Anas is a genus of dabbling ducks. It includes the pintails, most teals, and the mallard and its close relatives. It formerly included additional species but following the publication of a molecular phylogenetic study in 2009 the genus was split into four separate genera. The genus now contains 31 living species. The name Anas is the Latin for "duck".

Systematics

The genus Anas was introduced by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae. Anas is the Latin word for a duck. The genus formerly included additional species. In 2009 a large molecular phylogenetic study was published that compared mitochondrial DNA sequences from ducks, geese and swans in the family Anatidae. The results confirmed some of the conclusions of earlier smaller studies and indicated that the genus as then defined was non-monophyletic. Based on the results of this study, Anas was split into four proposed monophyletic genera with five species including the wigeons transferred to the resurrected genus Mareca, ten species including the shovelers and some teals transferred to the resurrected genus Spatula and the Baikal teal placed in the monotypic genus Sibirionetta.

Species

There are 31 extant species recognised in the genus: Extinct Species Formerly placed in Anas:

Phylogeny

Cladogram based on the analysis of Gonzalez and colleagues published in 2009.

Fossil record

A number of fossil species of Anas have been described. Their relationships are often undetermined: Several prehistoric waterfowl supposedly part of the Anas assemblage are nowadays not placed in this genus anymore, at least not with certainty: Highly problematic, albeit in a theoretical sense, is the placement of the moa-nalos. These may be descended from a common ancestor of dabbling ducks such as the Pacific black duck, Laysan duck, and mallard. Phylogenetically, they may even form a clade within the traditional genus Anas. However, when compared to these species – which are representative of dabbling ducks in general – the moa-nalos are a radical departure from the Anseriforme bauplan. This illustrates that in a truly evolutionary sense, a strictly phylogenetic taxonomy may be difficult to apply.