Photographed on an Exocarpos, perhaps Nipaecoccus exocarpi as it doesn't seem to match illustrations I could find for the other species listed in DJ Williams 1985 'Australian mealybugs' but I didn't disturb it so it is hard to tell.
Thanks Roger, I couldn't find any records for this species on Exocarpos so didn't consider it. However, it seems this has become a pest species on many plant species all over the world so so I shouldn't be surprised Exocarpos turns up as a host.