Diamesa hyperborea Holmgren, 1869

Diamesa hyperborea Holmgren View in CoL

( Figs 3 View FIGURES 1–7 , 11 View FIGURES 8–14 , 25–26 View FIGURES 23–26 )

Diamesa hyperborea Holmgren, 1869: 48 View in CoL ; Oliver 1962: 6; Halvorsen et al. 1982: 117; Langton & Visser 2003: 24; Ashe & O’Connor 2009: 277; Stur & Ekrem 2020: 18.

Adiamesa ursus Kieffer, 1918: 104 View in CoL ; Kieffer in Kieffer & Thienemann 1919: 42.

Diamesa ursus ( Kieffer, 1918) Saether 1968: 458 View in CoL ; Serra-Tosio 1971: 227.

Material examined. 1 adult male, NORWAY: Finse , near Blåisen. Flying over small rocky stream, 13.VIII.1980, leg. E. Willassen.

Description

Adult male (n = 1). Total length 4.2 mm. Total length/wing length 1.1.

Coloration. Dark brown to brown. Legs brown. Wings grayish, venation brownish.

Head. Eyes hairy, reniform. Temporal setae including 3–4 preoculars, 14 verticals, 6–8 postorbitals. Clypeus with 14 setae. Antenna with 13 flagellomeres and reduced plume of setae ( Fig. 3 View FIGURES 1–7 ); flagellomeres with 1–4 setae, maximal length of which 108 µm; terminal flagellomere with 1 seta, 92 μm long in basal part and with 1 subapical setae, 48 μm long. Length of 1–13 flagellomeres (μm): 100, 48, 52, 48, 48, 44, 40, 44, 48, 40, 60, 36, 192; AR 0.36.

Palpomere length (μm): 68, 108, 164, 132, 168. Palpomere 3 in distal part with sensilla capitata with diameter 24 μm. Head width/palpal length 1.05. Antennal length/palpal length 1.25.

Thorax. Antepronotum with 8 ventrolateral setae. Dorsocentrals 17, prealars 12. Scutellum with 20 setae.

Wing ( Fig. 11 View FIGURES 8–14 ). Length 3.76 mm, width 1.04 mm. Anal lobe rounded-angular. Squama with 43 setae, 44–80 μm long, in 2 rows. R and R 1 with 33 setae, R 4+5 with 20 setae. RM/MCu 2.6–3.0.

Legs. Spur of front tibia 60 µm long. Spurs of mid tibia 64 and 56 µm long. Spurs of hind tibia 100 and 56 µm long. Hind tibial comb with 17–18 setae. Length (μm) and proportions of leg segments are as in Table 5.

Hypopygium ( Figs 25–26 View FIGURES 23–26 ). Tergite IX with 18 setae from one side and anal point, 192 µm long. Laterosternite IX with 12–13 setae. Transverse sternapodeme 184 μm long and 52 μm width. Gonocoxite 426 µm long; inferior volsella 316 µm long, wider at the base, gradually narrowing towards apex, with short setae along inner edge. Basimedial setal cluster with 4–5 setae, 40–44 µm long ( Fig. 25 View FIGURES 23–26 ). Gonostylus 336 µm long, slightly curved, in basal third it is widened, along the inner edge with a small angular protrusion, distal thirds are narrow ( Fig. 26 View FIGURES 23–26 ). HR 1.27.

Pupa. Described by Serra-Tosio 1971 and Langton & Visser 2003.

Larva. Described by Stur & Ekrem 2020.

Distribution. Palaearctic species, known from Bear Island, Faroe Island, Finland, Iceland and Norway ( Ashe & O’Connor 2009, Stur & Ekrem 2020).