The white-winged duck or white-winged wood duck (Asarcornis scutulata) is a large species of duck, formerly placed in the genus Cairina and allied with the dabbling ducks. However, mtDNA cytochrome b and NADH dehydrogenase subunit 2 sequence analysis[2] and the biogeographical pattern of distribution indicate that the anatomical similarity to the Muscovy duck is deceiving.[citation needed] Thus, this species might more appropriately be placed in a monotypic genus, as Asarcornis scutulata, which appears to be unrelated to the Muscovy duck but closer to the diving ducks.

This is one of the largest species of duck. In fact, among all wild species called duck, only the steamer ducks are larger and heavier on average. The muscovy duck also attains sizes that nearly rival the white-winged duck but may average a bit smaller in a wild state. Length is 66–81 cm (26–32 in) and wingspan is 116–153 cm (46–60 in).[3] Males weigh 2.94–3.9 kg (6.5–8.6 lb), while females weigh 1.95–3.05 kg (4.3–6.7 lb).[4][5] The most noticeable feature on adult birds, is the dark body contrasting with a whitish head and neck. Males have mostly dull yellowish bill, blackish mottling on the head and upper neck, white lesser median coverts and inner edges of tertials and bluish-grey secondaries. In flight, white wing-coverts contrast with the rest of the wings. Females are smaller and usually have more densely mottled head and upper neck. The juvenile is duller and browner.