(Figs 1–30)
Type material. Holotype male, RUSSIA: 1 PL-male, Kamchatka Peninsula, Kol’ River, 8.vi. 2005, T. Travina. Paratypes: 11 males, Primorye Territory, Sikhote-Alin Nature Reserve, Kolumbe River near “Ust’-Prokhodnaya” field station, 9.viii. 2005, O. Zorina; 1 male, Samarga River at about 2.5 km upstream of the mouth of Kuksy Stream, 3.viii. 2006, O. Zorina; 1 male, Lazovskiy Nature Reserve, Perekatnaya River about 500 m of " America " field station, 6–7.vii. 2007, O. Zorina; 1 male, Lazovskiy Nature Reserve, basin of Praymushka River, Kaplanov Stream, 10.vii. 2007, O. Zorina; 1 male, Khabarovsk Territory, basin of Amur River, Khingan River at about 2 km of Obluch’e Village, 25.vi. 2004, T. Arefina-Armitage; 3 males, Pravyy Khingan River, 31.vii. 2003, O. Zorina; 1 male, stream at about 5 km of Briakan Village, 21.vii. 2006, E. Makarchenko; 1 male, Khakubera River, 4– 5.viii. 2005, E. Makarchenko; 2 males, Chernaya River, 29.vi. 2005, T. Tiunova; 1 P-male, 1 PL-male, 8 L, Sushchevskiy Stream, 12.viii. 2004, S. Zolotukhin; 1 male, Amur Territory, basin of Arkhara River, Solokachy, 26.vii. 2003, O. Zorina; 1 РL-female, Zeya River near Sokhatino Village, 19.vii. 2006, T. Tiunova; 1 P-male, same data, 16.vi. 2001, S. Kocharina; 4 males, PL-male, P-female, L, Magadan Territory, Tauy River, 17.vii. 2011, S. Kocharina; 6 males, Sakhalin Island, Uskovka River, 6–7.viii. 2001, V. Teslenko; 10 males, Tym’ River ca. 15 km of Palevo Village, 8.viii. 2001, V. Teslenko; 3 males, Avgustovka River ca. 13 km of Boshnaykovo Village, 23.vii. 2003, E. Makarchenko; 2 males, Orlovka River, 25.vii. 2003, E. Makarchenko; 1 male, Schmidt Peninsula, Sukharnyy Stream, 8–12.viii. 2003, E. Makarchenko; 4 males, lake and stream in the “Three brothers” mountain system, 12.viii. 2003, E. Makarchenko; 1 P-male, 4 P-females, same data, 18.vi. 2005, T. Travina; 5 P-males, 9 Pfemales, same data, 2005 yeaгs, T. Travina; 2 PL-males, Zabaykalsk Territory, Kadalinka River, 10.vi. 2007, N. Saltanova.
Etymology. Named in honour of the Japanese entomologist Professor Masaaki Tokunaga from Kyoto Imperial University.
Diagnostic characters. WL 1.10–1.35; AR 0.57–0.73; anal point with long and narrow apical part; basal part of superior volsella oval form without tubercle. Pupa with narrow and long thoracic horn (width 15–21 µm); tergite IV without posterolateral patches of spines; segment VIII with anal spurs (2–5) of different length. Larva with setae SIII usually simple sometimes bifurcate; AR 1.12–1.41; pedestal with 2–7 apical tubercles; blade of antenna usually not extend far beyond apex of 5 th segment.
Male (n= 15). Total length 2.2–2.7 mm; wing length 1.10–1.35 mm. Total length / wing length 1.61–1.88.
Colouration. Adult males characterize by following pattern of body coloration:
Antenna, thorax, abdomen and legs brown.
Mesonotal stripes and postnotum brown or dark brown, ground colour and scutellum yellowish-brown; abdomen yellowish-brown or brown; legs yellowish with brown distal third of femora, proximal third and distal end of tibiae, ta 1–5 gradually darkened toward ends, tibiae sometimes brown.
Mesonotal stripes and postnotum brown or dark brown, ground colour of thorax and scutellum yellowishbrown or brown; abdomen yellowish with brown longitudinal band; legs yellowish, ta 1–5 gradually darkened toward ends.
Mesonotal stripes and postnotum dark brown, ground colour and scutellum yellowish; abdomen brown; legs yellowish with brown spots on proximal and distal ends of femora and tibiae and proximal end of ta 1.
Head. Frontal tubercles well-developed, 15–18 µm long, 9–12 µm wide. Antenna 640–760 µm long; ultimate flagellomere 240–320 µm long; AR 0.57–0.73. Verticals 6–10. Clypeus with 9–11 setae. Maxillary palp 276–315 µm long; length of palpomeres 2–5 (in µm): 39, 60–69, 69– 87, 108 – 126. Palp length / head width 0.86 – 0.74; antenna length / palp length 2.22–2.32.
Thorax chaetotaxy. Acrostichals 0–4, dorsocentrals 5–8, prealars 1. Scutellum with 2 setae.
Wing 0.36–0.44 mm wide (Fig. 1). Veins R+R 1 with 13–20 setae, R 4 + 5 with 2–6, M 1 + 2 with 12–24, M 3 + 4 with 13– 22, Cu 1 with 0–5, Cu 2 with 0–10 and An with 0–5 setae. Cell r 4 + 5 with about 50 setae, m 1 + 5 with 14–25, m 3 + 4 with 4– 15 setae. VR 1.3–1.6.
