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

Rheocricotopus (P.) binotatus sp. nov. urn:lsid:zoobank.org:act: 2DB1E3E1-D7C7-4D36-94F0-AD188BEF6C63 Fig. 16, Table 14 Diagnosis Male Abdomen bicoloured, usually with tergites I and IV entirely or largely yellow, remaining tergites brown to dark brown. AR very low (less than 0.5). Humeral pit large, oval. Wing cuneiform with a very long costal extension and bare squama. Fore LR high (ca 0.9) Superior volsella triangular, thin. Inferior volsella triangular, apically rounded. Crista dorsalis triangular, occasionally large. Etymology From the Latin ‘ binotatus ’ (‘bi-noted’), referring to the largely brown abdomen with two yellow tergites. Type material Holotype CHINA – Yunnan • ♂; Jinping, Ma’andi, unnamed stream; 22°46′ N, 103°31′ E; 1360 m a.s.l.; 8 Jun. 2017; J. Chen leg.; JNU, JNU 170723009. Paratypes CHINA – Yunnan • 3 ♂♂; Puer, Ximeng, Mengsuo, Wangmo brook; 22°18′ N, 99°36′ E; 1215 m a.s.l.; 24 Apr. 2022; Y.J. Liang leg.; JNU, JNU 23020507 • 1 ♂; Anning, Qinglongxia, Shuishenqiao; 25°3′ N, 102°20′ E; 1770 m a.s.l.; 27 Apr. 2017; J. Chen leg.; JNU 170811008. – Xizang • 1 ♂; Nyingchi, Medog, Beibeng, Hanmi waterfall, No. 3 bridge; 29°14′ N, 95°8′ E; 970 m a.s.l.; 11 Aug. 2015; H.Q. Tang leg.; JNU. Description Male (n = 6) Total length 1.9–2.4, 2.2 (4) mm. COLOURATION. Head brown to dark brown on vertex. Thorax mostly dark brown except yellow pleural membrane and pale HP; scutal vittae indistinct. Abdomen (Fig. 16A) bicoloured; T I and IV entirely yellow, remaining tergites brown to dark brown; occasionally T IV (Fig. 16B) with narrow anterior dark band, T V with narrow anterior yellow band. Legs brown to dark brown. HEAD. Temporals 2–4, 3. AR 0.24–0.44, 0.30. Clypeus with 5–8, 7 setae. Lengths (μm) of Pm 1–5: 22–34, 29; 49–62, 52; 91–123, 102; 101–135, 116; 199–300, 240 (5), respectively. Pm 4 /Pm 3 1.0–1.2, 1.1, Pm 5 / Pm 4 1.8–2.2, 2.0 (5). Pm 3 with numerous SCl on 2 oval depressions. THORAX. Lateral Aps 4–8, 6 (4). Ac 8–12, 11 (4), longest 11–16, 14 (3) μm long; Dc 5–6, 6 (4), including 1–2, 2 (4) H; Pa 3 (4); Scts 4 (4). HP (Fig. 16C) moderately large, oval. WING (Fig. 16D). Length 1.4–2.0, 1.6 mm. AnL much reduced, wing cuneiform. C extended well beyond end of R 4+5, extension 86–123, 101 μm long. VR 1.1. R with 5–12, 9 setae; R 1 with 0–1, 1 seta; R 4+5 with 0–3, 2 setae. Sq bare. LEGS. P 1 with single ti spur 37–42, 39 (5) μm long; P 2 with 2 ti spurs 20–25, 23 (4) and 20–25, 21 (3) μm long; P 3 with 2 ti spurs 39–49, 44 (5) and 17–22, 20 (4) μm long. P 2 without Sch. P 3 with ti comb of 11–13, 12 (5) bristles. Lengths and proportions of legs as in Table 14. ABDOMEN (Fig. 16E). T II–VII laterally with 2 pairs of longitudinal rows of setae, VIII with irregularly scattered setae. Hypopygium (Fig. 16F) with AnP apically pointed, bearing 6–11, 8 lateral setae. Gc 160–185, 168 (5) μm long, 2.7–4.1, 3.4 (5) × as long as broad at middle, with SVo thin, triangular, rounded at apex; IVo somewhat double-layered, with apically rounded dorsal lobe. Gs (Fig. 16G) 64–79, 69 (5) μm long; CD triangular, occasionally large, arising from apical half of Gs. HR 2.3–2.5, 2.4 (5). Female, pupa and larva Unknown. Distribution The new species is known from Yunnan Province and Xizang Autonomous Region in Oriental China. Remarks The male most resembles that of R. (P.) albulus sp. nov. in the oval and large humeral pit, the largely brown abdomen with yellow tergites I and IV; the wedge-shaped wing with squamal setae reduced in number and a long costal extension; and the apically rounded triangular inferior volsella, but differs from it in the entirely brown to dark brown foretibia, and the relatively slender anal point with a sharply pointed apex. In the latter, the foretibia is whitish except the dark brown basal ⅓ and distal end, and the anal point is stout and apically rounded. The male is somewhat similar to that of R. (P.) godavarius Lehman, 1969 also in the bicoloured abdomen with whitish tergites I and IV, the cuneiform wing with a bare squama and a well-projected costal extension, but separable by the moderately large humeral pit. According to Lehmann (1969: 355), in R. (P.) godavarius the small humeral pit is composed of partly fused small holes.