Leptogaster nikiforovi sp. nov.

Figs 14–23

Diagnosis. (Figs 14–21). Body length 9.0–14.5 (holotype 11.0) mm. 9–14 mystacal macrosetae white (Fig. 15). Postocular setae white, postocular macrosetae black; occipital and lower occipital setae white (Figs 15). Scape and pedicel dark brownish, postpedicel black. Scutellum with few white short apical setae. 1 dorsocentral, 1 notopleural and 1 supra-alar macroseta black (Fig. 14). Fore and mid femora yellow with brownish stripe anteriorly. Hind femur yellow with dark brownish spot on distal part. Fore and mid tibiae yellow with brownish stripe anteriorly. Hind tibia almost entirely dark brownish with yellow base and yellow stripe dorsally (Figs 14, 16). Tergite I with row of black macrosetae at posterior margin. Hypopygium black with long white setae (Figs 18–19).

Description. Male. (Figs 14–21). Body length 9.0–14.5 (holotype 11.0) mm. 9–14. Head black. Face silvery, frons and vertex silvery, sometimes bronze tomentose. 9–14 mystacal macrosetae white, restricted to lower fascial margin and displayed in more than one row, in length reaching apex of proboscis. Palpus black with few white setae. Proboscis black with few white proboscial and white labial setae. Postocular setae white, postocular macrosetae black. Orbital and ocellar setae absent. Occipital and lower occipital setae white. Scape and pedicel dark brownish, postpedicel black. Postpedicel longer than length of scape and pedicel combined. Style longer than half length of postpedicel. Scape and pedicel with yellowish or brownish setae (Fig. 15).

Thorax black. Anepisternum and katepisternum with long white setae anteriorly. Scutellum silvery brownish tomentose, with few white short apical setae. Mesonotal setae: 1 dorsocentral (occasionally absent), 1 notopleural and 1 supra-alar macroseta black (Figs 14). Scutum with bronze tomentum and scarce short black setae. Postpronotal lobe reddish, silvery tomentose. Pleuron silvery tomentose and sometimes with bronze tomentum dorsally.

Wings hyaline, veins brown (Figs 14, 16).

Legs. Fore and hind coxae reddish or brownish, mid coxa dark brownish. Coxae silvery tomentose with few short white setae. Trochanters yellow. Fore and mid femora yellow with brownish stripe anteriorly; with short black and white setae. Hind femur yellow with dark brownish stripes anteriorly and posteriorly, expanding at midlength and retracting subapically, forming a dark brownish spot distally. Fore and mid tibiae yellow with brownish stripe anteriorly; with short white setae and few white macrosetae. Hind tibia almost entirely dark brownish, with yellow base and yellow stripe dorsally. Tibiae with short white setae and few white macrosetae. Fore, mid and hind tarsi dark brownish or black, tarsomeres I yellow and dark brownish apically. Tarsi with white and black setae and macrosetae. Claws and empodium black. (Figs 14–16).

Abdomen. Tergites and sternites black with short white setae, longer on sternites, especially in the last. Tergites with bronze and brownish tomentum dorsally and greyish tomentum laterally. Tergite I with row of black macrosetae at hind margin (Figs 14, 18–19).

Hypopygium black with long white setae, some brownish. Epandrium elongated, relatively narrow, curved at apex. Phallus medium sized and curved in the middle. Ejaculatory apodeme large and rounded (Figs 18–21).

Body length range 9.0–14.5 (holotype 11.0) mm.

Female. Similar to male, but longer in length (Fig. 17).

Material examined. Holotype, ♂: Russi a, Altai Republic, Ulagansk y Distr., 14 km SE Aktash, Chuya Riv., h= 1570 m, [50º13’59’’N 87º45’28.3’’E], 13.VII.2016, V. Sakhvon, ♂ (BSU). Paratypes: same place, 29. VI – 13.VII.2016, V. Sakhvon, 12♂, 11♀ (BSU); same place, 28. VI.2022, V. Sakhvon, 2♂, 2♀ (BSU); 12 km SE Aktash, Chuya Riv., h= 1570 m, [50º13’51.1’’N 87º42’58.9’’E], 4.VII.2016, V. Sakhvon, 3♂, 4♀ (BSU); 24 km NWW Aktash, Chuya Riv., h= 1040 m, [50º21’31.1’’N 87º16’14.8’’E], 30. VI.2016, V. Sakhvon, ♂ (BSU); same place, 28. VI.2022, V. Sakhvon, ♀ (BSU). Kosh-Agachsky Distr., 15 km SE Kurai, Chuya Riv., h= 1600 m, [50º11’9.8’’N 88º7’4’’E], 5.VII.2016, V. Sakhvon, 3♂, 8♀ (BSU); same place, 5.VII.2016, V. Sakhvon, ♂, ♀ (FSC); same place, 5.VII.2016, V. Sakhvon, ♂, ♀ (MSU); same place, 15–16. VI.2022, V. Sakhvon, 5♂, 8♀ (BSU).

Distribution. Russia.

Etymology. The species is named after academician Mikhail Nikiforov, a well-known Belarusian ornithologist.

Habitat. Leptogaster nikiforovi sp. nov. was collected in the Altai Mountains in the vicinity of Aktash to the southeast of the Kurai steppe. Robber flies were found among forbs along the river bank, as well as in steppe areas (Fig. 23).

Remarks. Until recently, the fauna of robber flies of Russia includes six species and two subspecies from Leptogaster Meigen, 1803 (L. cylindrica cylindrica (De Geer, 1776), L. cylindrica hispanica Meigen, 1838, L. fumipennis Loew, 1871, L. guttiventris Zetterstedt, 1842, L. nartshukae Lehr, 1961, L. pubicornis Loew, 1847, L. rutulica Astakhov, 2019 and L. stackelbergi Lehr, 1961) (Lehr, 1988; Astakhov, 2019). The examination of material from Altai Republic enabled to record L. bivittata Lehr, 1975 from Russia for the first time and describe one new species— L. nikiforovi sp. nov. At the same time, only four species have been recorded from Altai Republic: L. cylindrica cylindrica, L. stackelbergi, L. bivittata and L. nikiforovi sp. nov. The males of the new species differ in having mystax with 9–14 macrosetae in contrast of L. stackelbergi and L. bivittata (6–8 mystacal macrosetae in both species). L. nikiforovi sp. nov. can be distinguished from L. cylindrica cylindrica by dark brownish scape and pedicel and black postocular macrosetae (at least pedicel reddish yellow and postocular macrosetae mainly white or yellow in L. cylindrica cylindrica). The most similar subspecies from Russian fauna is L. cylindrica hispanica, but males of the new species can be distinguished from L. cylindrica hispanica by the following diagnostic character states: 9–14 mystacal macrosetae, hind femur yellow with a dark brownish spot on distal part, black sternites, black hypopygium (see key to species).

Also, the male of the new species is very similar to the male of Leptogaster affinis Lehr, 1972 from Mongolia (Lehr, 1972), but differs in having 9–14 mystacal macrosetae (14–18 mystacal macrosetae in L. affinis), hind femur with a dark brownish ring-shaped spot on distal part (hind femur yellow with only black stripes on distal part in L. affinis), by the wing morphology (combined length of R 4 and R 5 longer than the length of R 4+ 5 in Leptogaster nikiforovi sp. nov. while combined length of R 4 and R 5 is equal to the length of R 4+ 5 in L. affinis) and by having the hypandrium with a rounded posterior border (posterior border of hypandrium with a projection in L. affinis).