Polypedilum (Pentapedilum) trukense (Tokunaga)

Oyewo, Emmanuel Adeoye & Saether, Ole A., 2008, Revision of Polypedilum (Pentapedilum) Kieffer and Ainuyusurika Sasa et Shirasaki (Diptera: Chironomidae), Zootaxa 1953, pp. 1-145 : 114-116

Polypedilum (Pentapedilum) trukense (Tokunaga)

( Figs 38A–F)

Pentapedilum trukensis Tokunaga, 1940a: 223 .

Polypedilum (Pentapedilum) trukensis Tokunaga, 1964: 601 .

Material examined. PALAU: Babelthuap Island, Ngerehelong, 1 male, 08.v.1957, C. W. Sabrosky (M-1); Babelthuap Island , Ngaremlengui, 1 female, 03.vi.1957, light trap, C. W. Sabrosky (M-1)( BM). FEDER- ATED STATES OF MICRONESIA: Truk, Moen Island, Mt. Teroken , 150 m a.s.l., male, 27.xii.1952, light trap, J. L. Gressitt (M-9) ( BM) .

Diagnostic characters. The superior volsella differs from all other known members within the subgenus by having a peculiar broad, hairy base and a small beak-like projection similar to some members of the subgenus Uresipedilum . The female can be distinguished by the narrow brush-like ventrolateral lobe. The wing length is only 0.88 mm, while all other species examined had a wing length of more than 1.00 mm.

Male (n = 2)

Total length not measurable. Wing length 1.02–1.03 mm. Wing length / length of profemur 2.31–2.38. Brown.

Head. AR 0.80–0.87. Ultimate flagellomere 287–291 µm long. Clypeus with 17 (1) setae. Palpomere lengths (in µm): 23, 26, 70, 75, fifth palpomere lacking. Third palpomere with 3 sensilla clavata.

Thorax. Acrostichals 7–11, dorsocentrals 10–14, prealars 3–4. Scutellum with 7 (1) setae.

Wing. Anal lobe reduced. VR 1.31–1.38. Brachiolum with 1 seta, Sc with 7, R with 22, R 1 with 15, R 4+5 with 25, M with 1, RM with 0, M 1+2 with 36, M 3+4 with 14, Cu with 17 (2), Cu 1 with 5, PCu with 27 and An with 20 setae. Cells r 4+5, m 1+2, m 3+4, cell m basal of RM, cu plus an with few and sparse macrotrichia. Squama damaged, with 2 setae according to Tokunaga (1940a).

Legs. Scale on foretibia 21–31 µm long, rounded, without apical spur. Spurs on midtibia 28–43 µm long, on hind tibia 37–51 µm long. Comb on midtibia 12–14 µm long, combs on hind tibia 13–22 µm and 12–19 µm long. Width at apex of foretibia 29–31 µm, of midtibia 33–35 µm, of hind tibia 33–37 µm. Length and proportions of legs as in Table 48.

Hypopygium ( Figs 38A). Tergite IX with 10 median setae, laterosternite IX with 2 setae. Anal point 35 µm long, 6 µm wide at base, nearly parallel-sided towards 2–5 µm wide apex. Transverse sternapodeme 21 µm long; phallapodeme 49–51 µm long. Gonocoxite 84–96 µm long. Superior volsella ( Fig. 38C) 49–51 µm long, with very broad base, with 1 seta apically on base, no inner seta and short minute beak-like projection, numerous microtrichia present on base. Inferior volsella ( Fig. 38B) 70–79 µm long, with broad apex and prominent apical seta. Gonostylus 103–114 µm long. HR 0.82.

Female (n = 1)

Wing length 0.88 mm. Wing length / length of profemur 2.15. Coloration similar to male.

Head. Temporal setae 7 including 2 inner verticals, 3 outer verticals, 2 postorbitals. Clypeus obscure. Palpomere lengths (in µm): 24, 23, 35, 51, 70. Fifth palpomere / third palpomere 2.0.

Thorax. Acrostichals 6, dorsocentrals 10. Scutellum with 4 setae.

Wing. Anal lobe reduced. VR 1.23. Brachiolum with 1 seta, Sc with 0 seta, R with 10, R 1 with 5, R 4+5 with 14, M with 0, RM with 1, M 1+2 with 21, M 3+4 with 6 setae. Cells with very few macrotrichia. Squama damaged.

Legs. Scale on foretibia 26 µm long. Spurs on midtibia broken, on hind tibia 30 µm long. Comb on midtibia 14 µm long, combs on hind tibia 14 µm and 12 µm long. Width at apex of foretibia 40 µm, of midtibia 36 µm, of hind tibia 40–51 µm. Length and proportions of legs as in Table 49.

Genitalia (not clear) ( Fig. 38D). Gonocoxite with IX 4setae, tergite IX with 16 setae, segment X with 3 setae. Cercus 31 µm long, 5 µm wide at apex. Notum 100 µm long. Dorsomesal lobe ( Fig. 38F) 66 µm long, 34 µm wide; ventrolateral lobe with straight brush ( Fig. 38E), apodeme lobe not discernible. Postgenital plate minute, broadly triangular.

Remarks. The illustration of the volsella in Tokunaga (1964: 591) is not accurate. The superior volsella is stout, more or less rounded and the gonostylus is very slender.

Distribution. Known from Caroline Islands, Federated States of Micronesia and Palau.