page_title: Diving duck
section_title: Systematics
hierarchical_section_title: Diving duck / Systematics
caption_attribution_description: Hardhead (Aythya australis) female, Hurstville Golf Course, New South Wales, Australia
context_page_description: The diving ducks, commonly called pochards or scaups, are a category of duck which feed by diving beneath the surface of the water. They are part of Anatidae, the diverse and very large family that includes ducks, geese, and swans.
  The diving ducks are placed in a distinct tribe in the subfamily Anatinae, the Aythyini. While morphologically close to the dabbling ducks, there are nonetheless some pronounced differences such as in the structure of the trachea. mtDNA cytochrome b and NADH dehydrogenase subunit 2 sequence data indicate that the dabbling and diving ducks are fairly distant from each other, the outward similarities being due to convergent evolution.
  Alternatively, the diving ducks are placed as a subfamily Aythyinae in a subfamily Anatidae which would encompass all duck-like birds except the whistling-ducks.
  The seaducks commonly found in coastal areas, such as the long-tailed duck, scoters, goldeneyes, mergansers, bufflehead and eiders, are also sometimes colloquially referred to in North America as diving ducks because they also feed by diving; their subfamily is a very distinct one however.
context_section_description: Three genera are included in the Aythyini. The marbled duck which makes up the monotypic genus Marmaronetta, however, seems very distinct and might have diverged prior to the split of dabbling and diving ducks as indicated by morphological and molecular characteristics. The probably extinct pink-headed duck, previously treated separately in Rhodonessa, has been suggested to belong into Netta, but this approach has been questioned. DNA sequence analyses, which would probably resolve this question, have not been conducted to date for lack of suitable material. It might be an early divergence from the dabbling duck lineage. The molecular analysis also suggests that the white-winged duck should be placed into a monotypic genus Asarcornis which is fairly close to Aythya and might belong into this subfamily.
caption: Female A. australis, the only Australian representative of Aythyinae
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