Noumea closei from South Australia

Thanks Stuart,
I am pretty sure, from the white marks, that this is Noumea closei. However if you look at the Bass Strait colour form of Noumea sulphurea you will see it is almost identical externally. There is an interesting story attached to how I first realised there were two species involved. N. closei when preserved in formalin turns dark brown, sometimes almost black, while Noumea sulphurea gradually loses all its colour, becoming translucent white. One day when I was choosing some specimens to dissect I decided I had better check some dark and some light coloured ones just in case I had missed something. To my great surprise I found their radular morphology was quite different.

Using the preserved colour of a slug is not the most practical way to identify a species, but as with species of Rostanga, sometimes external shape and colour just isn't enough.
Best wishes,
Bill Rudman