WRBU: Culicidae Genera - Culex
- Culicidae » Culicinae » Culicini
- Representative species shown here: Culex pipiens
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Genus-specific Diagnostic Characters, Adult Stage
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Name-bearing Type
- 1758:602 [pdf not available]
- Type Species: Culex pipiens
Classification
- Subfamily Culicinae, tribe Culicini. Culex is a large and important genus of mosquitoes. It includes 768 species. Seven species are without subgeneric placement; the remainder are divided between 26 subgenera (number of species in parentheses): Acalleomyia (1), Acallyntrum (8), Aedinus (4), Afroculex (1), Allimanta (1), Anoedioporpa (12), Barraudius (4); Belkinomyia (1), Carrollia (18), Culex (198), Culiciomyia (55), Eumelanomyia (77), Kitzmilleria (1), Lasiosiphon (1), Lophoceraomyia (112), Maillotia (9), Melanoconion (160), Micraedes (8), Microculex (33), Neoculex (26); Nicaromyia (1); Oculeomyia (19), Phenacomyia (3), Phytotelmatomyia (4), Sirivanakarnius (1), Tinolestes (3).
Distribution
- Species of Culex occur in all zoogeographical regions. They range from the tropics to cool temperate regions, but do not extend to the extreme northern latitudes where only Aedes and Ochlerotatus occur. Worldwide distribution, known from all faunal regions.
Phylogeny
- Belkin (1962) indicated that the affinities of the subgenera of genus Culex were obscure, but surmised that Lutzia is an ancient derivative that appears to have a strong affinity with subgenus Culex. It is generally assumed that the Melanoconion Group of subgenera, i.e. Aedinus, Anoedioporpa, Belkinomyia, Carrollia, Melanoconion, Micraedes, Microculex and Tinoleste, includes the most derived mosquitoes of the genus (Belkin, 1968a; Berlin, 1969c; Adames & Galindo, 1973; Sirivanakarn, 1983). Sirivanakarn (1983) noted that Melanoconion shares several anatomical features with the “more primitive” and widespread subgenus Neoculex, suggesting that an offshoot of Neoculex may have given rise to the Melanoconion Group. Valencia (1973) suggested that Carrollia and the closely related Deinocerites and Galindomyia share a similar evolutionary history as derivatives from a primitive stock of subgenus Melanoconion. Miller et al. (1996) used sequence divergence in the ITS1 and ITS2 regions of rDNA to infer relationships between 14 species representing four subgenera of Culex. Neighbour-joining analyses produced a tree (rooted on Melanoconion) that supported the notion that Melanoconion bears a number of resemblances with Neoculex, and Lutzia shares an ancestry with subgenus Culex.
- Navarro & Liria (2000) conducted a parsimony analysis of 30 characters of larval mouthparts (mandibles and maxillae) to infer the phylogenetic relationships of Deinocerites and seven subgenera of Culex. The phylogeny indicated that genera Lutzia and Culex formed distinct monophyletic clades, with Lutzia being the more primitive of the two. Although only New World species were included in the analysis, members of the Melanoconion Group formed a distinct monophyletic clade in a sister-group relationship with subgenus Culex. It is interesting to note that this clade included Deinocerites in an unresolved polytomy with Anoedioporpa, Melanoconion and Microculex in a derived position relative to Carrollia.
Characteristics
- Culex adults are usually drab, unicolorous mosquitoes, but some species of the subgenus Culex have markings on the legs and pale spots on the wings similar to Anopheles. Culex are characterised by the presence of distinct pulvilli and the absence of prespiracular setae and postspiracular setae (the latter are present in Australian Cx. postspiraculosus). These characters, however, will not distinguish Culex from Deinocerites, Galindomyia and Lutzia. Culex differs from Deinocerites and Galindomyia in having the apical flagellomere of the antenna much shorter than the first flagellomere, and differs from Lutzia in having few (usually one) lower mesepimeral setae. Culex larvae are distinguished from other genera by the following characters: seta 2-C usually absent; seta 3-C located on dorsal side of head, sometimes absent; palatal brushes normal, not developed fro grasping prey; mandible normal, without lateral lobe at base; maxillary brush present, well developed; seta 12-I and comb always present; siphon with three or more pairs of prominent setae (seta 1-S); pecten normally present; saddle usually complete, sometimes incomplete and greatly reduced but never divided into dorsal and ventral sclerites or longer than the siphon; ventral brush (seta 4-X) usually with three or more pairs of setae. See Culicini.
Bionomics
- Culex larvae occur primarily in semi-permanent or permanent bodies of ground water, but a large number of species live exclusively in leaf axils, tree-holes, rock-holes and crab-holes. Some utilise artificial containers as well as the normal ground-water habitats. A few species, including the filarial vector Cx. quinquefasciatus, are found in organically polluted waters. Culex females mainly bite at night. Many species attack humans and other mammals. Some species are known to feed on birds and some are known to feed on amphibians and reptiles.
Medical
- Several species of subgenera Culex and Melanoconion are of medical importance. Melanoconion mainly occurs in the Neotropical Region, with some species reaching northward into the USA. Several species of the subgenus are important vectors of encephalitis and other arboviruses. Subgenus Culex has species in all zoogeographic regions, and contains most of the medically important and pest species of the genus. Culex fuscocephala, Cx. tritaeniorhynchus, Cx. gelidus and Cx. vishnui transmit Japanese encephalitis virus in the Oriental Region and Cx. tarsalis, Cx. nigripalpus, Cx. restuans and Cx. pipiens are recognised vectors of encephalitis viruses in North America. Murray Valley encephalitis and Ross River viruses in Australia are spread by Cx. annulirostris. Three closely related species, Cx. univittatus, Cx. neavei and Cx. perexiguus, transmit West Nile fever virus in Africa. Rift Valley fever virus is transmitted by Cx. pipiens in Egypt and Cx. theileri in southern Africa. A few species of the subgenus, especially Cx. quinquefasciatus, are important vectors of Wuchereria bancrofti in the tropics. Culex pipiens and Cx. antennatus are important vectors of filarial worms in Egypt. Some species of the genus may be involved in the transmission of Brugia malayi.
Important References
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Included Taxa
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The materials presented in the Classification, Distribution, Phylogeny, Characteristics, Medical, and Important References sections, and links to subgenera, are reproduced with permission of Mosquito Taxonomic Inventory, moderated by Ralph Harbach on behalf of the contributors who retain copyright. For additional information on reuse parameters, please contact Mosquito Taxonomic Inventory. Images and maps, unless otherwise attributed, and links to the literature are provided by the WRBU. |