Key to the species of Knowltonia

1 Brown or coppery, abdomen comparably colored beneath.......................................................................... 2

- Green, sometimes with weak to strong bronzy or coppery reflections, rarely, bluish or with pronotum violet or predominantly coppery; abdomen green (often bright) or dark beneath............................................ 4

2 Elytra with 3 pairs of distinct, usually strongly marked irregular black or violaceous-black spots that sometimes coalesce longitudinally and usually are narrowly margined with blue-green ........................... 3

- Elytra without black spots, or with weakly marked middle and apical pair (rarely, the latter are strongly evident); if present, basal pair smaller and indistinct; spots not coalesced or margined with blue-green..... .................................................................................................................................. alleni (Cazier) (in part)

3 Male with rami of antennomeres 5–10, or at least 5–6 noticeably asymmetrical (Fig. 8); of antennomere 11 distinctly asymmetrical; dark form known only from Texas .................. atrifasciata (LeConte) (in part)

- Male with rami of antennomeres 5–11 subequal to equal in length (Fig. 4); dark form known from Idaho, Nevada, Utah ........................................................................................................ biramosa Fisher (in part)

4 Abdomen beneath usually green, occasionally with coppery reflection, rarely violet or bluish; if dark, then

male antennomeres 5–10, and usually 11 nearly or entirely symmetrical (Fig. 4); widespread, though not known in Colorado Desert region................................................................................................................ 5 - Abdomen black with coppery, brassy, sometimes slightly greenish reflection; male antennomeres 4–10 highly asymmetrical, the inner rami (when present) at most elongate-triangular, antennomere 11 elongate, sometimes with a tiny inner tooth (Fig. 7); species largely of the Colorado Desert region .... calida (Knull)

5 Abdomen beneath green, occasionally with coppery reflection; male antennomeres, at least 5, 6 and, especially, 11 noticeably asymmetrical, the inner rami usually more stout (Fig. 8)........................................... 6

- Abdomen beneath green or dark, rarely violet or bluish; male antennomeres 5–10, and usually 11 nearly or entirely symmetrical (Figs. 4–5) ....................................................................... biramosa Fisher (in part)

6 Elytra without black spots, or with weakly marked middle and apical pair (rarely, the latter are strongly evident); if present, basal pair smaller and indistinct; spots not coalesced or margined with blue-green..... .................................................................................................................................. alleni (Cazier) (in part)

- Elytra with 3 pairs of distinct, variably sized, usually strongly marked irregular black or violaceous-black spots that only rarely coalesce longitudinally and are narrowly margined with blue-green ......................... ..................................................................................................................... atrifasciata (LeConte) (in part)