Pseudacteon obtusatus 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 : 223-224

12. Pseudacteon obtusatus Liu et Cai

( Figs. 16A–F , 25E–F )

Pseudacteon obtusatus Liu et Cai, 2013: 56 .

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 side bearing 2 strong setulae at rear margin; sternite VI brown, reduced to a narrow strip in middle, bearing 2 short setae and 2–3 minute setulae on each ill-defined side; dorsum of oviscape with about 10–12 minute setulae on sub-apex.

Female. Frons ( Fig. 16A ) brown, with 20–24 setulae. Supra-antennal setae as strong as adjacent frontal setae, upper pair higher than lower fronto-orbital setae. Second row of frontal setae slightly concave, upper interfrontal setae further apart than either is from an upper fronto-orbital seta. Flagellomere 1 brown, sub-globose. Palpus brown, with four setae, apical one longer than maximum width of palpus.

Thorax brown. Scutellum with two pairs setae, posterior twice length of anterior. Legs brown. Ratios of lengths of fore tarsomeres about 1.07: 0.87: 0.86: 0.86: 1, with all five bearing a setal palisade ( Fig. 16C ). Setal palisade extends two thirds length along mid tibia, palisade comprising more than 25 setulae ( Fig. 16D . Setae below basal half of hind femur a little shorter than those of anteroventral row of outer half ( Fig. 16E ). Wing ( Fig. 16B ) length 1.36–1.42 mm, width 0.7–0.75 mm, width/length 0.53. Costal index 0.38. Costal ratio 1.87: 1. Costal cilia 0.06 mm. Alula with 3 setae. Haltere brown.

Abdomen. Tergites brown with minute sparse setulae only. Tergites II–V all very much broader than long, but progressively narrowing from tergite II onwards. Tergite VI reduced to a narrow anterior strip in middle but each lateral side bearing 2 strong setulae at rear margin ( Fig. 25E ). Venter grayish brown and segments 1–5 bare. Sternite VI brown, reduced to a narrow strip in middle, bearing 2 short setae and 2–3 minute setulae on each ill-defined side ( Fig. 25F ). Oviscape brown. The dorsum of the oviscape with about 10–12 minute setulae on sub-apex ( Fig. 16F ).

Male. Unknown.

Distribution. China (Gansu).

Specimens examined. 2♀ (paratype): China, Gansu, Wen County, Qiujiaba (32.92° N, 104.32° E; 2270 m), 7-Aug-2011, Yunlong Cai.

Remarks. This species is similar to P. shennongjianus sp. nov., it differs from the latter by brownish body colour, longer apical seta of palpus and without small sclerotized pieces behind main sterniteVI. 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, 1995 , but it is different from the latter in having the continuous sternite VI and a palisade extending 3/4 length of mid tibia.

Figures

FIGURES 16A–F. Pseudacteon obtusatus 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 25A–J. Tergite VI and sternite VI of females. A–B. P. rudisetosus Disney et Michailovskaya; C–D. P. pullum Michailovskaya; E–F. P. obtusatus Liu et Cai; G–H. P. linzhiensis sp. nov.; I–J. P. shennongjianus sp. nov. Scale bar = 0.1mm.