Polypedilum (Tripodura) arcuatum Zhang & Wang

Zhang, Ruilei, Song, Chao, Qi, Xin & Wang, Xinhua, 2016, Taxonomic review on the subgenus Tripodura Townes (Diptera: Chironomidae: Polypedilum) from China with eleven new species and a supplementary world checklist, Zootaxa 4136 (1), pp. 1-53 : 9-10

Polypedilum (Tripodura) arcuatum Zhang & Wang sp. n.

( Figure 3 )

Polypedilum sp16._SC_song 165, 166, 167; Song et al. 2016: 542.

Type material. Holotype: male (BDN. 07832), CHINA, Xizang Autonomous Region, Xia Zayü, Dongqiong Village, 1700m, 24. V. 1988, light trap, C. Deng. Paratypes: 1 male, as the holotype. 4 males, Xizang Autonomous Region, Xia Zayü, Ba’antong, 1600m, 19. V. 1988, sweep net, C. Deng.

Etymology. From Latin, arcuatus , bent like a bow, referring to the gonostylus arched in the middle like a bow. Diagnostic characters. The species is easily distinguished from other members of the subgenus by low AR (0.28–0.33), wing markings and the arched gonostylus.

Male imago (n=5, when otherwise stated). Total length 2.45–3.13, 2.73 mm. Wing length 1.55–1.78, 1.68 mm. Total length/ wing length 1.46–1.76, 1.62. Wing length/ length of profemur 2.52–2.79, 2.69.

Coloration. Head dark brown. Thorax yellowish brown to dark brown. Legs yellowish brown to brown, femora with a pale sub-apical ring. Abdominal segments yellowish brown to brown.

Head. AR 0.28–0.33, 0.32 (4). Ultimate flagellomere 155–220, 186 µm long. Temporal setae 13–16, 15. Clypeus with 17–20, 19 setae. Tentorium 100–120, 113 µm long; 20–28, 26 µm wide. Palpomere lengths (in µm): 30–43, 37; 33–43, 37; 88–95, 91; 88–100, 95; 150–168, 161.

Wing ( Figure 3A ). Wing with markings, but obscure on wing margin. VR 1.28–1.33, 1.30. R with 13–21, 17 setae; R1 with 12–16, 13; R4+5 with 25–30, 28. Squama with 7–9, 8 (4) setae.

Thorax. Dorsocentrals 15–20, 17, including 3–4, 4 humerals; acrostichals 15–19, 17; prealars 5–6, 6. Scutellum with 16–22, 19 setae.

Legs. Terminal scale ( Figure 3B ) of front tibia 38–48, 40 µm long, triangular and apically pointed. Spur of middle tibia 45–50, 47 um long including 25–28, 26 µm long comb, un-spurred comb 23–25, 24 µm long, spur of hind tibia 43–50, 48 µm long including 25–28, 27 µm long comb, un-spurred comb 25–28, 27 µm long. Width at apex of front tibia 40–48, 44 µm, of middle tibia 43–50, 47 µm, of hind tibia 50–63, 56 µm. Lengths (in µm) and proportions of legs as in Table 1 .

Hypopygium ( Figure 3C, D ). Tergite IX with 8–12, 10 median setae. Laterosternite with 2–3, 2 setae. Anal point 60–73, 66 µm long, lateral projection 13–15, 24 µm long. Phallapodeme 70–90, 81 µm long; transverse sternapodeme 35–45, 41 µm long. Gonocoxite 108–138, 129 µm long. Superior volsella ( Figure 3 C ) pad–like, expanded distally, with 4–5 short inner setae and 2 long outer apical setae. Inferior volsella 88–115, 103 µm long, with 7–11, 9 oral setae and an apical seta. Gonostylus 113–145, 129 µm long, with 5–7 long setae along inner margin. HR 0.94–0.97, 0.95. HV 1.91–2.21, 2.04.

Distribution. The species was collected from Xizang Autonomous Region (Oriental China).

Remarks. The present new species resembles P. (T.) yammoune Moubayed, 1992 but differs from the latter in the shape of the gonostylus: the gonostylus short and tapering from the half part to the apex in the new species, the gonostylus long and parallel-sided in the latter.

Figures

FIGURE 3 A – D. Polypedilum (Tripodura) arcuatum Zhang & Wang sp. n. A. Wing. B. Fore tibial scale. C. Superior volsella. D. Hypopygium, dorsal and ventral view.