Tachydromia punctifera (Becker)

Shamshev, Igor V. & Grootaert, Patrick, 2024, Revision of the described Nearctic species of the genus Tachydromia Meigen (Diptera: Hybotidae), Zootaxa 5403 (2), pp. 151-196 : 183-185

Tachydromia punctifera (Becker)

( Fig. 15 )

Tachista punctifera Becker, 1900: 32 . Type localities: Russia, Krasnoyarskiy Territory, “Island Nikander” and “Dudinka”. Tachydromia punctifera : Chvála, 1975: 240 (♂).

Notes on type series. Becker (1900) noted the following material: “ 3 Weibchen [female] von der Insel Nikander und Dudinka. (Sahlberg)”. Chvála (1970) examined one syntype from Becker’s Collection in Berlin. A second syntype is deposited in Helsinki ( MZH) and it was examined by I.S. in 2019. The depositary of the third syntype (taken from “Island Nikander”) is unknown. The syntype in Helsinki bears a lectotype label (red, hand-written). However, this designation was never published.

Material examined. NORTH AMERICA. CANADA. Nunavut: Chesterfield , 21.vii.1950, J. R . Vockeroth (1 ♂, 2 ♀, CNC); same locality, 30.vii.1950, J. R . Vockeroth (6 ♂, 5 ♀, CNC); same locality, 28.vii.1950, J. R . Vockeroth (1 ♂, CNC); same locality, 12.viii.1950, J. R . Vockeroth (1 ♀, CNC); same locality, 9.viii.1950, J. R . Vockeroth (1 ♀, CNC); same locality, 15–16.viii.1950, J. R . Vockeroth (1 ♂, 2 ♀, CNC); Coral Harbour , 15– 16.viii.1959, W. R . M. Mason (1 ♀, CNC) . Yukon: Dempster Hwy , km 95, swept from stream edge, 19.vii.1982, D.M. Wood (1 ♀, CNC) . USA. Alaska: Cape Thompson , 22–25.vii.1961, R . Madge (1 ♂, 4 ♀, CNC). EURASIA . RUSSIA. Chukotka Autonomous Okrug: Chukotka, upper flow of river Kanchalan , 1974, A. Kischinskiy (1 ♂, 1 ♀, ZISP). Krasnoyarskiy Territory : Medvezhiy , env. Norilsk , 6.vii.1967, Gorodkov (1 ♀, ZISP) . Sakha (Yakutia) Republic: Chokurdakh , swampy floodplain of river Indigirka , 7.viii.1972, Gorodkov (1 ♀, ZISP) .

Diagnosis. The species is distinguished by the following combination of characters: palpus lacking black, subapical seta; legs almost uniformly dark brown; proepisternum pruinose only on lower portion. Male: palpus bicoloured, not divided into two lobes apically, strongly broadened and flattened on apical black portion.

Redescription. Male ( Fig. 15A ). Length: body 2.2–2.3 mm, wing 2.2 mm. Head black, with pale setation. Occiput (including posterior portion of vertex) almost entirely densely greyish pruinose, only with shiny patch behind mouth-opening; 2 moderately long vertical setae, some similar setae around neck and near mouth-opening; row of short postoculars. Ocellar triangle shiny; ocellars nearly as long as postverticals, lateroclinate. Frons shiny, slightly broadened towards ocellar tubercle, rather broad; above antennae 3.0–4.0 times as broad as anterior ocellus. Antenna blackish brown. Postpedicel subglobular; stylus subapical, short, nearly 2.0 times as long as pedicel and postpedicel combined. Proboscis blackish brown. Palpus ( Fig. 15B ) modified, bicoloured, somewhat longer than proboscis, undivided apically; very narrow on about basal half, strongly broadened on apical half; pale yellow on narrow part and black on broadened part, covered with scattered pale setae of different lengths; lacking subapical seta.

