Tachyempis universalis ( Melander, 1910 )

Shamshev, I. V. & Grootaert, P .., 2024, Revision of the Nearctic species of the genus Tachyempis Melander, 1928 (Diptera: Hybotidae), Russian Entomological Journal 33 (1), pp. 124-135 : 132-134

Tachyempis universalis ( Melander, 1910)

Figs 3 , 14–16 .

Tachydromia universalis Melander, 1910: 60 (♂ and ♀), fig. 16 (wing). Type locality: USA, Chester County, Pennsylvania (by lectotype designation).

Tachyempis nervosa Melander, 1928: 290 (♀). Type locality: USA, California, Stanford ; syn.n.

NOTES ON TYPE SERIES. Tachydromia universalis : Melander [1910] noted the following material: “ Described from five specimens collected in the following widely separated localities: Chester County, Pennsylvania, June , 1902 (J. C. Bradley), Algonquin , Illinois, July 17, 1896 (Dr. Wm. Nason), and Austin, Texas.”

Tachyempis nervosa : Melander [1928] described this species from a single female: “ Holotype, Stanford University, California, July, 1915 ( Melander )” .

TYPE MATERIAL EXAMINED. Tachydromia universalis : Syntypes: Penn. Chester Co. 6 [hand-written] // TYPE Tachydromia universalis Mel. [red label] // AL Melander Collection 1961 (♂, USNM); same data except red label “ Paratype ” (2 ♀♀ [on one pin], USNM); sex? [abdomen missing], Austin Tex // Paratype Tachydromia universalis Mel. [red label] // AL Melander Collection 1961 ( USNM); Algonquin, Ill. 7.17.94–134 [data hand-written] // 5206 [hand-written] // Paratype Tachydromia universalis Mel. [red label] // AL Melander Collection 1961 (1 ♀, USNM) .

Tachyempis nervosa : Holotype, ♀, labelled: Stanford / Jul'15, Cal. / AL Melander // TYPE / Tachyempis / nervosa Mel. [led label] // AL Melander / Collection / 1961 ( USNM).

ADDITIONAL MATERIAL EXAMINED. USA, Virginia: Great Falls , 14.ix.1913 // Fredk Knab Collection // Tachyempis universalis Mel. not type (1 ♀, USNM) . Washington: Almota, 25.v.1913 // AL Melander, Collection, 1961 (3 ♂♂, USNM); Goldendale, 23.vii.1921, A.L. Melander // AL Melander, Collection, 1961 (1 ♀, USNM); Lake Chelan , Lucerne, 29.vii.1919, A.L. Melander // AL Melander, Collection, 1961 (1 ♀, USNM); 6 mi. S. Wawawai, on Snake R ., Whitman Co., 700 ft., 22.vi.1977, W. Turner, dripping spring // N.E. Woodly Collection, Donated 2002 // ♂ Tachyempis universalis Melander , det. W. Turner (1 ♂, 1 ♀, USNM) .

DIAGNOSIS. Small greyish species; occiput almost entirely greyish pruinose, only with small shiny spot near margin of mouth-opening laterally; frons and vertex entirely greyish pruinose (including ocellar triangle). Male: palpus whitish; female: palpus mostly brownish.

REDESCRIPTION. Male ( Fig. 3 ). Length: body 1.6– 1.8 mm, wing 1.6–1.7 mm. Head black. Occiput almost entirely greyish pruinose (including vertex), only with small shiny spot near margin of mouth-opening laterally; 2 very short black wide apart lateroclinate verticals; scattered short pale setae on lower part, row of similar postoculars. Ocellar triangle pruinose; 2 short, black, lateroclinate ocellars. Frons rather broadly V-shaped, near anterior ocellus nearly 2 times as broad as above antennae, with slightly bowed margins opposite ocellar triangle, above antennae about 2.5 times as broad as anterior ocellus; entirely greyish pruinose. Antenna with scape and pedicel yellow to brownish yellow, postpedicel and stylus brown; postpedicel small, rather drop-like; stylus apical, nearly 3.0 times as long as pedicel and postpedicel combined, faintly pubescent. Proboscis brown. Palpus unmodified, ovate, moderately large, slightly longer than proboscis, whitish; clothed in dense minute silvery white setulae giving to palpus silvery glisten, bearing scattered, short, pale, fine setae.

Thorax entirely black, with black setae; postpronotal lobe and mesoscutum subshiny, faintly pale grey tomentose (dorsal view); prosternum, proepisternum, scutellum, postnotum and entire mesopleuron densely whitish grey tomentose. Postpronotal lobe elongate oval, lacking prominent setae, with scattered minute setulae. Mesonotum with 1 moderately long, strong notopleural (usually with additional short seta anteriorly), 1 postalar and 4 scutellars (apical pair moderately long, strong, inclinate, lateral pair minute); some minute setulae present behind postpronotal lobe and on notopleural depression anteriorly; acrostichals minute, biserial, lacking on prescutellar depression; dorsocentrals uniserial, minute (1 prescutellar pair longer).

