Hypselodoris obscura & H. infucata

Dear Rebecca,
Firstly, by remarkable coincidence, the photo at the top of the page from Callala Bay, is the very animal you ask about.

Now about Hypselodoris infucata, Hypselodoris obscura and Hypselodoris saintvincentius. H. obscura seems to be restricted to New South Wales and the most southern part of Queensland. I know of records of H. saintvincentius in South Australia and southwestern Western Australia. Hypselodoris infucata seems to have a wide Indo-West Pacific distribution. One complication to this neat picture is that southerly currents and eddies can sometimes bring tropical species as far south as southern New South Wales on the east coast of Australia, and to South Australia by way of the Leuwin Current down the west coast.

Why don't I just accept they are all forms of one species? There is one consistent radular difference. Throughout its range from east Africa to at least Darwin in northern Australia, Hypselodoris infucata has a distinct tricuspid innermost lateral tooth while in H. obscura and H. saintvincentius the innermost lateral tooth is bicuspid.

Concerning the photos in Wells & Bryce:
#139, which they identify as H. infucata, from southwestern Australia, is H. saintvincentius.
#140, which they identify as H. obscura, from Dampier Archipelago in northwestern Australia, doesn't look like that species to me and is probably a colour form of H. infucata.

Best wishes,
Bill Rudman.