Diamesa japonica Tokunaga

(Figs. 23–27)

Diamesa japonica Tokunaga, 1936: 542; Makarchenko 1981: 110, 1985: 76, 2006: 261, 2021: 440; Ashe & O’Connor 2009: 278.

Diamesa kurobemijikaia Sasa et Okazawa, 1992: 60 .

Material examined. JAPAN: 2 adult males, Honshu, Tochigi Prefecture, Okunikko, Nikko City, Nikko National Park, Toyamazawa River, alt. 1450 m a.s.l., 21. III.1991, leg. R. Ueno . RUSSIA: 23 adult males, Kurile Islands, Kunashir Island, Sernovodsk Village, Tiurino River, 20.IV.1978, leg. E. Makarchenko.

Description

Adult male (n = 14). Total length 3.1–4.2 mm. Wing length 2.76–3.17 mm. Total length/wing length 0.90– 1.40.

Coloration. Head, thorax, legs and hypopygium dark brown; antenna and palpomeres brown; abdomen light brown to dark brown; wing greyish, veins brownish.

Head. Eyes hairy. Temporal setae including 4–12 frontals, 6–15 verticals and 4–8 postorbitals. Clypeus with 2–8 setae. Antenna with 8 flagellomeres and reduced plume of setae (Fig. 23); number and length of these setae on 1–7 flagellomeres respectively: 2–3 (28–40 μm), 1–2 (28–36 μm), 1–2 (26–40 μm), 0, 0, 0, 0; terminal flagellomere in basal part with 5–6 setae, 60–80 μm long and with 2 subapical setae, 40–52 μm long. Flagellomeres 1–8 length (μm): 71–88, 34–38, 25–34, 25–30, 25–34, 25–34, 32–38, 193–218; AR 0.68–0.81. Antennal length/palp length 1.05–1.38. Palpomeres lengths (in μm): 32–40; 52–63; 88–105; 76–105; 105–147. Palpomere 3 in distal part with sensilla capitata with diameter 20–24 μm. Palpomeres 1–5 length/head width 0.80–1.38.

Thorax. Antepronotum with 7–12 ventrolateral setae. Dorsocentrals 6–10, prealars 5–8, scutellars 11–24.

Wing. R and R 1 with 15–25 setae; R 4+5 with 8–12 setae. Costa extension ca 48 μm long. RM length/MCu length 2.0–3.6. Anal lobe well developed, rounded. Squama with 18–25 setae 28–52 μm long. VR 0.96–1.0.

Legs. Spur of front tibia 34–46 μm long; spurs of mid tibia 40–55 μm long; of hind tibia 50–71 μm and 32–50 μm long. Hind tibial comb with 20–22 setae. Lengths and proportions of leg segments as in Table 8.

Hypopygium (Figs. 24–27). Tergite IX with 7–11 setae (from one side), 20–40 μm long and wedge-shaped anal point 63–136 μm long, angled downwards (Fig. 25) and covered in basal 2/3 with numerous microtrichia forward and laterally directed (Figs. 24–25). Laterosternite IX with 9–11 setae, 28–32 μm long. Transverse sternapodeme (TSA) triangular, with a spire-shaped apex (Fig. 27), 124–128 µm high, 190–196 µm wide at the base; TSA height/ TSA width 0.65–0.70. Gonocoxite 350–492 μm long; inferior volsella absent; superior volsella in form of angular tubercle. Gonostylus slightly curved, 220–236 μm long, with numerous, proximally directed strong setae (Figs. 26–27), 44–52 μm long; megaseta 6–8 μm long. HR 1.92–2.23.

Pupa was described by Tokunaga (1936).

Larva unknown.

Distribution. East Palaearctic island species. Known from Japan and Kunashir Island (Kurile Islands).