Robackia lukini, Orel, 2018

Orel, Oksana V., 2018, New species of the non-biting midges of Tribe Chironomini (Dptera, Chironomidae) from the Bolshekhekhtsyrsky Reserve (Russia, Khabarovsk Territory), Zootaxa 4461 (2), pp. 269-276 : 273-276

Robackia lukini sp.n.

( Figs 6–10 , 20–23)

Type material. Holotype: 1 male, Russia, Khabarovsk Territory, Bolshekhekhtsyrsky Nature Reserve, Amurskaya Channel, Sosninsky Stream , 7.VIII.2008, leg. N.M. Yavorskaya. Paratypes : 1 male, some data as holotype; 2 males, some data as holotypes, Bykov Stream , 15.VII.2007, leg. N.M. Yavorskaya.

Derivatio nominis. The new species is named in honor of Alexander Lukin, the gamekeeper of the Bolshekhekhtsyrsky Nature Reserve, which provided a great help in collecting the material.

Diagnostic characters. The species can be separated from other species of genus Robackia by the following combination of features: superior volsella 95–105 µm long, with 2 preapical setae and slightly widened membranous apex; inferior volsella elongated triangular form and densely covered with microtrichia; gonostylus knife-like, with slightly concave inner margin and protrusion in the proximal third.

Description. Adult males (n=4). Total length 4.6–4.8 mm. Wing length 1.92–1.95 mm. Total length/wing length 2.36–2.50.

Coloration. Flagellomere dark brown, basal segment brownish yellow; ground color of thorax and scutellum yellowish; mesonotal stripes yellowish brown; postnotum and abdomen brown; fore legs brown, sometimes median part of fe, preapical part of ti and proximal part of ta1 yellowish; middle and hind legs yellowish, ta1–5 gradually darken towards the end.

Head. Head width 632 µm. Frontal tubercles absent. Antenna 1218–1323 µm long. Ultimate flagellomere 840– 945 µm long. AR 2.20–2.75. Verticals 12–20. Clypeus with 12–17 setae. Maxillary palp 632–704 µm long, lengths of last 4 palpomeres (in µm): 64; 168–192; 152–160; 248–288. HW/PL 0.96–1.00; Al/Pl 1.93–2.02.

Thorax. Antepronotals 1–4, acrostichals 10–17, dorsocentrals 8–13, prealars 4–5, supraalars 1. Scutellum with 11–12 setae.

Wing. Width 0.5–0.6 mm. Veins R with 4–6, R1 without setae, R4+5 with 1–2 setae. Squama with 12–16 setae; brachiolum with 2–3 setae. VR 1.09–1.12.

Legs. Spurs of middle tibia 27–31 µm, of hind tibia 27–34 µm long. Lengths and proportions of legs as in

Table 4.

Hypopygium ( Figs 6–10 , 20–23). Tergite IX without median setae. Laterosternite IX with 2–4 setae. Anal point 54–68 µm long, 17–24 µm wide, expanded in the apical 1/3, with 12–15 short dorso-lateral setae, sometimes they are also located at the base of the anal point; the projections at the base of the anal point are covered with long microtrichia and bear 3–4 setae. Gonocoxite 102–136 µm long, with 4–6 inner setae. Transverse sternapodeme 51– 68 µm long. Phallapodeme 102–119 µm long. Superior volsella length 95–105 µm, with 2 preapical setae (length 24–34 µm), located at a distance of 7–17 µm from each other, microtrichia absent; the membranous apex is slightly widened. Inferior volsella in the form of an elongated triangular lobe densely covered with microtrichia. Gonostylus knife-like, 211–228 µm long and 71–75 µm wide; the inner margin is slightly concave and has a protrusion in the proximal third, with 1 apical seta and 6 inner setae. HR 0.48–0.65.

Female, pupa and larva unknown.

Remarks. The new species is very different from all known species of the genus Robackia Saether, 1977 by the original structure of hypopygium, namely, by the presence of a membrane-like apical lobe on the superior volsella, by the triangular shape of the inferior volsella and the knife-shaped form of the gonostylus.

Distribution. Known only from the typical habitat—Bolshekhekhtsirsky Nature Reserve (Khabarovsk Territory).

Figures

FIGURES 6–10. Details of hypopygium structure of the male of Robackia lukini sp.n. 6—dorsal view of hypopygium; 7, 8— posterior margin of tergite IX and anal point in dorsal view; 9, 10—superior and inferior volsellae in dorsal view. Scale bars 50 µm.