Polypedilum (Tripodura) trapezium 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 : 33-35

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

( Figure 15 )

Type material. Holotype: male (BDN. 1561), CHINA: Guangxi Autonomous Region, Longsheng County, Sanmen Town, 27. V. 1990, X. Wang, light trap.

Etymology. From Greek, trapezion, trapezium , referring to the shape of the superior volsella. Diagnostic characters. The species differs from other species of the subgenus by trapezium shaped superior volsella, slender and pointed lateral projection of anal point and wing marking pattern.

Male imago (n=1). Total length 2.65 mm. Wing length 1.40 mm. Total length/ wing length 1.88. Wing length / length of profemur 2.23.

Coloration. Head and abdominal segments brown. Thorax brown with darker vittae, postnotum and preepisternum, halteres brown. All femora brown with yellow apices; fore tibia yellow; fore tarsus I–IV yellow with brown apices, tarsus V yellow. Mid and hind tibiae yellowish brown; mid and hind tarsi lost.

Head. AR 0.88. Ultimate flagellomere 399 µm long. Temporal setae 8, including 2 inner verticals, 3 outer verticals and 3 postorbitals. Clypeus with 16 setae. Tentorium 113 µm long, 33 µm wide. Palpomere lengths (in µm): 26, 36, 81, 83, 138.

Wing ( Figure 15A ). Wing with 5 markings, 1 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, 1 obscure spot extending along wing distal margin. VR 1.33. R with 12 setae, R1 with 9, R4+5 with 11. Squama with 5 setae.

Thorax. Dorsocentrals 10; acrostichals 10; prealars 3. Scutellum with 8 setae.

Legs. Terminal scale ( Figure 15B ) of front tibia 29 µm long, triangular and apically pointed. Spur of middle tibia 42 um long including 21 µm long comb, un-spurred comb 16 µm long, spur on hind tibia 42 µm long including 23 µm long comb, un-spurred comb 13 µm long. Width at apex of front tibia 39 µm, of middle tibia 39 µm, of hind tibia 44 µm. Lengths (in µm) and proportions of legs as in Table 1 .

Hypopygium ( Figure 15C, D ). Anal tergite bands not fused at base. Tergite IX with 6 median setae. Laterosternite with 2 setae. Anal point 68 µm long, lanceolate; lateral projection 18 µm long, slender and pointed. Phallapodeme 78 µm long; transverse sternapodeme 34 µm long. Gonocoxite 112 µm long. Superior volsella ( Figure 15C ) trapezium-shaped, tapered distally, with 3 strong setae at apex. Inferior volsella 83 µm long, with 11 setae, some of them split. Gonostylus 143 µm long, with 6 long setae along inner margin. HR 0.78. HV 1.85.

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

Figures

FIGURE 15 A – D. Polypedilum (Tripodura) trapezium Zhang & Wang sp. n. A. Wing. B. Fore tibial scale. C. Superior volsella. D. Hypopygium, dorsal and ventral view.