Tachydromia aemula (Loew)

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 : 153-155

Tachydromia aemula (Loew)

( Fig. 1 )

Tachista aemula Loew, 1864a: 16 , 22 (♀). Type locality: Czech Republic, “Karlsbrünn” [= Karlova Studánka].

Tachydromia aemula : Chvála, 1970: 455, figs 32–34; Chvála, 1975: 239, figs 564–566, 760.

Material examined: CANADA. Ontario: Eugenia Falls (44.18.8N, 80.36.5W), sweep path in forest, 27.vi.2007, T. A. Wheeler (1 ♀, LEM) ; Newtonville , 26.ix.1983, J. R. Vockeroth (1 ♂, CNC) ; 7 mi. E of Griffith , 4.vii.1990, B.E. Cooper (1 ♂, 1 ♀, CNC) ; Ottawa , swept over bare path Acer wood, 27.vi.1991, J. R. Vockeroth (1 ♂, CNC) ; Ottawa, damp second growth Acer - Betula wood, 20.viii.2000, J. R. Vockeroth (1 ♂, CNC) ; Ottawa, Stony Swamp (45.18.2N, 75.50.2W), sweep path in open forest, 14.vi.2007, T. A. Wheeler (1 ♀, LEM) ; Lake Simcoe , Sibbald Point Prov. Pk., swp humid forest along stream, 01.vii.2002, S.E. Brooks (1 ♀, LEM) . Quebec: 5 km N of Old Chelsea , 23.vi.1987, A. Borkent & B. Bissett, CD878 (1 ♂, CNC) ; Terrasse-Vaudreuil Molson Nature Reserve (45.23.57N, 73.58.81W), sweep path in forest, 01.vii.1999, T. A. Wheeler (1 ♂, LEM) ; Hudson, Park Lévy Macdonald (45.27N, 79.09W), sweep near stream, 15.vi.2001, S.E. Brooks (1 ♂, 1 ♀, LEM) ; Hudson, Park Lévy Macdonald (45.27N, 79.09W), sweep near stream, 26.vi.2001, S.E. Brooks (1 ♂, 1 ♀, LEM) ; 1.2 km W Camperdown nr. Reasemarsh , swp. beach & shoreline marsh, 01.vii.2001, S.E. Brooks & C. Chenard (2 ♀, LEM) ; Rigaud, Park Lévy Macdonald (45.27N, 79.09W), swp, 01.vii.2002, S.E. Brooks (1 ♀, LEM) . USA. New York: Tompkins Co., Salmoa Ck. , 16.vi.1981, D.J. Bickel (1 ♂, CNC) .

Diagnosis. The species is distinguished by the following combination of characters: proepisternum tomentose; fore femur with rows of black, anteroventral and posteroventral spinule-like setae on about apical 1/2–2/3; legs mostly yellow, hind femur on apical 1/2–3/4 and all tibiae (except extreme base) brown; wings shortened, with entirely separated brown bands.

Redescription. The species was fully redescribed and illustrated by Chvála (1970, 1975). Only crucial characters are provided herein. Male ( Fig. 1 ). Body length 1.6–2.5 mm. Occiput almost entirely shiny, only with spot of faint greyish pruinosity just above neck; vertex, ocellar triangle and frons shiny. Antenna with scape and pedicel yellow, postpedicel and stylus brown. Palpus unmodified, brown, slender, nearly as long as proboscis, clothed in numerous adpressed silvery setae, bearing 1 black, short preapical seta. Thorax with prothoracic sclerites (except postpronotal lobe) densely whitish grey tomentose. Legs mostly yellow; mid and hind coxae near base (in darker specimens entirely), fore and mid femora near apex dorsally brownish; hind femur on apical 1/2–3/4 and all tibiae (except extreme base) brown; tarsomeres 1–3 apically (less distinct on fore tarsus), tarsomeres 4–5 entirely brownish. Fore femur with rows of black, anteroventral and posteroventral spinule-like setae on about apical 1/2–2/3 becoming thinner and paler near base. Mid femur unmodified; similar ventral vestiture to fore femur, posteroventral spinules somewhat longer. Mid tibia with weakly prominent apicoventral projection. Wing usually shortened but length and shape variable; brownish bands entirely separated. Halter with brownish stem and pale yellow knob. Hypopygium blackish brown, small, elongate oval ( Chvála 1970, fig. 34). Female. Mid tibia lacking apical projection. Otherwise as in male.

Remarks. Tachydromia aemula is a very common European species. In North America, T. aemula is locally recorded in eastern part only. It is possible that this species was introduced to the continent; e.g., with soil commonly used in the past as ship ballast or with some fragments of decaying wood.

The photo of the male habitus of this species was also published by Sinclair et al. (2023: 148, fig. B), as Tachydromia sp.

Distribution. Holarctic. North America (first record): Canada (Ontario, Quebec), USA (New York). Eurasia: Austria, Belgium, Czech Republic, Denmark, England, Estonia, Finland, France, Georgia, Germany, Hungary, Ireland, Norway, Poland, Russia (European part), Slovakia, Slovenia, Sweden, Switzerland, the Netherlands, Ukraine.

Figures

FIGURE 1. Tachydromia aemula (Loew). Male habitus, lateral view (Canada, Quebec; CNC).