Phylum Chordata Bateson, 1885 - chordates
   Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758
     Subclass Neornithes Gadow, 1893 see Clade Neornithes Gadow, 1893
       Superorder Neognathae Pycraft, 1900 see Cohort Neognathae Pycraft, 1900
         Order Anseriformes Wagler, 1831 - waterfowl and screamers
           Family Anatidae Vigors, 1825 - ducks, geese, swans
             Subfamily Anatinae Vigors, 1825 - pond ducks
               Genus Mergus Linnaeus, 1758
                 1 Mergus cucullatus Linnaeus, 1758 see Lophodytes cucullatus (Linnaeus, 1758)
                 2 Mergus albellus Linnaeus, 1758 see Mergellus albellus (Linnaeus, 1758)
                 3 Mergus octosetaceus Vieillot, 1817 - Brazilian merganser
                 4 Mergus serrator Linnaeus, 1758 - red-breasted merganser
                 5 ‡Mergus australis Hombron & Jacquinot, 1841 - Auckland Island merganser
                 6 Mergus squamatus Gould, 1864 - scaly-sided merganser
                 7 Mergus merganser Linnaeus, 1758 - goosander