Ablabesmyia (Karelia) illinoensis Malloch

Ablabesmyia (Karelia) illinoensis (Malloch)

(Figs 2 A; 3 A; 4 A, H; 5 C; 6)

Material examined. CANADA: Manitoba, Lake Winnipeg: Pine Dock, 1 male, 10.vii. 1969; 3 km off Grand Rapids, 1 male, 13.vii. 1969; Gull Harbour, 1 male, 16.vii. 1969; Gimli Government Wharf, 1 male, 24.vii. 1969; Victoria Beach, 25.vii. 1969; Beaver Point, 2 males, 6. & 11.viii. 1971; 20 Mile Creek, 2 males, 6.viii. & 1.ix. 1971; Hecla Island, 10 males, 27.vii. 1971; Beaver Creek, emergence trap, 1 male, 14.vii. 1971, 1 male reared from larva, 8.vi. 1971.

The blade of the aedeagus of the male in all the Lake Winnipeg specimens is broad to near apex and with a short pointed mesally directed apex (Fig. 6 D; Roback 1959 figs 38, 39) i. e. different from that drawn by Roback (1971 fig. 561) and closer to A. (K.) philosphagnos (Roback 1971 fig. 564). Roback (1971 fig. 588), however, seems to indicate a blade close to the one found in the Lake Winnipeg population. The larval maxillary palp has an indication of a partially sclerotized third basal segment, i.e. different from Roback (1985 fig. 34).

Pupa (n = 1). Total length 5.62 mm. Exuviae pale.

Cephalothorax. Thoracic horn (Fig. 2 A) 527 µm long, 221 µm wide, 2.38 times as long as wide; respiratory duct (Fig. 2 A) expanded at apex to form a T, but can take different appearances depending on viewing angle. Thoracic comb (Fig. 2 A) consisting of about 13–16 larger and 10 minute spines.

Abdomen. Anal lobe (Fig. 3 A) 1.15 times as long as wide, outer margin distad of distal setae with 1–2 erect spinules and about 7 weaker ones.

Fourth instar larva (n = 1). Head capsule length 1.04 mm.

Head. Antenna as in Fig. 4 A. Lengths of antennal segments (in µm): 485, 78, 6, 5. AR 6.08. Basal antennal segment 31 µm wide, ring organ 0.54 from base, blade 82µm Apical style of second segment 9 µm long, accessory style 5 µm long. Mandible 187µm long. Maxillary palp (Fig. 5 C) with a weakly sclerotized base or basal segment 22 µm long and 19 µm wide, and 2 additional segments; penultimate segment 50 µm long, 17 µm wide; ultimate segment 58 µm long, 10 µm wide. Ligula (Fig. 4 H) about 110 µm long. Paraglossa 56 µm long. Hypopharyngeal pecten with 19 teeth.

Abdomen. Procercus 136 µm long, 50 µm wide, 2.72 times as long as wide. Anal setae 859 µm long, supraanal seta 423 µm long, supraanal seta/anal setae 0.49. Anal tubules 270 µm long. Posterior parapods about 870 µm long, with 2 claws distinctly darker than the rest.

Remarks. Malloch (1915: 376) in his description of the pupa mentions a long conspicuous hair on the thoracic horn. This in most likelihood is a hair from the thorax.

Distribution and ecology. The species is known from the Northwest Territories and Alberta to Québec and from New York and Maine to Colorado, New Mexico, Kansas and West Virginia (Oliver et al. 1990: 11) and possibly from North and South Carolina (Roback 1985: 174, Hudson et al. 1990: 3, Epler 2003, Ashe & O’Connor 2009: 122). Miller (1941: 63) found A. (K.) illinoensis both above and below the thermocline of the oligotrophic Costello Lake, Ont. In Lake Winnipeg the species apparently is most common in the Narrows with records also from Victoria Beach, Gimli and Grand Rapids.