Re: Fryeria guamensis from Nthn Mariana Ids

August 21, 2009
From: Yuji Fujie

Concerning message #11656:

Dear Dr.Bill,
Fryeria guamensis is very common in Saipan. I think this animal to be one of the most beautiful of the Phyllidiidae.

Locality: (LauLau Beach, 6m, Saipan, Northern Mariana Islands, Pacific Ocean, 21 September 2007, Side of the rock. Length: 30mm. Photographer: Yuji Fujie.

We do not sometimes understand the difference with Phyllidia tula

Would you give advice to us, please ?
Best regards,

Yuji Fujie, 2009 (Aug 21) Re: Fryeria guamensis from Nthn Mariana Ids. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Yuji,

Some of these phyllidiids are not easy to distinguish. One basic difference is that in species of Phyllidia the anus opens dorsally while in species of Fryeria it opens in the posterior midline under the mantle edge. There is some evidence to suggest in a couple of species of Fryeria that the position of the anus is variable, but we need more information.

One distinctive difference, if you remember to look, is that Phyllidia tula has a black line on the sole of foot while Fryeria guamensis does not. A more subtle difference is that in Fryeria guamensis the large tubercles in the centre of the mantle are arranged in longitudinal lines and the individual tubercles are arranged in an alternating pattern with the tubercles on each side.

In Phyllidia tula the tubercles are usually rounded, and those in the centre are arranged in a fairly random pattern. The tubercles gradually decrease in size from the centre to the outside of the mantle, but there can be a few small tubercles anongst the large central ones.
Best wishes,
Bill Rudman

Rudman, W.B., 2009 (Aug 21). Comment on Re: Fryeria guamensis from Nthn Mariana Ids by Yuji Fujie. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Fryeria guamensis

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