Re: Halgerda in temperate Australian waters?

October 7, 2002
From: Leander Wiseman

I thought this photo of a Halgerda may be of interest. These Halgerda are regulars in Jervis Bay, New South Wales [Australia}. Is this likely to be Halgerda willeyi?

Leander Wiseman

Wiseman, L., 2002 (Oct 7) Re: Halgerda in temperate Australian waters?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Leander,
Thanks for the photo. Animals from the New South Wales coast can sometimes be a problem to identify because we don't know whether they are a 'local endemic species' [that is found only in New South Wales] or whether they are members of a tropical species, which some to venture this far south as larvae in warm currents. My feeling is that this is a southern population of the tropical Halgerda willeyi. However there is still some confusion over how much colour variation we can expect to find in that species. If you look at the pages on Halgerda elegans and Halgerda cf. graphica you will see examples of other specimens from New South Wales which show similarities and differences to your animal.

Basically we still have to sort this problem out. The first thing that needs doing is comprehensive study of the New South Wales populations to see how variable the colour patterns are and whether there is more than one species.
Best wishes,
Bill Rudman

Rudman, W.B., 2002 (Oct 7). Comment on Re: Halgerda in temperate Australian waters? by Leander Wiseman. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Halgerda willeyi

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