Pseudacteon trapeziformis Zhang et Liu

Liu, Guang-Chun & Disney, R. Henry L., 2022, Revision of the ant-parasitizing genus Pseudacteon Coquillett (Diptera, Phoridae) from China, Zootaxa 5138 (3), pp. 201-237 : 206-209

3. Pseudacteon trapeziformis Zhang et Liu

( Figs. 3A–F , 4A–F , 24C–D )

Pseudacteon trapeziformis Zhang et Liu, 2019: 448 .

Diagnosis. Female. Apical seta shorter than maximum width of palpus; setal palisade 1/2 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 with 3–4 setulae; sternite VI long, trapezoid, with 8–10 long setae on rear margin; dorsum of oviscape with 8–10 small setulae on each side, three of those near apex longer; venter of oviscape with 5 long setulae each side. Male. Setal palisade 2/3 length of mid tibia; fore tarsomere 5 longer than tarsomere 1; palpus apical seta less than 1.5 length of maximum width of palpus.

Female. Frons ( Fig. 3A ) brown, with 20–30 setulae. Supra-antennal setae as strong as adjacent frontal setae, lower pair being closer together and a little higher than lower fronto-orbital setae. Lower interfrontal seta near eye margin, but not directly under lower fronto-orbital seta. Lower fronto-orbital setae even nearer eye margin and a little lower on frons than upper supra-antennal setae. Second row of frontal setae almost straight, with upper interfrontal setae clearly further apart than either is from an upper fronto-orbital seta. Flagellomere 1 brown to pale brown and subglobose. Palpus whitish yellow, with short setae, apical one longer than adjacent setulae and shorter than maximum width of palpus. Labrum brown, small and triangular. Labella yellowish brown and tip of glossa brown.

Thorax brown. Scutellum with two pairs of setae, posterior twice length of anterior. Legs yellowish brown to brown, hind femora being darkest. Ratios of lengths of fore tarsomeres about 0.61: 0.57: 0.58: 0.46: 1, with all five bearing a setal palisade ( Fig. 3C ). Setal palisade extends more than 1/2 length of mid tibia ( Fig. 3D ). Setulae below basal half of hind femur longer than those of adjacent setulae of anterior face, but clearly shorter and weaker than those of anteroventral row of outer half ( Fig. 3E ). Wing ( Fig. 3B ) length 1.25–1.36 mm, width 0.65–0.68 mm, width/length 0.51. Costal index 0.40–0.42. Costal ratios 1.19–1.28: 1. Costal cilia 0.053–0.059 mm long. Costa with 16–18 dorsal setulae. Alula with 2 setae. Veins brown, thin veins being paler. Membrane brownish gray. Haltere pale yellow.

Abdominal tergites brown and tergites 1–5 with sparse minute setulae only. Tergite VI ( Fig. 24C ) reduced to a narrow anterior strip in middle but each lateral quarter bears 3–4 setulae at rear margin. Oviscape arched. The dorsum of the oviscape with about 8–10 small setulae each side, three of those near apex are a little longer ( Fig. 3F ). The venter of the oviscape with 5 longer setulae each side. Venter brown. Sternite VI ( Fig. 24D ) trapezoid, with 8–10 long setae on rear margin and some setulae on both sides.

Male. Frons ( Fig. 4A ) brown, with 14–20 setulae. Supra-antennal setae as strong as adjacent frontal setae, lower pair being closer together and a little higher than lower fronto-orbital setae. Lower interfrontal seta near eye margin, and directly under lower fronto-orbital seta. Lower fronto-orbital setae even nearer eye margin and a little lower on frons than upper supra-antennal setae. Second row of frontal setae concave, with upper interfrontal setae clearly further apart than either is from an upper fronto-orbital seta. Flagellomere 1 brown and subglobose. Palpus pale yellow, with long setae, apical one as long as or a little longer than maximum width of palpus. Labrum and labella pale yellow.

Thorax brown. Scutellum with two pairs of setae, posterior twice length of anterior. Legs yellowish brown to brown, hind femora being darkest. Ratios of lengths of fore tarsomeres about 0.94: 0.69: 0.69: 0.69: 1, with all five bearing a setal palisade ( Fig. 4C ). Setal palisade extends more than 1/2 (0.60) length of mid tibia ( Fig. 4D ). Setulae below basal half of hind femur clearly shorter and weaker than those of anteroventral row of outer half ( Fig. 4E ). Wing ( Fig. 4B ) length 1.28–1.30 mm, width 0.66–0.67 mm, width/length 0.52. Costal index 0.41–0.42. Costal ratios 1.33:1. Costal cilia 0.053–0.060 mm long. Costa with 16 dorsal setulae. Alula with 2 setae. Veins brown, thin veins being paler. Membrane brownish gray. Haltere pale yellow.

Abdominal tergites brown and tergites 1–6 with sparse minute setulae only. Venter brown. Male terminalia ( Fig. 4F ) brown, anal tube pale yellow. Left side of epandrium slender and tapered, with some setulae at apex. Right side of epandrium a little broad, with setulae apically.

Distribution. China (Jilin).

Material examined. 5♀ 3♂, Jilin, Yanbian, Tuan, Erdaobaihe (42°11′17.38″N, 128°10′24.65″E; 1120m), 31- July-2014, Jianfeng Wang ; 6♀ 2♂, Jilin, Baishan, Fusong (42°02′38.74″N, 127°47′31.17″E, 1033 m), 27-Jul-2014, Jianfeng Wang ; 2♀, Jilin, Yanbian, Wangqing (43°24′23.71″N, 131°01′09.35″E, 556 m), 8-Aug-2014, Jianfeng Wang ,.

Remarks. This species is easily recognized from other species in having a trapezoid sternite VI and a row of 8–10 setulae on its rear margin. In the key to Russian Far East ( Disney and Michailovskaya 2000), the species runs to couplets 4 to P. rudisetosus Disney et Michailovskaya, 2000 , it is immediately distinguished from the latter by the shape of sternite VI and its chaetotaxy. In the key to European species ( Disney 2009), the new species runs up to couplet 4 to P. brevicauda Schmitz, 1925 , it differs from the latter by shorter and thicker setae of palpus and shape of sternite VI. The male of the species is similar to that of P. setipalpatus Disney et Michailovskaya, 2000 , it differs from the latter by apical seta less than two times of the maximum width of palpus and fore tarsomere 5 longer than tarsomere 1.

Figures

FIGURES 3A–F. Pseudacteon trapeziformis Zhang et Liu, female.A. head, anterior view; B. wing, dorsal view; C. fore tarsus, anterior view; D. mid tibia, posterior view; E. hind femur, anterior view; F. ovipositor, dorsal view. Scale bar = 0.1mm.

FIGURES 4A–F. Pseudacteon trapeziformis Zhang et Liu, male. A. head, anterior view; B. wing, dorsal view; C. fore tarsus, anterior view; D. mid tibia, posterior view; E. hind femur, anterior view; F. male terminalia, left view. Scale bar = 0.1mm.

FIGURES 24A–J. Tergite VI and sternite VI of females.A–B. P. quadrisetalis Liu et Cai; C–D. P. trapeziformis Zhang et Liu; E–F. P. inticlinatus sp. nov.; G–H. P. setipalpatus Disney et Michailovskaya; I–J. P. reticulatus sp. nov. Scale bar = 0.1mm.