Rheocricotopus (P.) monovittatus sp. nov. urn:lsid:zoobank.org:act: 7AEB1E75-CB86-48E4-B2DA-DEE68C31F1C1 Fig. 21, Table 19 Diagnosis Male Abdomen largely dark brown, with tergite I entirely yellow, and tergites II bearing an anterior yellow band. AR relatively high (near 1.0). Scutum with 4 strong acrostichal setae near apex; longest more than 25 μm long. Humeral pit large, circular. Wing with an obtuse anal lobe and a very short costal extension (length15–20 μm). Superior volsella thin, triangular. Inferior volsella triangular with a beak-like apex. Crista dorsalis small, triangular. Etymology From the Greek ‘ mono -’ (praef.) (‘one’), and the Latin ‘ vittatus ’ (‘banded’), referring to the whitish anterior band on the abdomen. Type material Holotype CHINA – Guangdong • ♂; Fengkai, Heishiding NNR, site 3; 23°27′ N, 111°51′ E; 310 m a.s.l.; 5 Apr. 2022; H.Q. Tang leg.; JNU, JNU 23032701. Paratypes CHINA – Guangdong • 2 ♂♂; Xinyi, Mt Yunkai NNR; 22°16′ N, 111°11′ E; 1130 m a.s.l.; 12 May 2020; S.X. Luo leg.; JNU, JNU 24033120. Description Male (n = 3) Total length 2.4–2.8 (2) mm. COLOURATION. Body mostly dark brown. Thorax dark brown with yellow or whitish pleural membrane; 3 scutal vittae distinct, dark brown. Abdomen (Fig. 21A) bicoloured; T I entirely yellow; T II largely dark brown with anterior, narrow transverse yellow band; T III–IX uniformly dark brown. Legs entirely dark brown. HEAD. Temporals 3. AR 0.97 (1). Clypeus with 12–14, 13 setae. Lengths (μm) of Pm 1–5: 30–37 (2), 39–44 (2), 64–69 (2), 93 (2), 160 (1), respectively. Pm 4 /Pm 3 1.4–1.5 (2), Pm 5 /Pm4 1.7 (1). Pm 3 with 1–2, 1 SCl; Pm 4 without SCl. THORAX. Lateral Aps 3–5 (2). Ac 4 (2), located near apex of scutum, longest 27 (1) μm long; Dc 7–10 (2), including 1–3 (2) H; Pa 3 (2); Scts 6–9 (2), uniserial. HP (Fig. 21B) circular, moderately large, its margin faintly visible in a pale pleural area. WING (Fig. 21C). Length 1.5 mm. C extension very short, 15–20, 17 μm long. VR 1.1. R with 3–4, 4 setae; R 1 and R 4+5 bare. AnL developed, obtuse. Sq with 7 setae. LEGS. P 1 with single ti spur 37–39, 39 μm long; P 2 with 2 ti spurs 15–17 (2) and 12–15 (2) μm long; P 3 with 2 ti spurs 37–39, 39 and 15–20, 17 μm long. P 2 with one Sch on ta 1. P 3 with ti comb of 9–11, 10 bristles. Lengths and proportions of legs as in Table 19. ABDOMEN. Hypopygium (Fig. 21D) with AnP triangular, pointed apically, bearing 6–8, 7 lateral setae. Gc 148–160, 155 μm long, 3.0–3.4, 3.2 × as long as broad at middle, with SVo thin, triangular, apically rounded; IVo triangular, apically somewhat beak-shaped. Gs (Fig. 21E) 66–69, 67 μm long, gently curved upwards at apex, with CD preapical, small and triangular. HR 2.22–2.41, 2.31. Female, pupa and larva Unknown. Distribution The species occurs only in Guangdong Province in Oriental China. Remarks The male is similar to that of R. (P.) hanmiensis sp. nov. in the combination of following features: bicoloured abdomen with largely yellow tergite I, anteriorly yellow and posteriorly dark brown tergite II, and uniformly dark brown tergites III–IX; entirely brown legs; and moderately large, circular humeral pit, but separable from it by the high antennal ratio (AR ca 1.0), the longer acrostichal setae (longest setae more than 25 μm) located near the apex of scutum, the inconspicuous costal extension (length15–20 μm), and the hypopygial anal point with lateral setae only. The latter has antennae of a relatively low antennal ratio (AR ca 0.5); 7–8 shorter acrostichal setae (longest setae 15 μm) along the scutal midline; a moderately long costal extension (ca 50 μm); and an anal point with basal as well as lateral setae. The male specimens (NK 24090 and 24091) from Jiangxi Province, China, identified as R. (P.) robacki (Beck & Beck, 1964) by Liu et al. (2014a: 25) are very similar to those of R. (P.) monovittatus sp. nov. in the position and the reduced number of acrostichal setae, the wing with a very short costal extension and an obtuse anal lobe, and the triangular inferior volsella with a somewhat beak-shaped apex. However, it will remain unclear if these species are conspecific until more material is available.

Published as part of Niitsuma, Hiromi & Tang, Hongqu, 2026, Taxonomic review of Rheocricotopus Brundin, 1956 (Diptera: Chironomidae: Orthocladiinae) from East Asia, with descriptions of twelve new species, pp. 1-114 in European Journal of Taxonomy 1037 on pages 72-74, DOI: 10.5852/ejt.2026.1037.3157, http://zenodo.org/record/18507203