Polypedilum (Uresipedilum) excelsius Townes

Saether, Ole A., Andersen, Trond, Pinho, Luiz C. & Mendes, Humberto F., 2010, The problems with Polypedilum Kieffer (Diptera: Chironomidae), with the description of Probolum subgen. n., Zootaxa 2497, pp. 1-36 : 22-24

Polypedilum (Uresipedilum) excelsius Townes stat. n.

Figs 26–31

Polypedilum pedatum excelsius Townes, 1945: 55 .

Material examined. CANADA: British Columbia, Marion Lake at dock and on west shore, 2 males, 7 & 25.v.1965, A.L. Hamilton ( ZMBN).

Diagnostic characters. The males apparently differ from P. p e d a t u m by having R4+5 reaching apex of wing, projection of superior volsella clearly longer than base, third palpomere with 2–3 lanceolate sensilla clavata, squama with about 16 setae and M without setae.

Male (n = 2, except when otherwise stated). Total length 4.39–4.75 mm. Wing length 2.70–3.01 mm. Total length / wing length 1.58–1.63. Wing length / length of profemur 2.47–2.51.

Coloration. Thorax brown with darker vittae, postnotum, preepisternum and much of anepisternum; scutellum pale. Legs beyond coxae pale brown. Abdomen brown, gonocoxite and gonostylus pale.

Head. AR 1.04–1.12. Ultimate flagellomere 633–671 μm long. Temporal setae 12–16 including 3–4 inner verticals, 3–5 outer verticals and 6–7 postorbitals. Clypeus with 25–26 setae. Tentorium 128–150 μm long, 56–68 μm wide at sieve pore. Stipes 150–165 μm long, 45 μm wide. Palpomere lengths (in μm): 41–45, 56– 68, 221–244, 135–165, 229–263. Third palpomere with 2–3 lanceolate sensilla clavata, longest 23 μm long.

Thorax ( Fig. 27 ). Acrostichals 20 (1); dorsocentrals 17–23, including 2 scutal fossal setae in one specimen; prealars 7–8. Scutellum with 22–24 setae.

Wing ( Fig. 28 ). VR 1.15–1.29. R2+3 well separated from R1. R4+5 strongly curved at apex, ending at wing tip. Brachiolum with 2 setae, R with 28–31, R1 with 28–35, R4+5 with 46–55 setae, M bare. Squama with 16 setae.

Legs. Scale on fore tibia ( Fig. 26 ) 38–45 μm long, rounded, without spur. Spur of mid tibia 60–64 μm long including comb, unspurred comb 26 μm long. Spur on hind tibia 64–71 μm long including comb, unspurred comb 30–34 μm long. Width at apex of fore tibia 38–45 μm, of mid tibia 64–68 μm, of hind tibia 71–74 μm. Length and proportions of legs as in Table 3.

fe ti ta1 ta2 ta3 ta4

p1 1096–1200 945–1096 1106–1171 728–794 614–680 473–491

p2 1229–1436 1087–1200 567–614 378–416 302–321 170

p3 1370–1531 1276–1436 879–983 529–586 482–510 279–284

ta5 LR BV SV BR

p1 189–194 1.07–1.17 1.57–1.61 1.84–1.96 3.6–4.0

p2 95 0.51–0.52 3.05–3.25 4.08–4.29 4.4–6.7

p3 113–132 0.68–0.69 2.52–2.61 3.01–3.02 4.0–6.3 Hypopygium ( Figs 29–30 ). Tergite IX with 10–13 strong median setae and altogether 8–10 setae to each side of base of anal point. Anal point 79–90 μm long, parallel-sided. Transverse sternapodeme 68 μm long, phallapodeme 116 μm long. Gonocoxite 184–214 μm long. Gonostylus 165–191 μm long, with 1 apical seta and 4–6 long setae along inner margin. Base of superior volsella ( Fig. 31 ) sparsely covered with microtrichia, 45–49 μm long; with 75–86 μm long apicolateral seta and and row of 6 baso-ventral, inner setae; apical projection 56–60 μm long, upturned at apex. Inferior volsella 135–143 μm long, tapering, with 14–15 setae. HR 1.11–1.12. HV 2.49–2.66.

Remarks. Maschwitz and Cook (2000: 106) synonymized the two subspecies of P. pedatum since they found intermediates in the extent of the downturned curvature of the apical part of wing vein R4+5. In our specimens R4+5 reaches the wing tip in P. excelsius , but ends distinctly before the wing tip in P. pedatum . The projection of the superior volsella is distinctly longer than the base in P. excelsius , at most as long as base in P. pedatum . We found several other differences in measurements making us believe that the two subspecies should be regarded as separate species rather than be synonymized. However, the differences in the number of setae on squama, the number of sensilla clavata on third palpomere, presence or absence of setae on vein M and the other differences in measurements found may not hold up when associated material can be examined.

Figures

FIGURES 26 – 31. Polypedilum (Uresipedilum) excelsius Townes, 1945, male. 26 – spur of foretibia. 27 – thorax. 28 – wing. 29 – hypopygium, dorsal view. 30 – hypopygium with tergite IX and anal point removed, dorsal view left, ventral view right. 31 – superior volsella.