Silver Teal Spatula versicolor
This species was formerly placed in the genus Anas. Puna Teal Spatula puna was formerly considered to be a race of Silver Teal but is now separated as a distinct species.
I have only encountered this South American species in wildfowl collections.
captive Silver Teal, Blakeney quayside collection (Norfolk, UK), 7th November 2003