Polypedilum (Tripodura) bilamella 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 : 10-12

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

( Figure 4 )

Polypedilum (Tripodura) pullum (Zettstedt) , sensu Wang, 2000: 646.

Type material. Holotype (BDN.10066), male, CHINA, Xizang Autonomous Region, Ya’dong County, Yacheng, 26. VIII. 2003, light trap, H. Xue. Paratypes: 1 male, Hubei Province, Shengnongjia Natural Conversation, Hongping, 1800m, 18. VII. 1997, light trap, Y. Du. 3 males, Sichuan Province, Guanxian County, 11. VII. 1985, light trap, X. Wang. 3 males, Sichuan Province, Luding County, 7. VI. 1996, light trap, X. Wang. 6 males, Sichuan Province, Kangding County, Zheduo River, 2120m, light trap, 8. VI. 1996, X. Wang. 3 males, Sichuan Province, Yajiang County, Sandaoqiao, 2460m, 9. VI. 1996, sweep net, X. Wang. 8 males, Sichuan Province, Xiangcheng County, Shuoqu River, 2750m, 12. VI. 1996, light trap, X. Wang. 3 males, Sichuan Province, Garzê County, Yajiang, 2830m, 14. VI. 1996, light trap, X. Wang. 1 male, Sichuan Province, Kangding County, Wasigou, 2000m, light trap, 15. VI. 1996, X. Wang. 2 males, Sichuan Ya’an City, Zhougong River, 18. VI. 1996, light trap, X. Wang. 6 males, Sichuan Province, Baoxing County, Xilong Town, 1100m, 19. VI. 1996, light trap, X. Wang. 4 males, Yunnan Province, Dali City, Diancangshan, 2520m, 23, V. 1996, light trap, B. Wang. 3 males, Yunnan Province, Eryuan County, Niujie Township, Futianlin, Meici River, 2262m, light trap, 24. V. 1996. C. Zhou. 1 male, Shannxi Province, Zhouzhi County, Banfangzi Town, 10. VIII 1994, W. Bu. 1 male, Shannxi Province, Ningshan County, Xunyangba, 16. VIII. 1994, sweep net, B. Wen. 5 males, Gansu Province, Yuzhong County, Xinlong Mountain, 2200m, 30–31. VII. 1993, sweep net, W. Bu. 1 male, Gansu Province, Yuzhong County, Maxian Mountain, 5. VIII. 1993, sweep net, W. Bu. 1 male, Gansu Province, Yongdeng County, Liancheng Township, Tulugou, 2300m, 16. VIII. 1993, light trap, W. Bu. 13 males, Ningxia Autonomous Region, Liuban Mountain Natural Converse, 6. VIII. 1987, X. Wang.

Etymology. From Latin, bi, two and lamella, lamella, thin plate, referring to the anal point with two dorsal lobed lamellae.

Diagnostic characters. Wing is full of gray marking. Anal point bears tow dosal lobed lamellae. Lateral projection of anal point is well developed.

Male imago (n=20). Total length 2.10–3.60, 2.89 mm. Wing length 1.43–2.10, 1.78 mm. Total length/ wing length 1.39–1.88, 1.63. Wing length/ length of profemur 2.17–2.82, 2.56.

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

Head. AR 0.40–0.73, 0.54. Ultimate flagellomere 90–410, 250 µm long. Temporal setae 10–14, 12; including 2–4, 3 inner verticals; 4–8, 5 outer verticals and 2–6, 4 postorbitals. Clypeus with 13–27, 19 setae. Tentorium 100– 150, 118 µm long; 20–35, 26 µm wide. Palpomere lengths (in µm): 28–50, 37; 30–48, 38; 75–113, 96; 90–128, 109; 173–228, 192.

Wing ( Figure 4A ). Wing widely coved with obscure markings. VR 1.19–1.35, 1.29. R with 14–25, 20 setae; R1 with 11–20, 15; R4+5 with 22–38, 29. Squama with 6–16, 10 setae.

Thorax. Dorsocentrals 17–24, 20, including 2–4, 3 humerals; acrostichals 13–22, 18; prealars 4–7, 5. Scutellum with 12–28, 18 setae.

Legs. Terminal scale ( Figure 4B ) of front tibia 33–55, 44 µm long, triangular and apically pointed. Spur of middle tibia 40–65, 49 um long including 20–33, 26 µm long comb, un-spurred comb 18–28, 23 µm long, spur of hind tibia 40–65, 52 µm long including 25–40, 30 µm long comb, un-spurred comb 23–38, 28 µm long. Width at apex of front tibia 40–53, 46 µm, of middle tibia 43–65, 51 µm, of hind tibia 45–70, 59 µm. Lengths (in µm) and proportions of legs as in Table 1 .

Hypopygium ( Figure 4C–E ). Anal tergite bands fused basal. Tergite IX with 6–18, 10 median setae. Laterosternite with 2–3, 2 setae. Anal point 53–88, 72 µm long, lateral projection 13–33, 22 µm long. Phallapodeme 65–100, 89 µm long; transverse sternapodeme 25–53, 42 µm long. Gonocoxite 103–163, 136 µm long. Superior volsella ( Figure 4C ) pad–like, expanded distally, with 5–6 short inner setae and 2–3 long apical setae. Inferior volsella 95–140, 120 µm long, with 8–13, 11 setae. Gonostylus 120–193, 164 µm long, with 5–7 long setae along inner margin. HR 0.69–0.92, 0.83. HV 1.53–1.94, 1.77.

Distribution. It was collected from both Palaearctic and Oriental China.

Remarks. The present new species is very close to P. (T.) decematoguttatum (Tokunaga) , P. (T.) napahaiense Zhang & Wang sp. n. and P. (T.) mengmanense Zhang & Wang sp. n. in male hypopygial morphology that the anal point bears two dorsal lobed lamellae. We must be very careful when we observe above 4 species under microscope, because the dorsal lobed lamellae is transparent and easy to ignore in dorsal view. The above 4 species show a bit difference in wing markings and the length of lateral projection of anal point; Song et al. (2016) have certified these bit differences can result in inter-specific divergence by molecular data. Wang (2000) had wrongly identified some specimens of P. (T.) bilamella Zhang & Wang sp. n. collected from Ningxia Autonomous region as P. (T.) pullum (Zetterstedt) .

Figures

FIGURE 4 A – E. Polypedilum (Tripodura) bilamella Zhang & Wang sp. n. A. Wing. B. Fore tibial scale. C. Superior volsella. D. Hypopygium, dorsal and ventral view. E. Inferior volsella.