Nasimyia megacephala sp. nov.

(Figs 1–10)

Diagnosis. Body stout, large head markedly broader than thorax (Fig. 1); last flagellomere not swollen toward apex (Fig. 7); wing greyish infuscate, with distinct spots in cell r2+3 (stigma) and around vein R4 (Fig. 2); posterior margin of male genital capsule rounded (Fig. 10), aedeagal complex with long proximal part (fig. 9).

Descriptions. Male. Body length 5.5–6.0 mm, wing length 4.0– 4.4 mm.

Head (Figs 1, 3–4) large, distinctly broader than thorax, shining black, about 0.6 times as long as broad in dorsal view and 0.9 times longer than high in profile. Ocellar tubercle shining black, bare, distinctly prominent. Posterior part of head slightly concave, postocular rim not visible in dorsal view. Eyes dark brown, bare and contiguous, upper facets larger than lower. Upper frons shining black, small, as broad as anterior ocellus; lower frons subtriangular, black and bare, with a longitudinal median groove. Antenna (Fig. 7) 2.5 times as long as head, scape cylindrical, pedicel more cup-shaped, both yellowish brown and about equal in length; flagellum with 8 flagellomeres, first flagellomere yellowish brown at base and gradually darkened toward end, following flagellomeres brown and last two flagellomeres black; whole antenna densely haired; relative lengths of antennal scape, pedicel and flagellomeres 1.4:1.2:1.4:1.4:1.1:0.9:1.0:1.4:1.3:1.7, relative widths of antennal scape, pedicel and flagellomeres 8.0:9.0:8.5:9.0:9.0:9.0:8.5:8.0:8.0:7.8 (sometimes last flagellomere tapered). Face shining black, nose-like medial projection with sparse hairs on the protuberance; lateral vitta consisting of white tomentum distinct along eye margin. Occiput not visible in lateral view. Proboscis yellowish, with sparse yellow hairs. Palpus with a yellow basal segment and black apical segment.

Thorax (Fig. 1) relatively stout and short, approximately 1.5 times longer than wide; mostly black, with a very narrow and inconspicuous whitish yellow line from postpronotal callus to base of wing, with dense punctation and decumbent golden and black short hairs. Scutellum with rounded and unarmed posterior margin. Legs wholly yellow, with yellow short hairs. Wing (Fig. 2) brownish infuscate with contrasting hyaline spot in anterior part of cell R2+3. Halter black with yellow stem.

Abdomen flat and slender, slightly narrower than the thorax, about 2.5 times longer than wide. Dorsum shining black, with dense punctation and mixed growth of black and pale hairs; hairs at base more erect and longer than on apical part. Venter black with pale short hairs. Male terminalia (Figs 8–10) yellowish brown, epandrium (Fig. 8) subquadrate, gonocoxite (Figs. 10) with dark elliptical lateral spot, aedeagal complex (Fig. 9) tripartite in distal part, lobes about as long as compact basal part.

Female. Body length 5.0– 6.2 mm, wing length 4.0– 4.5 mm. Similar to male but head (Figs 5, 6) with separated eyes, about 0.6 times as long as broad in dorsal view and 0.7 times longer than high in profile. Frons shining black, nearly parallel-sided, width of frons about 0.3 times width of head, lateral longitudinal vitta consisting of white hairs visible along each eye margin. Antennal scape and pedicel yellowish brown, flagellum dark brown to black. Facial projection larger and more pointed than in male. Cercus twosegmented.

Specimens examined. Holotype 3, China, Yunnan Province, Mts. Gaoligong, 1800–2400m, Baoshan, 29.v. – 3.vi.2009, Zaihua Yang & Bin Li leg. Paratypes: 23, 3ƤƤ, with same locality labels.

Etymology. The specific name is derived from the Latin words “ mega ” (= big) and “ cephale ” (= head) referring to the conspicuous head.