Tachydromia phengites Melander, 1928

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 : 179-181

Tachydromia phengites Melander

( Fig. 13 )

Tachydromia phengites Melander, 1928: 282 . Type localities: Canada, “ Ridgeway, Ontario ”; USA, “ Falls Church , Virginia”.

Notes on type series. Melander (1928) noted the following material: “ five specimens, Falls Church, Virginia, received from Nathan Banks, and Ridgeway, Ontario, received from M.C. Van Duzee ”.

Type material examined. SYNTYPES: ♂, Falls Church, Va. 8 July // Paratype, T. phengites Mel. [red label, species name hand-written] // A.L. Melander Collection 1961 // Tachydromia phengites Mel. [hand-written]; ♀, Ridgeway Ont. 7-7-12 MC VanDuzee // Paratype, T. phengites Mel. [red label, species name hand-written] // A.L. Melander Collection 1961 ( USNM).

Additional material examined: CANADA: Ontario: Ridgeway , 07.vii.1912, M.C. Van Duzee (1 ♀, USNM) ; Marmora , 11.vi.1952, J. R. Vockeroth (1 ♂, CNC) ; Marmora , 26.vi.1952, J. R. Vockeroth (3 ♂, 6 ♀, CNC) ; Marmora , 1.vii.1952, J. R. Vockeroth (1 ♀, CNC) ; Marmora , 8.vii.1952, J. R. Vockeroth [1 ♂ — Tachydromia phengites , det. Cooper 19] (2 ♂, 2 ♀, CNC) ; Marmora , 21.vii.1952, J. R. Vockeroth (1 ♀, CNC) ; Marmora , at grass roots, 30.vii.1952, J. R. Vockeroth (1 ♀, CNC) ; Ottawa , Acer negundo , 28.vi.1952, J.F. McAlpine (1 ♂, CNC) ; Bell’s Cor. , 1.vii.1952, J.F. McAlpine (1 ♀, CNC) ; 18 km E Gananoque , ex. shrubby meadow, 9.vi–15.vi.1977, Redner & Dondale // brachypterous Tachydromia (1 ♀, CNC) ; Murphy’s Point Prov. Park, 7 km S Rideau Ferry, ex Acer woods, 11.vii.1993, J.M. Cumming (56 ♂, 64 ♀, CNC) . USA: New York: Tompkins Co., Salmon Ck. , 16.vi.1981, leg. D.J. Bickel (1 ♀, CNC) .

Diagnosis. The species is distinguished by the following combination of characters: occiput entirely shiny; proepisternum tomentose; wing somewhat shortened, with entirely separated brownish bands; male fore tibia with black subapical spot anteriorly.

Redescription. Male ( Fig. 13A ). Length: body 1.6–1.8 mm, wing 1.2–1.3 mm. Head black. Occiput entirely shiny; 2 inclinate, short, black vertical setae; some scattered black setae around neck and near mouth-opening; row of pale minute postoculars. Ocellar triangle subshiny, ocellars short, lateroclinate. Frons shiny, slightly broadened towards ocellar triangle; above antennae nearly 2.0 times as broad as anterior ocellus. Antenna with postpedicel and stylus brownish to brownish yellow, scape and pedicel slightly paler. Postpedicel subglobular; stylus subapical, very long, nearly 5.0 times as long as pedicel and postpedicel combined. Proboscis brown. Palpus unmodified, slender, long, somewhat shorter than proboscis, brown; clothed in scattered dark setae, with 1 short (nearly half as long as palpus) black subapical seta.

