Rare seen nudibranch

Hi Folks,does somebody know what type of nudibranch this is. I've spent an evening searching my books and googled, but i found noanswer or description about it.I encountered this beautiful "Nudibranch" in Sardinia/Italy on the border between sand and poseidonia seeweed covered rocks 10mt/30ft deep.He/she was about 15cm/8 inch long and was "gliding" rather quick for a nudibranch/sea slug

Thansk a lot!

Chris

P.S. The brown "thing" on his back are not branchies, it's some piece of marine growth.

P.P.S Zooming in the original RAW photo i discovered that the brown "thing" may be the branchies, but i remeber that it was a piece of algea or something else.

I could be wrong, but it looks like some kind of Spanish Dancer to me.

wikipedia

Stew

Looks like a Platydoris argo, and the "branchies" are the gills.

Cheers,

Marli

@ Stew: No, there are no spanish dancer in the mediterrean sea, but maybe something similar, but thanks anyway!

@ scubamarli: BINGO! You got it! Thanks very much!

There is only one strange thing, the one i photographed measured the size of my palm (i measured it after taking the photos) and the descriptions i found talk

of a size of 5-10 cm, but my palm is 15cm. Anyway, it looks exactly as some of the pictures i found searching for Platidoris Argo.

Thanks a lot guys!

Chris