(Figs. 4–17)
Material. Holotype: adult male, Russian Far East, Jewish Autonomous Region, Obluchie District, Fedotkin Spring of Bidzhan River basin (Amur River basin), N 48 º 38 ' 409 '', E 131 º 37 ' 217 '', 27.III. 2013, leg. E. Makarchenko. Paratypes: 3 males, the same data as holotype except 10–12.IV. 2012, leg. E. Makarchenko; 2 males, 8 larvae, the same data as holotype except 5–6.IV. 2014, leg. E. Makarchenko; 3 males, the same data as holotype except Lopatinskyi Spring, N 48 º 37 ' 810 '', E 131 º 39 ' 114 '', 7.IV. 2014, leg. E. Makarchenko; 2 males, Kamchatka Peninsula, Ozernaya River, 9.VI. 1998, leg. T. Travina; 1 mature pupa, 7 pupae, 1 pupal exuviae, 3 larvae, 1 larval skin from pupa, the same region, Plotnikova River, 24–26.IV. 2004, leg. T. Travina; 1 larva, Magadan Region, Ol’sky District, Uglikan River (Ola River Basin), 7.IV. 2013, E. Khamenkova; 3 mature pupae, the same region, Ola River, 12–13.V. 2013, E. Khamenkova; 1 larva, the same place, 8.VII. 2013, E. Khamenkova.
Adult male (n= 4)
Total length 2.75–4.15 mm. Wing length 2.32–2.74 mm. Total length/wing length 1.2–1.5.
Head. Temporal setae 9–13, including 5–9 verticals and 4 postorbitals. Clypeus with 8–10 setae. Antenna with 13 flagellomeres and well developed plume; AR 1.46–1.85. Palp with 5 palpomeres, length of 4 distal palpomeres (in µm): 48 –64, 88–112, 56– 112, 172 – 200.
Thorax. Dark brown. Antepronotum without lateral setae. Dc 6–7, Pa 3–4, scutellum without setae.
Wing. R and R 1 with 7–8 setae, R 4 + 5 with 0–1 setae subapically. R 4 + 5 ending distal of apex M 3 + 4. Costa extension 12–80 µm. Anal lobe well developed, rounded. Squama with 14–19 setae.
Legs. Spur of fore tibia 52–60 µm long. Spurs of mid tibia 24–28 µm and 20 µm long. Spurs of hind tibia 60 µm and 20–24 µm long. Hind tibial comb with 11–13 setae. Fore leg without pseudospurs on ta 1; mid and hind legs with 2 apical pseudospurs on ta 1 and ta 2; sometimes hind legs with 1 apical spur on ta 2. Mid leg on ta 1 in basal part with 0–8 sensilla chaetica. Lengths and proportions of leg segments as in Table 2.
Hypopygium (Figs. 4 –12). Tergite IX and anal point with 12–17 setae. Anal point nearly parallel-sided, 28–36 µm long and 10–12 µm wide near apex. Laterosternite IX with 5–8 setae on each side. Transverse sternapodeme 100–112 µm long, with sharply triangular oral projections. Virga 8–16 µm long, like comb, consisted of 5–7 short setae. Gonocoxite 200–240 µm long; inferior volsella with roundish naked dorsal part and roundish ventral part placed below its dorsal part, covered by microtrichia and several setae (Figs. 7, 10). Gonostylus 96–100 µm long, with well developed high preapical crista dorsalis (Fig. 6); megaseta 12 µm long.
Pupa (n= 4). Total length 3.50–4.45 mm. Colouration brown. Exuviae brownish, with darker lateral parts of tergites VI–IX.
Cephalothorax. Frontal apotome without tubercles and frontal setae. Thoracic horn absent but present pore and 3 precorneals (length in µm): Pc 1 108–128, Pc 2 60–68, Pc 3 28–32. Distance between Pc 1 and Pc 2 40–88 µm; distance between Pc 2 and Pc 3 12–32 µm. Antepronotum without setae. Dorsal surface of mesonotum rugose, in the middle part with 1–2 rows of pointed tubercles. Three dorsocentrals weak and hair-like; distance between Dc 1 and Dc 2 180–200 µm; between Dc 2 and Dc 3 12–16 µm.
Abdomen. Tergite I with shagreen of small spinules in middle part. Shagreen of tergite II covers almost its entire surface and consists of spinules almost the same size, sometimes at the posterior edge they are slightly larger. Shagreenation of tergites III–VIII as in Fig. 13, namely spinules of anterior and posterior parts larger than spinules deposited between these parts. Sometimes spinules in middle part very small and sparse. Sternites II–III with shagreen composed of small spinules in middle part and with lateral longitudinal stripes of spinules. Sternites I–IV, IX without shagreen. Sternites VI–VIII with weak shagreen in some parts. Segment I without lateral setae or sometimes with 1 pair of setae. Segments II–V with 2–3 pairs of lateral setae; segments VI–VIII with 3 pairs of lateral setae; all lateral setae hair-like. Anal lobe 304–340 µm long. Male genital sac overreaching anal lobe. Anal macrosetae 112 µm long (Fig. 13). Anal macrosetae length/anal lobe length 0.33–0.37.
Fourth instar larva (n = 5). Total length 2.8–3.4 mm.
Head. Head capsule brown or dark brown, postoccipital margin black. Head length 300–325 µm, head width 225–250 µm. S I–III of labrum simple and hair-like, S IV like small tubercles. Pecten epipharyngis consisting of 3 scales, middle scale narrowest. Premandible 76 µm long, in apical part expanded and rounded, with 1 tooth. Antenna with 5 segments, length of segments 1–5 (in µm): 52–56: 20–24: 10–12: 6–10: 4–8; segment 3 longer than segment 4, rarely segments 3 and 4 of equal length (n= 1); one large and two small ring organs in proximal 1 / 4 of basal segment; apex of segment 2 with stylus 12 µm long and lauterborn organs as long as 3 rd segment; blade ending at base of segment 5 (Fig. 17); AR 1.17–1.30. Mandible 104–112 µm long, with 3 inner teeth and 1 apical tooth equal to first inner tooth or somewhat longer; other 2 inner teeth equal; seta subdentalis stout, with pointed apex (Fig. 16). Mentum high and subtriangular, with 3 equal median teeth and 4 pairs of lateral teeth. Beard of ventromental plates consisted of a tuft of long setae (Fig. 14). Very often apical part of mentum in mature larvae erased (Fig. 15). Posterior parapods slightly shorter than anal tubules or both structures of equal length. Anal tubules of one pair wider than anal tubules of other pair. Procercus 16 µm long and 24–28 µm wide, with 2 short lateral setae and 6 apical setae 432–608 µm long; rarely 5 apical setae present (n= 1). Body segments I–VII with 2 pairs of lateral setae: one pair of setae simple and one pair plumose (sometimes bifid); plumose setae placed at posteroventral corner of segment. Segment VIII with 1 pair of simple setae. Sometimes simple on one side and plumose seta on opposite side of the same segment.
Diagnostic characters. See the keys.
Etymology. The specific epithet is derived from first letters of the names of rivers in the basin, where the new species was collected: pl —Plotnikova River, ola —Ola River, bi —Bidzhan River. Distribution. Known from the type locality in Kamchatka and Magadan Regions, Amur River basin of the Russian Far East.