Re: Thordisa filix? from northern Spain

March 27, 2008
From: Juan Lucas Cervera

Concerning message #21053:

Dear Bill and Jacinto,

I think this species is not Thordisa filix (the westernmost record is from the Strait of Gibraltar) but T. azmanii Cervera & Garcia-Gomez , 1989. This last species has been recorded from northern Iberian Peninsula (from Asturias) by Ortea and Martinez (1990) under the name of T. diuda Marcus, 1955. However, in a recent paper Chan and Gosliner (2006) confirm that both species are different.

The angle of the light from the flash does not permit to appreciate the browish ground color of this species (much darker than T. filix). Moreover, the papillae have an opaque white pigmentation (not present in T. filix) and the number of papillae are lower than in T. filix.

Although it is difficult to see, I can appreciate that the upper regions of rhinophores and gills are also white (the lower region are dark brown).

Fron an internal point of view, T. filix has a prostate completely different from the remaining species of the genus, since is arranged as a very big spiral visible inmediately when you dissect this species.

  • Chan, J.M. & Gosliner. T.M. 2007. Preliminary Phylogeny of Thordisa (Nudibranchia: Discodorididae) with Descriptions of Five New Species. The Veliger, 48(4): 284–308..
  • Cervera, J. & Garcia Gomez, J. 1989  A new species of the genus Thordisa. (Mollusca: Nudibranchia) from the southwestern Iberian Peninsula. The Veliger, 34(4): 382–386.
  • Ortea, J. & Martínez, E. 1990. Captura en la Concha de Artedo de Thordisa diuda Marcus, 1955 (Nudibranchia: Doridacea), un nuevo molusco anfiatlántico. Boletín de Ciencias de la Naturaleza del Instituto de Estudios Asturianos, 40: 3-11.
  • Ortea, J. A. & Valdes, A. 1995. Una nueva especie de Thordisa Bergh, 1877 (Mollusca: Nudibranchia: Discodorididae) de las costas Angola. Avicennia, 3:35–41.


Cervera, J.L., 2008 (Mar 27) Re: Thordisa filix? from northern Spain. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks Lucas,
It's species like this that need a local expert to be sure. Concerning the distribution of T. filix, I used the Table III in your checklist (Cervera et al, 2006) and thought Galicia was one of the 'spots' for that species, but misread the spots. However on checking I see you list it as occurring on the Portugese coast which suggests it has an overlapping distribution with T. azmanii which seems confined to the Atlantic coast. I would be grateful if you could clarify that.

Also what is the animal that Ortea & Martínez (1990) identified as T. diuda? In your checklist you identify it with T. azmanii but from their illustration of its reproductive system, its prostate is not the spiral shape you say is characteristic of T. azmanii.

  • Cervera, J. L., Calado, G., Gavaia, C., Malaquias, M. A. E., Templado, J., Ballesteros, M., García-Gómez, J. C., & Megina, C. (2006) An annotated and updated checklist of the opisthobranchs (Mollusca: Gastropoda) from Spain and Portugal (including islands and archipelagos). Boletín Instituto Espanol de Oceanografía  20: 1-122.

Best wishes,
Bill Rudman

Rudman, W.B., 2008 (Mar 27). Comment on Re: Thordisa filix? from northern Spain by Juan Lucas Cervera. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Thordisa azmanii

Related messages

  1. Re: Thordisa filix? from northern Spain
    From: Juan Lucas Cervera, March 27, 2008
  2. Thordisa filix? from northern Spain
    From: Jacinto PĂ©rez, March 26, 2008

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