Bilyjomyia algens (Coquillett) Coquillett, 2009

Niitsuma, Hiromi & Watson, Charles N., 2009, Bilyjomyia, a new genus of the tribe Macropelopiini from the Holarctic (Diptera: Chironomidae), Zootaxa 2166, pp. 57-68 : 62-64

Bilyjomyia algens (Coquillett) new combination

Tanypus algens Coquillett, 1902: 90 ; Walley 1928: 584.

Ablabesmyia algens: Johannsen 1905: 149 ; Kieffer 1906: 43.

Anatopynia (Macropelopia) algens: Sublette 1964: 109 ; Sublette & Sublette 1965: 145. Psectrotanypus (Apsectrotanypus) algens: Roback 1971: 105 .

Macropelopia (Macropelopia) species A: Roback 1978: 161.

Macropelopia (Apsectrotanypus) algens: Roback 1984: 13 .

Macropelopia algens: Fittkau & Murray 1986: 88 , fig. 523C, I.

Apsectrotanypus algens: Oliver et al. 1990: 8 ; Watson 1998: 242.

Material examined. 1 male, USA: Oregon, 11.viii.1992, leg. B. Bilyj; 2 males with their pupal and larval exuviae, 1 female with its pupal and larval exuviae, 3 pupae with 1 of their larval exuviae, 2 pupal exuviae, 1 larva, Washington, 23.vi.1993, leg. C. Watson; 2 larvae, Montana, 9.vi.1996, leg. C. Watson; 2 larvae, Colorado, date unknown, leg. C. Watson.

Description. Male (n = 2). Body length 5.5–6.4 mm.

Coloration. Head yellowish, pedicel brown. Thorax mostly light brown, vittae darker, antepronotum, scutellum, and membranous pleural areas pale. Wing with single dark band. Legs generally yellowish; apex of femur, base of tibia, and ta4, 5 dark brown. Abdominal tergites I–V yellowish; T.VI–VIII extensively dark brown. Hypopygium dark brown.

Head. Temporals 50–51. AR 1.9–2.0. Clypeus with 15–23 setae. Pm5 1.5 times as long as Pm4.

Thorax. Antepronotals 23–24, acrostichals about 100–150, dorsocentrals about 60–75, humerals about 25–30, supra-alars 43–45, postalars 1, pteropleurals 6–10, mesosternals 2–3, scutellars 61–67, postnotals 13–18. Small scutal tubercle present, 44 μm long, 8 μm high (n = 1).

Wing. Length 4.3–4.4 mm. Squama with 80–95 setae; VR 0.90.

Legs. Spur of foretibia 90–95 μm long with 18–20 lateral teeth; spurs of midtibia 98 and 70–78 μm long each with 19–20 lateral teeth; spurs of hind tibia 100 and 65–75 μm long with 16–17 and 18 lateral teeth, respectively; comb of hind tibia consisting of 11–12 spines. LR1 0.70–0.71; LR2 0.58; LR3 0.65–0.69. BR1 4.8–5.6; BR2 4.0–4.1; BR3 5.1–5.4. Claw pointed apically with 4–5 basoventral spines.

Hypopygium. Tergite IX with 3–7 posterior setae (n = 3). Gonocoxite 250–275 μm long, 2.4–2.5 times as long as broad at middle. Gonostylus 140–145 μm long with 1 apical megaseta; HR 1.6–1.7. Phallapodeme with strong bend near mesial end.

Female (n = 1). Body length 4.7 mm.

Coloration. Similar to male, except all abdominal tergites pale. Wing pattern more extensive, but base of anal cell pale.

Head. Temporals 49. Antenna with terminal flagellomere almost as long as preceding 3 segments together; AR 0.25. Clypeus with 27 setae. Pm5 1.7 times as long as Pm4.

Thorax. Antepronotals 34; acrostichals, dorsocentrals and humerals numerous; supra-alars 57; postalars 1; pteropleurals 10; mesosternals 16; scutellars 92; postnotals 6. Scutal tubercle not apparent.

Wing. Length 4.4 mm. VR 0.90. Squama with 78 setae.

