Tachydromia monocercus, Shamshev, Igor & Grootaert, Patrick, 2008

Shamshev, Igor & Grootaert, Patrick, 2008, New and little-known species of the genus Tachydromia Meigen (Diptera, Hybotidae) from Thailand, Zootaxa 1830, pp. 21-36 : 32-33

Tachydromia monocercus sp. nov.

( Figs 17–19 , 29 )

Diagnosis. Antenna and palpus brownish. Scutum with 1 pair of long presutural dorsocentrals. Legs with complicated colour pattern; fore tarsomeres 4 and 5, hind tibia (except base) and hind femur on apical 2/3 brown. Wing with 2 broad brownish bands connected on cells r1 and r2+3. Halter pale.

Description. Male. Wing 1.8 mm. Head black in ground-colour. Eyes extending beyond ocellar tubercle. Frons shining, slightly widened toward ocellar tubercle, above antennae nearly 1.5 times as broad as anterior ocellus. Two moderately long black ocellars. Occiput shining; with 2 long cruciate black setae in upper part, several shorter setae on middle part and some setulae near neck and on lower part. Antenna entirely brownish; postpedicel small, elongate oval; stylus very long. Proboscis entirely brownish. Palpus unmodified, narrow, elongate oval, brownish, with 1 short black and 1 pale, minute subapical setae.

Thorax brown in ground-colour, largely shining; prominent setae black; prothoracic sclerites (except postpronotal lobe) finely pollinose. Postpronotal lobe large, lacking conspicuous setae. Mesonotum with 2 notopleural (posterior one longer), 1 long postalar and 2 similar scutellar setae; acrostichals lacking; dorsocentrals uniserial, very few in number, lacking on prescutellar depression, 1 presutural pair nearly as long as posterior notopleural.

Legs long, with complicated colour pattern; fore femur rather brownish yellow dorsally near apex; fore tibia almost entirely brownish, paler basally; fore tarsomeres 4 and 5 brown; mid leg with similar pattern to fore leg; hind femur brown on apical 2/3; hind tibia almost entirely brownish, brownish yellow basally; hind tarsomeres 2 and 3 apically, tarsomeres 4 and 5 entirely brownish; otherwise legs yellow. Coxae with yellowish to brownish yellow setae of different lengths; no setae between fore and mid coxae. Fore femur slightly thickened, with minute ventral unmodified setulae and thin long setae near base. Fore tibia somewhat spindlelike, with unmodified setation. Fore basitarsus with subapical brush of black spinules ventrally. Mid femur slender; with anteroventral and posteroventral short black spinule-like setae on apical 2/3 and several pale setulae near base. Mid tibia slender, bearing ventral spinule-like setulae (one subapical stronger). Mid basitarsus with subapical brush of black spinules ventrally. Hind femur slender, with rows of short anteroventral and posteroventral setae. Hind tibia slender, lacking prominent bristles, with rounded posterior apical comb.

Wing ( Fig. 29 ) normally developed, rounded at apex, with typical venation for the genus; with 2 broad brownish bands connected on cells r1 and r2+3. One short basal costal seta present. Vein R1 meeting costa before wing midway. Proximal section of vein R4+5 somewhat longer than Rs. Vein R2+3 straight. Veins R4+5 and M1+2 parallel toward wing-apex. Crossveins r-m and bm-cu separated. Cells br and bm extending to 1/3 of wing. Halter pale.

Abdomen brownish, subshining, covered mostly with scattered, short, black setulae; segments 7 and 8 with moderately long setae. Terminalia ( Figs 17–19 ) moderately large, dark brown, elongate oval. Right cercus rather short, subrectangular, with several setae of different lengths and bearing 5 short subapical spines on inner side. Left cercus hardly prominent. Right epandrial lamella subrectangular, covered with numerous setae of different length, lacking ventral process. Right surstylus broad, rather long, curved inward, with numerous moderately long subapical setae and several spines on inner side. Left surstylus bilobed; upper lobe broad, rather long, with numerous setae of different length; lower lobe small, with several short setae.

Female. Unknown.

Material examined. Holotype male: THAILAND Sakon Nakhon Phu Phan NP Behind office 17°03.521'N 103°58.450'E 322 m Pan traps 13–14.vii.2006 Winlon Kongnara leg. T195.

Derivatio nominis. The name alludes to the greater prominence of the right cercus.

Distribution. Thailand.

Remarks. Provisionally, the new species could be assigned to the T. arrogans group sensu Chvála (1970) due to possessing pollinose prothoracic sclerites, very long stylus, brownish palpi, wing with two bands and moderately large, elongate oval terminalia. However, the new species has, like the T. connexa group, 2 notopleural bristles. The main distinguishing features between T. monocercus sp. nov. and other species known from the Oriental Region are given in the key.

Figures

FIGURES 17 – 19. Tachydromia monocercus sp. nov. 17. right epandrial lamella, ventral view. 18. epandrium with cerci. 19. left surstylus, lateral view. Scale 0.1 mm.

FIGURES 24 – 31. Wings. 24. Tachydromia phanensis sp. nov. 25. Tachydromia phu sp. nov. 26. Tachydromia tigeri sp. nov. 27. Tachydromia ocellata sp. nov. male. 28. Tachydromia luang Shamshev, Grootaert. 29. Tachydromia monocercus sp. nov. 30. Tachydromia doi sp. nov. 31. Tachydromia ocellata sp. nov. female.