Tachydromia incompleta (Becker)

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 : 170-172

Tachydromia incompleta (Becker)

( Fig. 9 )

Tachista incompleta Becker, 1900: 33 (♀), Pl. 2, fig. 1. Type locality: Russia, “Insel Nikander” [= Nikandrovskie Islands , mouth of Yenisei River, Krasnoyarskiy Territory].

Tachydromia anderssoni Chvála, 1970: 494 , figs 73–75. Type locality: Sweden, Karesundo [= Karesuando, Torne lappmark].

Tachydromia incompleta : Chvála, 1975: 242, figs 574–576, 762 (synonymy of T. anderssoni ).

Notes on type series. The holotype of T. incompleta is deposited in Helsinki (MZH) and was examined by I.S. in 2019. In addition, the holotype and two paratypes of T. anderssoni were examined in Lund (MZLU) and Moscow (ZMMU), respectively.

Material examined. NORTH AMERICA. CANADA. Alberta: Dunvegan, N side Peace River , 11– 25.vii.1995, S. Boucher (1 ♀, CNC) ; same locality, pan trap in grass, 19–28.vi.1995, S. Boucher (1 ♀, CNC) . EURASIA. RUSSIA. Altay Republic: middle flow of river Ulandryk , 27.vi.1964, Grunin (1 ♂, ZISP) ; Kosh-Agach distr. , 60 km SSW Kosh-Agach, 2200m, 49°38´N, 88°29´E, 29.vi.2014, leg. I. Shamshev (8 ♂, 9 ♀, ZISP) . Sakha (Yakutia) Republic: Verkhoyansk , shore of river Yana , willow shrub, 12–14.viii.1972, Gorodkov (1 ♂, 3 ♀, ZISP) ; Udachny , 21.vii.1988, Gorodkov (1 ♀, ZISP) ; Ebelyakh, shore of river Anabar, Gorodkov (1 ♀, ZISP) ; left shore of river Yana, near Verkhoyansk , sedge swamp, 23.vii.1974, Nartshuk (1 ♂, ZISP) ; Indigirka River, mouth of River Inyali , 20.vi.1976, V. Kovalev (1 ♀, ZMMU) . SWEDEN: Abisko, Lpl. , 3.viii.1951, J. R. Vockeroth (1 ♀, CNC) ; same locality, 13.viii.1951, J. R. Vockeroth (1 ♂, CNC) .

Recognition. The species is distinguished by the following combination of characters: palpus without black subapical seta; proepisternum shiny. Male: palpus yellow on basal part, blackish brown on apical 1/4 to 1/2; mid tibia with 2 closely set, long subapical setae posteriorly. Female: palpus uniformly pale yellow.

Redescription. The species was fully redescribed and illustrated by Chvála (1970 [as T. anderssoni ], 1975). Only crucial characters are provided herein. Male ( Fig. 9A ). Length: body 2.2–2.6 mm, wing 2.4–2.6 mm. Occiput (including posterior portion of vertex) densely greyish pruinose on about upper half (nearly level of lower margin of neck), shiny on lower half (usually with small spot of pruinosity just behind mouth-opening); 2 short vertical setae. Ocellar triangle shiny; ocellars minute, lateroclinate. Frons shiny.Antenna with scape and pedicel yellow, postpedicel and stylus brown. Palpus nearly as long as proboscis, without excision, narrow (sometimes slightly broadened apically), yellow on basal part, brown to blackish brown on apical 1/4 to 1/2 (colour intensity and size of dark space somewhat varying), covered with scattered pale setae, lacking black subapical seta. Thorax with proepisternum shiny. Legs colour: fore coxa and trochanters of all legs yellow, mid and hind coxae usually mostly yellowish brown, yellow at apex (sometimes entirely brown); mid and hind femora largely yellow, brownish subapically and dorsally, hind femur entirely brown; tibiae almost entirely brown, yellow near extreme base; tarsi brownish, mid and hind basitarsi mostly brownish yellow. Mid tibia lacking apical projection, with 2 closely set, long setae posteriorly. Wing normally developed; with two brownish, entirely separated bands (darker on about anterior half of wing). Vein R 2+3 straight, thickened and strongly turned toward costa subapically. Halter with brownish stem and pale yellow knob. Hypopygium black, small, elongate oval; as in T. chelana . Female ( Fig. 9B ). Palpus uniformly pale yellow to whitish. Mid femur with finer setae closer to base; mid tibia lacking subapical setae.

Remarks. Tachydromia incompleta belongs to the T. punctifera group of species sensu Chvála (1975).

Distribution. Holarctic. North America (first record): Canada (Alberta); Eurasia: Finland, Mongolia, Norway, Russia (north of European part, Siberia, Far East), Sweden.

Figures

FIGURE 9. Tachydromia incompleta (Becker), habitus, lateral view (Sweden, Abisco; CNC). A. Male. B. Female.