Chrysotus hubenovi, Kechev & Naglis & Negrobov, 2022

Kechev, M., Naglis, S. & Negrobov, O. P., 2022, A new species Chrysotus hubenovi and new data on the family Dolichopodidae (Diptera) of Bulgaria, Zoosystematica Rossica 31 (1), pp. 27-41 : 29-37

Chrysotus hubenovi sp.nov.

( Figs 2 , 3 )

Holotype. Male , Bulgaria, West Rhodope Mts., Yagodina Vill., Buinovska Reka River, 1100 m, sweep netting, 10.IX.2020, M. Kechev leg.

Paratypes. 1 male, 1 female, with same data as for holotype .

Description. Male. Body length 2.0 mm; wing length 2.3 mm.

Head ( Fig. 2A, B ). Frons shining, dark metallic-green. Occiput black. Face below antennae dark, narrow, one-third as wide as diameter of eye. Lower parts of eyes touching anteriorly. Clypeus black with grey pruinosity. Palp dark, small. Proboscis brownish. Antennae ( Fig. 2A ) positioned above middle of head; scape small, conical, yellow; pedicel twice as long as scape, yellow, with crown of black setulae at apex; postpedicel ovate-triangular, higher than long, black, covered with white hairs ( Fig. 2B ); arista black.

Thorax. Mesonotum metallic-green, dorsal part shining with blue reflection. Two pronotal setae, one posthumeral, one supraalar and one postalar setae; five pairs of strong dorsocentral setae; acrostichals biseriate; scutellum with one pair of strong marginal scutellar setae and one pair of smaller lateral ones.

Wing ( Fig. 2C ) transparent. C ending at wing apex; R 1 ending in basal third. R 2+3 straight. R 3+4 and M parallel, slightly bent anteriorly. Anal lobe small. Lower calypter yellow, with white setae. Halter white.

Legs. Fore leg ( Fig. 2D ): coxa and trochanter black; coxa with black hairs and setae; femur from base to apical two-thirds dark metallic-green, shining, apical third yellow, with black hairs; tibia entirely yellow; first tarsal segment yellow, tarsal segments 2–5 black; length ratio (from tarsomere 5 to femur): 1.0: 1.5: 1.5: 2.0: 4.5: 8.7: 9.0.

Mid leg ( Fig. 2E ): coxa and trochanter black; femur in basal two-thirds dark metallic-green with black setae, apical third yellow, with three anterior setae at apex; tibia yellow with black setae, one strong black anterodorsal seta at base and four apical setae; first tarsal segment mainly yellow, dark et apex; tarsal segments 2–5 black; length ratio (from tarsomere 5 to femur): 0.8: 1.0: 1.4: 1.8: 4.7: 8.2: 8.5.

Hind leg: coxa with one long black lateral seta; femur ( Fig. 2F ) entirely dark metallic-green with black setae; tibia yellow with one dorsal seta at base and one dorsal seta at middle; first tarsal segment yellow from base to middle, black from middle to apex; tarsal segments 2–5 black; length ratio (from tarsomere 5 to femur): 1.2: 1.0: 1.8: 2.8: 4.2: 13.0: 13.7.

Abdomen. Dark green, shining, covered with black setae.

Hypopygium ( Fig. 3A–D ): epandrium black, semiglobular; lateral epandrial lobe slightly projected, bearing three setae; surstylus with fused lobes, bearing one thick apical spine and two subapical ventral setae; hypandrium short, simple; phallus thick, long, with one broad lateral subapical lobe; cercus elongate-triangular, yellow, covered with long black setae.

Female. Body length 2.5 mm; wing length 2.8 mm.

Similar to male. Scape and pedicel yellow; postpedicel black, covered with white hairs; arista black. Mesonotum dark green, with slight blue reflection at apex. Coxa and trochanter black; femur dark green; tibia yellow; first tarsal segment of all legs yellow at base, black at apex; other tarsal segments black.

Comparison. Up to now, two species of Chrysotus with yellow antennae were known in the Palaearctic, Ch. corniger Negrobov et Maslova, 1995 described from the Primorskiy Territory in the Russian Far East ( Negrobov & Maslova, 1995) and Ch. polleti Olejniček, 1999 described from Bulgaria (Olejniček, 1999). Chrysotus hubenovi sp. nov. is similar to these species in yellow coloration of antenna and can be distinguished from them using the following key:

1. Antenna (scape, pedicel and postpedicel) entirely yellow. Dorsal surface of apical third of mid tibia covered with silvery microtrichia..... Ch. polleti

– Antennal scape and pedicel yellow, postpedicel black. Dorsal surface of mid tibia without silvery microtrichia................................. 2

2. Fore and mid femora from base to apical two-thirds dark metallic-green, with apical third yellow; phallus with one broad lateral subapical lobe ( Fig. 3A, B )............ Ch. hubenovi sp. nov.

– Femora entirely yellow; phallus without lateral subapical lobe ( Fig. 4 )............... Ch. corniger

Etymology. The new species is named after the Bulgarian dipterist Zdravko Hubenov (National Museum of Natural History, Sofia, Bulgaria).

Habitat. The specimens of Ch. hubenovi sp. nov. were collected along the banks of a small mountain river between the beech and coniferous vegetation belts (Electronic supplementary material 1: A). Dominant trees near the river are hornbeam ( Carpinus betulus ), beech ( Fagus sylvatica ), willow ( Salix caprea ), spruce ( Picea abies ) and white pine ( Pinus sylvestris ). Dominant hygrophilous plant on the banks is butterbur ( Petasites hybridus ).

Figures

Fig. 2. Chrysotus hubenovi sp. nov., male. A, head; B, antenna; C, wing; D, fore leg; E, mid leg; F, hind leg. Scale bars: 0.3 mm (B, D–F), 0.5 mm (C). Photos by M. Kechev.

Fig. 3. Chrysotus hubenovi sp. nov., male. A, B, hypopygium, lateral view; C, apex of phallus, lateral view; D, apex of phallus, ventral view. Scale bars: 0.1 mm. Photos and drawings by M. Kechev.

Fig. 4. Chrysotus corniger Negrobov et Maslova, 1995, male. A, hypopygium, lateral view; B, phallus, lateral view (modified from Negrobov & Maslova, 1995). Scale bars: 0.1 mm.