Tachydromia monacha 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 : 177-179

Tachydromia monacha Melander

( Fig. 12 )

Tachydromia monacha Melander, 1928: 283 . Type locality: USA, Washington, Pullman .

Tachydromia monaca : Melander, 1965: 474; Yang et al., 2007: 440. Error or emendation.

Notes on type series. Melander (1928) described this species from female sex only: “ one specimen, Pullman , Washington, May 30, 1913 ” .

Type material examined. HOLOTYPE ♀, labelled: Pullman, Washington, 30 May 13 [= 1913] // TYPE, T. monacha Mel. [red label, species name hand-written] // A.L. Melander Collection 1961 ( USNM).

Additional material examined: NORTH AMERICA. CANADA. Alberta: Morrin, 4.vi.1929, G.F. Manson (1 ♀, CNC); Valleyview , 6.vi.1961, A. R. Brooks (1 ♀, CNC). British Columbia: Summit Lake, mi. 392 Alaska Hwy , 4500’, 11–14.vii.1959, R. E. Leech (1 ♂, 3 ♀, CNC); same locality, 4700’, 15.vii.1959, R. E. Leech (1 ♂, 1 ♀, CNC); same locality, 4500’, 17–19.vii.1959, R.E. Leech (1 ♂, 5 ♀, CNC). Northwest Territories: Yellowknife , 1.vi.1953, J.G. Chillcott (1 ♀, CNC). Saskatchewan: Saskatoon , 27.v.1925, N.J. Atkinson (1 ♀, CNC); same locality, 17.v.1926, K.M. King (1 ♀, CNC); same locality, 25.v.1926, K.M. King (1 ♀, CNC); same locality, 3.vi.1926, K.M. King (2 ♂, 8 ♀, CNC); same locality, 21.vi.1926, K.M. King (1 ♀, CNC). Yukon: Ross River, 132°30′ 61°56′, 3000’, 21.vi.1960, J.E.H. Martin (2 ♂, CNC). USA. Alaska: Fairbanks , 14.vi.1952, W.R. Mason (1 ♀, CNC). California: Nevada Co., Prosser Creek @ Hwy 89, 39°23′50.2″N 120°11′13.9″W, 14.vii.2012, S.E. Brooks (1 ♀, CNC). EURASIA. RUSSIA. Altay Republic: 10 ♂, 14 ♀, Kosh-Agach distr. , 20 km W Belir, Dzhelo River , 2100 m, 49°57′N, 87°52′E, 24–25.vi.2014, leg. I. Shamshev (10 ♂, 14 ♀, ZISP) .

Diagnosis. A small robust species (body 1.5–2 mm), distinguished by the following combination of characters: proepisternum tomentose; legs almost uniformly brown, only knees yellowish; wings faintly brownish in cells r 1 and r 2+3, halter with dark knob.

Redescription. Male (described for first time, Fig. 12A ). Length: body 1.6–1.8 mm, wing 1.6–1.7 mm. Head black. Occiput faintly pruinose above neck and narrowly behind mouth-opening, otherwise shiny; 2 inclinate, long, black vertical setae; some black setae around neck, finer pale setae near mouth-opening and row of pale minute postoculars. Vertex and ocellar triangle shiny; ocellar setae short, lateroclinate. Frons shiny, slightly broadened towards ocellar triangle; above antennae nearly 3.0 times as broad as anterior ocellus. Antenna brown. Postpedicel subglobular; stylus subapical, short, nearly 1.5 times as long as pedicel and postpedicel combined. Proboscis brown. Palpus unmodified, elongate oval, short (shorter than proboscis), brown; clothed in scattered yellowish to yellowish brown setulae, with 1 short (nearly as long as palpus) black subapical seta.

