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

Rheocricotopus (P.) albulus sp. nov. urn:lsid:zoobank.org:act: AF7E61C1-8946-48DE-9D37-724065943320 Fig. 14, Table 12 Diagnosis Male Abdomen bicoloured, with tergites I and IV entirely or largely yellow, remainings entirely dark brown. Humeral pit oval, large. Wing cuneiform with a few squamal setae and distinct costal extension. Foretibia bicoloured, subapically with a broad whitish band. Anal point robust with blunt apex. Superior volsella plate-like, roundly protruded. Inferior volsella triangular, apically rounded. Crista dorsalis distinct, triangular. Pupa Frontal setae absent. Segments II–VIII with only 3 L-setae; anal lobe without setal fringe. Etymology From the Latin ‘ albulus ’ (‘whitish’), referring to the broadly whitish foretibia of the adult. Type material Holotype CHINA – Yunnan • ♂; Xishuangbanna, Yiwu, Guafengzhai; 22°00′ N, 101°35′ E; 1360 m a.s.l.; 26 Apr. 2017; J. Chen leg.; JNU, JNU 170512011. Paratype CHINA – Yunnan • 1 ♂ (pharate); Ximeng, Lake Mengsuo, stream near Laomoye; 22°38′ N, 99°35′ E; 1270 m a.s.l.; 20 Jan. 2015; H.Q. Tang leg.; JNU. Description Male (n = 2) Total length 2.0 (1) mm. COLOURATION. Head dark brown on vertex. Thorax mostly dark brown except yellow pleural membrane; scutal vittae indistinct. Abdomen (Fig. 14A–B) bicoloured; T I and IV entirely yellow, remaining tergites dark brown; occasionally T IV with anterior narrow transverse dark band. Legs (Fig. 14C) brown to dark brown, with foretibia broadly whitish bearing dark brown basal ⅓ and distal end. HEAD. Temporals 2–3. AT 0.40–0.56. Clypeus with 7–8 setae. Lengths (μm) of Pm 1–5: 32 (1), 54 (1), 103 (1), 116 (1), 224 (1), respectively. Pm 4 /Pm 3 1.1 (1), Pm 5 /Pm 4 1.9 (1). Pm 3 with numerous SCl on 2 oval depressions. THORAX. Lateral Aps 4–6. Ac 13–16, longest 12–15 μm long; Dc 5–6, including 1–2 H; Pa 3; Scts 4. HP (Fig. 14D) oval, large. WING (Fig. 14E). Length 1.6 (1) mm. AnL much reduced; wing cuneiform, widest at around end of Cu 1. C extension 62 (1) μm long. VR 1.1 (1). R with 2 (1) setae; R 1 and R 4+5 bare. Sq with 0–1 seta. LEGS. P 1 with single ti spur 32–39 μm long; P 2 with 2 ti spurs 22 and 20 μm long; P 3 with 2 ti spurs 42–49 and 20–22 μm long. P 2 without Sch. P 3 with ti comb of 12 bristles. Lengths and proportions of legs as in Table 12. ABDOMEN (Fig. 14F). T II–III with one pair of longitudinal, lateral setal rows, IV–VII with 2 pairs of longitudinal, lateral setal rows. Hypopygium (Fig. 14G) with AnP robust, apically blunt, bearing 8 lateral setae. Gc 145–175 μm long, 3.6 (1) × as long as broad at middle, with SVo thin, roundly projected; IVo simple, triangular, with rounded apex. Gs 71–74 μm long, with subapical, triangular CD. HR 2.0–2.4. Pupa (n = 1) Total length 3.6 mm. COLOURATION. Exuviae pale brown with dark abdominal Apo. CEPHALOTHORAX. FA (Fig. 14H) weakly rugose; FS absent. Thoracic horn 294 μm long, and 3.0 × as long as broad. Pc 1–3 arranged in triangle. Lengths (μm) of Dc 1–4: 49, –, 25, 25, respectively. Distances (μm) of Dc 1 –Dc 2, Dc 2 –Dc 3, Dc 3 –Dc 4: 52, 76, 15, respectively; these setae arranged in line. Distance ratio of Dc 1 –Dc 2 to Dc 2 –Dc 3 0.68. ABDOMEN (Fig. 14I). Tergal spinulation indistinct; at least T IV with weak, extensive spinulation, T IX with anterior spinulation; these spinules sporadic and faint. Spine rows present on posterior margins of T II–VIII; these spines strong on T VII–VIII. Posterior margins of T II–V and conjunctives III/IV–V/ VI without anteriorly directed spinules. S IV–VII each with rows of spines on posterior margin. PSB present, but small, on A II–III. Segment I with 2 L-setae, II–VIII each with 3 L-setae, some L-setae apically split. L 1, 2 -setae relatively long at least on A II–IV, these almost ½ × as long as segment length; L 3 -seta slightly shorter than L 1, 2 -setae. AL 246 μm long, 1.9 × as long as broad, without lateral taeniae; male genital sac 1.1 × as long as AL. Female and larva Unknown. Distribution The species is known only from Yunnan Province in Oriental China. Remarks In the key by Saether (1986: 69), the male will not pass couplet 2 due to the oval, large humeral pits and a low antennal ratio of 0.4. In Lehmann (1969: 377), the male will key to that of R. (P.) godavarius Lehmann, 1969 because of the bicoloured abdomen and the cuneiform wing with a few squamal setae, but differs from it in the oval and large humeral pit. According to Lehmann (1969: 361–362, 372 fig. 14b) and Saether (1986: 72), R. (P.) godavarius has indistinct, small humeral pits consisting of several small holes. The pupa is characterized by the absences of frontal setae and anteriorly directed spinules on the posterior margins of tergites II–V and conjunctives III/IV–V/VI, the abdominal segments II–VIII with three L-setae only on each side, and the anal lobe lacking of setal fringe, and the combination of these features is unique in Rheocricotopus. The pupa resembles that of R. (P.) tirolus Lehmann, 1969 in the lack of frontal setae and the anal lobe lacking a setal fringe, but R. tirolus has median spinules on the conjunctives III/IV and IV/V, and four L-setae on the segments VI–VIII, whose L 4 -setae are short or vestigial, and taeniate on the segment VIII (Saether 1986: 76).