Thorax blackish brown, prothoracic sclerites (except postpronotal lobe) entirely densely whitish grey tomentose, postpronotal lobe and scutum (dorsal view) subshiny (faintly sculptured, less distinct on prescutellar depression), scutellum and postnotum faintly tomentose; mesopleuron largely shiny, only meron faintly tomentose. Postpronotal lobe large, elongate oval, with scattered minute setulae, lacking conspicuous setae. Mesonotum with 1 black, short strong notopleural, 1 minute postalar and 4 scutellars (inclinate apical pair nearly as long as notopleural seta, laterals minute); some minute setulae present behind postpronotal lobe and on notopleural depression anteriorly; acrostichals almost lacking, some scattered minute setulae present anteriorly; dorsocentrals uniserial, numerous, mostly minute, 1 prescutellar pair somewhat longer.

Legs largely brownish yellow; fore and mid coxae brownish; fore tibia rather yellow with black, rounded subapical spot anteriorly (varying in size); hind femur and tibia brownish (except extreme base); tarsomere 4 of all legs darker apically, tarsomere 5 brownish. Fore coxa clothed in numerous short hair-like setae; whitish pruinose anteriorly. Fore femur thickened, pubescent ventrally, with short anteroventral and posteroventral brownish yellow setulae becoming longer closer to base. Fore tibia somewhat spindle-shaped, with unmodified setation. Mid femur slender, with anteroventral and somewhat longer posteroventral black spinule-like setulae; 2 moderately long setae near base. Mid tibia with slightly prominent apical projection, bearing ventral spinule-like setulae. Hind leg unmodified; hind femur with rows of short anterodorsal and posterodorsal setae.

Wing distinctly shortened, narrow, rounded at apex; two broad, brownish, entirely separated bands. Costal seta lacking. Rs very short. Vein R 1 meeting costa before wing mid-length. Vein R 2+3 almost straight, gently upturned meeting costa, thin throughout. Veins R 4+5 and M 1+2 parallel near wing-apex. Vein M 4 very faint on subapical portion. Cell r 1 narrower than subequal cells r 2+3 and r 4+5. Cell bm very narrow. Crossveins r-m and bm-m broadly separated. Calypter brownish, with scattered fringe. Halter with pale knob and brownish yellow stem.

Abdomen brownish, shiny, covered with scattered black setae longer on pregenital segments.

Hypopygium ( Fig. 13B–D ) rather large, elongate oval, blackish brown. Right epandrial lamella ( Fig. 13C ) rather subglobular viewed laterally, bearing 7–8 unmodified long setae apically; broad ventral projection bearing 3 long, flattened setae. Right surstylus separated from epandrial lamella, bilobed; ventral lobe digitiform, long; dorsal lobe short; both lobes with simple, short setae. Left epandrial lamella ( Fig. 13D ) small, with short setae apically. Left surstylus barely separated from epandrial lamella, elongate, excised apically, with scattered, unmodified short setae. Cerci ( Fig. 13B ) separated, with unmodified short to moderately long setae; right cercus digitiform, narrow, long; left cercus somewhat shorter and broader than right cercus, slightly produced apically. Hypoproct not produced beyond apices of cerci.

Female ( Fig. 13E ). Fore tibia entirely yellow. Mid femora with more numerous anteroventral and posteroventral setulae. Mid tibia lacking apical projection. Otherwise as in male. Cercus brownish, long, slender, with minute setulae.

Remarks. Tachydromia phengites belongs to the T. fuscinervis group ( Shamshev & Grootaert 2018). The species has shortened wings. Cumming et al. (2018) did not list Tachydromia among saproxylic empidoids collected in a temperate deciduous forest in Quebec, Canada by emergence traps placed over decayed logs of American beech ( Fagus grandifolia Ehrhart ) and sugar maple ( Acer saccharum Marshall ). However, label data of a very long series of T. phengites from Ontario, Canada indicate that this species might be saproxylic because it was taken “ex Acer woods”.

Distribution. Canada (Ontario), USA (New York, Virginia).

Figures

FIGURE 13. Tachydromia phengites Melander (Canada, Ontario; CNC). A–D. Male. 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. E. Female habitus, lateral view.Abbreviations: cerc—cercus; lft sur—left surstylus; rt sur—right surstylus. C–D: scale bar is 0.1 mm.