Parent: Anatidae (Ducks)

└─ Mergus (Greater mergansers)

└─── Mergus australis

└─── Mergus merganser (Common merganser)

└─── Mergus octosetaceus (Brazilian merganser)

└─── Mergus serrator (Red-breasted merganser)

└─── Mergus squamatus (Scaly-sided merganser)