Opalimosina setifera, Cao & Yang & Dong, 2024

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 : 363-364

8. Opalimosina setifera sp. nov.

( Figs. 10 , 11 )

Description. Male ( Figs. 10F–G ). Body length 1.1–1.4 mm, wing 1.0– 1.3 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 than others; 2 fronto-orbital bristles; 7–9 fronto-orbital setulae forming a long row between interfrontal bristles and eye. Eye oval, its longest diameter about 2.3–2.5 times as long as shortest genal height. Antenna brown, postpedicel slighter brown; arista about 6.7–6.9 times as long as postpedicel and shortly ciliate.

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 pair of acrostichal setulae slightly enlarged (shorter than anterior dorsocentral bristles). Scutellum roundly triangular, with a pair very long bristles, laterobasal bristle shorter. Two katepisternal bristles, anterior one minute. Legs brown. Mid tibial chaetotaxy as in Fig. 10C , ventrally with 1 anteroventral bristle at basal 1/2 and 1 strong apical bristle; hind tibia ( Fig. 10D ) with 1 small ventral preapical spur. Wing ( Fig. 10E ) lightly infuscate, with distinct longitudinal darkening along costa, 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=1.1–1.2, second costal sector subequal to third; outer corners of dm rectangular and with short appendages of M1 and M4 beyond dm-m; r-m–dm-m: dm-m =1.8–2.0. 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. Posteromedial part of S5 ( Fig. 11D ) slightly concave, with a pair of ventrally curved processes and a series of short robust setae arranged in oblique row at base of each process. S6 with a concave pocket at middle covered by posterior part of S5.

Genitalia: Epandrium ( Figs. 11A–B ) sparsely and shortly setulose. Cercus short, with a broadly rounded apex, a short and robust, apically blunt, spine ventromedially and a long seta dorsolaterally. Hypandrium relatively long. Surstylus ( Fig. 11C ) flat, with pointed anterior corner; posterior corner blunt, with a few short setae internally, a few setae and 2 strong bristles externally (anterior and posterior corners both with 2 robust bristles). Basiphallus with slender, ventrally recurved and apically pointed epiphallus (with a posterior spinule in the middle). Distiphallus generally complex with well sclerotized basal part and membranous apex; dorsal part narrows from base and bifurcates at tip, ventral part anterodorsally with 2 pointed structures at each side touching together beneath bifurcated tip of dorsal part and connecting with membranous apex (closing medially). Postgonite long, straight, with blunt membranous apex ( Fig. 11E ).

Female ( Figs. 10A–B ; 11F–G ). Body length 1.3–1.5 mm, wing 1.3–1.4 mm. C -index=1.2–1.3, r-m–dm-m: dmm =1.7–2.3. Abdomen: Tergites sparsely and shortly setulose. Sternites with relatively dense setosity. T7 with sparse setulae and a pair of long setae. T8 simple, laterally extended and bearing thin ventral projection on each side. T10 fused with cerci. Cercus with some setulae and 1 slightly flattened seta at tip. S7 simple, with sparse setulae and two pairs of longer setae at middle and sides of posterior margin. S8 with posteriorly a pair of medial processes and posteromedially a rough circular area with minute papillae on the surface. S10 huge, narrowly horseshoe-shaped in ventral view and laterally extended to dorsal, with sparse setulae in dorsal part and covering cerci ventrally. 3 spermathecaes shallow cupped.

Type material: Holotype. CHINA: Shanxi: ♂, Lvliang, Pangquangou, Badaogou , 1930 m, 15.vii.2023, Leyou Zhang ( EMCAU).

Paratypes. CHINA: Shanxi: 5♂, 2♀, same data as holotype, Leyou Zhang ; 1♂, 3♀, same data as holotype, Meilin Li. Lvliang, Pangquangou : 1♂, 4♀, Xitagou , 1993 m, 16.vii.2023, Leyou Zhang ; 1♂, Xitagou Meilin Li; 1♂, Bashuigou , 1885 m, 17.vii.2023, Leyou Zhang ; 1♀, Dungou , 1691 m, 20.vii.2023, Meilin Li ; 2♀, Kangdongzigou , 1857 m, 21.vii.2023, Leyou Zhang ; 2♀, Kangdongzigou , Meilin Li. Jilin : 1♀, Wangqing, Dangshuhe , 500 m, 4.vii.2023, Yuetian Gao ; 1♀, Helong, Wolongguanhuzhan , 737 m, 6.vii.2023, Yishen Xiao (all EMCAU) .

Etymology: The specific name is derived from Latin “ setifera ” (= setiferous), refers to the row of short setae on male sternite 5.

Comments: The short ventral preapical hind tibial spur of O. setifera sp. nov. is typical of many Opalimosina . While O. setifera sp. nov. lacks the large hind tibial spur typical of most species of Opalimosina , it clearly belongs in this genus due to the distinct hind tibial spur and large epiphallus. Within Opalimosina , the most similar species is O. aculeata sp. nov., but O. setifera sp. nov. has only a short ventral preapical hind tibial spur unlike the more typical long spur found in O. aculeata sp. nov.. Opalimosina setifera sp. nov. is best characterized by several distinctive characters, including the robust ventromedial spine at the apex of the male cercus, the straight slender postgonite and the characteristic posteromedial area of male sternite 5, differing so from its closest relative, O. aculeata sp. nov..

Figures

FIGURES 10. 10A–B. Opalimosina setifera sp. nov. female habitus. 10A, lateral; 10B, dorsal; 10C–G. male habitus. 10C, mid tibia anterior; 10D, hind tibia anterior; 10E, wing; 10F, lateral; 10G, dorsal. Scale bars: (A–B, E–G) = 1 mm; (C–D) = 0.5 mm.

FIGURES 11. 11A–E. Opalimosina setifera sp. nov. structures of male postabdomen. 11A, terminalia posterior; 11B, terminalia lateral; 11C, surstylus lateral; 11D, S5–S7 ventral; 11E, phallus and associated structures lateral; 11F–G. female postabdomen. 11F, dorsal; 11G, ventral. Scale bar: 0.1 mm.