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 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 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:
ImageCommon NameScientific nameDistribution
African black duckAnas sparsaeastern and southern sub-Saharan Africa from South Africa n north to South Sudan and Ethiopia with outlying populations in western equatorial Africa, in south east Nigeria, Cameroon and Gabon.
Yellow-billed duckAnas undulatasouthern and eastern Africa.
Meller's duckAnas mellerieastern Madagascar.
Pacific black duckAnas superciliosaIndonesia, New Guinea, Australia, New Zealand, and many islands in the southwestern Pacific, reaching to the Caroline Islands in the north and French Polynesia in the east
Laysan duckAnas laysanensisHawaiian Islands
Hawaiian duckAnas wyvillianaHawaiian islands
Philippine duckAnas luzonicathe Philippines
Indian spot-billed duckAnas poecilorhynchaPakistan and India
Eastern spot-billed duckAnas zonorhynchaSoutheast Asia
MallardAnas platyrhynchosAlaska to Mexico, the Hawaiian Islands, across Eurasia, from Iceland and southern Greenland and parts of Morocco in the west, Scandinavia and Britain to the north, and to Siberia, Japan, and South Korea, in the east, south-eastern and south-western Australia and New Zealand
Mottled duckAnas fulvigulaGulf of Mexico coast between Alabama and Tamaulipas and Florida
American black duckAnas rubripesSaskatchewan to the Atlantic in Canada and the Great Lakes and the Adirondacks in the United States
Mexican duckAnas diaziMexico and the southern United States.
Cape tealAnas capensissub-Saharan Africa
White-cheeked pintailAnas bahamensisCaribbean, South America, and the Galápagos Islands
Red-billed tealAnas erythrorhynchasouthern and eastern Africa
Yellow-billed pintailAnas georgicaSouth America, the Falkland Islands and South Georgia
Eaton's pintailAnas eatoniisland groups of Kerguelen and Crozet in the southern Indian Ocean
Northern pintailAnas acutaEurope, Asia and North America
Eurasian tealAnas creccanorthern Eurasia
Green-winged tealAnas carolinensisNorth America except on the Aleutian Islands
Yellow-billed tealAnas flavirostrisArgentina, the Falkland Islands, Chile, Peru, Bolivia, Uruguay, and Brazil.
Andean tealAnas andium Andean highlands of Colombia, Venezuela, and Ecuador
Sunda tealAnas gibberifronsIndonesia.
Andaman tealAnas albogularis Andaman Islands and Great Coco Island
Grey tealAnas gracilisAustralia and New Zealand
Chestnut tealAnas castaneaTasmania and southern Victoria, New Guinea and Lord Howe Island
Bernier's tealAnas bernieriMadagascar
Brown tealAnas chlorotisNew Zealand
Auckland tealAnas aucklandicaAuckland Islands south of New Zealand
Campbell tealAnas nesiotis New Zealand

Extinct Species
Formerly placed in Anas:
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 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.