Ablabesmyia (Ablabesmyia) aspera (Roback)

Saether, Ole A., 2011, Notes on Canadian Ablabesmyia Johannsen, with keys to known Nearctic immatures of the genus (Diptera: Chironomidae), Zootaxa 3069, pp. 43-62 : 54-56

Ablabesmyia (Ablabesmyia) aspera (Roback)

( Fig. 8 A–C)

Material examined. CANADA: Manitoba, Lake Winnipeg, 3 km off McCreary Island, 1 male, 15.vii. 1969; Grand Rapids Government Wharf, 3 males, 28.vii. 1969; Pine Dock, 8 males, 31.vii. 1969; Beaver Point, 3 males, 27.vii. & 6.viii. 1971; Old Fishing Dock, 1 male, 18.viii. 1971; Calder's Dock, 11.viii. 1971.

Male (n = 2–3). Total length 4.16–4.67 mm. Wing length 2.30–2.50 mm. Total length/wing length 1.81–1.87. Wing length/profemur 2.73–2.86. Thorax brown to dark brown, vittae not too distinct; preepisternum anepisternum and postnotum dark brown; scutellum more pale. Tergite I with weak anterior infuscation, tergite II–V clear, tergites Vi–VII dark, tergite VIII dark in anterior half. Front leg with femur dark in 0.74–0.88, slightly infuscate at base; tibia with dark band at 0.13–0.21, 0.58–0.63 and 0.94–1.00; ta1 with band at 0.31–0.40 and 0.88–1.00; ta2 and ta3 dark band at apex, ta4 and ta5 darker. Mid leg with femur dark in 0.76–0.88, slightly infuscate at base; tibia with dark band at 0.15–0.23, 0.63–0.68 and 0.94–1.00; ta1 with band at 0.30–0.39 and apex; ta2 and ta3 dark band at apex, ta4 and ta5 darker. Hind leg with femur dark in 0.75–0.87, slightly infuscate at base; tibia with dark band at 0.15–0.24, 0.51–0.63 and 0.93–1.00; ta1 with band at 0.30–0.39 and apex; ta2 and ta3 dark band at apex, ta4 pale in basal half, dark in apical half; ta5 dark. Wing with dark spots exactly as in Roback (1971 fig. 606).

Head. AR 1.92–2.12. Temporals 35–36, consisting of about 10–11 inner verticals, 12–15 outer verticals and 10–13 postorbitals. Clypeus with 35–38 setae. Cibarial pump, tentorium, and stipes as in Fig. 8 A. Tentorium 188– 221 µm long, 64–71 µm wide. Stipes 158–169 µm long, 56–60 µm wide. Palp lengths (in µm): 53–56, 131–150, 161–188, 120–135, 263–315.

Thorax. Antepronotum with 12–15 setae. Scutum anteriorly with row of about 30–35 tubercles. Dorsocentrals 34–42, acrostichals about 50–55, prealars 26–28, supraalar 1. Scutellum with 28–32 setae.

Wing. VR 0.82–0.88. Brachiolum with 2 setae, squama with 48–53 setae.

Legs. Spur of front tibia 60–64 µm long, with about 11 teeth; spurs of middle tibia 71–79 µm and 34 µm long, of hind tibia 71–83 µm and 38–41 µm. Width at apex of front tibia 53–60 µm, of middle tibia 56 µm, of hind tibia 56–60 µm. Pseudospurs on ta1 and ta2 of mid and hind leg and occasionally on ta3 of hind leg and ta2 of front leg, 56–75 µm long, placed in apical half. Lengths and proportions of legs as in Table 1 .

Hypopygium ( Fig. 8 B, C; Roback 1971 fig. 7). Tergite IX with 2 setae. Gonocoxite 218–240 µm long, gonostylus 191–210 µm long. Transverse sternapodeme 49–56 µm long, 23–34 µm wide. Blade (superior volsella) 66– 71 µm long, dorsal lobe 45–52 µm long, lateral lobe 26–35 µm long, pars ventralis 24–26 µm long. Apex of gonostylus with about 12 teeth in 12 by 12 µm wide apex. HR 1.14–1.15, HV 2.18–2.24.

Remarks. The larva named Pentaneurini sp. A and assumed to be A. (A.) basalis in Hamilton (1965) keys to A. (A.) aspera except that Hamilton gives an AR of 5.0–5.7 while Roback (1985 Table 10) gives an AR of 4.5–5.2. A. (A.) aspera is listed in Roback (1985: 201) as present in Marion Lake.

A. (A.) aspera is closely related to A. hauberi ( Roback 1985:197) . The blade of the male aedeagus is supposed to be slightly sinuate in A. (A.) hauberi straight in A. (A.) aspera . The largest specimen examined here, from Beaver point, is distinctly sinuate, while the others are very slightly sinuate. According to Bohdan Bilyj (pers. comm.) on uncompressed hypopygia the blade in A. (A.) aspera is curved (or slightly sinuate) upwards (dorsally) so that the focusing has to be adjusted from the base to the apex, while in A. (A.) hauberi the blade lies in the same dorsoventral (horizontal) plane and curves laterally. There are also subtle differences in the dorsal lobe. Once any sort of pressure is placed on the hypopygium then this directional difference of the blade is no longer observable. At least the specimen with the most apparently sinuate blade is as in A. (A.) aspera . All measurements of the examined specimens are as mentioned by Roback (1971: 369) and larger than those given for A. (A.) hauberi . A complete description is given here in order to facilitate the separation of the two species.

Distribution. The species is known from British Columbia to New Hampshire and south to Florida and California ( Roback 1985: 201; Oliver et al. 1990: 10; Hudson et al. 1990: 3; Spies 1999; Epler 2003, 2010; Caldwell 2009; Ashe & O’Connor 2009: 113).

Figures

FIGURE 8. Ablabesmyia spp., male. A – C. A. (A.) aspera Roback, cibarial pump, tentorium and stipes (A), aedeagus (B), hypopygium (C). D – F. A. (A.) basalis (Walley), cibarial pump, tentorium and stipes (D), aedeagus (E), hypopygium (F).

Tables

TABLE 1. Ablabesmyia (Ablabesmyia) aspera (Roback). Lengths (in µm) and proportions of legs:

fe p1 851–907 p2 964–1021 p3 945–1030	ti 1077–1134 973–1049 1295–1323	ta1 851–973 709–841 1105–1229	ta2 ta3 548–643 392–454 463–501 345–387 633–699 463–491	ta4 236–288 203–255 274–340
continued.
ta5 p1 142–170 p2 113–123 p3 142–170	LR 0.79–0.86 0.73–0.81 0.85–0.93	BV 1.90–2.07 2.24–2.38 2.06–2.21	SV 2.04–2.26 2.83–2.84 2.28–2.29	BR 3.6–3.8 5.3–7.9 6.6