Subgenus Opifex Hutton, 1902
Opifex fuscus Hutton, 1902.
Subfamily Culicinae, genus Opifex. Subgenus Opifex is monobasic. Subgenus abbreviation – Opi.
The only species of subgenus Opifex, a large mosquito, bears the following unique and distinctive features. ADULTS – Vertex of head with setae instead of erect scales; antenna with fully developed scape, flagellomeres 2–4 of males each with dorsal basal swelling bearing a greatly enlarged spine-like seta; maxillary palpus short, about 0.5 and 0.7 length of proboscis in females and males respectively, palpomere 4 of females club-shaped with invaginated sense organ at apex; wing of males as well as females with setae at base of subcosta; foreleg markedly shorter than mid- and hindlegs; tarsi of males with conspicuous hydrofuge fringe of setae on ventral surface; ungues of females equal, toothed, ungues of males simple, foreungues extremely large; abdominal terga and sterna II–VII with numerous setae and very sparse scales as in subgenus Nothoskusea. FEMALE GENITALIA – Nearly completely retracted into segment VIII; tergum VIII about 0.65 length of sternum VIII, with a few scales on posterior 0.4–0.6 and numerous setae on posterior 0.6–0.7; sternum VIII without scales, with dense hydrofuge setae distally and densely spiculose invaginated caudal membrane, setae 1–3-S long, inserted in more or less diagonal line from anteromesal area to caudolateral comer, basolateral seta absent; tergum IX comprised of 2 lateral plates separated by narrow membrane; cercus without scales, setae on distal 0.5–0.6 of dorsal surface; postgenital lobe poorly sclerotised; upper vaginal sclerite a small short broad lobe extending inward and situated some distance caudally from hinge; lower vaginal sclerite absent; insula lip-like, very short, with 2–4 setae on each side of midline. MALE GENITALIA – Segment VIII markedly shortened; tergum IX without lobes, with lateral patches of numerous short setae; gonocoxite with dense hydrofuge setae on dorsal, lateral and ventral surfaces, mesal surface membranous from base to apex; gonostylus very short, stout, with rounded basomesal swelling, gonostylar claw stout, spiniform, deeply inserted at apex of gonostylus; claspette a long setose plate-like sclerite on mesal membrane of gonocoxite; aedeagus long, simple; cercal setae strongly developed, numerous. LARVAE – Prothoracic and metathoracic pleural setal groups (setae 9–12-P,T) very small, all setae normally single; mesothoracic pleural setal group (setae 9–12-M) borne immediately adjacent (close) to seta 8-M; seta 6-VI large, developed like seta 6-V; pecten reduced, represented by few simple widely spaced spines; seta 6-S very long, aciculate; segment X without acus; seta 1-X inserted on margin of saddle; ventral brush (seta 4-X) with 8 or 8.5 pairs of setae. PUPAE – Median keel of cephalothorax very strongly developed; trumpet short, extremely broad, trumpet index about 1.1; seta 1-I reduced, with few simple branches; seta 3-III inserted caudad of level of seta 5; seta 5-IV,V usually single; seta 9-VII small, similar to seta 9-II–VI, inserted ventrally near caudolateral margin; seta 1-Pa usually single. See genus Opifex.
The following characters diagnose subgenus Opifex in the phylogeny of Reinert et al. (2009). ADULTS – Vertex of head without erect scales, decumbent scales of vertex, interocular scales and ocular scales all broad; scutellar scales of middle and lateral lobes all broad; lower prealar scales absent; midungues of males both simple. FEMALE GENITALIA – Postgenital lobe broader than cercus, ratio of ventral width at distal 0.20 to cercus width at mid-length ≤ 0.65, setae inserted on entire ventral surface. MALE GENITALIA – Sternum IX bare; gonocoxite without scales, lateral setae mostly short, gonostylus attached subapically, proximal part broad, median part noticeably broader than proximal part, gonostylus/gonocoxite index 0.30−0.40. LARVAE – Seta 1-A short, length ≤ 3.0 diameter of antenna at point of attachment; seta 7-C ≤ 0.19 length of dorsal apotome; seta 6-S noticeably longer than distal width of siphon. PUPAE – Trumpet without tracheoid area; seta 1-II with ≤ 3 branches (rarely 4-branched); seta 3-II inserted lateral to seta 2-II, longer than seta 6-II, thicker than seta 1-II; seta 3-VI inserted mesal to seta 1-VI; seta 9-VII shorter than seta 6-VII.
Subgenera Opifex and Nothoskusea were recovered as sister taxa based on two unique features of the antennae of males included in the phylogenetic study of the Aedini conducted by Reinert et al. (2004). However, phylogenetic analysis of New Zealand mosquito species based on rDNA ITS1 sequences (Cane et al., 2020) showed that Op. chathamicus may be more closely related to other aedine taxa than it is to Op. fuscus, suggesting that Nothoskusea should perhaps be recognised as a separate genus in the phylogenetic classification of the Aedini. See the phylogeny of genus Opifex.
The immature stages of Op. fuscus, the only species of subgenus Opifex, are found primarily in brackish, saline and hypersaline rock pools above high tide level, but they have also been found in a hole in a dead pohutukawa trunk, a fresh water stream and a horse trough (Belkin, 1968). Adult females are autogenous, but are known to seek blood meals at night. They attack and bite humans who enter their haunts. Males spend most of their time on the water surface searching for pupae, and precociously couple with females before they have fully emerged from their pupal exuviae.
The only included species of subgenus Opifex is not known or suspected of being of medical importance to humans.
New Zealand and Kermadec Islands.
Belkin, 1962 (as genus, New Zealand area, taxonomy, bionomics, distribution); Belkin, 1968 (as genus, New Zealand area, taxonomy, bionomics, distribution); Lee et al., 1988 (as genus, taxonomy, bionomics, distribution); Reinert, 2001 (as genus, female genitalia); Reinert et al., 2004 (subgeneric status, morphology, phylogeny); Reinert et al., 2006, 2008, 2009 (morphology, phylogeny).
fuscus Hutton, 1902