The systematic position of the Miocene anatid Anas[?] blanchardi Milne-Edwards

ABSTRACT

Anas[?] blanchardi (Milne-Edwards, 1863), an abundantly represented fossil duck from the lower Miocene of Saint-Gérand-le-Puy, Allier, France, has been recognized as systematically problematic in recent decades. Most recently, Cheneval (1983b) moved this fossil and closely related forms to Dendrochen (Miller, 1944), a purportedly dendrocygnine genus from the lower Miocene of South Dakota. We reexamined blanchardi using characters shown to be of phylogenetic utility in a recent phylogenetically analysis of the Anseriformes (Livezey, 1986). This reappraisal showed that blanchardi diverged from the rest of the Anatidae after Dendrocygna but before Stictonetta. A single “best” branching sequence for the included taxa—blanchardi, Thalassornis, and the Anserinae (geese and swans)—is not possible at present. Several possibly convergent characters indicate that blanchardi was moderately specialized for diving. We conclude that blanchardi (and provisionally its close relatives Anas[?] consobrina and Anas[?] natator) should be placed in a new genus Mionetta, and that Dendrochen should be listed tentatively as its sister genus. Together these two genera comprise the new subfamily Dendrocheninae, which should be listed following the Dendrocygninae.