Trigonotylus

Key to species of Trigonotylus from British Columbia, Yukon, adjacent Northwest Territories and Alaska, and the northwestern United States

1. Hind tibia strongly pilose.......................................................... longipes Slater and Wagner

- Hind tibia not strongly pilose............................................................................ 2

2. Antennal segment I thickened (Fig. 1 B)...................................................... antennatus Kelton

- Antennal segment I slender (Figs. 1 A, C–G)................................................................ 3

3. Antennal segment I dark, often completely dark brown to black; if segment I dark with pale mediodorsal stripe practically spanning full length of segment, than setae fine (Figs. 1 E–F)................................................... 4

- Antennal segment I pale, usually pale yellowish green or greenish brown to darker orange brown, often with indistinct reddish brown to brown stripes on apical region that reach beyond the midpoint of the segment; sometimes with three distinct red to reddish brown longitudinal stripes; if segment I slightly darkened with pale mediodorsal stripe practically spanning full length of segment, than setae stiff (Figs. 1 A, C, E, G)............................................................... 6

4. Antennal segment I less than length of pronotum; segment II short (1.33–1.57 in males and 1.47–1.83 in females); endosomal spicule short and straight (Fig. 2).............................................................. brooksi Kelton

- Antennal segment I equal to or longer than length of pronotum; segment II long (2.10–2.50 in males and 2.23–2.65 in females); endosomal spicule either long and straight or long and gently twisted (Figs. 1 J–K, 2)........................ 5

5. Antennal segment I with fine moderate length brown, suberect setae (Fig. 1 D); endosomal spicule straight (Figs. 1 J, 2).................................................................................................. exilis sp. n.

- Antennal segment I with coarse or stout moderate length black suberect setae; (Fig. 1 F) endosomal spicule gently twisted (Figs. 1 K, 2)............................................................................... setosus sp. n.

6. Endosoma without spicule and with field of spines basal to secondary gonopore; antennal segment I with three red to reddish brown longitudinal stripes (Fig. 1 C); labium longer than 1.7 mm [does not apply in Yukon Territory]; apex of clypeus rather pointed in dorsal view............................................................... caelestialium (Kirkaldy)

- Endosoma with spicule and either with or without field of spines basal to secondary gonopore (Fig. 2); antennal segment I without three reddish stripes; possibly diffusely red or reddish brown with pale mediodorsal stripe, or with diffuse reddish brown apical crown (Figs. 1 A, G); labium less than 1.7 mm [does not apply in Yukon Territory]; apex of clypeus narrow or slightly rounded in dorsal view........................................................................... 7

7. Endosomal spicule small and twisted (Fig. 2); body length short (3.80–4.50 in males and 4.18–5.30 in females); antennal segment I short (0.56–0.65 in males and 0.56–0.78 in females), pale green with contrasting black setae (Fig. 1 E, distal segments yellowish orange; female with hemelytral membrane usually not surpassing proctiger................. flavicornis Kelton

- Endosomal spicule either large and curved or small and straight with apex somewhat expanded (Fig. 2); body length long (4.70–6.10 in males and 5.50–7.10 in females); antennal segment I long (0.60–0.86 in males and 0.60–0.94 in females) with variable coloration and setae (Figs. A, G); remaining segments with variable coloration; female with hemelytral membrane usually surpassing proctiger............................................................................. 8

8. Endosoma with long curved spicule, without field of spines basal to secondary gonopore (Fig. 2); Antennal segment I with stiff black setae (Fig. 1 G); antennal segment II, distal portion of hind tibia, and tarsomeres I and II usually not suffused with red....................................................................................... viridis (Provancher)

- Endosoma with short straight spicule, with field of spines basal to secondary gonopore (Fig. 2); antennal segment I with finer black setae (Fig. 1 A); antennal segment II, distal portion of hind tibia and tarsomeres I and II usually suffused with red.......................................................................................... americanus Carvalho