Until now, H. mirabilis was known to survive only at Wilsons Promontory, Victoria. However, although previously thought to have died out in the Goulburn Valley, also in Victoria, the sp. sill occurs there - on floodplain lagoons (billabongs) of the Goulburn R. at Alexandra, and lagoons of the tributary Yea R. at Yea, some 30 km downstream from Alexandra. More significant in terms of conservation is its discovery in Mt William National Park, NE Tasmania. H. mirabilis can no longer be regarded as an endangered sp.