Subgenus Howardina Theobald, 1903
Aedes walkeri (Theobald, 1901), original combination: Culex walkeri.
Subfamily Culicinae, tribe Aedini, genus Aedes. Subgenus Howardina includes 34 species. Subgenus abbreviation – How.
The following morphological features distinguish subgenus Howardina (as genus) from other generic-level taxa of Aedini in the Neotropical Region. Characters that diagnose Howardina in the phylogenetic analysis of Reinert et al. (2009) are indicated with an asterisk (*). ADULTS – Vertex with a median stripe of narrow scales extended forward to eyes, *erect scales restricted to occiput; mesonotum with linear pattern of silvery or golden scales; scutellar scales narrow; thoracic pleura with silvery scales; *maxillary palpus of males with palpomeres 4 and 5 nearly straight relative to palpomere 3; *ungues of females simple (without teeth); abdominal terga of males with few relatively short lateral setae. FEMALE GENITALIA – *Tergum VIII with straight posterior margin; sternum VIII rather inconspicuous; ratio of ventral width of postgenital lobe at distal 0.20 to cercus width at midlength ≤ 0.65; insular setae inserted in lateral patches. MALE GENITALIA – Claspette small, *single basal plaque with *stout spiniform seta; aedeagus simple; proctiger without sternal arm. LARVAE – *Antenna spiculate; seta 5-C single; setae 1–3-P on common setal support plate; *seta 4-P longer than seta 3-P; seta 13-P present; seta 12-I absent; seta 2-VII branched; seta 12-VII single, inserted anterior to seta 13-VII in most species; *seta 1-VIII ≥ 1.10 length of seta 2-VIII; comb scales squamous, without median apical spine; *length of seta 1a-S 1.15−1.99 width of siphon; saddle incomplete with lateral margins near either side of ventral brush. PUPAE – Paddle with midrib strongly development, extending to or near apex of paddle. See genus Aedes.
Prior to the series of phylogenetic studies of Aedini by Reinert et al. (2004, 2006, 2008, 2009) it was generally assumed that Howardina shared affinities with subgenus Finlaya (in the broad traditional sense) based on similarities in all life stages (Edwards, 1932; Berlin, 1969; Belkin et al., 1970). Berlin (1969) also noted that the immature stages of Howardina are very similar to those of some species of genus Haemagogus. However, with the recognition that species traditionally grouped in Finlaya do not comprise a monophyletic taxon, it became apparent that the affinities of Howardina are uncertain. In the comprehensive study of Reinert et al. (2009), Howardina was placed as sister to a clade that includes five other New World subgenera of Aedes: Howardina + (Gymnometopa + (Kompia + (Aztecaedes + (Abraedes + Lewnielsenius)))). Interestingly, this group of generic-level taxa was sister to a clade that includes Haemagogus and three subgenera that were previously included in the broad traditional concept of Finlaya: (Finlaya + Danielsia) + (Downsiomyia + Haemagogus). Howardia was not associated with other generic-level taxa in the phylogeny of Wilkerson et al. (2015). Contrary to the finding of Reinert et al., Howardina was strongly supported as sister to Haemagogus in the maximum likelihood phylogeny of Soghigian et al. (2017) based on a number of molecular markers.
The immature stages of Howardina species are found in containers, including rock holes, tree holes, broken bamboo, fallen plant parts, axils of bromeliads and aroids, and flower bracts of Heliconia. A few species utilise various types of artificial containers. Adults of Howardina are active during the daylight hours. Females of a number of species are known to bite humans in forested areas, but their natural hosts are vertebrates that inhabit various strata from ground level to canopy in forests.
Some species of subgenus Howardina readily attack humans but little is known about the potential of these mosquitoes to harbour and transmit arboviruses. Experimental studies have shown that Ae. fulvithorax and other species of the subgenus can be infected with and maintain yellow fever virus, but they are not able to transmit the virus (Davis & Shannon, 1931; Whitman & Antunes, 1937; Boshell-Manrique & Osorno-Mesa, 1944, Bugher et al., 1944; Aitken, 1960). Bates (1949) suggested that species of Howardina may be able to transmit the virus if incubation is prolonged at favorable temperatures.
Neotropical Region.
Berlin, 1969 (revision); Reinert, 2002 (as subgenus of Ochlerotatus, female genitalia); Reinert et al., 2004, 2006, 2008, 2009 (as genus, morphology, phylogeny); Wilkerson et al., 2015 (phylogeny, classification); Soghigian et al., 2017 (phylogenetic relationships).
