Diostracus translucidus, Zhu & Tang & Yang, 2023

Zhu, Yajun, Tang, Chufei & Yang, Ding, 2023, Six new species of Diostracus Loew (Diptera, Dolichopodidae) from Tibet, ZooKeys 1163, pp. 1-46 : 1

Diostracus translucidus sp. nov.

Figs 25 , 26 , 27 , 28 , 29 , 30 , 31E , 32D

Type material.

Holotype: China • ♂, Tibet, Nyingchi, Medog, 80 k, 2013. IX. 13, leg. Gang Yao. Paratypes: • 2 ♀♀, same data as for holotype.

Diagnosis.

MSSC: palpus normal, not reaching apex of proboscis. Scutellum with pair of sc and four or five pairs of marginal hairs; CI with row of anterior hairs and two strong recurved spines at extreme apex; FI with a deep hollow at base; wing indistinctly tinged grayish; FII with row of dense ad on apical 2/5; wing apically with three translucent windows between vein C, vein R2+3, vein R4+5, and vein M1.

Description.

Male (Fig. 25A ). Body length 5.8 mm; wing length 6.0 mm.

Head (Fig. 26A ) dark metallic green with pale gray pollinosity. Eyes separated; face widened towards clypeus. Hairs and bristles on head black; lower postocular bristles including posteroventral hairs pale. Ocellar tubercle distinct, with pair of oc (lost), without posterior hairs; vt rather short, 0.2 × as long as pvt. Antenna brownish black; scape prolonged, without dorsal bristle; first flagellomere subtriangular, 1.3 × longer than wide; arista apicodorsal, 4.8 × as long as first flagellomere, nearly bare. Proboscis huge and brown, apex blackish with pale hairs; palpus lobate, not reaching apex of proboscis, without distinctive bristle.

Thorax dark metallic green with pale gray pollinosity; mesoscutum with pair of dark brown longitudinal stripe. Hairs and bristles on thorax black; six mostly hair-like dc except posterior most one dc longest and thick; acr absent; one h, one ph, one npl, one sa, one psa; scutellum with pair of sc (lost) and four or five pairs of marginal hairs (MSSC). Postnotum well developed, and convex. Propleuron with two or three sparse short pale hairs on lower portion.

Legs nearly entirely black except fore trochanter dark yellow, mid- and hind trochanters brownish black; claws prolonged (MSSC), empodium and pulvilli present. Hairs and bristles on legs black. CI depressed laterally, without distinctive bristle, but with row of anterior hairs and two strong recurved spines at extreme apex (MSSC); CII and CIII with clusters of anterior bristles at extreme apex. FI distinctly thickened, with a deep hollow at base, and row of three or four curved ventral spines and row of dense anterior bristles long the edge of the hollow (MSSC), basal 2/3 with row of four long yellow av (nearly as long as FI depth) (MSSC), apically with long thin pale hairs (MSSC) (Fig. 26C ); TI slightly thickened, with row of ad along whole length, ventral surface nearly bare (MSSC); It1 somewhat thicken, with row of long ad and pd along whole length (nearly as long as It1 depth), apical half flattened ventrally with two rows of short curved spines and rows of bristles along the edge, apically with a strong curved pv spine (MSSC) (Fig. 26C ); It2 with row of long curved anteroventral hairs along the whole length, apical half with two rows of long posterior bristles (MSSC); It3 elongated, base and apex somewhat swollen, nearly bare, except with row of three or four posteroventral hairs at base and four or five dorsal bristles at apex (MSSC); It4 with long ventral bristles apically (MSSC). FII with row of dense ad on apical 2/5 (MSSC); TII with two ad, 8 pd. FIII without outstanding bristle; TIII with row of long thin ad and long erect thin pd; IIIt1 with row of thin ad long whole length. Relative lengths of tibia and five tarsomeres: LI 5.3: 1.2: 2.2: 2.6: 0.4: 0.7; LII 7.3: 5.0: 2.4: 1.2: 0.6: 0.8; LIII 8.5: 4.8: 3.4: 1.6: 0.8: 0.8.

