Tachydromia pseliophora 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 : 182-183

Tachydromia pseliophora Melander

( Fig. 14 )

Tachydromia pseliophora Melander, 1928: 281 . Type locality: USA, “ Los Cerrites , California ”.

Notes on type series. Melander (1928) noted the following material: “ four specimens, Los Cerrites , California, April 3, 1915, collected by M.C. Van Duzee ” .

Type material examined. SYNTYPES: 1 ♂, 1 ♀, Los Cerritos, Cal., 3.04.1915, M.C. Van Duzee // Paratype, Tachydromia pseliophora Mel. [red label, species name hand-written] // Tachydromia pseliophora Mel. [hand-written] // A.L. Melander Collection 1961 ( USNM).

Recognition. The species is distinguished by the following combination of characters: proepisternum shiny; wing with entirely separated brownish bands; in male fore tibia with 2 black spots anteriorly.

Redescription. Male. Length: body 1.9 mm, wing 1.8 mm. Head black. Occiput with patch of fine pruinosity above neck, vertex shiny; 2 inclinate, short, black vertical setae; some scattered black setae around neck and near mouth-opening; row of pale minute postoculars. Ocellar triangle shiny, ocellars very short. Frons shiny, slightly broadened towards ocellar triangle; above antennae nearly 2.0 times as broad as anterior ocellus. Antenna with postpedicel and stylus brown, scape and pedicel yellowish. Postpedicel subglobular; stylus subapical, long. Proboscis brown. Palpus unmodified, elongate oval, somewhat shorter than proboscis, brownish; clothed in scattered dark setae, with 1 short black subapical seta.

Thorax blackish brown, largely shiny; prosternum faintly whitish grey tomentose, scutellum and postnotum faintly greyish tomentose. Postpronotal lobe large, elongate oval, lacking conspicuous setae, with scattered minute setulae. Mesonotum with 1 black, short strong notopleural, 1 minute postalar and 4 scutellars (inclinate apical pair nearly as long as notopleural setae, laterals shorter and thinner); some minute setulae present behind postpronotal lobe and on notopleural depression anteriorly; acrostichals lacking; dorsocentrals arranged in 2 irregular rows anteriorly (almost uniserial in female), becoming uniserial toward scutellum, numerous, mostly minute, 1 prescutellar pair somewhat longer (nearly as long as scutellar lateral setae).

Leg colour: largely yellowish; fore and mid femora somewhat brownish on subapical part dorsally, hind femur brownish on apical 3/4; fore tibia with 2 black spots anteriorly (first spot just before middle, second spot subapical), hind tibia almost entirely brownish (except extreme base); fore and mid tarsomere 4 brownish yellow, tarsomere 5 blackish, hind basitarsus almost entirely yellow (except apex), tarsomeres 2–5 brownish. Fore coxa clothed in unmodified setae, longer and stronger apically, 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, flattened on broader part, with denser setulae on black spots anteriorly. Mid femur slender; rows of black anteroventral and posteroventral spinule-like setulae becoming longer closer to base. Mid tibia lacking apical projection, bearing ventral spinule-like setulae. Hind leg unmodified; hind femur with rows of short anterodorsal and posterodorsal setae.

Wing normally developed, rounded at apex; two broad brownish bands entirely separated. One short costal seta. Rs short. Vein R 1 meeting costa before wing mid-length. Vein R 2+3 almost straight, slightly arched, gently upturned meeting costa, thin throughout. Veins R 4+5 and M 1+2 convergent towards wing apex. Vein M 4 distinct throughout. Cell r 1 narrower than subequal cells r 2+3 and r 4+5. Crossveins r-m and bm-m broadly separated. Calypter brownish, with scattered fringe. Halter with pale knob and brownish yellow stem.

Abdomen largely brownish, segments 1–2 and posterior margin of segment 3 brownish yellow; shiny, covered with scattered black setae longer on pregenital segments.

Hypopygium ( Fig. 14A–C ) rather large, elongate oval, blackish brown. Right epandrial lamella ( Fig. 14B ) rather subglobular viewed laterally, bearing 5 unmodified long setae apically; broad ventral projection bearing 4 long, flattened setae. Right surstylus separated from epandrial lamella, bilobed; ventral lobe digitiform, rather broad, long; dorsal lobe short, curved; both lobes with simple, short setae. Left epandrial lamella ( Fig. 14C ) small, with short setae apically. Left surstylus barely separated from epandrial lamella, elongate, excised apically, with scattered, unmodified short setae. Cerci ( Fig. 14A ) separated, with unmodified short to moderately long setae; right cercus digitiform, narrow, moderately long; left cercus somewhat longer than right cercus, mostly broad, narrowed apically. Hypoproct slightly produced beyond apices of cerci.

Female. Fore tibia uniformly yellow, otherwise as in male. Cercus brownish, long, slender, with minute setulae.

Remarks. Tachydromia pseliophora belongs to the T. fuscinervis group and is very similar to T. harti .

Distribution. USA (California).

Figures

FIGURE 14. Tachydromia pseliophora Melander, male terminalia (USA, California; syntype, USNM). A. Hypopygium, dorsal view. B. Right epandrial lamella and right surstylus, lateral view. C. Left epandrial lamella and left surstylus, lateral view. Abbreviations: cerc—cercus; epand—epandrium; hypd—hypandrium; hyprct—hypoproct; lft sur—left surstylus; rt cerc—right cercus; rt sur—right surstylus. A–C: scale bar is 0.1 mm.