The smew is a species of duck and is the only living member of the genus Mergellus. Mergellus is a diminutive of Mergus and albellus is from Latin albus "white". This genus is closely related to Mergus and is sometimes included in it, though it might be closer to the goldeneyes (Bucephala). The smew has hybridized with the common goldeneye.
Smew
Mergellus albellus female (closeup view).
Smew taking off
Male
Mergus is the genus of the typical mergansers fish-eating ducks in the subfamily Anatinae. The genus name is a Latin word used by Pliny the Elder and other Roman authors to refer to an unspecified waterbird.
Mergus
Image: MA I156484 Te Papa Mergus australis
Image: Mergus merganser merganser (male)
Image: Mergus serrator New Jersey USA winter 8