Tachydromia harti Malloch, 1919

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 : 169-170

Tachydromia harti Malloch

( Fig. 8 )

Tachydromia harti Malloch, 1919: 248 . Type locality: USA, Illinois, Havana .

Notes on type series. Malloch (1919) described this species from one male and three females.

Type material examined. HOLOTYPE ♂, labelled: INHS [= Illinois State Natural History Survey] / Insect Collection / 238,817 // Havana / Ill. [= Illinois] VI.5.18 [hand-written] // TYPE / Tachydromia / harti / ♂ Malloch [red label, hand-written] // Tachydromia / harti / Mall. Type [white label, hand-written] ( INHS). PARATYPE: INHS, Insect Collection, 238,818 // Havana, Ill. VI.5.18 [hand-written]; ALLOTYPE, Tachydromia harti Malloch ♀ (1 ♀, INHS).

Additional material examined: CANADA. Manitoba: Ninette, 15.vii.1958, J.G. Chillcott, Maple-Elm Floodplain Community (1 ♂, CNC); 5 km N of Spirit Sands, Spruce Wood Prov. Pk., 8.vii.1990 (15 km S of Carberry), M.D. Schwartz // ex Rosa sp. ( Rosaceae ) (1 ♂, CNC). USA. New Mexico: Grant Co., 14 mi. N Silver City, Cherry Crk., campground. 32.54.8N 108.13.6W, 7400’, Malaise nr. creek margin, 11–16.viii.2007, J.M. Cumming & S.E. Brooks (1 ♂, CNC); same locality, Malaise trap in meadow, 16–19.viii.2007, J.E. O’Hara (1 ♂, CNC).

Recognition. This species is distinguished in the male by the following combination of characters: prothoracic sclerites (including outer face of postpronotal lobe) densely silvery grey tomentose; fore tibia with 2 black spots on apical half anteriorly; wings with two broad, brown entirely separated bands.

Redescription. Male ( Fig. 8 ). Length: body 1.7–1.9 (holotype 1.7) mm, wing 1.6–1.7 mm. Head black. Occiput on upper part with large spot of greyish pruinosity reaching eye margins and covering posterior portion of vertex, some pruinosity just behind mouth-opening, otherwise shiny; 2 moderately long, black, widely separated, slightly inclinate and somewhat proclinate verticals; some black setae of different lengths near neck and laterally; row of minute postoculars; several pale setulae near mouth-opening. Ocellar triangle shiny; 2 very short, thin, black lateroclinate ocellars. Frons shiny, broadened towards ocellar triangle, narrow, above antennae 1.5–2.0 times as broad as anterior ocellus. Antenna with brownish postpedicel and stylus, scape and pedicel yellow; postpedicel subglobular, scarcely pubescent; stylus subapical, very long. Proboscis brown, short. Palpus unmodified, elongate ovate, shorter than proboscis, brownish, clothed in scattered short dark setae, bearing 1 longer black subapical seta (shorter than palpus).

Thorax entirely black, largely shiny; prothoracic sclerites (including outer face of postpronotal lobe) 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 black, moderately long, strong notopleural, 1 shorter postalar and 4 scutellars (apical pair nearly as long as notopleural seta; lateral pair minute); acrostichals lacking; dorsocentrals uniserial, minute, 1 prescutellar pair slightly longer.

Leg colour: largely yellow; hind femur almost entirely brown, yellow near base; fore tibia with two black subglobular spots anteriorly, one spot just beyond middle of tibia and second spot subapical; mid tibia near base (sometimes less distinct) and hind tibia (except extreme base) brown; fore tarsomeres 4–5, mid and hind tarsomeres 1–2 apically and tarsomeres 3–5 entirely brown. Coxae clothed in scattered pale to yellow unmodified setae; fore coxa densely whitish silvery grey tomentose anteriorly. Trochanters with unmodified setation. Fore femur thickened, faintly whitish pubescent ventrally, bearing rows of short brownish yellow anteroventral and posteroventral setae becoming longer closer to base, with some stronger setulae on about basal half dorsally. Fore tibia mostly dilated, with unmodified setation. Mid femur unmodified, slender, with anteroventral row of minute setulae and posteroventral row of stronger, black spinule-like setulae ending with several longer setae, bearing several yellow setae near base. Mid tibia with black ventral spinules, denser and irregularly arranged subapically; short slender apical projection bearing 2 spinules at tip. 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; with two broad uniformly brown entirely separated bands, hyaline space between bands with parallel sides. One very short costal seta present. Vein R 2+3 evenly arched on middle towards costa. Veins R 4+5 and M 1 parallel near wing apex. Crossveins r-m and bm-m broadly separated. Calypter brownish, with yellowish brown cilia. Halter with pale yellow knob and brown stem.

Abdomen largely brown, segments 1–2 paler (tergites usually yellowish brown, sternites brownish yellow to yellow), shiny, mostly with scattered setulae almost lacking on tergites;pregenital segments with long posteromarginal setae.

Hypopygium rather large, elongate oval, blackish brown. Right epandrial lamella rather subglobular viewed laterally, bearing several long, slightly flattened setae apically; small ventral projection bearing 3 long, flattened setae. Right surstylus separated from epandrial lamella, long, clavate (lateral view), curved near base; bearing simple, short setae. Left epandrial lamella small, with some short setae apically. Left surstylus not separated from epandrial lobe; rather large, broadly rounded apically, excised on ventral margin; bearing short, scattered setae. Cerci separated, with some unmodified, moderately long setae; right cercus long, narrow, falciform (dorsal view), with inner margin concave; left cercus short, broad, rather subrectangular. Hypoproct with apical portion long, slender, falciform, curved to right cercus, produced nearly to level of its apex.

Female. Fore tibia rather spindle-shaped, slenderer than in male, uniformly yellow, with minute ventral spinules. Mid tibia with uniformly arranged ventral spinules, lacking apical projection. Otherwise as in male. Visible parts of tergites 6–8 greyish pruinose. Cercus slender, brown, with minute setulae.

Remarks. Tachydromia harti belongs to the T. fuscinervis group of species ( Shamshev & Grootaert 2018). In the holotype, the right wing is absent, otherwise it is in good condition. Both specimens taken from Manitoba ( Canada) have aberrant venation including a crossvein connecting veins R 2+3 and R 4+ 5 in subapical portion.

Distribution. Canada (Manitoba), USA (Illinois, New Mexico).

Figures

FIGURE 8. Tachydromia harti Malloch, male habitus, lateral view (Canada, Manitoba; CNC).