Thorax black, prothoracic sclerites (except postpronotal lobe) entirely densely whitish grey tomentose, scutellum, notopleural depression (except upper anterior corner), meron and postnotum faintly greyish tomentose. Postpronotal lobe slightly elongate oval, lacking conspicuous setae, with scattered minute setulae. Mesonotum with 2 black notopleurals (anterior seta somewhat shorter), 1 moderately long postalar and 4 scutellars (cruciate apical pair nearly as long as posterior notopleural seta, laterals shorter); some minute setulae present behind postpronotal lobe and on notopleural depression anteriorly; acrostichals lacking; dorsocentrals uniserial, scattered, mostly minute, 1 prescutellar pair nearly as long as postalar seta.

Legs robust, almost uniformly brown, only knees of fore and mid legs usually yellowish. Fore coxa clothed in numerous pale setae; fore coxa anteriorly, mid and hind coxae laterally whitish grey tomentose. Fore femur strongly thickened, whitish pubescent ventrally, with short anteroventral and posteroventral pale setulae becoming longer closer to base. Fore tibia spindle-shaped, with unmodified setation. Mid femur somewhat narrower than fore femur, without basal excavation; rows of short anteroventral and posteroventral black spinule-like setae, bearing 2 long yellowish setae near base. Mid tibia lacking apical projection, with slightly prominent ventral spinule-like setulae. Hind femur nearly as wide as mid femur, unmodified, lacking prominent setae.

Wing normally developed, rounded at apex, with unmodified venation; membrane faintly brownish near meeting point of costa with R 1, in cells r 1 and r 2+3 (usually slightly darker along R 2+3 and R 4+5) and along middle portion of M 4. One very short basal costal seta. Vein R 2+3 straight. Veins R 4+5 and M 1+2 parallel throughout. Vein M 4 distinct throughout. Crossveins r-m and bm-m broadly separated. Cell r 1 nearly as broad as cells r 2+3 and r 4+5. Calypter brownish, with scattered fringe. Halter with brown knob and brownish yellow stem.

Abdomen brownish, largely shiny (except lateral margins and entire segments 6–8), with scattered dark setulae.

Hypopygium ( Fig. 12B–D ) large, concolorous with abdominal pregenital segments. Right epandrial lamella ( Fig. 12C ) rather subglobular, somewhat produced and bearing numerous long setae ventrally. Right surstylus not separated from epandrial lamella, short and subglobular (lateral view), with short setae. Left epandrial lamella ( Fig. 12D ) small, with short setae apically. Left surstylus barely separated from epandrial lamella; rather large, elongate oval, slightly broadly produced ventrally; numerous long setae on produced ventral portion. Cerci ( Fig. 12B ) separated, with unmodified, moderately long to short setae; right cercus very short, subglobular (dorsal view); left cercus rather subrectangular, narrow, much longer than right cercus. Hypoproct with apical portion rounded, not produced beyond apex of left cercus.

Female. Similar to male. Cercus brownish, long, slender, with minute setulae.

Remarks. Tachydromia monacha is a member of a complex of the species allied in the Palaearctic to T. halterata (Collin) ( T. connexa group sensu Chvála). Only two species of this complex have entirely black legs, including T. monacha and T. israeliensis Shamshev & Grootaert (known only from Israel) ( Shamshev & Grootaert 2009). Tachydromia monacha is very similar to T. halterata and especially to T. magadanica . Main differences between these species are indicated in the key.

Distribution. Holarctic. North America: Canada (Alberta, British Columbia, Northwest Territories, Saskatchewan, Yukon), USA (Alaska); Eurasia (first record): Russia (Altay Republic).

Figures

FIGURE12.Tachydromiamonacha Melander,male (Canada,BritishColumbia;CNC).A.Habitus,lateralview.B.Hypopygium, dorsal view. C. Right epandrial lamella and right surstylus, lateral view. D. Left epandrial lamella and left surstylus, lateral view. Abbreviations: cerc—cercus; lft sur—left surstylus; rt sur—right surstylus. B–D: scale bar is 0.1 mm.