Leuctra tenuis

1 Dorsal process on 7 th abdominal tergum tapering to a single, narrowly-rounded posterior lobe, overall shape triangular (Figs. 10 ‒11, 23‒25)..……………….………...........…… 2

1’ Dorsal process on 7 th abdominal tergum narrowing little posteriorly, overall shape variable (Figs. 1‒3, 19, 34‒36, 43, 48).……….… 3

2 Subanal lobe ca. ¾ length of the specillum (Figs. 28‒30, 32); specillum simple, lacking spurs or tubercles distally (Figs. 27, 31, 33)...…………………………...….… L. tenuis (Pictet)

2’ Subanal lobe ca. equal length to specillum (Figs. 14‒15); specillum with a prominent, laterally-directed spur (Figs. 12‒13) ………………………... L. schusteri sp. n. Grubbs

3 Posterior margin of 7 th abdominal dorsal process terminating along the same plane, overall shape symmetrically-trapezoidal (Figs. 43, 48).......................................…………………... 4

3’ Dorsal process on 7 th abdominal tergum variable, overall shape variable (Figs. 1‒3, 19, 34‒36)..…………………………………………… 5

4 7th abdominal dorsal process bearing three subtruncate lobes, lateral lobes small, medial lobe ca. 4X wider than lateral lobes (Fig. 43); specillum bearing tubercles distally and along the outer distal margin (Figs. 44‒47); late winter and spring-emergent species...... L. usdi Grubbs

4’ 7th abdominal dorsal process lacking distinct lateral lobes, essentially straight along posterior margin (Fig. 48); specillum lacking tubercles along distal outer margin and at the tips (Figs. 49‒52); autumn-emergent species ……………………………... L. variabilis Hanson

5 7th abdominal dorsal process bearing three rounded lobes, medial lobe narrowly-rounded posteriorly and nipple-like (Figs. 34‒36); autumn- and winter-emergent species.……………………………..… L. triloba Claassen

5’ 7th abdominal dorsal process lacking distinct lobes, medial posterior portion either broadlyrounded or subtriangular (Figs. 1‒3, 19); late spring- and summer-emergent species ….....… 6

6 7 th abdominal dorsal lobe broadly rounded posteriorly (Figs. 1‒3); specillum subtriangular distally (Figs. 4, 7, 9), subanal lobes recurved anteriorly, but not at tip (Figs. 4, 6, 9) …………………...…….. L. carolinensis Claassen

6’ 7 th abdominal dorsal process broadly subtriangular posteriorly (Fig. 19); specillum truncate distally (Fig. 22), subanal lobes sharply recurved anteriorly at tips (Figs. 21‒22).……………………………….. L. tenella Claassen