Re: Supplement to Pacific Coast Nudibranchs

July 23, 2004
From: Joao Pedro T. L. S. Silva

Concerning Dave Behren's supplement [m12698]: Although I'm not planning on going anywhere in the Pacific, I found this paper a very interesting reading. One thing puzzled me: the animals on photo D of the Plate 3 are identified as Ancula gibbosa. It looks just like Polycera quadrilineata (at least the specimens I've seen). What are the distinguishing characteristics?

PS: it's great to see the Forum in back on the move!
All the best,
Joao Pedro

Silva, J.P., 2004 (Jul 23) Re: Supplement to Pacific Coast Nudibranchs. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Joao Pedro,
If you have a look at the page on Ancula gibbosa you will see there is some discussion on whether it occurs on the west coast of Nth America. However the most obvious external difference between the two is that A. gibbosa has three or four lateral papillae on each side of the gill circle while the P. quadrilineata has only one
Best wishes
Bill Rudman


Ancula gibbosa

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