Anopheles

Anopheles (/əˈnɒfɪliːz/) is a genus of mosquito first described and named by J. W. Meigen in 1818. About 460 species are recognised; while over 100 can transmit human malaria, only 30–40 commonly transmit parasites of the genus Plasmodium, which cause malaria in humans in endemic areas. Anopheles gambiae is one of the best known, because of its predominant role in the transmission of the most dangerous malaria parasite species (to humans) – Plasmodium falciparum. The name comes from the Ancient Greek word ἀνωφελής anōphelḗs 'useless', derived from ἀν- an-, 'not', 'un-' and ὄφελος óphelos 'profit'. Mosquitoes in other genera (Aedes, Culex, Culiseta, Haemagogus, and Ochlerotatus) can also serve as vectors of disease agents, but not human malaria. The ancestors of Drosophila and the mosquitoes diverged 260 million years ago. The culicine and Anopheles clades of mosquitoes diverged between 120 million years ago and 150 million years ago. The Old and New World Anopheles species subsequently diverged between 80 million years ago and 95 million years ago. Anopheles darlingi diverged from the African and Asian malaria vectors ∼100 million years ago. The Anopheles gambiae and Anopheles funestus clades diverged between 80 million years ago and 36 million years ago. A molecular study of several genes in seven species has provided additional support for an expansion of this genus during the Cretaceous period. The Anopheles genome, at 230–284 million base pairs (Mbp), is comparable in size to that of Drosophila, but considerably smaller than those found in other culicine genomes (528 Mbp–1.9 Gbp). Like most culicine species, the genome is diploid with six chromosomes. The only known fossils of this genus are those of Anopheles (Nyssorhynchus) dominicanus Zavortink & Poinar contained in Dominican amber from the Late Eocene (40.4 million years ago to 33.9 million years ago) and Anopheles rottensis Statz contained in German amber from the Late Oligocene (28.4 million years ago to 23 million years ago). The genus Anopheles Meigen (nearly worldwide distribution) belongs to the subfamily Anophelinae together with another two genera: Bironella Theobald (Australia only) and Chagasia Cruz (Neotropics). The taxonomy remains incompletely settled. Classification into species is based on morphological characteristics – wing spots, head anatomy, larval and pupal anatomy, chromosome structure, and more recently, on DNA sequences. The genus has been subdivided into seven subgenera based primarily on the number and positions of specialized setae on the gonocoxites of the male genitalia. The system of subgenera originated with the work of Christophers, who in 1915 described three subgenera: Anopheles (widely distributed), Myzomyia (later renamed Cellia) (Old World) and Nyssorhynchus (Neotropical). Nyssorhynchus was first described as Lavernia by Frederick Vincent Theobald. Frederick Wallace Edwards in 1932 added the subgenus Stethomyia (Neotropical distribution). Kerteszia was also described by Edwards in 1932, but then recognised as a subgrouping of Nyssorhynchus. It was elevated to subgenus status by Komp in 1937, and it is also found in the Neotropics. Two additional subgenera have since been recognised: Baimaia (Southeast Asia only) by Harbach et al. in 2005 and Lophopodomyia (Neotropical) by Antunes in 1937.