Dichaetomyia univittata Couri & Pont & Daugeron 2010, sp. nov.

16. Dichaetomyia univittata, sp. nov.

(Figures 1–6)

Holotype. Male, deposited in MNHN, labelled: Vanuatu: Espirito Santo, Is 1200A [collect code], L-6, light, 18.xi.2006, R.L.K.

Diagnosis. Robust species; scutum yellow with a broad median brown vitta that becomes wider towards scutellum; legs yellow, hind tibia and all tarsi brown; dorsocentrals 2+4.

Description. Ground-colour yellow. Head with fronto-orbital plate and gena brown. Pedicel yellowishbrown, postpedicel brown with grey pollinosity. Arista brown. Palpus brown. Scutum yellow, with a broad median brown vitta that becomes wider towards scutellum. Anterior and posterior spiracles yellow, posterior one with black setae on margins. Pleura wholly yellow. Anepimeron with setulae brown above and yellow below. Wing clear. Calypters yellowish, margin of upper one brown. Legs yellow, hind tibia and all tarsi brown. Abdomen with syntergite 1+2 yellow, tergites 3 and 4 brown, and tergite 5 brown at base and yellow at tip.

Male. Length. Body: 6.5–7.8 mm, wing: 6.8 mm.

Head. Eye bare; separated at vertex by the width of the ocellar triangle. Vertical setae short. Frontal row with 1 strong pair of setae close to lunula, followed by 2 or 3 other short and thin pairs; reclinate orbitals minute. Antenna inserted at mid level of eye; postpedicel about 3.2 times as long as pedicel. Arista with long plumes. Palpus slightly clavate.

Thorax. Acrostichals 0+1; dorsocentrals 2+4; 2 postpronotals; 1 presutural; 2 intraalars; 2 supraalars; 2 postsupraalars. Notopleuron with two setae, the posterior seta a little shorter than the anterior, with or without setulae at their bases. Scutellum with one long subbasal and one long apical pair of setae, similar in size; no setulae on latero-inferior margin. Anepisternum with a series of 4 long setae and some fine setae on posterior margin. Katepisternals 1+2, the upper posterior one very long. Anepimeron with a tuft of setulae above and some scattered setulae on posterior half. Posterior spiracle with a row of setulae on lower and posterior margins. Lower calypter about twice as long as upper one. Wing veins bare. Fore femur with complete rows of posteroventral, posterodorsal and dorsal setae. Fore tibia without submedian seta, one dorsal and one posteroventral apical. Mid femur with a row of 4 long posteroventral setae on basal half; 3 preapical posterior to posterodorsal setae, the posterodorsal one shorter. Mid tibia with 2 posterior setae inserted at one-third and two-thirds, and with a strong apical seta on ventral and posteroventral surfaces. Hind femur with a complete anterodorsal row of setae, and 3–4 anteroventral setae on apical third. Hind tibia with one median anterodorsal and one median anteroventral; one anterodorsal and one dorsal preapical and one ventral apical.

Abdomen. Tergites 3–5 each with a marginal row of setae. Sternite 1 bare. Sternite 5 as in Fig. 1.

Terminalia. Cercal plate a little wider than high, with long setae on upper margin; surstylus large (Figs 2 and 3). Aedeagus as in Fig. 4.

Female. Length. Body. 6.5–6.8 mm, wing: 6.8 mm

Very similar to the male. Frons at vertex about 1/3 of head-width. 4–5 pairs of frontal setae. Vertical setae more developed than in male.

Ovipositor and spermatheca as in Figs 5 and 6.

Discussion. The species can be easily recognized by the large median brown vitta on the yellow scutum. In the key to Australian species by Pont (1969a), the new species runs to D. australis Pont (couplet 12) which can be immediately separated from the new species by its entirely yellow scutum.

Etymology. The name comes from the Latin adjective unus, meaning “one”, and the Latin noun vitta, meaning “ribbon” or “band”, and refers to the single brown vitta on scutum.

Material examined (all paratypes): MNHN: Vanuatu: Same label as holotype, 1 ♂ (MNRJ), 2 ♀ (MNHN, BMNH).

Comments. The species is endemic to Vanuatu.

Distribution. Vanuatu.