Polypedilum (Tripodura) scalaenum (Schrank)

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 : 31-33

Polypedilum (Tripodura) scalaenum (Schrank)

( Figure 14 )

Tipula scalaena Schrank, 1803: 73 .

Chironomus (Polypedilum) scalaenus Schrank, Edwards 1929: 402 .

? Polypedilum scalaenum (Schrank) , Albu 1980: 222.

nec. Polypedilum scalaenum (Schrank) , Ree & Kim 1981: 159, 212 Plate 17.

nec. Polypedilum (Tripodura) scalaenum Sasa, 1985: 8 ; 1988: 18.

Polypedilum (Tripodura) scalaenum (Schrank) , Townes 1945: 38; Rossaro 1985: 9 -table 2, 15- Fig.4 ; Wang 2000: 646; Langton & Pinder 2007: vol. I 186 key, vol. II 119 Fig. 228D.

Material examined: 4 males, CHINA, Fujian Province, Jianning County, the forestry bureau of county town, 25. IX. 2002; light trap, Z. Liu. 1 male, Fujian Province, Fuzhou City, Fuzhou Agricultural College, 22. IV. 1993, light trap, X. Wang. 1 male, Guangdong Province, Fengkai County, Heishiding Natural Reserve, 12. IV. 1985, light trap, X. Wang. 1 male, Sichuan Province, Ya’an City, the river behind Sichuan Agricultural University, 5. VI. 1996, light trap, X. Wang. 1 male, Guizhou Province, Guiyang City, Huaxi, 1050m, 23. VII. 1995, light trap, W. Bu. 1 male, Guizhou Province, Libo County, Maolan Natural Reserve, Sancha River, 420m, 28. VII. 1995, light trap, W. Bu. 9 males, Zhejiang Province, Tiantai County, Baihe Town, 8. VII. 2013, sweep net, X. Qi.

Diagnostic characters. The wing marking pattern, the shape of the anal point and apically rounded fore tibia scale will separate the species from others members of the subgenus.

Male imago (n=7). Total length 2.11–2.65, 2.37 mm. Wing length 1.22–1.58, 1.37 mm. Total length/ wing length 1.57–1.84, 1.74. Wing length/ length of profemur 2.02–2.30, 2.20.

Coloration. Head brown. Thorax dark brown with scutellum and halteres yellowish brown. Legs brown with femur bearing yellow sub-apical ring. Abdominal segments yellowish brown.

Head. AR 0.85–1.19, 1.08. Ultimate flagellomere 347–480, 439 µm long. Temporal setae 7–9, 8; including 2– 3, 2 inner verticals; 3–4, 3 outer verticals and 1–3, 2 postorbitals. Clypeus with 10–15, 13 setae. Tentorium 75–113, 106 µm long; 18–28, 23 µm wide. Palpomere lengths (in µm): 23–28, 26; 29–38, 33; 62–83, 73; 70–94, 87; 133– 150, 139.

Wing ( Figure 14A ). Wing with 4 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. VR 1.17–1.36, 1.28. R with 13–21, 17 setae; R1 with 9–14, 11; R4+5 with 16–21, 18. Squama with 4–7, 6 setae.

Thorax. Dorsocentrals 7–11, 10; acrostichals 8–13, 11; prealars 3–4, 3. Scutellum with 6–9, 7 setae.

Legs. Terminal scale ( Figure 14B ) of front tibia 29–40, 33 µm long, oval and apically rounded. Spur of middle tibia 39–47, 44 um long including 18–23, 21 µm long comb, un-spurred comb 15–23, 18 µm long, spur on hind tibia 48–55, 50 µm long including 23–28, 26 µm long comb, un-spurred comb 18–25, 22 µm long. Width at apex of front tibia 31–43, 37 µm, of middle tibia 34–45, 39 µm, of hind tibia 42–52, 45 µm. Lengths (in µm) and proportions of legs as in Table 1 .

Hypopygium ( Figure 14C, D ). Tergite IX with 6–10, 8 median setae. Laterosternite with 1–2, 1 setae. Anal point 31–55, 47 µm long, lanceolate, narrowed in the middle; lateral projection 10–23, 17 µm long, slender. Phallapodeme 57–75, 66 µm long; transverse sternapodeme 26–38, 32 µm long. Gonocoxite 99–109, 105 µm long. Superior volsella ( Figure 14C ) pad–like, expanded distally, with 2–3 short inner setae and 2 long apical setae. Inferior volsella 53–70, 64 µm long, with 11–16, 13 oral setae and an apical setae. Gonostylus 106–133, 121 µm long, with 5–7 long setae along inner margin. HR 0.77–1.00, 0.87. HV 1.79–2.24, 1.97.

Distribution. Widespread in Holarctic region. The species distributes both Oriental and Palaearctic China.

Remarks. The species is close to P. (T.) quadriguttatum , the differences between the two species see foregoing description on P. (T.) quadriguttatum . Albu (1980) described P. (T.) scalaenum form Romania; according to her figures, the wing marking in cell m1+2 distal to that in cell r4+5 and the anal point with a broad lateral projection, which are characteristics of P. (T.) quadriguttatum , it was probably a wrong identification. Ree & Kim (1981) described P. scalaenum from Korea with a slender and parallel-sided anal point, most likely it was a wrong identification. Sasa (1985, 1988) described the species from Japan with transparent lobe beside anal point and without wing markings, which also might be a wrong identification.

Figures

FIGURE 14 A – D. Polypedilum (Tripodura) scalaenum (Schrank). A. Wing. B. Fore tibial scale. C. Superior volsella. D. Hypopygium, dorsal and ventral view.

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.