Rheocricotopus (P.) beibengensis sp. nov. urn:lsid:zoobank.org:act: A37CDD0C-9EC6-4AD4-973A-11C5EEFA19EA Fig. 15, Table 13 Diagnosis Male Humeral pit large, circular. AR very low (less than 0.5). Scutum with rows of acrostichal setae. Wing cuneiform with a moderately long costal extension. Fore LR very high (more than 0.9). Superior volsella thin, triangular. Inferior volsella triangular with beak-like apex. Gonostylus sharply turned up apically, with small, subapical crista dorsalis. Etymology From the type locality, ‘Beibeng’, where is a small border township located in southern Xizang Autonomous Region. Type material Holotype CHINA – Xizang • ♂; Nyingchi, Medog, Beibeng Township; 29°13′ N, 95°07′ E; 1400 m a.s.l.; 9 Aug. 2015; H.Q. Tang leg.; JNU, JNU 25121501. Description Male (n = 1) Total length 1.7 mm. COLOURATION. Body mostly dark brown with thorax yellow on pleural membrane; HP paler. Legs brown. HEAD. Temporals 5. AR 0.33. Clypeus with 9 setae. Lengths (μm) of Pm 1–5: 27, 37, 71, 89, 172, respectively. Pm 4 /Pm 3 1.2, Pm 5 /Pm4 1.9. Pm 3 with 3 SCl on one circular depression. THORAX. Lateral Aps 3; Ac 9, longest 13 μm long; Dc 5, including 1 H; Pa 3; Scts 2. HP (Fig. 15A) moderately large, circular. WING (Fig. 15B). Length 1.3 mm. AnL much reduced, wing cuneiform. C extension well projected, 62 μm long. VR 1.1. R with 2 setae, R 1 and R 4+5 bare. Sq with 2 setae. LEGS. P 1 with single ti spur 30 μm long, P 2 with 2 ti spurs 15 and 13 μm long, P 3 with 2 ti spurs 36 and 16 μm long. P 2 without Sch. P 3 with ti comb of 12 bristles. Lengths and proportions of legs as in Table 13. ABDOMEN. Hypopygium (Fig. 15C) with AnP triangular, apically pointed, bearing 6 lateral setae. Gc 165 μm long with thin, triangular SVo; IVo triangular, apically with small, nearly bare, beak-like apex. Gs 59 μm long, sharply curved upwards at apex; CD small, slender, placed at subapex. HR 2.79. Female, pupa and larva Unknown. Distribution This species is known only from the type locality, Medog, Xizang Autonomous Region, in Oriental China. Remarks The male is similar to that of R. (P.) imperfectus in the combination of the gonostylus sharply up-turned apically, the low antennal ratio (AR ca 0.3), the wing with a reduced anal lobe and a moderately long costal extension, and the inferior volsella with a beak-like projection, but is distinct in the presence of acrostichal setae. According to Makarchenko & Makarchenko (2005: 129), the male of R. (P.) imperfectus has no acrostichal seta. This species also resembles R. (P.) chalybeatus if omitting the acrostichals, but can be separated from the latter by the cuneiform wing, the relatively low antennal ratio and the fardistant location of crista dorsalis from the apical megaseta. In the latter, the wing lobe is well developed, the antennal ratio is ca 1.0, and the crista dorsalis is tightly close to the megaseta.

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 56-58, DOI: 10.5852/ejt.2026.1037.3157, http://zenodo.org/record/18507203