Diplonevra bifasciata (Walker)

(Figs. 1, 2, 33, 49)

Phora bifasciata Walker, 1860: 172 (♀: Celebes).

Diploneura (Tristoechia) bifasciata (Walker): Schmitz 1929: 105.

Phora egregia Brues, 1911: 534 . Synonymized by Schmitz, 1929: 105. Phora bicolorata Becker, 1914: 88 . Synonymized by Schmitz, 1929: 105. Phora cinctiventris Senior-White, 1922: 154 . Synonymized by Schmitz, 1929: 79.

Male: Head. Frons black, subshining, with 16–18 scattered setae. Mean frontal width 0.41 of head width. First row of bristles convex, antial bristles further apart than either is from an anterolateral. Second row of bristles strongly concave, pre-ocellar bristles further apart than either is from a mediolateral. Supra-antennal bristles well below antials and close each other. Postpedicel brownish yellow, oval. Arista dark brown. Palpus dusky orange and 3 times as long as its breadth, with 6 bristles on ventral apex. Proboscis short, pale yellow. Thorax. Scutum and scutellum black. Anepisternum and anepimeron dark brown; the other part of pleuron pale yellow. Notopleuron with 4 bristles. Scutellum with 4 long bristles. Legs yellow except for tips of hind femora and hind tibiae and tarsi. Front tibia with a dorsal bristle two fifths of length from base and with 7–10 small differentiated hairs extending below this to the tip. Mid tibia with 2 longitudinal hair palisades, anterodorsal one sharply deflected onto anterior face and extending to the tip of tibia. Posterior face of hind trochanter with 1 stout differentiated bristle. Ventral region of posterior face of hind femur with 2 short bristles and several fine hairs, lacking ascending process. Hind tibia with 1 anterodorsal bristle. Wing 3.6–3.8 mm long. Costal index 0.51–0.52. Costal ratios 5.4–5.6:1.4–1.5:1. Costal cilia 0.06–0.07 mm long. Vein M1 straight. Axillary ridge with 3 bristles. All veins brown and membrane yellowish brown. Haltere pale yellow. Abdomen. Tergites dark brown except tergite 1 and anterior half of tergite 2 pale yellow, with small hairs on tergites 1–5, but longer hairs on tergite 6. Venter pale yellow. Hypopygium brown. Left side of epandrium narrow with 4–8 long hairs. Right side of epandrium broad, with about 8–10 long hairs toward posterior margin; ventral apex with an incurved hook. Left side of hypandrium elongate and arc-shaped apically; right side of hypandrium tomentose. Circus and stalk of circus pale yellow. Body length 3.0–4.0 mm.

Female. Head similar to male except as follows. Frons black, shinning. Postpedicel orange yellow. Proboscis pale yellow, elbowed, elongate, extending beyond postpedicel. Wing 4.5–5.6 mm long. Costal index 0.5–0.51. Costal ratios 7–8.5: 3.0–3.25:1. Costal cilia 0.1 mm long. Abdominal tergites 1 and 5 pale yellow, the other tergites dark brown. Body length 4.0–6.0 mm.

Distribution. China (Liaoning, Gansu, Guangdong, Guangxi, Guizhou, Yunnan, Hainan, Taiwan); Japan, Thailand, India.

Specimens examined. 2♂, Yunnan, Menglun (21°57'N, 101°15'E), 22–May–1991, Guangchun Liu ; 1♀, Yunnan, Mengyang (22°09'N, 100°91'E), 6–Jun–1991, Guangchun Liu ; 2♂ 5♀, Guangxi, Nonggang (11°35'N, 106°89'E), 3–Jun–1993, Yongsheng Cui ; 2♀, Hainan, Jianfeng (18°43'N, 108°48'E, 800m), 20–May– 2004, Guangchun Liu ; 1♂, Liaoning, Benxi, Xinbin (124°32E, 41°91N), 26–Aug–2009, Tao Li; 1♀, Guangdong, Nanling (24°45'N, 112°52'E, 1000m), 27–Jul–2011, Jianfeng Wang ; 1♂, 25–Jul–2011, Gansu, Huixian, Fengshan Mountain (33°46′E, 106°04′, 924m), Lixin Su ; 2♂, 19–Jul–2015, Guizhou, Libo County (25°17′N, 107°56′E), Zhiqiang Cheng, Chaoyi Zhang; 1♀, Guizhou, Libo County (25°17′N, 107°56′E), 21–Jul–2015, Chaoyi Zhang; 1♂, Guangxi, Mulun (25°09′N, 108°01′E), 24–Jul–2015, Zhiqiang Cheng ; 1♂ 1♀, Guangxi, Mulun (25°02′N, 108°02′E), 26–Jul–2015, Chaoyi Zhang ; 2♀, Guangxi, Mulun (25°02′N, 108°02′E), 26–Jul–2015, Zhiqiang Cheng.

Remarks. The species is one of the largest-sized scuttle flies in the genus. It is easily distinguished from other species by the following characters: hind tibia with 3 longitudinal hair palisades and 1 anterodorsal bristle before apical quarter; wing vein M1 straight; abdominal tergites 2–5 dark brown and venter pale yellow; Female abdominal tergites 1 and 5 yellow.