After going over the list of species in section Validae from Australia, I have to report that it was not difficult to find reasons to reject many of the possibilities. It was not easy to find a reason to make a strong recommendation. The name least likely to fail to match the present species is A. austrobulbosa, which, it happens, was described from South Australia; however, the only description of this species is limited:
Further collections and resulting dried material may help.
As a result of Kari’s post and a posting about A. sp-Ridley-2 on the MycoKey blog by Arthur Bennett, I revised and updated of the checklist for amanitas of Australia and New Zealand and added color coding to distinguish endemic and alien taxa. (I have some suspicions that at least one of the three limacellas is alien, but they all treated as endemic for the present.)
This checklist now has links (taxon by taxon) to the taxon pages of the WAO site: