|Female mallard (Anas platyrhynchos) with brood of young|
31 extant, see text
Anas is a genus of dabbling ducks. It includes the mallard, teals, pintails. It formerly included additional species but following the publication of a molecular phylogenetic study in 2009 the genus was spit into four separate genera. The genus now contains 31 living species. The name Anas is the Latin for "duck".
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 phylogentic 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 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.
There are 31 extant species recognised in the genus:
- African black duck, Anas sparsa
- Yellow-billed duck, Anas undulata
- Meller's duck, Anas melleri
- Pacific black duck, Anas superciliosa
- Laysan duck, Anas laysanensis
- Hawaiian duck, Anas wyvilliana
- Philippine duck, Anas luzonica
- Indian spot-billed duck, Anas poecilorhyncha
- Eastern spot-billed duck, Anas zonorhyncha
- Mallard, Anas platyrhynchos
- Mottled duck, Anas fulvigula
- American black duck, Anas rubripes
- Mexican duck, Anas diazi
- Cape teal, Anas capensis
- White-cheeked pintail, Anas bahamensis
- Red-billed teal, Anas erythrorhyncha
- Yellow-billed pintail, Anas georgica
- Eaton's pintail, Anas eatoni
- Northern pintail, Anas acuta
- Eurasian teal, Anas crecca
- Green-winged teal, Anas carolinensis
- Yellow-billed teal, Anas flavirostris
- Andean teal, Anas andium (formerly included in A. flavirostris)
- Sunda teal, Anas gibberifrons
- Andaman teal, Anas albogularis (formerly included in A. gibberifrons)
- Mascarene teal, Anas theodori (extinct)
- Grey teal, Anas gracilis
- Chestnut teal, Anas castanea
- Bernier's teal, Anas bernieri
- Brown teal, Anas chlorotis
- Auckland teal, Anas aucklandica
- Campbell teal, Anas nesiotis (formerly included in A. aucklandica)
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
- species in the genus Spatula, the shovelers
Cladogram based on the analysis of Gonzalez and colleagues published in 2009.
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 greeni (Brodkorb 1964) (Ash Hollow Late Miocene?/Early Pliocene of South Dakota, USA) – Nettion red-and-green head clade (doubtful)?
- †Anas ogallalae (Brodkorb 1962) (Ogalalla Late Miocene?/Early Pliocene of Kansas, USA) – Nettion red-and-green head clade (doubtful)?
- †Anas pullulans (Juntura Late Miocene?/Early Pliocene of Juntura, Malheur County, Oregon, USA) – Punanetta?
- †Anas cheuen Agnolín 2006 (Early-Middle Pleistocene of Argentina) – Dafila?
- †Anas bunkeri (Wetmore 1944) (Early -? Middle Pliocene – Early Pleistocene of WC USA) – Nettion red-and-green head clade?
- Bermuda Islands flightless duck †Anas pachyscelus Wetmore 1960 (Shore Hills Late Pleistocene of Bermuda, W Atlantic)
- †Anas schneideri Emslie 1985 (Late Pleistocene of Little Box Elder Cave, USA)
- †Anas elapsum (Chinchilla Late Pleistocene of Condamine River, Australia) ("Nettion")
- †Anas gracilipes (Late Pleistocene of Australia) ("Nettion")
- †Anas moldovica (Late Pliocene of Tchichmiknaia, Moldovia?Georgia?)
- †Anas sansaniensis Milne-Edwards 1868 [Dendrocygna sansaniensis (Milne-Edwards 1868) Mlíkovský 1988]
- †Anas strenuum (Late Pleistocene of Patteramordu, Australia) ("Nettion")
- †Anas itchtucknee McCoy 1963
- †Anas kisatibiensis [Anser kisatibiensis] (Early Pliocene of Kisatibi, Georgia)
- †Anas kurochkini Zelenkov & Panteleyev 2015
- †Anas lambrechti [Archaeoquerquedula lambrechti Stephens; Querquedula lambrechti; Archeoquerquedula Spillman 1942]
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 "Warnsdorf", 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 "Skalitz", Czech Republic), though possibly anseriform, cannot be placed with any certainty among modern birds at all.
- †"Anas" albae (Late Miocene of Polgárdi, Hungary), "A." eppelsheimensis (Early Pliocene of Eppelsheim, Germany), "A." isarensis (Late Miocene of Aumeister, Germany) and "A." luederitzensis (Kalahari Early Miocene of Lüderitzbucht, Namibia) are apparently Anatidae of unclear affiliations; the first might be a seaduck.
- †"Anas" integra and "A." oligocaena are now in Dendrochen.
- †"Anas" lignitifila from the Late Miocene of Tuscana has been moved to its own genus, Bambolinetta, being a highly unusual marine waterfowl.
- †"Anas" robusta is now tentatively placed in Anserobranta.
- †"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.
Highly problematic, albeit in a theoretical sense, is the placement of the moa-nalos. These are in may be derived from a common ancestor of the Pacific black duck, the Laysan duck, and the mallard, and an unknown amount of other lineages. Phylogenetically, they may even form a clade within the traditional genus Anas. However, as opposed to these species – which are well representative of dabbling ducks in general – the moa-nalos are the most radical departure from the anseriform bauplan known to science. This illustrates that in a truly evolutionary sense, a strictly phylogenetic taxonomy may be difficult to apply.
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