Legs extensively yellow to brownish yellow; mid and hind coxae rather brownish yellow; fore femur brownish yellow near apex dorsally, mid and hind femora brownish on about apical 1/3 dorsally (usually somewhat broader on hind femur); tibiae somewhat darkened at apex; tarsomeres 2–4 rather brownish yellow, tarsomere 5 brown. Coxae clothed in pale setae of different lengths; fore coxa densely whitish pruinose anteriorly. Trochanters with unmodified setation. Fore femur thickened, whitish pubescent ventrally, bearing minute anteroventral and posteroventral pale setulae becoming somewhat longer near base. Fore tibia spindle-shaped, with unmodified setation. Mid femur unmodified, slender, with anteroventral and longer posteroventral yellow spinule-like setulae becoming longer near base. Mid tibia unmodified, with hardly prominent ventral spinule-like setulae, lacking prominent apical projection. Hind femur and tibia unmodified, lacking prominent setae. Hind basitarsus with simple setulae.

Wing normally developed, rounded at apex, with unmodified venation; membrane lacking prominent pattern, almost uniformly faintly infuscate (somewhat darker along veins). One very short basal costal seta usually present. Second section of costa nearly 1.5 times longer than third section. Rs slightly longer than basal portion of vein R 4+5. Vein R 2+3 arched towards costa on basal part. Veins R 4+5 and M 1+2 parallel near wing-apex. Apical portion of M 4 as long as to slightly longer than its basal portion. Crossveins r-m and bm-m broadly separated; cross-vein bm-m transverse. Cell br and bm of subequal width. Cell r 1 nearly 2.5 times narrower than cell r 2+3. Calypter brown, with yellowish cilia. Halter with pale knob and brownish yellow stem.

Abdomen black brown, faintly greyish pruinose, tergites subshiny in dorsal view; covered with scattered minute setulae; pregenital segments with long, dark posteromarginal setae.

Hypopygium ( Figs 14–16 ) moderately large, elongate oval, concolorous with abdomen. Right epandrial lamella elongate oval, somewhat produced mid-ventrally, bearing scattered, simple setae. Right surstylus ( Figs 14, 15 ) differentiated, nearly digitiform, rather broad, long, overlapping terminalia posteriorly; bearing 2 moderately long closely set setae near base dorsally, with some scattered marginal setulae, no spine-like setae. Left epandrial lamella ( Fig. 16 ) strongly shifted anteriad relative to right epandrial lamella (dorsal view); rounded apically, with large basal apodeme; 2 long setae on subapical part. Left surstylus barely differentiated from epandrial lamella, elongate oval, moderately large, with moderately long setae along dorsal margin and at apex; with slender internal projection bearing scattered setulae at apex. Cerci ( Fig. 14 ) separated; left cercus shifted anteriad relative to right cercus, basal portion produced inside epandrium; right cercus small, subglobular, bearing moderately long simple setae; left cercus digitiform, very slender, slightly curved (left lateral view), in lateral view nearly as long as left surstylus, bearing cluster of several moderately long to rather long setae on about middle, 2 short, somewhat stronger setae at apex. Subepandrial sclerite semicircular, bare.

Female. Palpus largely brownish, paler closer to base. Otherwise as in male. Abdominal segments 6–8 densely pruinose. Cercus moderately long, slender, with scattered setulae.

DISTRIBUTION. USA (California, Illinois, Pennsylvania, Texas, Virginia, Washington) .

KEY TO NEARCTIC SPECIES OF TACHYEMPIS

1. Thorax with pale setae; 1 moderately long, postpronotal seta present. Palpus subrectangular. [Additional characters: palpus pale yellow in male and dusky yellow in female (usually slightly darkened apically in both sexes)] .......... ......................................................... T. agens (Melander)

– Thorax with black setae; postpronotal seta absent. Palpus oval ................................................................................ 2

2. Frons and vertex entirely greyish pruinose (including ocellar triangle) ................................... T. universalis (Melander)

– At least vertex shiny between eye margin and ocellar triangle ........................................................................... 3

3. Frons and vertex entirely shiny (including ocellar triangle). Palpus with dark subapical seta. Male: hind basitarsus with simple setulae ........................................... T. calva (Melander)

– Only vertex shiny between eye margin and ocellar triangle. Palpus with pale setulae. Male: hind basitarsus with 1 strong, long, black, dorsal subapical seta ......................... .......................................................... T. cinerea Melander

Figures

Figs 1–3. Tachyempis Melander, habitus: 1 — T. agens (Melander), ♀, paratype, antero-lateral view; 2 — T. calva (Melander), ♂, lateral view; 3 — T. universalis (Melander), ♂, lateral view. Рис. 1–3. Tachyempis Melander, габитус: 1 — T. agens (Melander), ♀, паратип, вид спереди и сбоку; 2 — T. calva (Melander), ♂, вид сбоку; 3 — T. universalis (Melander), ♂, вид сбоку.

Fig. 14–16. Tachyempis universalis (Melander), ♂: 14 — hypopygium, dorsal view; 15 — right surstylus, lateral view; 16 — left epandrial lamella, lateral view. Abbreviations: epand — epandrium; hypd — hypandrium; lft cerc — left cercus; lft sur — left surstylus; rt sur — right surstylus. Scale bar is 0.1 mm. Рис. 14–16. Tachyempis universalis (Melander), ♂: 14 — гипопигий, вид сверху; 15 — правый сурстиль, вид сбоку; 16 — леваЯ лопасть ЭпандриЯ, вид сбоку. СокращениЯ: epand — Эпандрий; hypd — гипандрий; lft cerc — левый церк; lft sur — левый сурстиль; rt sur — правый сурстиль. Масштаб: 0,1 мм.