Neornithes Gadow, 1893 - living birds
   Neognathae Pycraft 1900 see Cohort Neognathae Pycraft, 1900
     Galloanserae Sibley, Ahlquist & Monroe Jr., 1988 see Subcohort Galloanserae Sibley, Ahlquist & Monroe Jr., 1988
       [Order] Anseriformes Wagler, 1831 - waterfowl and screamers
         Family Anatidae Vigors, 1825 - ducks, geese, swans
           Subfamily Anatinae Vigors, 1825 - pond ducks
             Genus Aythya Boie, 1822 - hardhead
               Aythya australis (Eyton, 1838) - hardhead
                 1 Aythya australis australis (Eyton, 1838)
                 2 Aythya australis extima Mayr, 1940