Aglaja tricolorata from Malta

Dear Patricia,
Thanks very much for this photo of Aglaja tricolorata. When I revised this family in the 1970s it was very important to sort out the Mediterranean species, as the genus names Doridium and Aglaja  were based on animals from there. Unfortunately the literature was quite confusing and it was not until quite recently that good descriptions have appeared. I must say however that the name of A. tricolorata [tricolorata (= three colours)] does make me wonder if we have misidentified this species, which is essentially dark brown and white.

The drawing alongside is a good example of the confusion. It is an illustration of Aglaja tricolorata from Vayssiere (1880 - as Doridium membranaceum) and was copied by Pilsbry (1896) and Pruvot-Fol (1954). The distinctive tentacular corners on the anterior parapodia are absent and the thin posterior flagellum is shown to originate from the top of the posterior shield when it in fact extends out from the ventral fold. The small dark specks are also misleading, as 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.

• 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.

Best wishes,
Bill Rudman