Aldisa sp. 2 from Heron Island

October 20, 1999
From: Julie Marshall

Dear Bill,

These are pictures of an Aldisa species found in September 1994 at Heron Island. It was 30 mm in size but other animals found over the years during the months from August to January varied from 20 mm to 40 mm. The major characteristics of this species are the regularly spaced low pustules on the dorsum, each of which has a black centre, and the two large pits, one behind the rhinophores and the other immediately in front of the gills (see enlargement). It also has two transverse lines of white speckles, sometimes fused, between the rhinophores and gills and these lines vary in their intensity between individuals. All animals have been found at low tide at the reef crest under dead coral slabs, usually singly or in pairs, but on one occasion (October 1990) six animals were found together. It lays a pale red spawn mass.

In colour this species resembles both Aldisa sanguinea and A. pikokai but both these species are a paler red and neither species has pustules with black centres.

Best wishes

Julie Marshall

Marshall, J., 1999 (Oct 20) Aldisa sp. 2 from Heron Island. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Julie,
Thanks for the photos. Aldisa seems to be one dorid genus which is fairly easy to identify externally. The generally red colour and the sponge-like pits on the mantle, seem to characterise most, if not all species.
Bill Rudman.


Aldisa sp. 2.

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