Apus is a genus of birds in the family Apodidae. They are called swifts in English. Not all swifts are in genus Apus, but all birds in Apus are swifts.
Taxonomy
Italian naturalist Giovanni Antonio Scopoli made the genus Apus in 1777. He did it by looking at tautonymy and the common swift. Carl Linnaeus named the common swift Hirundo apus in 1758. The name Apus is Latin for a swift. The word is from Ancient Greek : α, a, "without," and πούς, pous, "foot." People thought they were swallows without feet.
Before the 1950s, scientists disagreed about which animals should have the name Apus. In 1801, Bosc gave the small crustacean animals that we call Triops today the genus name Apus, and later writers continued to use it for them. In 1909, Keilhack said this was incorrect because there was already a group of birds called Apus. It was not until 1958 that the scientists in the International Commission on Zoological Nomenclature (ICZN) decided to use the name for only birds.
Species
The genus has 20 species:
Cape Verde swift, Apus alexandri
Common swift, Apus apus
Plain swift, Apus unicolor
Nyanza swift, Apus niansae
Pallid swift, Apus pallidus
African black swift, Apus barbatus
Malagasy black swift, Apus balstoni
Fernando Po swift Apus sladeniae
Forbes-Watson's swift, Apus berliozi
Bradfield's swift, Apus bradfieldi
Pacific swift, Apus pacificus
Salim Ali's swift, Apus salimalii
Blyth's swift, Apus leuconyx
Cook's swift, Apus cooki
Dark-rumped swift, Apus acuticauda
Little swift, Apus affinis
House swift, Apus nipalensis
Horus swift, Apus horus
White-rumped swift, Apus caffer
Bates's swift Apus batesi
Some birds in Apus are dead. Scientists learned about them from fossils, marks that their bones left in rocks: Apus gaillardi (Middle/Late Miocene of La Grive-St.-Alban, France) Apus wetmorei (Early - Late Pliocene? of SC and SE Europe) Apus baranensis (Late Pliocene of SE Europe) Apus submelba (Middle Pleistocene of Slovakia)
Scientists say the bird "Apus" ignotus is really in Procypseloides.