Tachydromia enecator Melander, 1902

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 : 163-166

Tachydromia enecator Melander

( Fig. 6 )

Tachydromia enecator Melander, 1902: 226 . Type localities: Canada, “ St. John’s Co., Quebec ”; USA “ Lance Creek , Wyoming”.

Tachista lundstroemi Frey, 1913: 73 , fig. 20. Type localities: Finland, “ Ab. Åbo [= Turku]; N. Helsinge; Ta. Kangasala; Kb. Nurmes; Kl. Parikkala; Ks. Kuusamo ”; syn. nov.

Tachydromia lundstroemi : Chvála, 1970: 450, figs 29, 30; 1975: 236, figs 558–560.

Notes on type series. Tachydromia enecator : Melander (1902) described T. enecator based on the female sex only: “ two females; St. John’s Co., Quebec (G. Chagnon); Lance Creek , Wyoming (Wheeler)”. We have not examined the syntypes but this species is surely correctly recognised based on its original description.

Tachista lundstroemi : Frey (1913) described T. lundstroemi based on two males and five females from Finland. All syntypes are in Frey’s Collection in Helsinki ( MZH) and they were examined by I.S. in 2019.

Material examined. NORTH AMERICA. CANADA. Alberta: Jasper , 14.viii.1932 (1 ♀, CNC) ; Banff , 29.vi.1922, E. Hearle (sex?, CNC) ; same locality, 22.vii.1924, E. Hearle (1 ♂, 1 ♀, CNC) ; same locality, 2.ix.1924, E. Hearle (1 ♀, CNC) ; High Level, Aspen Campground , 11.vii.1993, P.H. Arnaud Jr., field note 00976 (1 ♂, USNM) . British Columbia: Cranbrook, 22.vi, C. Garrett // donation of C.B.D. Garrett Collection to USNM (1 ♀, USNM) ; Salmon Arm , 9.vii.1925, A.A. Dennys (1 ♀, CNC) ; Alaska Hwy , 37 km W Ft. Nelson, intercept aspen-spruce forest, 12.vi.–5.ix.1984, S. & J. Peck (2 ♂, CNC) . Ontario: Ottawa , 4.viii.1926, G.S. Walley // Tachydromia enecator Mel. (1 ♂, CNC) . Northwest Territories: Yellowknife , 10.vii.1949, E.F. Cashman (1 ♀, CNC) ; same locality, 12.viii.1949, R. R. Hall (1 ♀, CNC) . Quebec: Mistassini , 15.vii.1944, A. Robert // Tachydromia enecator Mel. ♂, det. A. Robert (1 ♂, CNC) . Yukon: 14 mi. E Dawson , 1300’, 29.vii.1962, R. E. Leech (3 ♀, CNC) ; same locality, 1300’, 31.vii.1962, R. E. Leech (1 ♀, CNC) ; same locality, 2.viii.1962, P.J. Skitsko (1 ♀, CNC) ; Whitehorse, Robert Service campground // aspirated from tent service at night (10–11 pm), 28–30.vi.1997, T. A. Wheeler (1 ♂, 5 ♀, LEM) ; same locality, swept from tent surface at night, 27.vi.1997, T. A. Wheeler (1 ♀, LEM) ; same locality (60.42.1N 135.02.7W), on tent in late evening, 11.vii.1998, T. A. Wheeler (8 ♂, 1 ♀, LEM) . USA. Alaska: Douglas , 8.vii.1901 (1 ♀, USNM) ; Iditarod , 27.vii.1917, A.H. Twitchell Collector // Tachydromia enecator Mel. , det. J. R. Malloch (1 ♂, USNM) ; Camp 334, AlaskEngComm, 11.vii.1921, J.M. Aldrich coll. (1 ♀, USNM) ; Matanuska , RotaryTrapColl, 16.vii.1945, J.C. Chamberlin (1 ♀, USNM) ; Unalakleet , 14.vii.1961, B.S. Heming (1 ♂, CNC) . EURASIA. RUSSIA. Krasnoyarskiy Territory : Krasnoyarsk, 70 km W Kryuchkovo , 14–23.vii.2009, K. Tomkovich (1 ♂, ZMMU) . Buryatia Republic: Naran, env. Mondy , 2000 m, 19.vii.1965, Gorodkov (1 ♀, ZISP) .

Diagnosis. The species is distinguished by the following combination of characters: palpus brown, long, slender; proepisternum tomentose; legs almost uniformly dark brown, fore femur with black, spinule-like anteroventral and posteroventral setae; wings with entirely separated bands, vein R 2+3 with short, subapical appendix.

