Tachydromia magadanica Shamshev

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 : 175-177

Tachydromia magadanica Shamshev

( Fig. 11 )

Tachydromia magadanica Shamshev, 1993: 110 , figs 10–13. Type locality: Russia, Magadanskaya Province , env. Palatka, Khasyn.

Type material examined. The type material of this species is housed in ZISP and was re-examined by I.S.

Additional material examined. NORTH AMERICA. CANADA. Quebec: Fort Chimo , 5.vii.1954, E.E. Sterns (2 ♀, CNC) . Saskatchewan: Big River , 1.vi.1959, A. & J. Brooks (3 ♀, CNC) . Yukon: Dawson, 21.vi.1949, W.W. Judd (1 ♀, CNC); same locality, 30.vi.1949, W.W. Judd (1 ♂, CNC); Dempster Hwy km 135–145, spruce-willow forest, 14.vi.1984, S. & J. Peck (1 ♂, CNC) . USA. Alaska: mi. 236, Richardson Highway , 16.vi.1951, J.R. McGillis (1 ♀, CNC); Mile 236, Richardson Highway , 16.vi.1951, W.R.M. Mason (1 ♀, CNC); Mile 290, Richard Highway , 19.vi.1951, W.R.M. Mason (1 ♂, CNC); Miller House, Richard Highway , 1300’, 21.vi.1951, W.R.M. Mason (1 ♀, CNC); Umiat , 11.vii.1959, R. Madge (1 ♀, CNC); same locality, 11.vii.1959, J.E. R. Martin (2 ♀, CNC); same locality, 14.vii.1959, R. Madge (1 ♀, CNC); Unalakleet , 28.vi.1961, R. Madge (1 ♀, CNC). EURASIA. RUSSIA. Sakha (Yakutia) Republic: river Lyutenge , 16.vii.1925, A. Ivanov (1 ♂, 6 ♀, ZISP) .

Diagnosis. A small robust species, distinguished by a combination of the following characters: antenna with scape and pedicel yellow; proepisternum tomentose; legs extensively brown, fore coxae and trochanters as well as all femora at base yellow; male mid femur unmodified; wings faintly brownish on cells r 1 and r 2+3, halter with dark knob.

Redescription. Male ( Fig. 11A ). Length: body 1.6–2.2 mm, wing 1.8 mm. Head black. Occiput largely shiny; with large spot of faint pruinosity above neck (leaving narrow postocular space on upper part and vertex shiny) and some pruinosity just behind mouth-opening; 2 moderately long, black, widely separated inclinate verticals. Ocellar tubercle shiny; 2 short black lateroclinate ocellars. Frons shiny, somewhat broadened towards ocellar triangle, narrow, above antennae about 2.0 times as broad as anterior ocellus. Antenna with scape and pedicel yellowish to brownish yellow; postpedicel subglobular; stylus subapical, short. Proboscis brown. Palpus unmodified, ovate, shorter than proboscis, brownish, clothed in scattered short dark setae, bearing 1 longer, black subapical seta (nearly as long as palpus).

Thorax black, largely shiny; prosternum, proepisternum and meron (except shiny spot on middle) densely silvery grey tomentose, scutellum and postnotum faintly greyish tomentose. Postpronotal lobe moderately large, slightly elongate oval, lacking prominent setae, with scattered minute setulae. Mesonotum with 2 notopleurals (anterior seta somewhat shorter), 1 short postalar and 4–6 scutellars (apical pair long, inclinate; lateral pair(s) nearly half length of apicals); acrostichals lacking; dorsocentrals arranged in 1–2 irregular rows, minute, 1 prescutellar pair somewhat longer.

