Tachyempis cinerea Melander, 1928

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 : 130-132

Tachyempis cinerea Melander, 1928

Figs 11–13 .

Tachyempis cinerea Melander, 1928: 290 (♀). Type locality: USA, New Mexico, Alamogordo .

Tachyempis longipennis Melander, 1958: 296 (♂). Type locality: USA, Indiana, Ripley County; syn.n.

NOTES ON TYPE SERIES. Tachyempis cinerea : Melander [1928] described this species from the female sex only. He provided the following data: “ Two specimens; Alamogordo, New Mexico, type in the Academy of Natural Science, Philadelphia ” .

Tachyempis longipennis : Melander [1958] noted the following material: “ Holotype and two paratypes: Riply County, Ind., 14 July , 1955; Dr. Leland Chandler, collector. The type is deposited in the National Museum collection (No. 63,497). The two paratypes are placed in the collections of Purdue University and myself.”

TYPE MATERIAL EXAMINED. Tachyempis cinerea : Syntype, ♀, labelled: Alamogordo IV.30 [hand-written] 02 NM // Type T. cinerea Mel. [red label] // AL Melander Collection 1961 ( USNM).

Tachyempis longipennis : Holotype, ♂, labelled: Ripley Co. Ind. / 14–VII–1955 // L. zephyrum / colony [hand-written] // L. Chandler / Collr. // 5 [circled, hand-written] // Type No / 63497 / USNM [red label] // Holotype ♂ / Tachyempis / longipennis 1957 / det. Melander [hand-written] ( USNM). Paratype. Four upper labels with same data and style as holotype // Paratype Tachyempis longipennis Melander [hand-written] // AL Melander Collection 1961 (♂, USNM).

ADDITIONAL MATERIAL EXAMINED. CANADA, Ontario: Ottawa, nr. Uplands Airport, Malaise , 2–11.vi.1992, J.M. Cumming (1 ♂, CNC) . USA, Illinois: Cobden, Ill. , May 7–9, 1918, Coll. J. R.M. (1 ♀, USNM) ; Centerville, Ill. , Aug. 16, 1914, Sangamon R. (1 ♂, USNM) ; Urbana, Ill. , Aug. 10, 1916 (1 ♀, USNM) ; Urbana, Ill. , Jul. 5, 1915, on tree (1 ♀, USNM) ; Urbana, Ill. , Jul. 28, 1915, Sandy (1 ♂, USNM) ; Easten, Ill. , May 1, 1914, Central ditch (2 ♂♂, USNM) ; White Heath, Ill. , May 16, 1915 (1 ♂, USNM) . Kansas: Manhattan, Ks. , VI –8–1932, C.W. Sabrosky; ♂ – spine on metatar. 3; Tachyempis sp. , (nr. longispina Mel. / spine on hind metatar.), det. Sabrosky (1 ♂, 1 ♀, USNM) . Michigan: Wayne Co., Mich., Crosse Ile , July 25 1951, Geo. Steyskal (1 ♂, USNM) .

DIAGNOSIS. Small greyish species; occiput narrowly shiny along eye margin, vertex shiny between eye margin and ocellar triangle; antenna with scape and pedicel yellowish; legs extensively yellow. Male: hind basitarsus with 1 strong, long, black, dorsal subapical seta.

REDESCRIPTION. Male (habitus photo in Sinclair et al. [2023: 149, fig. C]). Length: body 1.5–1.8 mm, wing 1.5–1.6 mm. Head black. Occiput (except narrow shiny postocular space) faintly greyish pruinose; 2 short, black, wide apart, lateroclinate verticals; some scattered, short, pale setae on lower part, row of minute pale postoculars. Vertex shiny between eye margin and ocellar tubercle. Ocellar tubercle faintly pruinose; 2 short dark lateroclinate ocellars. Frons broadly V-shaped, near anterior ocellus nearly 2.5 times broader than above antennae, above antennae about 2.5 times as broad as anterior ocellus; with nearly straight margins; densely greyish pruinose on lower part, faintly pruinose closer to ocellar triangle. Antenna with scape and pedicel yellow to brownish yellow, postpedicel and stylus brown; postpedicel small, rather drop-like, more convex ventrally; stylus apical, rather short, 3.0–3.5 times as long as pedicel and postpedicel combined, short pubescent. Proboscis brown. Palpus unmodified, elongate ovate, nearly as long as proboscis; pale yellow, clothed in dense minute silvery white setulae giving to palpus silvery glisten in some view, with some scattered short yellowish setae along lower margin.

