Tachydromia petrabilis Smith, 1969

Shamshev, Igor & Grootaert, Patrick, 2010, The genus Tachydromia Meigen (Diptera: Hybotidae) from the Afrotropics, African Invertebrates 51 (1), pp. 207-207 : 212-213

Tachydromia petrabilis Smith, 1969

Fig. 12

Tachydromia petrabilis: Smith 1969: 73 , figs 82 (wing), 83 (right surstylus). Type locality: South Africa ,

Drakensberg Mts, Royal Natal National Park.

Diagnosis: Recognised by a combination of the following characters: occiput almost entirely shining; prothoracic sclerites (including postpronotal lobe) with inconspicuous pruinosity; legs with all femora entirely brownish; wing with bands connected on cell r 1; male mid femur with rows of unmodified anteroventral and posteroventral short setae.

Redescription:

Male:

Length: Body 1.5 mm, wing 1.5 mm.

Head: Eyes with posterior margin slightly produced beyond ocellar tubercle; vertex broader than frons in front of ocellar tubercle. Occiput, including vertex, entirely shining in holotype (very narrowly finely pollinose behind eyes in paratype female); 2 moderately long postvertical setae. Ocellar tubercle shining, ocellars minute. Frons shining, slightly widened toward ocellar tubercle. Antenna with postpedicel and stylus brownish, scape and pedicel somewhat paler. Postpedicel subglobular; stylus subapical, very long, nearly 3× as long as pedicel and postpedicel combined. Palpus unmodified, slender, shorter than proboscis, blackish; clothed in silvery setae, with rather short (slightly shorter than palpus) black subapical seta.

Thorax: Black, almost entirely shining, prothoracic sclerites (including postpronotal lobe) with inconspicuous pruinosity, scutellum and mediotergite (= metanotum) densely tomentose. Postpronotal lobe large, elongate, lacking conspicuous setae. Mesonotum with 1 long notopleural, 1 similar postalar and 4 scutellars (lateral pair very short, apical pair somewhat longer than notopleural seta, subparallel); acrostichals lacking; dorsocentrals uniserial, mostly minute, in holotype prescutellar pair obscured by pin (in paratype prescutellars very short, nearly as long as lateral scutellars); mesosternum and metasternum bare between posterior four coxae.

Legs: Fore and hind coxae yellow, mid coxa brownish basally; femora and tibiae brownish (the former paler on extreme base, rather yellowish on hind femur); tarsomeres 1 and 2 brownish apically, remaining tarsomeres entirely brownish. Coxae with yellowish unmodified setae. Fore femur thickened, pale pubescent ventrally, with yellowish anteroventral and posteroventral setulae becoming longer basally. Fore tibia slightly spindle-shaped. Mid femur slender, with rows of anteroventral and posteroventral spine-like setae (the latter darker and stronger). Mid tibia with short apical projection, bearing ventral spinule-like setulae. Hind leg unmodified, lacking prominent setae.

Wing: Normally developed, rounded at apex, with unmodified venation; two broad brownish bands connected on cell r 1. One short costal bristle present. Vein R 2+3 strongly arched about middle toward costa. Veins R 4+5 and M 1+2 parallel near wing apex. Vein CuM distinct throughout. Crossveins r–m and bm–cu broadly separated. Squama dusky yellow with concolorous fringe. Halter with pale knob and brownish yellow stem.

Abdomen: Brownish, shining, covered with scattered black setae longer on pregenital segment; segments 1–7 unmodified. Terminalia small, rather elongate oval, blackish brown. We did not dissect the holotype male to examine the terminalia but Smith (1969: 73) indicates that they are very similar to T. lilaniensis . His fig. 82 is the right surstylus viewed from the inner side, which is subtriangular, with a deep notch on the lower (dorsal) margin, bearing several subapical spinules on inner side.

Female.

As in male, but mid tibia with hardly prominent subapical projection, cercus brownish, long, slender, covered with minute setulae.

Holotype (examined): ơ SOUTH AFRICA: KwaZulu-Natal: on boulders / stream edge / 12.ix.63 / 1500 m [hand-written]; Royal Natal National Park [28°41.3'S: 28°56.2'E], Drakensberg Mts. / B. & P. Stuckenberg; running over lichenous boulders with the chalcid Holceupelmus [hand-written]; The chalcid was Holceupelmus sp. [hand-written] R.D. Eady det. 1963; HOLOTYPE ơ Tachydromia petrabilis [species name hand-written] K.G.V. Smith (NMSA). Note: The holotype is in good condition.

Paratype (examined): ^same data as in holotype ( NMSA) .

Distribution: South Africa, Lesotho. This species may have a wide distribution because, according to labels ( Smith 1969), it was collected over a long period including September, January and April. The flies were taken on boulders near a stream edge.

Remarks: Smith (1969) described this species after several specimens taken from three localities in the mountains of South Africa and Lesotho.

Figures

Fig. 12. Known distribution of Tachydromia species: • – T. freidbergi sp. n., 9 – T. lilaniensis, 0 – T. petrabilis,: – T. stuckenbergi sp. n., ♦ – Tachydromia sp.