Legs largely brown to blackish brown, with somewhat varying yellow pattern; fore coxa and trochanter always yellow; fore femur usually yellow at extreme apex and on basal 1/4 to 1/3, mid and hind femora yellow near extreme base (basal yellow section decreasing in length from fore femur to hind femur); “knees” and tibiae at extreme base yellow. Coxae clothed in scattered pale to yellow unmodified setae; fore coxa subshiny anteriorly. Trochanters with unmodified setation. Fore femur thickened, lacking ventral pubescence; bearing rows of thin anteroventral and posteroventral setae becoming longer closer to base, dark closer to apex and pale near base. Fore tibia thickened, with unmodified setation. Mid femur narrower than fore femur, unmodified (sometimes slightly broadly concave at basal part); rows of mostly minute anteroventral and stronger, spinule-like posteroventral setulae, with several long dark and pale setae near extreme base. Mid tibia slightly concave ventrally closer to apex, with slightly prominent ventral spinules and apical projection; covered with simple setulae near base. Hind femur slender, with short anteroventral setae. Hind tibia unmodified, lacking prominent setae. Tarsomeres of all legs unmodified.

Wing normally developed, rounded at apex, with unmodified venation; membrane faintly brownish near meeting point of costa with R 1, in cells r 1 and r 2+3 (usually slightly darker along R 2+3 and R 4+5) and along middle portion of M 4. One very short basal costal seta present (sometimes inconspicuous). Vein R 2+3 straight. Veins R 4+5 and M 1+2 parallel near wing-apex. Cell r 1 nearly as broad as cell r 2+3. Cell br broader than cell bm opposite arising Rs. Crossveins r-m and bm-m broadly separated. Calypter brownish, with yellowish brown cilia. Halter with brownish knob and yellow stem [halter not entirely yellow as mistakenly indicated in original description].

Abdomen brown to blackish brown; tergites faintly pruinose anteriorly and shiny posteriorly; sternites entirely shiny; mostly with scattered setulae, almost lacking on tergites; pregenital segments with long posteromarginal setae.

Hypopygium ( Fig. 11B–D ) large, subglobular, blackish brown. Right epandrial lamella ( Fig. 11C ) rather subglobular; with long, clavate ventral projection bearing numerous long setae. Right surstylus not separated from epandrial lamella, short, subglobular (lateral view), with short setae. Left epandrial lamella small, with short setae apically. Left surstylus ( Fig. 11D ) barely separated from epandrial lamella; rather large, elongate oval, slightly broadly produced ventrally; scattered short setae on produced ventral portion. Cerci ( Fig. 11B ) separated, with unmodified, moderately long to short setae; right cercus very short, rather subtriangular (dorsal view); left cercus rather subrectangular, narrow, much longer than right cercus. Hypoproct not produced beyond apex of left cercus.

Female. Mid femur unmodified, with regular rows of strong anteroventral and posteroventral mostly short setae, becoming longer and paler closer to base. Mid tibia unmodified. Otherwise as in male. Abdominal tergite 6 and visible parts of segments 7–8 pruinose. Cercus slender, rather short, with minute setulae.

Remarks. This species is very similar to T. halterata (Collin) . Tachydromia magadanica differs from T. halterata primarily by the following characters of the male: mid femur usually simple, at most sometimes slightly broadly concave at basal part (versus with distinct excavation near base); mid tibia with simple setulae (versus 2 closely set, spine-like setae near extreme base); produced ventral portion of left surstylus covered with sparse, short setae (versus numerous long setae, as in T. monacha ). The identity of T. halterata was confirmed by the examination of syntypes deposited in Oxford (OUMNH).

Tachydromia halterata is a broadly distributed species in Europe ( Chvála 1970). However, the eastern border of the area of this species is unclear. Chvála (1970: 476) noted a female from Becker’s collection taken from “Ural”. This locality most probably refers to the North Ural and the specimen may be T. magadanica . Tachydromia halterata is confirmed only from the centre of the European part of Russia ( Shamshev 2016).

Distribution. Holarctic. North America (first record): Canada (Quebec, Saskatchewan, Yukon), USA (Alaska); Eurasia: Russia (Far East; Siberia).

Figures

FIGURE 11. Tachydromia magadanica Shamshev, male (Canada, Yukon; CNC). A. Habitus, lateral view. B. Hypopygium, dorsal view. C. Right epandrial lamella and right surstylus, lateral view. D. Left epandrial lamella and left surstylus, lateral view. Abbreviations: cerc—cercus; lft sur—left surstylus; rt sur—right surstylus. B–D: scale bar is 0.1 mm.