Genus Opifex Hutton, 1902
Opifex fuscus Hutton, 1902.
Subfamily Culicinae, tribe Aedini. Opifex includes two species placed in separate subgenera: Nothoskusea and Opifex. Genus abbreviation – Op.
The adults of Opifex are large mosquitoes. They have a wide interocular space and frons, numerous scutal and abdominal setae, and setae are present at the base of the subcosta of the wing in females (and males of Op. fuscus) as in Culiseta. Males exhibit two unique features: the antennal flagellomeres have only a few short setae and the two apical flagellomeres are approximately the same length as the others. Larvae have seta 6-I–V usually at least triple, seta 7-I usually at least double, a relatively small dorsal saddle, a strongly developed ventral brush (seta 4-X) and small, rounded anal papillae. Opifex shares many features with Halaedes. See Aedini.
The following characters diagnose Opifex in the phylogeny of Reinert et al. (2009). ADULTS – Eyes broadly separated above antennal pedicels; interocular space with 6 or more setae; terminal 2 flagellomeres about same length as proximal flagellomeres, flagellar whorls of males with few short setae dispersed more or less around flagellomeres; palpomere 4 of maxillary palpus absent or vestigial in males; scutal fossal scales sparse; paratergal scales and subspiracular scales absent; base of subcosta of wing with ventral setae in females; laterotergite of abdominal tergum I without scales. MALE GENITALIA – Gonocoxite with setae on basomesal area of dorsal surface all slender; gonostylar claw a short claw-like spiniform, bluntly pointed. LARVAE – Seta 7-I < 0.45 length of seta 6-I; seta 1-II single. PUPAE – Seta 1-CT weakly developed, shorter than seta 3-CT.
Belkin (1962) considered many features of Op. fuscus to represent the most primitive conditions found within Aedini and believed that they were annectant with other tribes, but this was not corroborated in the cladistic analyses of Harbach & Kitching (1998), Reinert et al. (2004, 2006, 2008) and Wilkerson et al. (2015) based on morphological data. In the study of Reinert et al. (2009) based on more extensive morphological data, Opifex was recovered as the sister of Halaedes in a clade comprised of Acartomyia + (Jarnellius + (Halaedes + Opifex)), and this clade was sister to Ochlerotatus. A similar relationship but without Jarnellius, i.e. Acartomyia + (Halaedes + Opifex), was recovered in the analysis of Wilkerson et al. (2015). Opifex fuscus was recovered in a basal relationship to the Ochlerotatus Group of generic-level taxa (clade B) in the maximum likelihood phylogeny of Soghigian et al. (2017) based on seven molecular markers.
Opifex larvae occur in coastal rock-pools containing brackish, saline or hyper-saline water. The larvae of Op. fuscus have also been collected from a hole in a tree trunk projecting over the seashore, a fresh water stream and a horse trough. The adults of Op. chathamicus have not been encountered in nature, but females of Op. fuscus are known to attack at night and produce a painful bite. Males of the latter species exhibit a unique mating behaviour that includes precocious coupling with females before they have fully emerged from their pupal exuviae.
Opifex are not medically or economically important species.
The type species, Op. (Opifex) fuscus, is found in New Zealand and the Kermadec Islands; Op. (Nothoskusea) chathamicus is known only from the Chatham Islands.
Belkin, 1962 (subgenus Opifex, as genus, New Zealand area, taxonomy, bionomics, distribution); Belkin, 1968 (Opifex and Nothoskusea, as genus and subgenus of Aedes respectively, New Zealand area, taxonomy, bionomics, distribution); Lee et al., 1984 (subgenus Nothoskusea, as subgenus of Aedes, taxonomy); Lee et al., 1988 (subgenus Opifex, as genus, taxonomy, bionomics, distribution); Reinert et al., 2004, 2006, 2008, 2009 (morphology, phylogeny); Wilkerson et al., 2015 (phylogeny); Soghigian et al., 2017 (phylogenetic relationships).