Legs. Spur of foretibia 95 μm long with 19 lateral teeth; spurs of midtibia 105 and 80 μm long with 18 and 19 lateral teeth, respectively; spurs of hind tibia 108 and 80 μm long with 15 and 18 lateral teeth, respectively; comb of hind tibia consisting of 13 spines. Midleg with 16 sensilla chaetica on apical 0.07 of ta1, and hind leg with 16 sensilla chaetica on apical 0.05 of ta1. LR1 0.69; LR2 0.58; LR3 0.7. Claw pointed apically with 4–5 basoventral spines.

Genitalia. Notum 155 μm long, 1.5 times as long as rami. Segment X without setae. Seminal capsule ovoid, 110 μm long, 85 μm wide; capsule including neck region infuscated.

Pupa (n = 8). Body length 7.1–9.0 mm.

Coloration. Exuviae mostly brown; abdominal tergites lighter laterally and posteriorly.

Cephalothorax. Thoracic horn 495–636 μm long, 1.6–2.1 times as long as its broadest width. Plastron plate 202–343 μm long, 0.7–1.0 times as long as broad and occupying distal 0.41–0.54 of horn; median aeropyle occasionally indistinct; lateral aeropyle close to basolateral corner of plastron plate, and its opening prominent and spherical. Thoracic seta Dc1 55–88 μm long, 0.71–0.88 times as long as Sa; Dc2 3–8 μm long.

Abdomen. Scar of T.I 105–170 μm long, 0.32–0.45 times as long as tergite along median line. Tergite IV with D1-seta 175–220 μm long and 0.27–0.35 times as long as segment; with D2-seta 275–370 μm long and 0.44–0.57 times as long as segment; and with D3-seta 290–365 μm long and 0.46–0.61 times as long as segment. LS1-seta of A.VII located 0.47–0.60 from anterior margin, of A.VIII located 0.60–0.67 from anterior margin. Anal lobe 1167–1624 μm long, 2.7–2.9 times as long as broad, with posterior macroseta located 0.28–0.30 from anterior margin; outer margin either straight or slightly concave in distal third; inner margin with 15–23 spinules on distal 0.38–0.49. Male genital sac 0.32–0.35 times as long as anal lobe.

Fourth instar larva (n = 9). Total length 6.2–11.2 mm.

Head. Length 859–1066 μm. IC 0.71–0.73. Labral sclerite rounded, compact, and 0.07–0.10 times as wide as distance between two labral setae S2-S2. Cephalic seta S10 2.0 –2.5 times as long as S9. Antenna 1.2 times as long as mandible; AR 6.8–7.9; first segment 238–275μm long with ring organ placed 0.77–0.80 from base; blade 30 μm long, reaching middle of segment 4; accessory blade 25–28 μm long. Second segment 18–23 μm long, 3.5–4.0 times as long as wide; style 15 μm long, reaching segment 4; peg sensilla 8 μm long. Mandible 212–245 μm long. Basal segment of maxillary palp 60–75 μm long, 3.3–3.7 times as long as wide; ring organ located 0.21–0.27 from base. Dorsomental plate with 6–7 large teeth and usually 1 small tooth. Ligula 115–143 μm long, 1.5–1.6 times as long as its toothed width; median tooth 1.5–1.8 times as long as wide; inner laterals pointed forward. Paraligula 58–65 μm long; outer tooth 4–10 times as long as inner tooth. Pecten hypopharyngis with 1 or 2 broadened mesal teeth, 12–16 simple teeth and 5 or 6 small points.

Body. Procercus 3.8–4.1 times as long as wide.

Remarks. On the basis of a single specimen, Roback (1984) noted the pupa of Bilyjomyia algens has two aeropyles at basal corners of the plastron plate. Examination of more specimens, however, revealed that the pupa usually has three aeropyles. He also overlooked a bundle of tracheae running through the horn sac.

Roback (1978) assigned some unassociated pupae from western North America to the Macropelopia notata group as Macropelopia (Macropelopia) species A. It is apparent from his description and figures that they are Bilyjomyia algens .