Pygophora boninensis Snyder, 1965

(Figs. 1a–e, 2a–d, 11a, 12)

Pygophora boninensis Snyder, 1965: 230 . Holotype male (United States National Museum, Washington, United States America). Type locality: Omura, Chichijima Is., Japan.

Type material examined. Paratypes: JAPAN: 3 males and 1 female (BPBM), Camp beach, Omura, Chichijima Is., Ogasawara Iss., Tokyo., 5. V.–9. VI. 1958, F. M. Snyder; 1 male (BPBM), Okumura, Yankee town, Chichijima Is., Ogasawara Iss., Tokyo, 8–15. IV. 1958, F. M. Snyder ; 1 female (BPBM), same locality and collector to the preceding data, 12. V.–9. VI. 1958 .

Diagnosis. Male. First flagellomere 3.8–4.0 times as long as pedicel; wing with brown spot on tip of R2+3; hind tibia with 1 posteroventral seta, short and slender apical lobe; abdominal sternite 5 slender and bifurcated posteriorly, with membranous area at middle, short projections at inside and many short setae on posterior 2/ 5 in ventral view; surstylus broad, round apically in lateral view, slender with many setae in dorsal view.

Redescription. Male. Head. Fronto-orbital plate, frontal vitta, face, parafacial yellowish white; gena and occiput gray. Antenna creamy yellow except 3rd aristomere brown; palpus and labella creamy; prementum dark or reddish brown. Vertex approximately 1/4 of head width; frons above lunule approximately 1/3 of head width; parafacial very narrow in the middle, approximately 1/21 of head width; gena narrow, approximately 1/11 of head height; ocellar triangle small, not reaching lunule; 2 frontal setae; 2 reclinate orbital setae; fronto-orbital plate without any supplemental setula; 2 supravibrissal setae; 1 vibrissa; 1–2 subvibrissal setulae; 1 genal seta; compound eye bare. First flagellomere 3.8–4.0 times as long as pedicel; 1 st aristomere as long as wide; 2nd aristomere longer than wide; 3rd aristomere thickened on basal 1/5; arista plumose only on basal half.

Thorax. Scutum, postpronotum, scutellum, and pleura black in ground color, with gray pruinosity; anterior and posterior spiracles creamy. Two proepisternal setae, anterior one shorter than posterior one; 2–3 proepimeral setae; 2 postpronotal setae; acrostichal seta fine; 1 presutural and 3 postsutural dorsocentral setae; 1 presutural and 2 postsutural intra-alar setae; 1 presutural and 1 postsutural supra-alar setae; 2 postalar setae; 2 notopleural setae; 5–6 anepisternal setae; 3 katepisternal setae, forming equilateral triangle; anepimeron, katepimeron, meron, katatergite, and anatergite bare; apical scutellar seta as long as basal one; prosternum bare.

Wing. Brownish hyaline with brown spot on tip of R2+3; tegula, basicosta, and all veins brown; upper and lower calypters white; halter creamy. Vein M not bending anteriorly at apical part; distance of M between crossveins r-m and dm-cu shorter than distance between crossvein dm-cu and wing margin; crossvein dm-cu nearly straight, longer than ultimate section of vein CuA1.

Legs. Fore coxa, all trochanters, femora, tibiae, tarsi, and pulvilli creamy yellow; mid and hind coxae gray in basal part, creamy yellow apically; all claws brown. Fore tibia with 2–4 anterodorsal, 1 posterior, 2 preapical dorsal, and 3 apical ventral setae; mid femur with 2 preapical posterior setae; mid tibia with 2 posterodorsal, 2 preapical dorsal, and 3 apical ventral setae; hind tibia with 2 anterodorsal, 1 anteroventral, 2 posterodorsal, 1 posteroventral, 2 preapical dorsal, 3 apical ventral setae, short and slender apical lobe; pulvillus rectangular in shape.

Abdomen. Creamy yellow in ground color with gray pruinosity at middle; tergite 4 with three black spots. Tergites 3 and 4 with several discal and marginal setae; tergite 5 with several discal, marginal setae, and dorsal keel; sternite 5 slender and bifurcated posteriorly, with membranous area at middle, short projections at inside and many short setae on posterior 2/ 5 in ventral view.

Male terminalia. Tergite 6 very slender; syntergosternite 7+8 small with several setae; sternite 6 slender and symmetric; epandrium nearly semicircular and notched laterally with many setae; surstylus fused with epandrium, broad, round apically in lateral view, slender with many setae in dorsal view; cerci fused with epandrium, bifurcated apically with several setae in dorsal view; hypandrium broad and nearly semicircular; pregonite very small and round apically; postgonite broad and curved dorsally at middle, hook-like apically; phallus curved dorsally, broad, and hook-like with large membranous areas laterally at apical part.

Female. Differing from male as follows: first flagellomere shorter than in male, 2.5–2.7 times as long as pedicel; wing hyaline without brown spot; hind tibia without posteroventral seta and apical lobe; abdominal tergite 3 with three black spots; abdominal tergite 5 without dorsal keel.

Female terminalia. Tergite 6, sternites 7 and 8 strongly reduced with some setulae; sternite 6 broad with setae; hemitergite 7 small and bare; hemitergite 8 narrow with some setulae on posterior margin.

Body length. 6.1–7.0 mm.

Additional material examined. OGASAWARA ISLANDS: 4 males and 1 female (EUM), Mt. Mikazuki, Chichijima Is., 25–26. V. 1973; 1 female (EUM), Kita-fukurozawa, Chichijima Is., 26. V. 1973; 1 male and 1 female (EUM), Camp beach, Omura, Chichijima Is., 5. V.–9. VI. 1958.

Distribution. Japan (Ogasawara Iss.: Chichijima Is.).

Bionomics. Unknown.

Remarks. This species resembles Pygophora macularis (Wiedemann) and P. maculipennis Stein, but it is distinguished from them by having 1 posteroventral seta on hind tibia and slender surstylus in dorsal view in male. However, females of P. boninensis are not able to identify without locality data.