Aplysia sydneyensis
Sowerby, 1869

Superfamily: APLYSIOIDEA
Family: Aplysiidae


This species has never been well defined so I am hesitant to accept all previous identifications. Specimens which seem to be this species are reported from southern Queensland, New South Wales, Tasmania, Victoria in southeastern Australia.


Two animals showing colour variation. Long Reef, Sydney, NSW, Australia. Many animals in tide pools often in mating pairs. 19 September 1978. AM C111827. Photo: John Fields.

Aplysia sydneyensis was originally described from a shell, and as Eales (1960) comments it has never been clearly defined. Eales, and subsequent workers have based their interpretation of the species on specimens identified by Australian zoologists as A. sydneyensis. This is a somewhat unsatisfactory situation, but it applies to many Aplysia names. We can either declare almost all species names in the genus to be impossible to identify, or persevere with in validating certain of the many species names available through usage. It is of course possible that the animal we are calling A. sydneyensis has a much wider distribution than is presently recognised. If so, there may be an earlier name for this species.

The body is translucent clear with a blotches of white and various shades of brown. Sometimes there can be a greenish tinge. There can sometimes be a pattern of dark brwon or blackish lines forming a reticulate pattern over the head and parapodia, and sometimes, as in the upper photo, there can be scattered dark brown rings. The mantlel covering the shell has a characteristic pattern of rays radiating out from the foramen. The rays can be dark brown lines, rows of spots, or in some cases white bands. The mantle foramen is small, sometimes contracted into a raised papilla. It grows to approx 150mm in length. It produces a deep purple coloured ink, as distinct from the wine red coloured ink of Aplysia dactylomela.

• Bebbington, A. (1977) Aplysiid species from Eastern Australia with notes on the Pacific Ocean Aplysiomorpha (Gastropoda: Opisthobranchia). Transactions of the Zoological Society of London, 34: 87-147.
• Eales, N.B. (1960) Revision of the world species of Aplysia (Gastropoda, Opisthobranchia). Bulletin of the British Museum (Natural History), Zoology, 5(10): 267-404.
• Sowerby, G.B. (1869) Aplysia In: Conchologia Iconica, 17. Reeve: London.

Authorship details
Rudman, W.B., 2002 (November 27) Aplysia sydneyensis Sowerby, 1869. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/aplysydn

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