Pagastia (s. str.) laojun Wu et Tang, 2025

Wu, Zehao & Tang, Hongqu, 2025, Description of two mountain midges (Diptera, Chironomidae, Diamesinae) from China, Zootaxa 5642 (3), pp. 287-292 : 288-290

Pagastia (s. str.) laojun Wu et Tang , sp. nov.

Figure 1

http://zoobank.org/ urn:lsid:zoobank.org:act:A4614995-CDA4-4C97-854E-6CFBBF2E958D

Material Examined. Holotype, M, CHINA: Yunnan Province, Lijiang City, Yulong County, Laojunshan (shan = mountain) National Geopark , 19.iv.2024, leg. SN Ma. Paratypes: 4 males, all as the holotype .

Etymology. For the type locality, Mt. Laojun, a famous scenic spot also called the 99-lake group in Yunnan Province. To be treated as a noun in apposition.

Description

Adult male (n = 5). Total length 5.3–5.5, 5.4 mm. Wing length 3.1–3.5, 3.4 mm. TL/WL 1.54–1.71, 1.63.

Head. Antenna with 13 flagellomeres, last flagellomere 940–970, 955 μm long. AR 2.19–2.21, 2.20. Temporals 20–24, 22, including 8–10, 10 verticals, 6–8, 6 orbitals and 5–6, 6 postoculars. Palpomere lengths (in μm): 45–60, 53; 90–110, 99; 175–215, 195; 215–220, 218; 250–255, 253. Clypeus with 22–30, 26 setae.

Thorax. Acrostichals 24–28, 26; dorsocentrals 23–30, 27; prealars 10–20, 15; scutellars 27–40, 33.

Wing. R with 27–34, 29 setae; R 1 with 14–16, 15 setae; R 4+5 with 14–16, 15 setae; squama with 40–52, 46 setae. VR 0.73–0.90, 0.85.

Legs. Spur of fore tibia 85–90, 89 μm long; spurs of mid tibia 60–70, 63 and 60–80, 70 μm; spurs of hind tibia 55–60, 59 and 70–95, 85 μm long. Hind tibia comb with 10–15, 11 setae. Lengths and proportions of legs as Table 1 .

Hypopygium ( Figs. 1A–F ). Tergite IX with 15–18 setae on each side. Laterosternite IX with 8–10 setae. Anal point 75–95, 86 μm long, with a round apical peg, diameter 15–18 μm ( Fig. 1D ). Only lateral aedeagal lobe present, apex pointed ( Fig. 1F ). Gonocoxite 270–330, 304 μm long, gonostylus 150–180, 163 μm long, with a shallow protuberant lobe near the middle and a heel in the apex. Megaseta 15–20, 16 μm long. HR 1.54–2.2, 1.89.

Female and immatures. Unknown

Remarks. In the latest key to the known Holarctic species of Pagastia ( Makarchenko & Hansen 2020, p. 175) , the new species keys to couplet 8, but anal point with a rounded apical peg ( Fig. 1D ), in contrast to the pointed apical peg as represented by P. (s. str.) hidakamontana Endo and P. (s. str.) donoliveri Makarchenko & Hansen. If the shape of apical peg is omitted, P. (s. str.) laojun resembles P. (s. str.) donoliveri further by the shape of gonostylus with outer heel. However, the combination of round apical peg and the shape of gonostylus is distinct and unique, which can be easily separated from congeners. Currently, the species is only known in the type locality.

Figures

FIGURE 1. Pagastia (s. str.) laojun sp. nov., male adult, A–B, D, color photos of the hypopygium: A, dorsal view, B, ventral view; C–F, line drawings of the hypopygium: C, dorsal view, D, anal point, E, lateral aedeagal lobe F, ventral view (scale bar 100 μm).