Thorax black, largely shiny, with pale setation; prosternum and lower part of proepisternum densely whitish grey tomentose; notopleural depression, scutellum and postnotum with greyish tomentose. Postpronotal lobe large, elongate oval, with scattered minute setulae, lacking conspicuous setae. Mesonotum with 1 long notopleural, 1 postalar and 4 scutellars (apical pair long, lateral pair somewhat shorter); some minute setulae present behind postpronotal lobe and on notopleural depression anteriorly; acrostichals lacking; dorsocentrals uniserial, mostly minute, 1 prescutellar pair long (nearly as long as apical scutellars).

Legs almost uniformly blackish brown, knees yellowish, tarsomeres 1–2 usually somewhat paler; mostly with pale setation. Fore coxa clothed in numerous pale setae and densely silvery grey tomentose anteriorly; mid and hind coxae with patch of similar tomentum laterally. Fore femur thickened, whitish pubescent ventrally, with short thin anteroventral and posteroventral setae becoming longer closer to base. Fore tibia spindle-shaped, with unmodified setation. Mid femur somewhat thickened, with similar pattern of ventral vestiture to fore femur. Mid tibia lacking apical projection, bearing ventral black spinule-like setulae becoming 2 serial on about subapical 1/4; 2 closely set short, black subapical setae. Hind femur unmodified, lacking prominent setae. Hind tibia and tarsus unmodified.

Wing normally developed, rounded at apex, with unmodified venation; usually faintly infuscate, with brownish patch below meeting of vein R 1 with costa (sometimes less distinct); similar patch near meeting of vein R 2+3 with costa; somewhat darker along veins. One very short, basal costal seta present. Vein R 2+3 straight, thickened and strongly turned towards costa subapically. Veins R 4+5 and M 1 parallel throughout, close to each other. Crossveins r-m and bm-m broadly separated. Cell r 1 slightly broader than cells r 2+3 and r 4+5. Calypter brownish, with scattered fringe. Halter with brownish stem and pale knob.

Abdomen black, shiny; tergites narrowly faintly pruinose laterally, mostly with scattered minute setulae more numerous and longer on tergites 6–8; sternites covered with numerous setulae; sternite 8 with longer posteromarginal setae; pregenital segments unmodified (except segment 8).

Hypopygium ( Fig. 15C–E ) black, small, elongate oval. Right epandrial lamella rather subtriangular viewed laterally, bearing unmodified long setae apically; without ventral projection or lobe. Right surstylus ( Fig. 15E ) separated from epandrial lamella, undivided; rather small, subtriangular, with rounded apex; bearing numerous marginal, spinule-like setae. Left epandrial lamella ( Fig. 15D ) small, with short setae apically. Left surstylus barely separated from epandrial lamella, elongate, narrow, with long setae. Cerci ( Fig. 15C ) separated, with unmodified short to moderately long setae; right cercus digitiform, moderately long; left cercus rather elongate oval, slightly broader on middle but nearly as long as right cercus. Hypoproct slightly produced beyond apices of cerci.

Female. Palpus unicoloured ( Fig. 15F ), unmodified, almost uniformly pale yellow, somewhat darkened apically, long (longer than proboscis), strip-like, truncate apically, covered with scattered pale setulae. Mid tibia with less distinct ventral spinules. Otherwise as in male. Abdominal segment 6 almost entirely shiny, narrowly pruinose anteriorly; segment 7 mostly pruinose, narrowly shiny laterally; visible parts of segment 8 pruinose. Cercus brownish, long, slender, with minute setulae.

Remarks. Tachydromia punctifera belongs to the T. punctifera group of species sensu Chvála (1975).

Distribution. Holarctic. North America (first record): Canada (Nunavut, Yukon), USA (Alaska); Eurasia: Finland, Norway, Russia (East Siberia), Sweden.

Figures

FIGURE 15. Tachydromia punctifera (Becker) (Canada, Northwest Territories; CNC). A–E. Male. A. Habitus, lateral view. B. Head, anterior view. C. Hypopygium, dorsal view. D. Right surstylus, lateral view. E. Left epandrial lamella and left surstylus, lateral view. F. Female head, anterior view. Abbreviations: cerc—cercus; lft sur—left surstylus; rt sur—right surstylus. C–E: scale bar is 0.1 mm.