Tachydromia achterbergi, Grootaert, Patrick & Shamshev, Igor, 2009

Grootaert, Patrick & Shamshev, Igor, 2009, First records of Tachydromia Meigen and Tachypeza Meigen (Diptera: Hybotidae) from Viet Nam, with descriptions of four new species, Zootaxa 2249, pp. 33-43 : 35-36

Tachydromia achterbergi sp. nov.

( Figs. 1–3 )

Diagnosis. Recognised by yellow palpus bearing moderately long subapical seta, long presutural dorsocentral seta, yellow hind femora and tibiae and halters with brown knob.

Description. Male. Body 2.6 mm, wing 2.5–2.7 mm. Head black. Eyes extending beyond ocellar tubercle. Frons shining, slightly widened toward ocellar tubercle, above antennae nearly as broad as anterior ocellus. Two pairs of moderately long ocellars. Occiput shining; with 2 long dark setae in upper part, several similar setae on middle part laterally and some fine pale setae near neck and on lower part. Basal antennal segments yellowish; postpedicel slightly paler, short, oval; stylus long, brownish, short pubescent. Proboscis entirely brown. Palpus unmodified, elongate oval, yellow, with 1 moderately long yellow subapical seta.

Thorax black brown in ground-color, largely shining; prominent setae black; prosternum, scutellum and mediotergite finely tomentose. Postpronotal lobe large, lacking conspicuous setae. Mesonotum with 1 long notopleural, 1 short postalar and 2 long scutellar setae; acrostichals lacking; dorsocentrals uniserial, few in number, mostly minute, 1 presutural pair long (as long as scutellars).

Legs almost entirely yellow, fore tibia with subapical ventral brown patch, fore basitarsus on apical 2/3 and entire tarsomeres 4 and 5 contrastingly black, tarsomeres 2 and 3 pale, mid and hind tarsomeres 4 (except basal part) and 5 brownish. Fore coxa with pale unmodified setae. Fore femur strongly thickened, with anteroventral and posteroventral short setulae longer basally. Fore tibia spindle-shaped. Fore tarsomere 1 with patch of black ventral spinules on subapical portion. Mid femur slightly thickened, with shallow excavation and ventral swelling nearer to base, bearing 1 dark short spine sitting on swelling (with several smaller paler spinules) and 1 similar dark spine beyond excavation. Mid tibia slender, with hardly prominent ventral spinule-like setulae. Hind femur slender, with rows of short anterodorsal and posteroventral setae. Hind tibia slightly thickened toward apex, lacking prominent bristles.

Wing normally developed, rounded at apex, largely finely brownish infuscate, with large brown patch near meeting point of vein R2+3 with costa, paler basally. One short basal costal seta present. Vein R1 meeting costa somewhat before wing midway. Proximal section of vein R4+5 subequal to 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 about 1/3 of wing. Halter with brown knob and pale stem.

Abdomen brown, with unmodified tergites and sternites (except segment 8), subshining, covered mostly with scattered, short, black setae longer on pregenital segments, sternite 8 with long posteromarginal setae; tergite and sternite 8 hardly separated, tergite 8 broadly concave posteriorly, narrowly strongly sclerotised anteriorly, lacking setation medially.

Terminalia ( Figs. 1–3 ) rather small, dark brown, elongate oval. Right cercus very small, subtriangular, with some short unmodified setae. Left cercus rather subrectangular, with short unmodified setae. Right epandrial lamella subglobular, with numerous long submarginal unmodified setae. Right surstylus small, differentiated from epandrium, bilobed, with short unmodified setae. Left epandrial lamella with several short subapical unmodified setae. Left surstylus barely differentiated from epandrium, with numerous long marginal setae. Hypandrium humped, with 4 minute setulae.

Female. Body: length: 2.7–2.8 mm, wing: 2.6–2.7 mm. Fore leg almost entirely yellow, only tibia brownish yellow anteriorly and posteriorly, tarsomere 4 brownish apically and tarsomere 5 entirely brownish. Mid femur unmodified, with rows of anteroventral and posteroventral thin setae, the latter somewhat longer. Otherwise as in male. Cercus brownish, long.

Material examined. Holotype male, VIET NAM: Lam Dong, Bidoup Nuiba nr. Dalat, 1650–1700 m, Malaise Trap 1–12, 12– 15.10.2005, Rain forest and Pinus , leg. C. Van Achterberg and R. de Vries [Naturalis].

Paratypes: 6 females, same data as in holotype.

Derivatio nominis. The specific epithet refers to the collector's name, Cees van Achterberg.

Distribution. Viet Nam.

Remarks. The new species can be distinguished from other species of Tachydromia known from the Oriental Region as it has been given in the key.

Figures

FIGURES 1 – 3. Tachydromia achterbergi sp. nov. 1. right epandrial lamella, lateral view. 2. hypopygium, dorsal view. 3. left epandrial lamella, lateral view. LEL: left epandrial lamella; LS: left surstylus; REL: right epandrial lamella; RS: right surstylus.