Redescription. Male ( Fig. 6A ). Length: body 2.9–3.3 mm, wing 2.9–3.2 mm. Head black. Occiput largely shiny, with large spot of greyish pruinosity above neck (leaving narrow postocular space and vertex shiny) and small spot just behind mouth-opening; 2 short, black, wide apart proclinate verticals, some short black setae above neck, row of minute postoculars, several short, thin setae near mouth-opening. Ocellar triangle shiny; 2 minute, black lateroclinate ocellars. Frons shiny, slightly widened towards ocellar triangle, rather broad, above antennae about 2.5 times as broad as anterior ocellus. Antenna uniformly brown to blackish brown; postpedicel subglobular, scarcely pubescent; stylus slightly subapical, very long. Proboscis short, brown. Palpus unmodified, long, slender, strip-like, nearly as long as proboscis, brown, clothed in minute dark setulae; bearing 1 very short, black subapical seta.

Thorax uniformly black to brownish black, largely shiny; prothoracic sclerites(except upper part of proepisternum and postpronotal lobe) and meron posteriorly densely silvery grey tomentose, scutellum and postnotum finer greyish tomentose. Postpronotal lobe large, elongate oval, lacking prominent setae, with scattered minute setulae. Mesonotum with 1 short black notopleural, 1 slightly shorter postalar and 4 scutellars (apical pair nearly as long as postalar seta; lateral pair minute); acrostichals lacking; dorsocentrals uniserial, minute, 1 prescutellar pair somewhat longer.

Legs almost uniformly brown to blackish brown, only knees and basitarsi somewhat yellowish. Coxae clothed in scattered pale to yellow, unmodified setae; fore coxa densely silvery grey tomentose anteriorly. Trochanters with unmodified setation. Fore femur slightly thickened, whitish pubescent ventrally, bearing rows of black anteroventral and posteroventral spinule-like setae almost throughout (less conspicuous near base). Fore tibia slightly thickened, with row of stronger ventral setulae. Mid femur unmodified, slender, faintly pubescent ventrally closer to base, with anteroventral and posteroventral rows of black, spinule-like setae throughout. Mid tibia bearing black ventral spinules, with short apical projection. 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; two broad brownish entirely separated bands darker closer to costa. One short, black basal costal seta present. Vein R 2+3 almost straight, rather sharply upturned to costa, subapically usually with short appendix directed downwards. Veins R 4+5 and M 1 parallel near wing-apex. Crossveins r-m and bm-m broadly separated. Cell r 1 subequal in width to cell r 2+3. Calypter brownish, with concolourous cilia. Halter brownish (colour intensity of knob somewhat varying).

Abdomen brown to blackish brown, shiny, mostly with scattered setulae almost lacking on tergites; pregenital segments with long posteromarginal setae.

Hypopygium ( Fig. 6B–D ) small, elongate oval, blackish brown. Right epandrial lamella rather subtriangular viewed laterally, with numerous unmodified, moderately long setae; without ventral projection. Right surstylus ( Fig. 6C ) separated from epandrial lamella, rather subrectangular, bilobed, with spine-like submarginal setae. Left epandrial lamella ( Fig. 6D ) small, with scattered simple setae. Left surstylus barely separated from epandrial lamella, rather short, broadly rounded at apex, with simple setae longer along lower margin. Cerci ( Fig. 6B ) separated, both rather digitiform, left cercus slightly longer and broader; with some unmodified moderately long setae. Hypoproct not produced beyond apices of cerci.

Female. Mid tibia lacking apical projection. Otherwise as in male. Abdominal segment 6 entirely shiny, tergite 7 broadly pollinose dorsally otherwise segment 7 shiny, segment 8 pollinose. Cercus slender, black, with minute setulae.

Remarks. Tachydromia enecator belongs to the T. arrogans group of species sensu Chvála (1970). However, this species shows some affinities to the T. punctifera group (e.g., similar modification of apex of R 2+3).

Distribution. Holarctic. North America: Canada (Alberta, British Columbia, Northwest Territories, Ontario, Quebec, Yukon), USA (Alaska); Eurasia: Finland, Great Britain, Russia (north-west of the European part, Ural, East Siberia, Far East), Sweden.

Figures

FIGURE 6. Tachydromia enecator Melander, male (Canada, Alberta; CNC). A. Habitus, lateral view. B. Hypopygium, dorsal view. C. 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.