Preliminary Key to Nearctic Kathroperla Species

1 Lateral pronotal margin of adults usually entirely yellow; female subgenital plate usually reaching posterior margin of sternum 9 (Fig. 4 in Stark & Surdick 1987); egg collar absent and chorionic striations absent (Figs. 20-25); dorsal margin of epiproct usually bicolored with a black anterior band adjacent to a dark brown band (Fig. 1 in Stark & Surdick 1987); basal male cercal segments about 3 times long as wide ………………………………………….. K. takhoma

1’ Lateral pronotal margins of adults with black pigment extending at least a third of the margin length, but often completely dark (Fig. 15); egg collar present, chorionic striations present although sometimes indistinct (Figs. 1-6, 9-14); dorsal margin of epiproct narrow and black; basal male cercal segments about 2-2.5 times long as wide ………………………………...…… 2

2 Dorsolateral margin of male epiproct slanted conspicuously caudad (Fig. 16); egg chorion covered with fine bead-like tubercles poorly organized into striations (Figs. 9-14) ………………………….………………. K. siskiyou

2’ Dorsal margin of male epiproct almost straight; egg chorion covered with thick tubercles organized into well-developed longitudinal striations (Figs. 1-6) …………....….…... K. perdita