Thordisa filix
Pruvot-Fol, 1951

Suborder: DORIDINA
Family: Dorididae


Previously known only from western Mediterranean. Reported here from Turkey.


Istanbul, Turkey. Divesite: Yassiada, 30 September 2001.
UPPER: Depth: 28m, Size: approx. 5cm.
LOWER: Depth: 26m, Two animals approx. 5cm, 3cm long. [Lower left - Close-up to show two tubercle types on mantle]. PHOTOS: Baki Yokes.

There are few records of this endemic Mediterranean species. It is characterised externally by the pale translucent white or yellowish mantle with diffuse brown spots and it has four gills. The mantle is covered by two types of tubercles: most are short and rounded, and a few that can extend into long tapering papillae.

• Cattaneo-Vietta, R. R. Chemello, R. Giannuzzi_Savelli, R. (1990) Atlas of Mediterranean Nudibranchs.
• Schmekel, L. & Portmann, A. (1982) Opisthobranchia des Mittelmeeres. Springer-Verlag: Berlin. 410pp.

Authorship details
Rudman, W.B., 2001 (October 15) Thordisa filix Pruvot-Fol, 1951. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

Related messages

Re: Thordisa filix? from Turkey

March 12, 2002
From: Juan Lucas Cervera

Dear Bill,
Concerning Baki Yoke's animal from Turkey, I've only seen Thordisa filix once. It was a single specimen from Portugal (Atlantic). The colour pattern was different, with rhinophores and tubercules darker, with 3 big dark spots on the back. I dissected this specimen to confirm the correct identification (a very and unique characteristic very coiled prostate). I attach a photo of this specimen. The gills are retracted in this photo.

Cervera,J.L., 2002 (Mar 12) Re: Thordisa filix? from Turkey. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks Lucas,
Thordisa villosa in the Indo-West Pacific is quite variable in colour so it could be the same with T. filix. Baki's photo shows some small brown spots in the dorsal midline which may represent the large ones in your photo.
Best wishes,
Bill Rudman.

Rudman,W.B., 2002 (Mar 12). Comment on Re: Thordisa filix? from Turkey by Juan Lucas Cervera. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thordisa filix? from Turkey

October 17, 2001
From: Baki Yokes

Dear Bill,
Recently I encountered a nudibranch species which I had never seen before. They are so flat that it is nearly impossible to take a clear picture of them, since they are almost embedded to the surface they are found on. The gills seem to indicate a Thordisa species. What is your opinion?

They were photographed at Istanbul, Turkey Divesite: Yassiada], 30 September 2001.
UPPER PHOTO: Showing extended gills - Depth: 28m, approx. 5cm long.
LOWER PHOTOS: A pair 3, 5cm long: Lower Left photo showing maginified view of mantle showing nature of papillae. Depth: 26m
Photos by Baki Yokes.

Best wishes

Yokes, B., 2001 (Oct 17) Thordisa filix? from Turkey. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Baki,
I think this is Thordisa filix Pruvot-Fol, 1951. I am not familiar with the species but your animal looks like Thordisa and the ilustrations of Thordisa filix in Mediterranean books appear to be the same. As far as I know it has been rarely found, and only in the western Mediterranean, so if my identification is correct, yours is a new record for the northeastern Mediterranean.

Best wishes,
Bill Rudman

Rudman, W.B., 2001 (Oct 17). Comment on Thordisa filix? from Turkey by Baki Yokes. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from