Thorax entirely black, with black setae; postpronotal lobe and scutum almost shiny (dorsal view), very faintly light grey tomentose (more distinct in anterior view); prosternum, proepisternum and entire mesopleuron rather densely whitish grey tomentose (in some view prosternum and proepisternum appearing denser tomentose), scutellum and postnotum densely greyish tomentose. Postpronotal lobe elongate oval, lacking prominent setae, with scattered minute setulae. Mesonotum with 1 moderately long, strong notopleural, 3 minute setulae on postsutural supra-alar face, 1 very short 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, arranged in 1–2 rows, lacking on prescutellar depression; dorsocentrals uniserial, minute (1 prescutellar pair longer).

Legs colour: largely yellow; mid and hind coxae sometimes brownish at base; fore and mid femora brownish on apical part dorsally, hind femur brownish on about apical 1/3–1/2; fore tibia brownish to brownish yellow (except extreme base), hind tibia brownish yellow at apex; tarsomeres 2–4 of all legs slightly darkened at apex, tarsomere 5 brown (in darker specimens fore tarsus slightly darker). Coxae clothed in pale setae of different lengths, fore coxa anteriorly, mid and hind coxae laterally densely whitish pollinose. 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 ventral spinule-like setulae towards apex; lacking prominent apical projection. Hind femur and tibia unmodified, lacking prominent setae. Hind basitarsus with 1 long, black, dorsal, appressed seta (2/3 to 3/4 of tarsomere 2 length).

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

Abdomen black brown, subshiny, faintly greyish pruinose (except slightly denser pruinose tergite 1 and shiny sternite 1); covered with scattered minute setulae; pregenital segments with long posteromarginal setae.

Hypopygium ( Figs 11–13 ) moderately large, elongate oval, concolorous with abdomen. Right epandrial lamella elongate oval, somewhat produced mid-ventrally, bearing scattered, simple setae. Right surstylus ( Figs 11, 12 ) 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. 13 ) 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. 11 ) separated; left cercus shifted anteriad relative to right cercus, basal portion produced inside epandrium; right cercus small, rather subtriangular (dorsal view), bearing moderately long simple setae; left cercus digitiform, very slender, strongly curved (left lateral view), in left lateral view longer than left surstylus, bearing cluster of several moderately long to rather long setae on about middle, 2 spinule-like setae at apex. Subepandrial sclerite semicircular, bare.

Female. Legs sometimes slightly darker. Hind basitarsus lacking dorsal seta. Otherwise as in male. Abdominal segments 6– 8 pruinose. Cercus moderately long, slender, with scattered setulae.

REMARKS. Tachyempis cinerea can be readily distinguished from other Nearctic species of the genus by a curious, spine-like seta at the apex of hind basitarsus of the male. However, T. longispina Melander, 1928 known from Cuba and Jamaica as well as an undescribed species from Dominicana have this character as well.

Melander [1958] provided a description of interesting behaviour of T. cinerea (as T. longipennis ): “This little fly was taken from a nesting site of the bee Lasioglossum zephyrum (Smith) , where it would station itself near the nest entrance of the bee and make rapid passes at incoming pollen-laden bees.”

The photo of the male habitus of this species was published by Sinclair et al. [2023: 149, fig. C], as Tachyempis sp.

DISTRIBUTION. Canada (Ontario); USA (Kansas, Illinois, Indiana, Michigan, New Mexico) .

Figures

Fig. 11–13. Tachyempis cinerea Melander, ♂: 11 — hypopygium, dorsal view; 12 — right surstylus, lateral view; 13 — left epandrial lamella, lateral view. Abbreviations: epand — epandrium; hypd — hypandrium; lft cerc — left cercus; lft sur — left surstylus; rt sur — right surstylus; sbepand scl — subepandrial sclerite. Scale bar is 0.1 mm. Рис. 11–13. Tachyempis cinerea Melander, ♂: 11 — гипопигий, вид сверху; 12 — правый сурстиль, вид сбоку; 13 — леваЯ лопасть ЭпандриЯ, вид сбоку. СокращениЯ: epand — Эпандрий; hypd — гипандрий; lft cerc — левый церк; lft sur — левый сурстиль; rt sur — правый сурстиль; sbepand scl — субЭпандриальный склерит. Масштаб: 0,1 мм.