Wing (Fig. 26B ) hyaline, indistinctly tinged grayish, apically with three translucent windows between vein C, vein R2+3, vein R4+5, vein M1 (MSSC); vein M with brown strip on middle section (MSSC); veins dark brown; crossvein m-cu somewhat curved. Squama yellow with yellow hairs. Halter brown.

Abdomen (Fig. 26D ) nearly as long as head and thorax combined, dark metallic green with pale gray pollinosity. Abdomen with sparse pale pubescence. Tergites II-V with triangular hyaline area on posterior margin (MSSC); Sternite II medially with a digitiform anterior process (MSSC) (Fig. 26D ), Sternite IV with a pair of long brown band-like sclerites (Figs 27 , 28A , 29A ); Sternite V longer than Sternite IV, split into pair of sclerites (Figs 27 , 28A , 29A ). Hypandrium not distinctly swollen.

Male genitalia (Figs 28B, C , 29B, C ): Epandrium slightly longer than wide. Epandrial lobe long, wavy, band-like, with an acute basal process, one short bristle at tip. Surstylus thick, lamellated, with two short spines. Hypandrium short thick, apically with a shallow, V-shaped apical incision. Cercus rather short (1/3 as long as epandrium length), spoon-shaped, with dark yellow hairs on outer surface, apical ones long (nearly as long as cercus length), and subapically with group of dense erect dark yellow bristles on inner surface.

Female (Figs 25B , 31E ). Body length 7.4-7.6 mm; wing length 7.8-8.0 mm. Same as male, except MSSC. FI without distinct bristles; TI with three ad, two pd; FII with two ad; TII with one ad, one pd, apically with three bristles; FIII bare; TIII with four ad, apically with two bristles. Wing (Fig. 32D ) hyaline, indistinctly tinged grayish, crossvein m-cu straight, forming acute angle with CuA1.

Female genitalia (Fig. 30 ): Abdominal segments VII and VIII slender; tergite VIII divided into two sclerites; epiproct split into pair of hemitergites, apically with row of eight strong curved spines; hypoproct semicircular; dorsal lobes of cercus somewhat elongated, with dark yellow bristles; ventral lobes of cercus short, apex rounded.

Distribution.

China (Tibet).

Remarks.

The new species is unique. It has prolonged scapes, small palpus, and convex postnotum. But the huge proboscis, stout body and specialized structures of legs indicate that the new species belongs to Diostracus .

Etymology.

New species name refers to the translucent windows on male wing.

Figures

Figure 25. D. translucidus A male; lateral view B female, lateral view. Scale bar: 1 mm.

Figure 26. D. translucidus male A head, lateral view B apex of wing C LI, anterior view D abdomen, lateral view. Scale bars: 1 mm.

Figure 27. D. translucidus male, apex of abdomen A dorsal view B ventral view C lateral view. Scale bar: 1 mm.

Figure 28. D. translucidus male A abdominal Sternite IV and V, male genitalia removed, ventral view B male genitalia, lateral view C male genitalia, ventral view. Scale bar: 1 mm.

Figure 29. D. translucidus male A abdominal Sternite IV and V, male genitalia removed, ventral view B male genitalia, lateral view C male genitalia, ventral view. Scale bar: 1 mm.

Figure 30. D. translucidus female, abdomen A dorsal view B lateral view C ventral view. Scale bar: 1 mm.

Figure 31. Female antenna, lateral view A D. acutatus, show apical arista B D. acutatus, show subapical arista C D. fasciculatus D D. polytrichus E D. translucidus. Scale bars: 1 mm.

Figure 32. Apex of female wing A, B D. acutatus C D. fasciculatus D D. translucidus E D. polytrichus. Scale bar: 1 mm.