Opalimosina aculeata, 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 : 355-357

2. Opalimosina aculeata sp. nov.

( Figs. 2 , 3 )

Description. Male ( Figs. 2A–B ). Body length 1.4–1.5 mm (holotype 1.4 mm), wing 1.4 mm. General color brown to dark brown.

Head generally dark brown, gena lighter brown; postvertical bristle well developed; 4 interfrontal bristles, foremost one a little shorter; 2 fronto-orbital bristles; 7 additional fronto-orbital setulae forming a long row between interfrontal bristles and eye. Eye oval, its longest diameter about 2.1 times as long as shortest genal height. Antenna brown, postpedicel lighter brown; arista about 5.4 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 (slightly 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 enlarged (nearly as long as anterior dorsocentral bristle). Scutellum elongated and rounded triangular, with a pair very long bristles, laterobasal bristle shorter. Two katepisternal bristles, anterior one minute. Legs brown. Mid tibial chaetotaxy as in Fig. 2D (similar to O. mirabilis ), ventrally with 1 anteroventral bristle at basal 1/2 and 1 strong apical bristle; hind tibia ( Fig. 2C ) with 1 conspicuous long curved ventral preapical spur. Wing ( Fig. 2E ) lightly infuscate, with distinct longitudinal darkening along costa, veins brownish; costa brown, with a pair of subequal costal bristles at base, and slightly extending beyond R4+5; R2+3 sinuate, apex distinctly bent up to C; R4+5 gently curved forward; C -index=1.0–1.2, 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 =2.5–2.6. Alula small, narrow, pointed. Halter with brown knob and paler stem.

Abdomen brownish with darker apex. Tergites and sternites sparsely and shortly setulose. T1+2 short and simply sclerotized. S5 ( Fig. 3D ) with an arc-shaped membranous stripe separating posteromedial part from anterior part; posteromedial part with several long setae on each side, a pair of ventrally curved processes, and two clusters of robust spines at bases of processes. Posteromedial part of S6 pigmented, with minute papillae on the surface.

Genitalia: Epandrium ( Figs. 3A–B ) sparsely and shortly setulose. Cercus short, with a broadly rounded apex, 1 long seta and some short setulae. Surstylus ( Fig. 3C ) flat; anterior part bifurcate and pointed, with internal setae at outer point; posterior corner blunt, with a few setae, 1 long and robust bristle and 2 thinner bristles. Basiphallus with slender, ventrally recurved and somewhat sinuous, apically pointed epiphallus. Distiphallus generally complex with well sclerotized basal part and membranous apex; dorsal part narrows from base and bifurcates at tip (dorsally with small backward pointed structure at each side); ventral part anterodorsally with 2 pointed structures at each side touching together beneath bifurcated tip of dorsal part and connects with membranous apex (closing medially) from both sides. Postgonite slender, elongate, sinuate and with membranous blunt apex ( Fig. 3E ).

Female ( Figs. 2F–G ; 3F–G ). Body length 1.7 mm, wing 1.5 mm, darker and with more robust setae than male. Wing relatively narrow, C -index=1.5, r-m–dm-m: dm-m =2.3, costa slightly concave at the middle.

Tergites sparsely and shortly setulose; sternites with relatively dense setosity. T7 with 2 long setae on each side. T8 divided into 2 plates (with 2 very long setae on each part), laterally extended and with wide ventral appendage. T10 (= epiproct, supraanal plate) fused with cerci. Cercus with 1 short robust apical bristle. S7 simple, sparsely setulose with two pairs of long setae. S8 weakly sclerotized posteromedial notch, with clear boundary between weakly sclerotized region and well sclerotized region and simply protuberated anteroventrally (like a ridge). S10 (= hypoproct, subanal plate) arc-shaped, with a pair of long anterolateral setae. 3 Spermathecaes, shallow cupped.

Type material: Holotype. CHINA: Yunnan: ♂, Bingzhongluo, Gongdangshenshan , 2554 m, 9.viii.2023, Qicheng Yang ( EMCAU).

Paratypes. 1♂, Same data as holotype, Qicheng Yang ; Yunnan : 1♂, Lushui, Pianmadaolu, 2284 m, 13.viii.2023, Qicheng Yang (all EMCAU) .

Etymology: The specific name is derived from the Latin “ aculeata ” (= spiny, thorny), refers to the robust spines on the male sternite 5.

Comments: This species can be distinguished from congeners by the distinctive male fifth sternite with an arc-shaped membranous stripe, a pair of ventrally curved processes, and two clusters of robust spines. It is most similar to O. setifera sp. nov., from which it differs in having a sinuate postgonite and short, robust spines between bases of the posteromedial processes of S5. Opalimosina setifera sp. nov. has a straight postgonite and short, slender bristles between the bases of the posteromedial processes of S5. There are also distinct differences in the structures of the female postabdomen of both species: O. aculeata sp. nov., has long T7, divided T8 and anteroventrally simply protuberated S8; O. setifera sp. nov., has shorter T7, intact T8 and the S8 with posteriorly a pair of medial processes and posteromedially a rough circular area with minute papillae on the surface.

Figures

FIGURES 2. 2A–E. Opalimosina aculeata sp. nov. male habitus. 2A, lateral; 2B, dorsal; 2C, hind tibia anterior; 2D, mid tibia anterior; 2E, wing; 2F–G. female habitus. 2F, lateral; 2G, dorsal. Scale bars: (A–B, E–G) = 1 mm; (C) = 0.2 mm; (D) = 0.2 mm.

FIGURES 3. 3A–E. Opalimosina aculeata sp. nov. structures of male postabdomen. 3A, terminalia posterior; 3B, terminalia lateral; 3C, surstylus lateral; 3D, S5–S7 ventral; 3E, phallus and associated structures lateral; 3F–G. female postabdomen. 3F, dorsal; 3G, ventral. Scale bar: 0.1 mm.