Diamesa lupus Willassen 1985

Diamesa lupus Willassen

(Figs. 16–18)

Diamesa lupus Willassen, 1986: 127; Ashe & O’Connor 2009: 281.

Material examined. U.S.A.: Paratype, adult male, Alaska, Glacier Bay, Wolf Creek, 12.VIII.1979, leg. A.M. Milner, Z. M. Bergen Type N 83; 1 adult male, Alaska, Juneau, Hebert River, about 0.5 mi. downstream of glacier, 20.II.2010, 58.532 N, 134.692 E, leg. J. Hudson; 2 adult males, the same data, except 28.X.2012, leg. J. Hudson; 1 adult male, Michigan, Washtenaw Co., Huron River, Hudson Mills Metro Park, 23.III.2013, leg. P. Hudson.

Description

Adult male (n = 4, except when otherwise stated).

Coloration. Dark brown to black. Wings greyish, with brownish veins.

Head (Fig. 18). Eyes hairy, reniform. Temporal setae including 1–2 frontals, 6 verticals and 9 postorbitals. Clypeus with 2–4 setae. Antenna with 8 flagellomeres and reduced plume of setae; terminal flagellomere with 3–4 basal setae, 60–64 μm long and 2 subapical setae, 16–20 μm long. Length of 1–8 flagellomeres (μm): 84–92, 28–48, 32–38, 28–32, 30–32, 24–32, 40–48, 104–116; AR 0.35–0.39. Palpomere length (μm): 28–40, 48–60, 88–96, 80–88, 96–128. Palpomere 3 in distal part with sensilla capitata with diameter 16–20 μm. Head width/palpal length 1.15–1.21. Antennal length/palpal length 1.04–1.14.

Thorax. Antepronotum with 7–10 ventrolateral setae. Dorsocentrals 5–9, prealars 2–3, scutellars 10–19, epimeron II with 0–1 seta.

Wing. Length 2.65–2.76 mm, width 0.90–0.92 mm. Costal extension absent. Anal lobe rounded, sometimes slightly reduced. Squama with 13–19 setae. R and R 1 with 10–13 setae, R 4+5 with 4–6. R 2+3 visible only in basal part. RM/MCu 2.4–2.6.

Legs. Spur of front tibia 32–36 µm long. Spurs of mid tibia 36–40 µm long. Spurs of hind tibia 60–72 µm and 36 µm long. Hind tibial comb with 17–21 setae. Length (μm) and proportions of leg segments as in Table 6.

Hypopygium (Figs. 16–17). Laterosternites very extended beyond posterior margin of tergite IX, divided into two parts by curved apodeme, ventro-caudal part more weakly sclerotized than the rest of hypopygium, with weak setae and microtrichia. Tergite IX with posterior margin from gently rounded to partly straight, tergite bands Yshaped, anal point reduced. Transverse sternapodeme (TSA) triangular, usually with a spire-shaped apex (Figs. 16–17), 100–112 µm high, 180–188 µm wide at the base; TSA height/TSA width 0.56–0.60. Gonocoxite 280–292 µm long; superior volsella with dense microtrichia, without setae. Gonostylus 180–200 µm long, curved, narrowed about 0.5 from base, with 3–5 apical teeth and megaseta which in form of wide terminal spine, 8–10 μm long; HR 1.46–1.62.

Pupa and larva unknown.

Distribution. Rare Nearctic species, known only from U.S.A. (Alaska ans Michigan) and Canada (Alberta) (Ashe & O’Connor 2009).