Aedes varipalpus (Coquillett, 1902), original combination: Culex varipalpus.
Subfamily Culicinae, tribe Aedini, genus Aedes. Subgenus Jarnellius includes five species. Subgenus abbreviation – Jar.
Adults of species of subgenus Jarnellius are distinguished from the adults of all other New World aedine taxa by the presence of white patches on the maxillary palpus and apical white rings on the tarsi; larvae are characterized by a poorly developed ventral brush comprised of 6 pairs of usually double setae that are gradually stronger distally.
Subgenus Jarnellius is characterised by the following combinations of characters. Characters that diagnose Jarnellius in the phylogenetic analyses of Reinert et al. (2009) are indicated by an asterisk (*). ADULTS – Maxillary palpus of females dark-scaled with pale-scaled areas, *maxillary palpus of males with palpomeres 4 and 5 nearly straight; scutal fossa with white lines of scales on lateral and posterior margins (lines not expanded mesally); *scutellum with broad scales on lateral lobes; postpronotum with narrow scales dorsally and broad scales ventrally; hypostigmal scales absent; *mesepimeron with 2 patches of white scales; *metameral scales present; hindtibia dark-scaled with white scales basally; hindtarsomere 1 with broad basal and apical white bands, hindtarsomeres 2 and 3 with broad apical white bands; fore- and midungues (both sexes) each with 1 tooth. FEMALE GENITALIA – Cercus moderately long and wide, apex sharply rounded, without scales, *cercus/dorsal postgenital lobe index 3.24–4.78; *upper vaginal sclerite absent. MALE GENITALIA – Ninth tergal lobes with about 6 (4–8) setae; gonocoxite with strong setae and scales on lateral 0.33 of dorsal surface, short setae becoming stronger toward apex on mesal 0.67 of dorsal surface, basal tergomesal lobe with a strongly differentiated apically curved seta and 1–3 smaller slender setae, gonostylus strongly curved apically, gonostylar claw spiniform, about 0.3 length of gonostylus; claspette filament slightly longer than stem, flattened beyond middle, apex sharply recurved. HABITAT OF IMMATURE STAGES – *Phytotelmata (tree holes). LARVAE – Antenna without spicules; *seta 1-C spiniform; *seta 6-C branched (double); *seta 4-P as long or shorter than seta 3-P; *seta 8-P multi-branched; *seta 2-T, *seta 3-I, *seta 3-II and *seta 3-VII single; seta 7-I and 7-II similar, single (occasionally double in Ae. sierrensis), moderately long to long; *seta 1-VII and *seta 3-VII ≥ 0.94 and 0.48–0.85 dorsal length of segment X respectively; *seta 1a-S 1.15–1.99 width of siphon; ventral brush (seta 4-X) attached to grid with only transverse grid bars, seta 4a-X long, *seta 4d-X single or double (rarely triple), not plumose. PUPAE – *Seta 2-CT very strongly developed, considerably longer that seta 3-CT; *seta 1-II with 3 or fewer branches (rarely 4-branched); *seta 3-II as thick or thicker than seta 1-II; seta 5-II inserted lateral to seta 4-II; *seta 6-III single; *seta 2-V inserted anterior to seta 3; *seta 5-V shorter than following tergum; *seta 6-VII inserted posterior and mesal to seta 9-VII. See Aedes.
Arnell & Nielsen (1972) noted that the relationships of Jarnellius (their Varipalpus Group) and other aedine taxa were obscure. Based on distributions, rather simple male genitalia and probable tropical origin, Arnell & Nielsen stated that the group seemed to be an ancient lineage, with Ae. laguna “probably closest to the ancestral stock”. In the phylogeny of Aedini recovered in the study of Reinert et al. (2009) based on morphological data, subgenus Jarnellius was recovered in a clade comprised of subgenera Acartomyia + (Jarnellius + (Halaedes + Opifex)), which was sister to the large genus Ochlerotatus. Jarnellius was not associated with other generic-level taxa in the phylogeny of Wilkerson et al. (2015). In the maximum likelihood phylogeny of Soghigian et al. (2017) based on seven molecular markers, species of subgenus Jarnellius comprised a monophyletic lineage in a sister relationship with two species of subgenus Ochlerotatus.
The immature stages of Jarnellius species are usually found in tree holes. Females are known, with the exception of Ae. deserticola, to avidly bite humans who enter their haunts during daylight hours and at dusk.
Species of subgenus Jarnellius are of no known medical or economic importance to humans.
Western Nearctic Region – Canada (British Columbia), Mexico (Baja California Sur, Sonora) and the United States (Arizona, California, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington).
Arnell & Nielsen, 1972 (as Varipalpus Group of Aedes subgenus Ochlerotatus, taxonomy, keys); Reinert et al., 2006, 2008, 2009 (as genus, morphology, phylogeny); Reinert, 2010 (as genus, female genitalia); Wilkerson et al., 2015 (phylogeny, classification); Soghigian et al., 2017 (phylogenetic relationships).