Rheocricotopus (Psilocricotopus) nippobifasciatus Niitsuma & Tang, 2026, sp. nov.

Rheocricotopus (P.) nippobifasciatus sp. nov. urn:lsid:zoobank.org:act: 032182DE-9C3F-4F22-9E3F-8487EE62CECF Fig. 22, Table 20 Diagnosis Male Abdomen bicoloured. Tergites I, II and IV entirely yellow; tergite V brown, anteriorly with a transverse yellow band; remaining tergites entirely brown. AR somewhat low (less than 1.0). Humeral pit large, oval, distinct. Wing cuneiform with a well-developed costal extension. Fore LR high (ca 0.9). Superior volsella roundly protruded, thin. Inferior volsella triangular, with rounded apex. Crista dorsalis small, but distinct. Female Antenna with terminal flagellomere shorter than combined length of 3 rd and 4 th flagellomeres. Spermathecal duct looped. Etymology From the type locality Nippon, Japan, and Rheocricotopus (P.) bifasciatus, the male of which is very similar to that of the present species. Type material Holotype JAPAN – Shizuoka • ♂; Ikawa, Dainichi Pass, stream; 35°11′ N, 138°15′ E; 1100 m a.s.l.; 29 Aug. 1999; H. Niitsuma leg.; NSMT, NSMT-I-Dip 36256. Paratypes JAPAN – Shizuoka • 4 ♂♂; same data as for holotype; NSMT, NSMT-I-Dip 36257 to 36260 • 1 ♂; same data as for holotype; 13 Sep. 1998; NSMT, NSMT-I-Dip 36261 • 7 ♂♂; same data as for holotype; 16 Jun. 2000; NSMT, NSMT-I-Dip 36262 to 36268 • 2 ♀♀; same data as for holotype; 16 Jun. 2000; NSMT, NSMT-I-Dip 36269 to 36270 • 1 ♂; Aoi-ku, Ashikubo; 35°2′ N, 138°22′ E; 77 m a.s.l.; 4 Apr. 1987; H. Niitsuma leg.; NSMT, NSMT-I-Dip 36271 • 1 ♂ 2 ♂♂; Shimizu, Ihara River; 35°4′ N, 138°27′ E; 202 m; 30 Jun. 1990; H. Niitsuma leg.; NSMT, NSMT-I-Dip 36272 to 36273. Description Male (n = 15) Total length 2.0–2.5, 2.3 mm. COLOURATION. Head dark brown on vertex. Thorax largely blackish brown except yellow pleural membrane and HP, and pale to dark brown preepisternum. Abdomen (Fig. 22A) bicoloured; T I, II, IV entirely yellow; T V brown with transverse yellow band on anterior ¼–½; remainings brown. Legs dark brown; P 1 somewhat darker than P 1, 2. HEAD. Temporals 4–6, 5. AR 0.53–0.63, 0.57 (14). Clypeus with 5–9, 7 setae. Lengths (μm) of Pm 1–5: 34–44, 39 (11); 57–69, 63 (11); 123–162, 136 (11); 123–160, 139 (11); 239–310, 277 (11), respectively. Pm 4 /Pm 3 1.0–1.1, 1.0 (11); Pm 5 /Pm 4 1.7–2.2, 2.0 (11). Pm 3 with 7–17, 12 (14) SCl on 2–3, 3 (14) oval depressions. THORAX. Lateral Aps 1–4, 2. Ac 10–20, 14 (13), and longest 10–16, 13 (13) μm long; Dc 6–10, 8 including 1–2, 2 H; Pa 2–3, 3 (14); Scts 4–5, 4 (13). HP (Fig. 22B) large, oval, occasionally indistinct in part. WING (Fig. 22C). Length 1.7–2.2, 1.9 mm. C well extended beyond end of R 4+5, extension 74–123, 93 μm long. VR 1.1. R with 8–14, 10 setae; R 1 with 1–5, 2 setae, and R 4+5 with 1–6, 4 setae. AnL much reduced. Sq with 0–2, 1 seta. LEGS. P 1 with ti spur 34–42, 39 μm long; P 2 with 2 ti spurs both 16–23, 19 μm long; P 3 with 2 ti spurs 37–46, 42 and 17–23, 20 μm long. P 2 with 0–2 Sch on ta 1, usually Sch absent. P 3 with ti comb of 12–14, 13 (14) bristles. Lengths and proportions of legs as in Table 20. ABDOMEN. Hypopygium (Fig. 22D) with AnP pointed apically, bearing 7–15, 10 lateral setae. Gc 160– 187, 172 μm long, 3.0–3.7, 3.4 (13) × as long as broad at middle, with SVo thin, roundly protruded; IVo apically rounded, occasionally with small apical projection. Gs (Fig. 22E) 74–84, 78 μm long, roundly convex in outer margin; subapically with CD small but distinct. HR 2.06–2.29, 2.20. Female (n = 2) Total length 2.5–2.7 mm. COLOURATION. Similar to male. SCa yellow. HEAD. Temporals 5–6. Antenna 5-segmented; Fm 5 98–106 μm long, shorter than combined length of Fm 3 and Fm 4; AR 0.35–0.38. Clypeus with 7–8 setae. Lengths (μm) of Pm 1–5: 39–44, 64, 138–140, 140–153, 271 (1), respectively. Pm 4 /Pm 3 1.0–1.1; Pm 5 /Pm 4 1.9 (1). Pm 3 with 8–14 SCl on 2–3 depressions. THORAX. Lateral Aps 2–3. Ac 20–21; Dc 8 including 2–3 H; Pa 3. Sct 4. WING. Length 1.9 mm. C extension well projected. VR 1.1. R with 16 setae; R 1 with 9 setae; R 4+5 with 23–28 setae. Sq with 1–2 setae. LEGS. P 1 with ti spur 18–21 μm long; P 2 with 2 ti spurs 20–21 and 18–20 μm long; P 3 with 2 ti spurs 44–47 and 23–25 μm long. P 2 with 4–6 Sch on ta 1; P 3 with 1 (1) Sch on ta 1. P 3 with ti comb of 14 bristles. Lengths and proportions of legs as in Table 20. GENITALIA (Fig. 22F). S VIII with 6 setae. T IX (Fig. 22G) undivided, with 9–10 setae. Gc IX with 7–8 setae on each side. Ce 64–66 μm long. No 98–106 μm long. SCa 103–108 μm long; spermathecal duct looped. Pupa and larva Unknown. Distribution The species is known from Palaearctic Japan only. Remarks The male is similar to that of R. (P.) bifasciatus Wang & Zheng, 1991 in the abdominal colour pattern of tergites I–II, IV entirely yellow and tergites III, VI–IX brown; the large, oval humeral pit; the wing with a much-reduced anal lobe and a long costal extension; the gonostylus with a small, preapical crista dorsalis, but separable from it by the largely brown tergite V with an anterior, transverse yellow band; and the smaller male antennal ratio (AR 0.50–0.65). According to the original description (Wang & Zheng 1991: 104) of R. (P.) bifasciatus, the tergite V is entirely black, and the antennal ratio is 0.9.