16. Pseudacteon calceoliformis sp. nov.

(Figs. 20A–F, 26C–D)

Diagnosis. Female. Apical seta longer than maximum width of palpus; tarsomere 5 shorter than tarsomere 1; setal palisade 2/3 length of mid tibia; setulae below basal half of hind femur shorter than those of anteroventral row of outer half; tergite VI reduced to a narrow anterior strip in middle but each lateral quarter bears 2 long and 2 short setulae in transverse row; sternite VI divided into two boot-shaped plate; dorsum of oviscape with about 3–4 minute setulae each side.

Female. Body length 1.24–1.26 mm. Frons (Fig. 20A) yellowish brown, with 28–30 setulae. Supra-antennal setae as strong as adjacent frontal setae, upper pair being higher on frons than lower fronto-orbital setae. Lower interfrontal seta directly under lower fronto-orbital seta. Second row of frontal setae clearly concave, with upper interfronal setae further from each other than either is from upper fronto-orbital seta. Flagellomere 1 yellow and subglobose. Palpus pale yellow, with 6 long setae, apical seta a little longer than maximum width of palpus. Labrum and labella pale yellow.

Thorax yellowish brown. Scutellum with two pairs of setae, posterior twice length of anterior. Legs yellow. Ratios of lengths of fore tarsomeres about 0.90: 0.71: 0.61: 0.59: 1, with all five bearing a setal palisade (Fig. 20C). Setal palisade terminates 2/3 (0.65) length of mid tibia (Fig. 20D). Setae below basal half of hind femur a little shorter than those of anteroventral row of outer half (Fig. 20E). Wing (Fig. 20B) length 1.35 mm, width 0.69 mm, width/length 0.51. Costal index 0.40. Costal ratios 1.42:1. Costal cilia 0.035–0.036 mm long. Costa with 16 dorsal setulae. Alula with 3 setae. Veins slightly yellow, membrane hyaline. Haltere whitish yellow.

Abdominal tergites yellowish brown and tergites I–V with sparse minute setulae on posterior margins. Tergite VI (Fig. 26C) reduced to a narrow anterior strip in middle but each lateral quarter bears 2 long and 2 short setulae in transverse row. Venter pale yellow. Sternite VI (Fig. 26D) long and wide, concaved in middle and with a bootshaped plate each side, with 2 short setulae at posterior margin. The dorsum of the oviscape with about 3–4 minute setulae each side. The venter of the oviscape without minute setulae (Fig. 20F).

Male. unknown.

Distribution. China (Shaanxi).

Etymology. The species epithet refers to the shape of sternite VI.

Specimens examined. Holotype. ♀, China: Shaanxi, Zhuque National Forest Park (33°49′11.58″N, 108°35′57.88″E,), 12-July-2012, Jianfeng Wang.

Remarks. This species is easily distinguished from other species of the genus by its boot-shaped sternite VI. It is a little similar to P. hexasetalis Liu et Wang, 2013, it differs from the latter by boot-shaped sternite VI and two pairs of supra-antennal setae.