Legs. Lengths and proportions of legs as in Table 1.
Hypopygium (Figs 2–5). Laterosternite IX with 1–4 strong setae. Anal point with parallel-sided apical part (length 15–21 µm, width 3 µm) and with broad triangular base (21–36 µm long) bearing 7–15 lateral setae. Gonocoxite 90–120 µm long, with 2–4 setae on inner margin. Superior volsella 24–42 µm long with digitiform apical part (12–15 µm long) bearing 2–4 setae, and with broad basal part bearing 2–5 setae and usually densely covered with microtrichia, sometimes number of microtrichia lower, reduced to 0-5. Median volsella 36–45 µm long with dense clump of subulate setae. Inferior volsella 54–75 µm long, with 15–20 setae. Gonostylus 75–105 µm long, 18–24 µm wide at about middle, apically pointed or rounded. HR 1.03–1.40.
Pupa (n= 9, males). Total length 2.60 mm.
Cephalothorax (Figs 6–8). Cephalic tubercle conical, 24–39 µm long. Spine-like frontal setae 78–90 µm long. Thoracic horn narrow, 168–240 µm long, 15–21 µm wide, covered with sparse small spines. Precorneals 3 (1 st 120– 165 µm long, 2 nd 105–204 µm long, 3 rd 96–210 µm long), antepronotals 2–3 (1 median 165–225 µm long and 1–2 lateral 105 µm long), dorsocentrals 4 (Dc 1 120–195 µm long, Dc 2 180–320 µm long, Dc 3 60–165 µm long, Dc 4 48– 81 µm long); distance between Dc 2 and Dc 3 54–90 µm. Wing sheath usually with a well-developed “nose”, rarely “nose” absent.
Abdomen (Figs 9–20) 1.7–2.6 mm long. Tergites II–VI with a pair of longitudinal bands of shagreen, broadened posterolaterally. Tergite VII without shagreen. Tergite VIII medially with paired patches of very fine shagreen. Hook row 180–225 µm long with 96–115 spines. Pleura of segments IV–V, sometimes VI, with longitudinal areas of shagreen (Figs 11–12). Pedes spurii B weakly developed or absent (Fig. 10). Sternites IV with a pair of longitudinal bands of pale spines laterally (Fig. 14), rarely sternite V with a pair of lateral bands. Lateral margin of segment VIII with 2–5 strong anal spurs different in length (Figs 15–20). Segments II–IV with weak L seta, V with 3 LS, VI–VII with 4 LS, VIII with 2 LS setae. Anal lobe with 8–19 taeniate setae.
Fourth instar larva (n= 8). Colouration. Green (in formaldehyde).
Head. Setae SIII usually simple sometimes bifurcate (Figs 21–22). Antenna 96–123 µm long (Fig. 23), length of segments (in µm): 51 –72, 15–18, 9, 12 –15, 9. AR 1.12–1.41. Pedestal with 2–7 apical projections (Fig. 24). Basal segment with ring organ at base and single 27–30 µm long seta. Blade 45–54 µm long, usually not extend far beyond apex of antenna, accessory seta 9–12 µm long. Lauterborn organ 30 µm long, not extend beyond antennal apex. Style 9 µm long. Seta SI comb-like 21–24 µm long (Fig. 25), SII 30–36 µm long. Premandible 45–63 µm long, with 5 teeth (Fig. 26). Mandible 66–102 µm long, 45–57 µm wide; seta subdentalis 45–57 µm long; mola with 1 spine; dorsal teeth, apical and 2 inner teeth brownish (Fig. 27). Maxillary palp 12–24 µm long. Mentum 60– 75 µm long, median tooth yellowish, 6 th pair of lateral teeth brownish (Figs 28–29). Ventromental plate 48–60 µm wide, 27–33 µm high; distance between ventromental plates 24 µm.
Body. Posterior parapod with 16 yellow simple claws. Anal tubules conical, upper pair 48–63 µm long, bottom pair 23–27 µm long. Procercus 45 µm long, with 8 simple or branched anal setae, and 1–2 dark brown spines (Fig. 30).
Remarks. The male of a new species is very similar to C. brevicosta (Edwards) in the shape of the hypopygium, but can be separated by a smaller size of the wing (WL 1.0– 1.35) and a lower value of the index of the antenna (AR 0.57–0.73), a long and parallel-sided apical part of the anal point. The male of C. brevicosta has wing length 1.5 –2.0 mm, AR 1.0– 1.26, short and conical apical part of the anal point. The male of C. tokunagai sp. n. closely resembles that described by Lindeberg (unpublished data) as C. arcticola, but C. tokunagai has gonostylus widest at mid length, while C. arcticola has gonostylus widest in the apical third. The new species is also similar to C. brevicosta in the pupal stage and can be separated by the presence of a slender and long thoracic horn and by the absence of posterolateral patches of spines on tergite IV. The larva also is close to C. brevicosta, but can be easily separated by the presence of 2–7 apical tubercles on pedestal of antenna, and the blade of antenna usually does not extend far beyond apex of 5 th segment.
Distribution and ecology. Constempellina tokunagai sp. n. was collected in the Primorye, Khabarovsk, Amur, Magadan and Zabaykalsk Territories, Sakhalin Island and Kamchatka Peninsula in the Russian Far East. Probably this species is widely spread in China and Japan. Constempellina tokunagai sp. n. has been recorded from many springs, streams and rivers. Larvae construct cases from sand.