Polypedilum (Tripodura) pollicium 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 : 28-29

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

( Figure 12 )

Type material. Holotype: male (BDN. 05849) CHINA, Hainan Province, Changjiang County, Bawangling Natural Reserve, 11. V. 1989, light trap, X. Wang.

Etymology. From Latin, pollicis, great toe, referring to the shape of the superior volsella like a great toe.

Diagnostic characters. The species differs from other members of the subgenus by the characteristic shape of the superior volsella and low AR (0.38).

Male imago (n=1). Total length 1.89 mm. Wing length 1.19 mm. Total length/ wing length 1.59. Wing length / length of profemur 2.26.

Coloration. Head and abdominal segments yellowish brown. Thorax brown, with darker vittae, postnotum, anepisternum and preepisternum. Fore femur brown with yellow ring in the middle; fore tibia brown with yellow apex; fore tarsus I yellow, II–V yellowish brown. Femora of mid and hind legs yellow, with brown rings at basal 1/ 4 to 1/2 and distal 1/6; the remaining parts yellowish brown.

Head. AR 0.38. Ultimate flagellomere 175 µm long. Temporal setae 13, including 4 inner verticals, 7 outer verticals and 2 postorbitals. Clypeus with 17 setae. Tentorium 101 µm long, 13 µm wide. Palpomere lengths (in µm): 21, 26, 36, 73, 112.

Wing ( Figure 12A ). Wing with 5 markings, 2 in cell r4+5, 1 in cell m1+2, 1 extending from basal cell m3+4 to distal cell cu1, 1 in middle of cell an. VR 1.34. R with 13 setae, R1 with 8, R4+5 with 16. Squama with 6 setae.

Thorax. Dorsocentrals 11; acrostichals 15; prealars 4. Scutellum with 4 setae.

Legs. Terminal scale ( Figure 12B ) of front tibia 36 µm long, triangular and pointed apically. Spur of middle tibia 42 um long including 18 µm long comb, un-spurred comb 18 µm long, spur of hind tibia 42 µm long including 21 µm long comb, un-spurred comb 18 µm long. Width at apex of front tibia 31 µm, of middle tibia 34 µm, of hind tibia 36 µm. Lengths (in µm) and proportions of legs as in Table 1 .

Hypopygium ( Figure 12C, D ). Tergite IX with 5 median setae. Laterosternite with 3 setae. Anal point 38 µm long, lanceolate; lateral projection 13 µm long, slender and apically pointed. Transverse sternapodeme 23 µm long. Gonocoxite 85 µm long. Superior volsella ( Figure 12C ) 52 µm long, like a great toe, narrowed in the middle, coved with microtrichiae and with 3 apical setae. Inferior volsella 81 µm long, with 5 setae confined to the apex. Gonostylus 117 µm long, with 3 long setae along inner margin. HR 0.74. HV 1.62.

Distribution. The species is only known from the type locality (Oriental China).

Remarks. It is unique in the new species that the superior volsella like a great toe, narrowed in the middle and the inferior volsella with only 5 setae distributed in distal margin.

Figures

FIGURE 12 A – D. Polypedilum (Tripodura) pollicium Zhang & Wang sp. n. A. Wing. B. Fore tibial scale. C. Superior volsella. D. Hypopygium, dorsal and ventral view.