Polypedilum (Tripodura) nudiprostatum, Zhang, Ruilei, Wang, Xinhua & Saether, Ole A., 2006

Zhang, Ruilei, Wang, Xinhua & Saether, Ole A., 2006, Two unusual species of Polypedilum Kieffer (Diptera: Chironomidae) from Oriental China, Zootaxa 1282, pp. 39-48 : 43-45

Polypedilum (Tripodura) nudiprostatum sp. n.

( Figs. 8–12 )

Type material

Holotype male, CHINA: Guangxi Autonomous Region, Longsheng County, Sanmen Town, 26.v.1990, light trap, X. Wang (BDN No.: 01560). Paratype: 1 male, Fujian Province, Jianning County, 26.ix. 2002, light trap, Z. Liu.

Diagnostic characters

The species differs from other species of Tripodura in the shape of the straight superior volsella and the trifid anal point with long lateral processes.

Description

Male (n = 1–2). Total length 1.89 mm. Wing length 1.08–1.24 mm. Total length / wing length 1.75. Wing length / length of profemur 2.37–2.45.

Coloration. Head brown except palpomere yellow. Thorax brown with darker vittae, postnotum and preepisternum. Abdominal segments entirely brown. Fore legs with femora yellow at distal 1/4, other parts brown; mid and hind legs with femora yellow at distal 1/5, others parts brown.

Head. AR 0.58–0.59. Ultimate flagellomere 242–273 m long. Temporal setae 8–9. Clypeus with 13–14 setae. Tentorium 78–94 m long, 20–31 m wide. Palpomere lengths (in m): 25–36, 26–28, 49–55, 65–75, 114–123.

Wing ( Fig. 8 ). VR 1.30–1.33. Brachiolum with 1 setae, R with 12–14, R1 with 8–9, R4+5 with 14–15 setae. Squama with 5–6 setae.

Thorax. Dorsocentrals 13–16, acrostichals 11–14, prealars 3–4. Scutellum with 9–10 setae.

Legs. Terminal scale ( Fig. 9 ) of front tibia 23–26 m long with small spine; spur on mid tibiae 34–42 m long including 18–20 m long comb, un­spurred comb 16–18 m long; spur on posterior tibia 39–42 m long including 21–23 m long comb, un­spurred comb 18–21 m long. Width at apex of front tibia 34–36 m, of mid tibia 46–57 m, of hind tibia 39– 42 m. Lengths (in m) and proportions of legs as in Table 2 .

Hypopygium ( Figs. 10–12 ). Anal tergite bands not fused basally, with 2–3 median setae. Laterosternite with 2 setae. Anal point broad, 63–68 m long, lateral projections very long, strongly sclerotized, without setae, with slightly spatulate apex. Phallapodeme 55–65 m long; transverse sternapodeme 29–34 m long. Gonocoxite 86–101 m long. Superior volsella ( Fig. 10 ) 52–60 m long, with 2 strong inner setae in apical 1/4, 1 outer subapical setae, and about 11–13 slender setae apically. Inferior volsella 65–72 m long, with 6 setae. Gonostylus 94–130 m long, with 3–4 long setae along inner margin and 1 apical seta. HR 0.78–0.91. HV 2.01.

Distribution

The species was collected in Guangxi and Fujian provinces in Oriental China.

Remarks

The superior volsellae of Tripodura either have a base and an apical extension as in other members of Polypedilum or are more or less pad­like or clavate without apical extension. However, there is a large variation within both types. In P. (T.) chelum Vårdal (Vårdal et al. 2002: Fig. 9 C, D) the base is strongly reduced, while other species have a superior volsella practically inseparable from typical Polypedilum s. str. Among the species without extension many are club­shaped and have secondary apical expansions almost appearing as lateral extensions. The superior volsella of P. (T.) abyssiniae Kieffer ( Vårdal et al. 2002: Fig. 17 I), for instance approaches the type found in Uresipedilum . Other species have a slender and even non­clavate superior volsella without a clear apical extension (Type B 2 in Bidawid & Fittkau 1995: Fig. 15). Examples are P. (T.) patulum Bjørlo (Vårdal et al. 2002: Figs. 13 H, I) and P. (T.) albosignatum Kieffer ( Vårdal et al. 2002: Fig. 14 D). The superior volsella of the present species best can be interpreted as an extreme form of the last type, i. e. without apical extension. The lateral projections of the anal point are narrow, parallel­sided, strongly sclerotized and without setae, i.e. different from nearly all other known species in the subgenus with trifid anal point and similar to that figured by Albu (1980: Fig. 151) for P. (T.) pullum (Zetterstedt) .

Figures

FIGURES 8 – 12. Polypedilum (Tripodura) nudiprostatum sp. n., male. 8. Wing. 9. Fore tibial scale. 10. Superior volsella. 11. Hypopygium, dorsal view. 12. Hypopygium, ventral view. Scales = 50 m.

Tables

TABLE 2. Lengths (in m) and proportions of legs of Polypedilum (Tripodura) nudiprostatum sp. n., male (n = 1 – 2).

fe	ti	ta1	ta2	ta3	ta4	ta5	LR
p1 441–525	297–347	651	399	315	242	126	1.88
p2 546–630	389–441	191	106	73	47	42	0.49
p3 578–630	462–546	305–378	168–196	147–175	95–106	58–64	0.66–0.69