Members of the parrotgenusPsittacula or Afro-Asian ring-necked parakeets as they are commonly known in aviculture originates found from Africa to South-East Asia. It is a widespread group, with a clear concentration of species in south Asia, but also with representatives in Africa and the islands of the Indian Ocean. This is the only genus of Parrot which has the majority of its species in continental Asia. Of all the extant species only Psittacula calthropae, Psittacula caniceps and Psittacula echo do not have a representative subspecies in any part of mainland continental Asia. The rose-ringed parakeet, Psittacula krameri, is one of the most widely distributed of all parrots. The other two Asian genera, Loriculus and Psittinus are represented by only two and one species respectively, which occur in the mainland part of Asia. The majority of the Loriculus species occur on islands. Moreover, since Loriculus is spread across both sides of the Wallace Line it can be considered more Australasian than Asian. These parrots mostly have green plumage, with adults having coloured heads. The bill is stout, and the tail is long and graduated. The genus Psittacula was introduced by the French naturalist Georges Cuvier in 1800. The type species was subsequently designated as the red-breasted parakeet. The name of the genus is a diminutive of the Latin word psittacus for a "parrot".
Species and phylogeny
Current taxonomy
The genus includes 16 species, of which three are extinct.
Recent genetic evidence has found that the genus Psittacula is likely paraphyletic; for example, genetic analysis has supported merging short-tailed parrots of the genus Tanygnathus,Psittinus, and the extinct Mascarinus with Psittacula. An alternative classification system to this was proposed by Braun et al. that splits the genus Psittacula into multiple monophyletic genera in order to preserve Tanygnathus, Psittinus, and Mascarinus as distinct genera. After the proposed split, the only remaining species in Psittacula sensu stricto are P. derbiana and P. alexandri. The list of split or monophyletic genera and species is displayed below:
The study has not yet classified P. bensoni or P. caniceps. It has also found that the rose-ringed and Alexandrine parakeets are likely paraphyletic species themselves, and thus need to be split into multiple species.
The Rothschild's or intermediate parakeetP. intermedia, found in northern India, was formerly considered a mystery, as only very few specimens were known. It has since been demonstrated to be a hybrid between the slaty-headed parakeetP. himalayana and the plum-headed parakeetP. cyanocephala. The taxonomy of the Réunion parakeet P. eques is also confusing. Extinct since 1770, little evidence even exists of the bird's existence. A study skin had been discovered at the Royal Museum of Scotland, explicitly referencing a book description of the Réunion birds. It is known from other descriptions, as well as illustrations of which it is unknown whether they were drawn from live or stuffed specimens. This may be the only material proof of these birds' existence. Taxonomists are unsure if the birds were a distinct species, or conspecific with the Mauritius parakeet, although genetic analysis supports it being a subspecies of the Mauritius parakeet.
