Chironomus (Lobochironomus)

Saether, Ole A., 2012, The Chironomus group (Diptera: Chironomidae) in Lake Winnipeg, Canada, Zootaxa 3275, pp. 1-19 : 14

Chironomus (Lobochironomus) sp.

( Fig. 8 C)

Material examined. Lake Winnipeg light traps: Pine Dock, 2 males, 31.vii. 1969; Hecla Island, 1 male, 24.viii. 1971.

Diagnostic characters. The adult male is characterized by its brown thorax and abdomen, its pale haltere knob, relatively high frontal tubercles, strongly spatulate anal point, low LR1 (1.73–1.78), few sensilla chaetica (4–9 on each of p2 and p3), and its superior volsella with a broad apical part immersed in the basal part.

Adult male (n = 3, except when otherwise stated)

Total length 4.56–5.83 mm. Wing length 2.69–3.35 mm. Total length/ wing length 1.69–1.86. Wing length / length of profemur 2.32–2.40. Thorax pale greenish brown with blackish brown markings. Abdomen brown. Haltere knob pale.

Head. AR 2.85–3.04. Temporals 28–31(2). Clypeus with 22–34 setae. Tentorium 183–218 µm long. Stipes 186–216 µm long. Frontal tubercles 23–28 µm high, 8–10 µm wide, about as in Shilova (1980 fig. 8A1). Palp lengths (in µm): 40–62, 53–77, 203–240, 186–233, 266–326.

Thorax. Antepronotum bare. Dorsocentrals 16–30, acrostichals 12–14, prealars 5–8, supraalar 1. Scutellum with 14–21 setae.

Wing. VR 1.07–1.08. Brachiolum with 2–3 setae, R with 32–41, R1 with 23–39, R4+5 with 41–47 setae. Squama with 10–26 setae.

Legs. Sensilla chaetica 5–9 at 0.71–0.79 to 0.92–0.94 of ta1 of p2, 4–6 at 0.72–0.74 to 0.92–0.93 of ta1 of p3. Lengths and proportions of legs as in Table 1.

Fe ti ta1 ta2 ta3 ta4 p1 1160–1395 824–1076 1631–1866 (2) 891–1009 (2) 689–807 (2) 555–622 (2) p2 1177–1395 992–1269 689–807 370–487 252–353 168–235 p3 1311–1479 1294–1631 992–1194 521–723 370–471 235–303

continued.

ta5 LR BV SV BR p1 193–235 (2) 1.73–1.78 (2) 1.62–1.63 (2) 1.32 (2) 3.5 (1) p2 84–126 0.64–0.69 2.89–3.27 3.15–3.33 3.8–4.9 p3 101–143 0.73–0.77 2.62–2.93 2.58–2.63 5.0–6.9 (2) Hypopygium ( Fig. 8 C). Tergite IX with 32–38 setae, laterosternites IX each with 3–5 setae. Phallapodeme 123–153 µm long. Transverse sternapodeme 60–67 µm long. Anal point 24–28 µm wide at apex, 11 µm wide at narrowest point. Gonocoxite 205–228 µm long, superior volsella with broad and flat apical part immersed in basal part and its microtrichia, gonostylus 205–240 µm long. HR 0.95–1.00, HV 2.22–2.43.

Remarks. This species also appears most closely related to C. (L.). dorsalis Meigen ( C. (L.) longipes Staeger ) ( Townes 1945: 112, Langton & Pinder 2007: 159, Martin 2012), but differs in the wider projection of the superior volsella. It most probably represent a new species, but in view of the incomplete descriptions of related species and the lack of associated immatures it is better to refrain from naming the species.

Figures

FIGURE 8. Hypopygium. A, B: Benthalia brunneipennis (Johannsen). C: Chironomus (Lobochironomus) sp.