Macrostomus argyrotarsis ( Bezzi, 1909 )

Rafael, José Albertino & Marques, Dayse Willkenia Almeida, 2019, Five new species of Macrostomus Wiedemann and a checklist of Empididae (s. str.) (Diptera) from Bolivia, Zootaxa 4567 (2), pp. 251-275 : 253-254

Macrostomus argyrotarsis ( Bezzi, 1909)

( Figs 2 A–C).

Rhamphomyia argyrotarsis Bezzi, 1909: 324 (holotype ♀). Melander, 1928: 186; Collin, 1933: 211 (cit).

Macrostomus argyrotarsis: Smith, 1961: 53 ; 1967: 30 (cat.); Rafael & Cumming, 2004: 446.

Diagnosis. Females of this species are slender, shiny, thorax and legs mainly yellow; postcranium with only a pair of occipital setae behind inner vertical seta; legs without pennate setae; hind tarsomere 1 whitish to silvery, elongate. Wing widely brown infuscate mainly in costal and apical margins, base narrowed and anal lobe very narrow. Tergites 1 and 2 reddish-brown, shiny.

Redescription. Holotype female. Body length from original description: “ 4.5 mm ”; wing length 5.0 mm. Head longer than higher. Inferior facets slightly larger than superior ones. Frons shiny brown to black, slightly wider than anterior ocellus width. One pair of proclinate ocellar setae. Face parallel sided, slightly narrower than frons. Postcranium wide, shinning brown to black, entirely slightly gray pruinose. Inner vertical seta stouter than outer vertical seta, latter subequal in length to uniseriate postocular row of setae; only 1 pair of occipital setae behind inner vertical seta. Antenna brown with pedicel dark yellow. Proboscis yellow. Thorax shiny yellow to brown, darker medially on scutum and mediotergite; scutellum concolorous with scutum; mesopleuron yellow pruinose. Thoracic chaetotaxy: 2–3 antepronotals weak; 1 postpronotal stout, 1 weak; 4 dorsocentrals; 1 presutural supraalar; 0 postsutural supra-alar; 1 postalar; 2 small proepisternals; 1 notopleural; 2 pairs of scutellars, inner pair stouter, convergent; 4 laterotergitals with two anterior setae stouter. Legs shiny yellow, except apex of hind femur, entire hind tibia brown to black; hind tarsomere 1 whitish to silvery. Hind femur slightly clavate. Hind tarsomere 1 as long as remaining tarsomeres combined. Legs longer setae: hind tibia with 2–3 longer dorsal setae at distal fifth. Wing ( Fig. 2A ) widely brown infuscated mainly in costal and apical margins; pterostigma inconspicuous; veins M 1 and M 2 somewhat indistinct distally; vein CuA+CuP evanescent; anal lobe very narrow. Halter dark brown. Abdomen lost beyond tergite 3. Originally described as “tergites 1–2 and respective sternites yellow, remaining with blue/black reflection; postabdomen peculiar, black, with black setae, wider at base and with apical lamellae dark, narrow”.

Male. Unknown.

Geographical records. Bolivia (La Paz); Peru (Madre de Dios), new record.

Type material examined. HOLOTYPE ♀: “ BOLIVIA [La Paz], San Carlos, Mapiri , i. 1903, 800 m” (SMTD).

Additional material. PERU: Madre de Dios, Mazuko , 13°02′51.1″S– 70°20′45.9″W, 382 m, 18.viii.2012, sweep, J.A. Rafael, R.R. Cavichioli, D.M. Takiya (1♀, MUSM).

Holotype condition. Distal half of postpedicel lost; right wing mounted on microslide; abdomen lost beyond tergite 3.

Variation. One female from Peru ( Fig. 2C ) with mesonotum darker, brown; hind leg ( Fig. 2B ) with 2 longer posterodorsal and 1 anterodorsal setae at distal third and tarsomeres 1–4 whitish to silvery, tarsomere 5 brown; wing with last section of vein M 4 longer than in holotype ( Figs 2C and 2A , respectively) and tergites 1–2 reddish brown, without blue reflection.

Figures

FIGURE 2. Macrostomus argyrotarsis (Bezzi, 1909). A. Wing, holotype ♀; B. Left leg, posterior view, peruvian specimen; C. Peruvian specimen pinned, lateral view. Scale bars, figures A–C = 1 mm.