Anas

''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
* Mariana mallard, ''Anas oustaleti''
* Mascarene teal, ''Anas theodori''
* Chatham Island Duck, ''Anas chathamica''

Formerly placed in ''Anas'':
* Bronze-winged duck, ''Speculanas specularis''
* Crested duck, ''Lophonetta specularioides''
* Baikal teal ''Sibirionetta formosa''
* Salvadori's teal, ''Salvadorina waigiuensis''
*species in the genus ''Mareca'', the wigeons (including the gadwall and the falcated duck)
*species in the genus ''Spatula'', the shovelers and related teals

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:
* †''Anas'' sp. (Late Miocene of China)
* †''Anas'' sp. (mid-sized species from the Late Miocene of Rudabánya, Hungary)
* †''Anas amotape'' (Campbell 1979) (Talara Tar Seeps, Late Pleistocene of Peru)
* †''Anas bunkeri'' (Wetmore 1944) (Early -? Middle Pliocene – Early Pleistocene of WC USA) – ''Nettion'' red-and-green head clade?
* †''Anas cheuen'' Agnolín 2006 (Early-Middle Pleistocene of Argentina) – ''Dafila''?
* †''Anas ganii'' Burchak-Abramovich, Suspanov and David 1996 (Late Pliocene/Early Pleistocene of Moldova)
* †''Anas greeni'' (Brodkorb 1964) (Late Miocene?/Early Pliocene of South Dakota, USA) – ''Nettion'' red-and-green head clade (doubtful)?
* †''Anas itchtucknee'' McCoy 1963 (Late Pleistocene of Florida, USA) doubtful validity
* †''Anas kisatibiensis'' Burchak-Abramovich and Mczedlidze 1995 (nomen nudum) (Early Pliocene of Kisatibi, Georgia)
* †'' Anas kurochkini'' Zelenkov & Panteleyev 2015 (Late Miocene of Sea of Azov, southern Russia)
* †''Anas lambrechti'' Spillman 1942 'Archaeoquerquedula lambrechti''(Pleistocene of Ecuador)
* †''Anas ogallalae'' (Brodkorb 1962) (Late Miocene?/Early Pliocene of Kansas, USA) – ''Nettion'' red-and-green head clade (doubtful)?
* Bermuda Islands flightless duck †''Anas pachyscelus'' Wetmore 1960 (Late Pleistocene of Bermuda, W Atlantic)
* †''Anas pullulans'' (Brodkorb 1961) (Late Miocene?/Early Pliocene of Oregon, USA) – ''Punanetta''?
* †''Anas schneideri'' Emslie 1985 (Late Pleistocene of Little Box Elder Cave, USA)

Several prehistoric waterfowl supposedly part of the ''Anas'' assemblage are nowadays not placed in this genus anymore, at least not with certainty:
* †''"Anas" basaltica'' (Late Oligocene of Czech Republic) is apparently an indeterminate heron.
* †''"Anas" blanchardi'', ''"A." consobrina'', ''"A." natator'' are now in '' Mionetta''
* †''"Anas" creccoides'' (Early-mid Oligocene of Belgium), ''"A." risgoviensis'' (Late Miocene of Bavaria, Germany) and ''"A." skalicensis'' (Early Miocene of Czech Republic), though possibly anseriform, cannot be placed with any certainty among modern birds at all.
* †''"Anas" albae'' (Late Miocene of Hungary), ''"A." eppelsheimensis'' (Early Pliocene of Germany) and ''"A." isarensis'' (Late Miocene of Germany) are apparently Anatidae of unclear affiliations
* †''"Anas" integra'' and ''"A." oligocaena'' are now in '' Dendrochen''.
* †''"Anas" lignitifila'' from the Late Miocene of Tuscany has been moved to its own genus, '' Bambolinetta'', being a highly unusual marine waterfowl.
* †''"Anas" luederitzensis'' (Early Miocene of Namibia) may belong within Oxyurini
* †''"Anas" robusta'' is now tentatively placed in '' Anserobranta''.
* †''"Anas" sansaniensis'' is now placed in '' Chenoanas''
* †''"Anas" velox'' (Middle – Late? Miocene of C Europe) and ''"A." meyerii'' (Middle Miocene of Öhningen, Germany; possibly the same species) do not seem to belong ''Anas'', and they may be ancestral dabbling ducks.

''Anas elapsum'' (Late Pleistocene of Australia) is now synonymised with the extant Hardhead. ''Anas gracilipes'' and ''Anas strenuum'' (Late Pleistocene of Australia) are both junior synonyms of the extant Chestnut teal.

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.

See also

* Mallard complex
* List of recently extinct birds
* Late Quaternary prehistoric birds
* List of fossil bird genera

References

External links

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{{Authority control

Dabbling ducks
Bird genera
Taxa named by Carl Linnaeus