Opalimosina spathulata, Hayashi, 2010

Cao, Wenqiang, Yang, Ding & Dong, Hui, 2024, A review of Opalimosina Roháček, 1983 (Diptera, Sphaeroceridae) from China with new records and two new species, Zootaxa 5551 (2), pp. 353-368 : 365-366

9. O. spathulata Hayashi, 2010

( Figs. 12 , 13)

Opalimosina spathulata Hayashi, 2010: 317 [bothsexes, illustr.]. Type locality: Japan, Okinawa, Ishigaki Is .

Description. Male ( Figs. 12A–B ). Body length 1.2 mm, wing 1.1 mm. General color brown to dark brown.

Head generally dark brown, gena brown; postvertical bristles well developed; 4 interfrontal bristles, foremost one a little shorter; 2 fronto-orbital bristles; 7 fronto-orbital setulae forming a long row between interfrontal bristles and eye. Eye oval, its longest diameter about 2.3 times as long as smallest genal width. Antenna brown, postpedicel slighter brown; arista about 6.3 times as long as postpedicel and shortly ciliated.

Thorax brown. Postpronotal lobe with 1 dorsolateral bristle, 2–3 small setulae along inner margin and 1 erect setula laterally; 2 postsutural dorsocentral bristles, anterior one short (but longer than dorsocentral setulae in front of it); about 6 rows of irregular acrostichal setulae in front of suture; prescutellar medial acrostichal setulae pair only slightly enlarged (shorter than anterior dorsocentral bristles). Scutellum roundly triangular, with a pair very long bristles, anterolateral seta shorter. Two katepisternal bristles, anterior one minute. Legs brown. Mid tibia ventrally with 1 anteroventral bristle at basal 1/2 and 1 strong apical bristle; hind tibia with 1 very long curved ventral preapical spur. Wing lightly infuscate, veins brownish; costa brown, with a pair of subequal costal bristles at base (outer one longer) and ending at R4+5; R2+3 sinuate, apex distinctly bent up to C; R4+5 gently curved forward; C - index=0.9, second costal sector is subequal (slightly shorter) to third; outer corners of dm rectangular and with short appendages of M1 and M4 beyond dm-m; r-m–dm-m: dm-m =2.1. Alula small, narrow, pointed. Halter with brown knob and paler stem.

Abdomen brown with dark brown apex. Tergites and sternites sparsely and shortly setulose. T1+2 short and simply sclerotized. S5 (Fig. 13D) posteromedially incised weakly, with two small characteristic patches posteriorly and a weakly sclerotized, semicircular area centrally; otherwise very sparsely and shortly setulose.

Genitalia: Epandrium (Figs. 13A–B) sparsely and shortly setulose, posterior ventral part with rather dense setosity. Cercus fused with epandrium and projecting ventrally, with a few setulae and 1 long seta. Hypandrium short. Surstylus (Fig. 13C) flat; anterior part bifurcated and pointed, with a few short setae medioventrally; posterior corner blunt, with a few short setae and 2 robust bristles. Basiphallus with slender, apically truncated epiphallus. Distiphallus generally complex and well sclerotized; dorsal part narrows from base and bifurcates at tip (dorsally with small backward pointed structure at each side); ventral part links beneath bifurcated tip of dorsal part and anterodorsally connects with well sclerotized apex (closing medially). Postgonite curved, with a strongly dilated and rounded apex (Fig. 13E).

Female. No specimens were found during this study.

Material examined: CHINA: Hubei: 1♂, Enshi, Badongjinsihou , 715 m, 14.vi.2023, Jiuzhou Liu . Yunnan: 1♂, Lushui, Pianmazhenwancaoping , 2162 m, 13.viii.2023, Yameng Wang . Jilin: 1♂, Antu, Dayangcha , 891 m, 20.vii.2023, Yishen Xiao (all EMCAU) .

Comments: Details of male sternite 5 and epandrial chaetotaxy recorded here differ from the original description ( Hayashi, 2010), as we found S5 has a more weakly sclerotized, semicircular area centrally and the epandrium has dense bristles ventrally and a little more slender. Other details correspond with the original description. This species is similar to O. calcarifera ( Roháček, 1975) and O. australis Hayashi, 2009 , but it differs from both these species by its male fifth sternite lacking posteromedial incision, longer and stronger hind tibial spur, and distinctly curved and more dilated postgonite. In O. calcarifera ( Roháček, 1975) , sternite 5 has a shallow incision, the hind tibial spur is shorter and the postgonite is straight. In O. australis Hayashi, 2009 S5 has a deep and narrow incision, the hind tibial spur is shorter and the postgonite is only slightly curved.

Figures

FIGURES 12. 12A–B. O. spathulata Hayashi, 2010 male habitus. 12A, lateral; 12B, dorsal. Scale bar: 1 mm.