Subfamily Culicinae, genus Culiseta. Subgenus Culiseta includes 12 species. Subgenus abbreviation – Cus.
The following combinations of characters distinguish subgenus Culiseta from the other subgenera of Culiseta. ADULTS ‒ Maxillary palpus of females with palpomere 5 sometimes distinctly white-scaled; maxillary palpus of males about as long as or longer than proboscis, usually with very long setae; palpomeres 4 and 5 more or less swollen, not upturned; scutellum usually with narrow scales (broad in Cs. niveitaeniata); antepronotum with setae and few scales, postpronotum with posterior setae and broad or narrow scales; prespiracular area usually with more than 7 setae, sometimes with few scales; wing often with darker clusters of scales, subcostal setae numerous, mediocubital and radiomedial crossveins usually approximated, if not then distance between them not more than length of mediocubital crossvein; tarsi uniformly dark-scaled or with basal pale bands; abdominal terga with more or less distinct basal pale bands. MALE GENITALIA ‒ Ninth tergal lobes usually with long setae; gonocoxite with distinct apicodorsal lobe or patch of setae, basal mesal lobe relatively small, conical, with numerous setae; gonostylus with apical usually bifid gonostylar claw; aedeagus with strongly sclerotised lateral plates, plates usually separated, egg-shaped. LARVAE ‒ Head not very broad; antenna short to moderately long, about 0.5 length of head, slightly flexed, seta 1-A inserted near mid-length of shaft, setae 2‒6-A usually short, inserted apically; comb of segment VIII with about 50 scales in triangular patch; siphon relatively short, index 2.5‒4.5, pecten comprised of strong spines, seta 1-S inserted at base, row of setae 1a-S present, seta 2a-S absent; saddle of segment X complete, ventral brush (seta 4-X) usually with 2‒5 precratal setae inserted on saddle. PUPAE ‒ Not well studied; seta 1-Pa present, seta 2-Pa apparently absent. See genus Culiseta.
The phylogenetic relationships of subgenus Culiseta have not been investigated. Maslov (1967, 1989) hypothesised that the subgenus is the “most primitive” of the genus, an early offshoot of an ancestral lineage, “Protoculicella”, in the Holarctic Region. From divergence times based on sequence data for nuclear protein-coding genes and fossil calibration points, it appears Culiseta may have evolved during the Jurassic (Reidenbach et al., 2009).
The immature stages of species of subgenus Culiseta are found predominantly in sunlit or shaded ground pools, ditches, pond margins, swamps and marshes among vegetation or plant debris. Larvae of Cs. annulata and Cs. inornata are sometimes found in artificial containers, and larvae of the former species and Cs. glaphyroptera have been found in tree holes. Larvae are mainly bottom feeders and remain submerged for long periods of time. Females overwinter and feed in the spring. They deposit their eggs in rafts. Little is known about the host preferences and feeding habits of adult females. The females of most species probably feed principally on birds, but some at least occasionally bite reptiles and mammals. Culiseta alaskaensis, Cs. annulata and Cs. subochrea frequently feed on humans.
Most species of subgenus Culiseta are not known or suspected vectors of pathogens. However, Cs. annulata is considered to be a potential vector of Tahyna virus (Ribeiro et al, 1988) and is known to transmit avian malarial plasmodia (Gutsevich et al., 1974). Culiseta inornata is considered a potential vector of western equine encephalitis and West Nile viruses (Turell et al., 2005), and is probably the chief vector of Cache Valley virus (Corner et al., 1980).
Holarctic Region. Eight species occur in the Palaearctic Region and five in the Nearctic Region. Culiseta alaskaensis has a Holarctic distribution and the Nearctic Cs. particeps extends into the Neotropical Region as far south as Panama.
alaskaensis (Ludlow, 1906)
subspecies alaskaensis (Ludlow, 1906)
subspecies indica (Edwards, 1920)
annulata (Schrank, 1776)
atlantica (Edwards, 1932)
bergrothi (Edwards, 1921)
glaphyroptera (Schiner, 1864)
impatiens (Walker, 1848)
incidens (Thomson, 1869)
inornata (Williston, 1893)
megaloba Luh, Chao & Xu, 1974
niveitaeniata (Theobald, 1907)
particeps (Adams, 1903)
subochrea (Edwards, 1921) (in Wesenberg-Lund, 1921)