Pseudacteon quadrisetalis Liu et Cai

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 : 203-205

1. Pseudacteon quadrisetalis Liu et Cai

( Figs. 1A–F , 24A–B )

Pseudacteon quadrisetalis Liu et Cai, 2013: 54 .

Diagnosis. Female. Apical seta longer than maximum width of palpus; 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 with 4 long and 4–5 short setulae; sternite VI clearly defined, with 4 very strong pin-shaped setae and some fine, long setulae; dorsum of oviscape with 3–4 short setulae on sub-apex of each side; venter of oviscape with 12–16 fine, long and transversely-inclined setulae arranged in two longitudinal rows.

Female. Frons ( Fig. 1A ) dark brown, with about 12–14 setulae. Frons with 2 pairs of supra-antennal setae, upper pair as high as lower fronto-orbital setae. Second row of frontal setae clearly concave, all four setae are equally distanced. Flagellomere 1 brown, subglobose. Palpus pale, very lightly tinged brown, with 4 long setae, apical one longer than maximum width of palpus.

Thorax brown. Scutellum with a pair of setae, posterior twice length of anterior. Legs yellowish brown. Ratios of lengths of fore tarsomeres 0.81: 0.77: 0.63: 0.61: 1, with all five bearing a setal palisade ( Fig. 1C ). Setal palisade extends 2/3 length along mid tibia and comprising 35–40 modified setulae ( Fig. 1D ). Setulae below basal half of hind femur shorter than those of anteroventral row of outer half ( Fig. 1E ). Wing ( Fig. 1B ) length 1.14–1.17 mm, width 0.57–0.59 mm, width/length 0.51. Costal index 0.38–0.39. Costal ratio 1.96: 1. Costal cilia 0.08 mm. Alula with 3 setae. Haltere brown.

Abdomen. Tergites brown with sparse minute setulae. Tergites II–V very much broader than long, but progressively narrowing from tergite II backwards. Tergite VI ( Fig. 24A ) reduced to a narrow anterior strip in middle but each side bears 4 long and 4–5 short setulae at rear margin. Venter brown. Sternite VI ( Figs. 1F , 24B ) clearly defined, with 4 very strong pin-shaped setae and some fine and long setulae. Oviscape brown. The dorsum of the oviscape arched, with 3–4 short setulae on sub-apex of each side. The venter of the oviscape with 12–16 fine, long and transversely-inclined setulae arranged in two longitudinal rows ( Fig. 1F ).

Male. Unknown.

Distribution. China (Liaoning, Jilin, Gansu).

Material examined. 2♀, Liaoning, Benxi, Mt. Wunv (41°19′58.76″N, 125°25′11.81″E), 5–Jul–2012, Meng Yang ; 1♀, Liaoning, Benxi, Erdaogou (41°7′50.66″N, 124°22′12″E), 4-Jul-2018, Jiao Zhang ; 2♀ (slides), Jilin, Yanbian, Wangqing, Mingyuegou (43°15′26.19″N, 129°55′35.23″E, 380 m), 7-Aug-2014; Jianfeng Wang ; 4♀, Jilin, Yanbian, Wangqing, Mingyuegou (43°15′26.19″N, 129°55′35.23″E, 380 m), 7-Aug-2014, Jianfeng Wang ; 1♀ (slide), Gansu, Wen County, Guanegou (33°55′12″N, 104°14′21″E; 2478 m), 10-Aug-2011, Yunlong Cai ; 1♀ (holotype), Gansu, Wen County, Guanegou (33°55′12″N, 104°14′21″E; 2478 m), 10-Aug-2011, Yunlong Cai ; 2♀ (paratyes), Gansu, Wen County, Qiujiaba (32°55′12″N, 104°19′12″E; 2270 m), 7-Aug-2011, Yunlong Cai .

Remarks. This species is easily recognized in having 4 very strong pin-shaped setae on abdominal sternite VI and transversely-inclined long setulae on the venter of the oviscape. In the key to European Pseudacteon ( Disney & Withers 2009) , the species runs to couplet 6, to P. fennicus Schmitz, 1927 . It differs from the latter in having 4 very strong, pin-shaped setae on sternite VI and 12–16 fine, long and transversely-inclined setulae on the venter of the oviscape. In the key to Pseudacteon of the Russian Far East ( Disney & Michailovskaya 2000), the species runs to couplet 4, to the putative female of P. pullum Michailovskaya , but it is different in having a uniformly brown sternite VI, with pin-shaped setae and 35–40 modified setulae of mid tibia setal palisade.

Figures

FIGURES 1A–F. Pseudacteon quadrisetalis Liu et Cai, 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, ventral 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.