Corethrella oppositophila Kvifte & Bernal

Kvifte, Gunnar Mikalsen & Bernal, Ximena E., 2018, A new species of frog-biting midge from Papua New Guinea with a key to the described Corethrellidae of the Australopapuan region (Diptera, Corethrellidae, Corethrella), ZooKeys 795, pp. 39-48 : 40-44

Corethrella oppositophila Kvifte & Bernal sp. n. Figs 1, 2

Type material.

Holotype male. PAPUA NEW GUINEA: Morobe province, Mount Wilhelm, 5.758978°S, 145.18607°E, 2200 m a.s.l., 27.X.2012, leg. Mogia, Lilip, Vohotny & Leponce (Malaise trap). Six paratype females, same locality as holotype but collection dates 17.X.2012, 22.X.2012, 25.X.2012, 28.X.2012, and 31.X.2012 (two specimens). All specimens in collections of RBINS.

Diagnosis.

Only extant species of Corethrellidae with the following combination of characters: wing with a mid-length band of dark pigmentation and scales, thorax brown with anterior two thirds of scutum, prosternum and katepisternum light brown, abdominal tergites light brown with anterior dark bands, dorsomedial seta of male gonocoxite parallel with proximalmost seta in dorsal row.

Description.

Adult male (n = 1). Head (Figs 1a, 2a, 2c) broader than long. Eyebridge of five rows of facets, constricting towards median. Four frontal setae present. Antenna (Figure 1c) with pedicel dark brown, scape and flagellum paler. Pedicel without setae longer than length of pedicel. Length of flagellomeres 120, 62.5, 62.5, 85, 115, 132.5, 132.5, 130, 130, 125, 117.5, 82.5, 65, 80, terminal flagellomere bifurcate. Three sensilla coeloconica on flagellomere I, one sensillum coeloconicum on each of flagellomeres IX–XIII. Palpus uniformly pale brown with segment III of uniform width or slightly broader at mid length, length of palpal segments 37.5, 42.5, 100, 77.5, N/A (5th palpal segments missing in specimen). Palpal segment I with single lateral elongate seta, seg ment II with two elongate setae, and one short. Clypeus broadly oval with single medial seta. Labellum oval. Cibarial pump, hypopharynx, tentorium and stipes as in Figure 2a.

Thorax brown with anterior two thirds of scutum, prosternum and katepisternum light brown. Dorsocentral row without elongate setae at posterior end. Prescutal suture narrow, extending more than two thirds of way to dorsocentral row. Anterior anepisternum divided diagonally into dorsal and ventral portions, dorsal portion about twice as large as ventral; posterior anepisternum undivided, posterior half without distinct setae. Haltere paler than thorax.

Wing (Figure 1d) 1.75 mm long, 0.48 mm wide, R1 1.31 mm long. Apex of R2 at level with M1. Membrane with patch of dark infuscation from Sc to stem of R2+3, paler infuscation present over crossveins r-m and m-cu. Midlength and subapical bands of pigmented scales present. Wing scales narrow, those on C nearly twice as wide as those on other veins.

Legs light brown with rings of darker pigmentations basally and subbasally on all femora and tibiae, more indistinct on midtibia. Fore- and midtarsi with banding. With only slender setae, lacking scales. Claws on fore- and midlegs unequal, hind leg claws equal, all simple, without basal prongs or empodia. Ratio of foreleg Ta3/Ta4 = 1.56.

Abdomen (Figure 1j) Light brown with darker brown mottled bands anteriorly on each tergite, sternites I–II pale, other sternites light brown with darker brown mottled bands anteriorly. Tergites and sternites VIII and IX light brown; length of segment VIII 112.5, distally 2.5 times as wide as base; hairless stripe medially on tergite IX 35 μm wide.

Genitalia (Figure 2 e–g). Gonocoxite uniformly pale brown, tapering gently towards apex; all setae of similar length; with well-defined dorsal row of six setae of uniform length and thickness. Dorsomedial seta stout, tapering from non-expanded base. Gonostylus sinuous, of equal thickness except tapering apically, one elongate, thick subbasal seta situated on inner surface (ventrally), with thick, blunt subapical peg; subbasal seta 0.4 length of gonostylus. Parameres comprised of a sclerotized S-shaped part and a less weakly sclerotized egg-shaped part. Aedeagus slender, tapering gradually to apex, reaching beyond dorsomedial seta, lateral margins meeting apically.

Adult female (n = 6) As for male, with following differences. Head (Figure 1b) Eyebridge of 5-6 rows of facets, constricting towards median. Coronal suture long, extending ventrally to between antennal bases. All available specimens with flagellum broken, length of preserved flagellomeres (n = 4) 70-80 (74), 42.5-45 (43), 45-50 (47), first flagellomere with three sensilla coeloconica. Length of palpal segments (n = 6, 6, 6, 4, 2) 35-50 (41), 40-47.5 (45), 87.5-97.5 (93), 70-80 (76), 80-95. Clypeus broadly hexagonal, with anterior margin about half length of posterior margin,, with 1-5 setae in single row. Mandibular teeth small, pointed. Labellum rectangular with apicomedial projection. Cibarial pump, hypopharynx, tentorium, and stipes as in figure 2b.

Thorax (Figure 1i) brown with anterior third of scutum, prosternum, mediotergite, metaepisternum, scutellum, and metakatepisternum light brown.

Wing (Figure 1e) 1.73-2.00 (1.79) mm long, 0.46-0.60 (0.53) mm wide. R1 1.19-1.35 (1.24) mm long.

Legs (Figure 1 f– 1h) Claws of each legs equal to those of others, equal on each leg, simple, with empodia slender, feather-shaped. Ratio of foreleg Ta3 / Ta4 = 1.35

Genitalia (Figure 1k) with 2-6 microseta subapically on proctiger.

Egg (n = 15, Figure 1I) length 240, width 127.5 mm.

Biology.

Females have biting mouthparts and one paratype was collected with blood in its gut (Figure 1k). Another paratype female was preserved with 15 eggs in her abdomen; these were not preserved well enough, however, to allow morphological comparison with other described Corethrellidae eggs.

Distribution.

Known only from the type locality on Papua New Guinea, where it was collected in a Malaise trap at 2200 m.a.s.l.

Etymology.

From Latin opposita, opposite, and Greek φίλος (philos), friend. "Opposites attract" - referring to the stark sexual dimorphism of the basal flagellomeres of the male and female antennae.

Remarks.

The new species keys to C. solomonis in Borkent (2008) but differs from that species by its thorax being more extensively brown (see description above and compare with Borkent 2008: fig. 38B) and having much shorter flagellomeres in the female. The male of C. solomonis is unknown.

The male and females of C. oppositophila Kvifte & Bernal sp. n. have been associated based on similarity of pigmentation, together with co-occurrence in the same Malaise trap at the same time.

Key to the described Corethrellidae of the Australopapuan region