The Mioceneverification needed"Aythya" arvernensis is now placed in Mionetta, while "Aythya" chauvirae seems to contain the remains of 2 species, at least one of which does not seem to be a diving duck.[2]
Louchart, Antoine; Mourer-Chauviré, Cécile; Guleç, Erksin; Howell, Francis Clark & White, Tim D. (1998): L'avifaune de Dursunlu, Turquie, Pléistocène inférieur: climat, environnement et biogéographie. C. R. Acad. Sci. Paris IIA327(5): 341-346. [French with English abridged version] doi:10.1016/S1251-8050(98)80053-0 (HTML abstract)