The taxon "Acari" is an informal category to cover the six orders of arachnids recognised in the AFD (see https://biodiversity.org.au/afd/taxa/Acari) which are called mites and ticks, but which may or may not be related.
Further reference: https://en.wikipedia.org/wiki/Acari
Acari (informal subclass) is listed in the following regions:
Canberra & Southern Tablelands | Southern Highlands | South Coast | Greater Brisbane
No sightings currently exist.