Aglaja tricolorata
Renier, 1807

Family: Aglajidae


Known from the Mediterranean and the west coast of Africa.


Locality: Sliema, 32 m, Malta, Mediterranean, 3 June 2004, sandy bottom. Length: 4 cm. Photographer: Patricia Peels.

The identification of Aglaja tricolorata has a confused history, and although most authors now consider the animal illustrated here to be A. tricolorata, I have a slight doubt because some reports describe an orange and a blue line at the edge of the parapodia, which has certainly not been noted in any specimen which looks like the accompanying photograph. Until Martinez et al's anatomical study (1993) of aglajids from the Iberian Peninsula, our knowledge of this species was based on Vayssiere (1880 - as Doridium membranaceum) and copied by Pilsbry (1896) and Pruvot-Fol (1954).

The species has distinctive tentacular corners on the anterior parapodia and a thin posterior flagellum extending out from the ventral fold of the posterior shield. The animal is a dark translucent brown with opalescent white spots scattered all over the dorsal surface and the sides. On the ventral surface the background colour is much more translucent and the white spots larger. Some reports say there are blue and orange lines along the parapodial edge but that seems to be a confusion with Philinopsis depicta. One thing that does puzzle me is why it is called tricolorata (= three colours) when only dark brown and white are found in this species. It is very similar in shape and colour to A. ocelligera from the west coast of Nth America.

  • Martinez, E., Ballesteros, M., Avila, C., Dantart, L. & Cimino, G. (1993) The family Aglajidae (Opisthobranchia: Cephalaspidea) in the Iberian Peninsula. Iberus, 11(1): 15-29.
  • Rudman, W.B. (1972) A comparative study of the genus Philinopsis Pease, 1860. (Aglajidae, Opisthobranchia). Pacific Science, 26(4): 381-99, 15 figs, 1 plate.
  • Pilsbry, H. A. (1896) Manual of Conchology; Structural and Systematic. With illustrations of the species. Vol. XVI.' (Eds G. W. Tryon and G. W. Tryon.) p. 262. (Academy of Natural Sciences: Philadelphia.)
  • Pruvot-Fol, A. (1954) Mollusques Opisthobranches. Faune de France, Paris 58: 1-460, Pl.1.
  • Rudman, W.B. (1974) A comparison of Chelidonura, Navanax and Aglaja with other genera of the Aglajidae (Opisthobranchia, Gastropoda). Zoological Journal of the Linnean Society, 54(3): 185-212.
  • Vayssière, A. (1880) Recherches anatomiques sur les mollusques de la famille des Bullides. Annales des Sciences Naturelles,  (ser 6), 6(4): 1-123.
Authorship details
Rudman, W.B., 2007 (January 31) Aglaja tricolorata Renier, 1807. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

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