Ablabesmyia (Asayia) annulata (Say)

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 : 59-60

Ablabesmyia (Asayia) annulata (Say)

( Figs 1 ; 2 G; 3 G, 4 G, N; 5 I; 9 D–F; 10)

Material examined. CANADA: Manitoba, Lake Winnipeg: Victoria Beach, 2 males, 9.vii. 1969; Pine Dock, 1 male, 10.vii. 1969; Gull Harbour, 8 males, 16.vii. 1969; Gimli Government Wharf, 3 males, 24.vii. 1969; Victoria Beach, 2 males, 25.vii. 1969; Matheson Island Government Wharf, 1 male, 26.vii. 1969; Grand Rapids Government Wharf, 6 males, 28.vii. 1969; McBeth Harbour, 3 males, 29.vii. 1969; Pine Dock, 3 males, 31.vii. 1969; Beaver Point, 29 males, 3 females, 30.vi. –19.viii. 1971; 20 Mile Creek, 8 males, 26.viii. & 1.ix. 1971; Old Fishing Dock, 691 males, 29.vi. –18.viii. 1971; Calder's Dock, 17 males, 6.vii. –8.ix. 1971; Hecla Island, 9 males, 25.viii. 1971; north of outer buoy of Red River, 1 male reared from larva, 4.vi. 1971; 12 km east northeast of Winnipeg Beach, 1 male reared from larva, 12.vi. 1971; east of Elk Island, 1 male reared from larva, 10.vii. 1971; South Basin, 71 larvae, 4.vi.–31.x. 1969; Narrows, 48 larvae, 4.vi.–31.x. 1969; North Basin, 6 larvae, 9.vii. –31.x. 1969.

This was the only Ablabesmyia common in the bottom samples of Lake Winnipeg. The male, illustrated in Fig. 9 D–F, shows a considerable variation in the coloration of the abdominal tergites. Some specimens have a completely dark abdomen. However, they are easily recognizable by means of the wings and the leg coloration. Furthermore, one of the reared specimens is a female with completely dark abdomen.

Pupa (n = 1–2). Total length 5.95–7.69 mm. Exuviae pale grayish brown.

Cephalothorax. Thoracic horn (Fig.G) 632–761 µm long, 307–368 µm wide, 2.06–2.07 times as long as wide, with apicolateral papilla 0.69–0.87 from base. Thoracic comb (Fig. G) consisting of 15–21 spines, the longest 55– 60 µm.

Abdomen. Tergites with shagreen of multibranched spinulae. LS1-seta on VII located at or posterior to midpoint. Anal lobe (Fig. G) 1.07–1.30 times as long as wide; 2 outer margin with 15 spinules distad of distal setae and about 25 spinules basad of basal seta.

Fourth instar larva (n = 11–16, except when otherwise stated). Total length 7.52–10.07, 8.79 mm. Head capsule length 1.10–1.44, 1.29 mm (107) (see Fig. 10 ).

Head. Antenna as in Fig. 4 G. Lengths of antennal segments (in µm): 558–730, 643 (105, see Fig. 10 ); 80–109, 99; 6–9, 8; 3–5, 4. AR 5.36–6.86, 6.01 (85, see Fig. 10 ). Basal antennal segment 40–50, 45 µm wide; ring organ 0.60–0.64, 0.62 from base; B1 84–110, 100 µm; accessory blade 84–104, 98 µm, long. Apical style of second segment 8–11, 9 µm long; accessory style 3–5, 4 µm long. Mandible 234–280, 252 µm long. Maxillary palp ( Fig. 5 I) 2-segmented; basal segment 62–78, 70 µm long, 20–24, 22 µm wide; apical segment 46–64, 58 µm long; 11–14, 12 µm wide. Ligula ( Fig. 4 N) 164–190, 178 µm long; apices of teeth even, median and inner teeth truncate with paler apices. Paraglossa 72–88, 82 µm long. Hypopharyngeal pecten with 18–21, 20 teeth.

Abdomen. Procercus 343–442, 391 µm high; 60–76, 67 µm wide at base; 5.08–7.02, 5.87 times as high as wide. Anal setae 1300–1509, 1379 µm long; supraanal seta 345–442, 391 µm long; supraanal seta/anal setae 0.25– 0.34, 0.29. Anal tubules 405–527, 469 µm long. Posterior parapods 1104–1594, 1388 µm long; with numerous strong spinulae on distal 0.4–0.5; without any darker claws.

Third instar larva. Head capsule length 0.69–0.85, 0.74 mm (21). AR 3.87–4.84, 4.32 (15). Basal antennal segment 312–374, 344 µm (21) long.

Second instar larva (n = 2). Head capsule length 0.42–0.47 mm. AR 3.52–3.60. Basal antennal segment 170– 184 µm long. (For distribution among instars of head capsule lengths, AR and length of basal antennal segments see Fig. 10 .)

Distribution and ecology. The species is known from Québec to Saskatchewan and south to California, Texas and Florida ( Roback 1971: 379; Hudson et al. 1990: 3; Oliver et al. 1990: 10; Spies 1999; Epler 2003, 2010; Caldwell 2009; Ashe & O’Connor 2009: 121). Sublette (1957: 381) found that A. annulata in Lake Texoma, Oklahoma and Texas, were littoral occurring in depths down to 6 m and with a maximum at 2 m. The unusually blunt teeth of the ligula of A. annulata suggests that the species has a specialized method of feeding, compared to other Ablabesmyia species.

Figures

FIGURE 1. Larval distribution of Ablabesmyia (Asayia) annulata (Say) and A. (A.) mallochi (Walley) in the benthos of Lake Winnipeg.

FIGURE 4. Ablabesmyia spp., larva. A – G. Antenna and antennal apex. H – N. Ligula. A, H. A. (Karelia) illinoensis (Malloch); B, I. A. (K.) philosphagnos Beck et Beck; C, J. A. (K.) pulchripennis (Lundbeck); D, K. A. (A.) mallochi (Walley); E, L. A. (A.) basalis (Walley); F, M. A. (A.) monilis auct nec L.; G, N. A. (Asayia) annulata (Say).

FIGURE 5. Ablabesmyia spp., larva, maxilla dorsal view (A), ventral view (B) and premandible (J). A, D, J. A. (Karelia) philosphagnos Beck et Beck; B, G. A. (A.) mallochi (Walley); C. A. (K.) illinoensis (Malloch); E. A. (K.) pulchripennis (Lundbeck); F. A. (K.) basalis (Walley); H. A. (A.) monilis auct nec L.; I. A. (Asayia) annulata (Say).

FIGURE 9. Ablabesmyia spp., male. A – C. A. (A.) monilis auct nec L., cibarial pump, tentorium and stipes (A), aedeagus (B), hypopygium (C). D – F. A. (Asayia) annulata (Say), cibarial pump, tentorium and stipes (D), aedeagus (E), hypopygium (F).

FIGURE 10. Head capsule length, antennal ratio, and length of basal antennal segment in different instars of Ablabesmyia (Asayia) annulata (Say), A. (A.) monilis auct nec L., and A. (A.) mallochi (Walley).