Phyllidia koehleri? and P. ocellata on red sponge

February 20, 2009
From: Marcel Tanke

Concerning message #22020:

Dear Bill,
We found this 2 phyllidiids feeding on a red sponge. The first, large one clearly Phyllidia ocellata. The second, small one, has the same yellow / orange main color. Could it be a juvenile P. ocellata? However, the long black stripes and small radial stripes on the edge of the mantle are uncommon for P. ocellata.

Pattern wise, the closed I could come is the white / black Phyllidiopsis sphingis.

Locality: Simalan Islands, site West of Eden , 20 m, Thailand, Adaman Sea, 29 January 2009. Length: 1 cm. Photographer: Marcel Tanke.

I checked several websites and books, no success.
Do you have any suggestions?

Best regards,
Marcel

marceltanke@cs.com

Tanke, M.A., 2009 (Feb 20) Phyllidia koehleri? and P. ocellata on red sponge. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22264

Dear Marcel,

Nice to get another observation linking phyllidiids to red sponges, though I don't think encrusting or thin forms like this would be easy to identify from photos only. It does however show the danger of thinking there is no food nearby when you see slugs crawling on sand - it is often only one sand grain beneath them!

Now to identfy your phyllidiids. The large one is indeed P. ocellata and your animal is identical to a David Brunckhorst photo of one from Thailand to be found on the species Fact Sheet.

I am pretty sure the small one is a colour form of Phyllidia koehleri. Normally it has three longitudinal black bands and ridges much like a species of Phyllidiopsis. However there is a photo in a message from Erwin Koehler [message #1533] of a specimen with radiating black bands on the mantle skirt much like in your animal. Your likening it to Phyllidiopsis sphingis is quite understandable. As I commented in an earlier message [#3741]  the colour pattern and thin longitudinal ridges down the body certainly are reminiscent of  species of Phyllidiopsis.

Best wishes,
Bill Rudman

Rudman, W.B., 2009 (Feb 20). Comment on Phyllidia koehleri? and P. ocellata on red sponge by Marcel Tanke. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22264

Factsheet

Phyllidia koehleri

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