Key to the North American species of Hemipenthes

1 Wing entirely infuscated (Fig. 19) ............................................................................................ 17. pullata (Coquillett)

- Wing with at least some area hyaline ......................................................................................................................... 2

2 Setulae on basicosta white and black ......................................................................................................1. albus, n. sp.

- Setulae on basicosta black ............................................................................................................................................ 3

3 Hind femur and tibia with abundant black, broad, flattened scales.............................................................................. 4

- Hind femur and tibia with slender scales...................................................................................................................... 5

4 Cell bm hyaline at center; CuA1 vein with just two sections (Fig. 12) .........................................11. inops (Coquillett)

- Cell bm entirely infuscated; CuA1 vein with just three sections (Fig. 14)......................... 13. lepidota (Osten Sacken)

5 Cell dm entirely hyaline or infuscated just at base ....................................................................................................... 6

- Cell dm at least with the basal third or more infuscated............................................................................................... 7

6 Cell bm entirely infuscated (Fig. 20) .................................................................................... 18. scylla (Osten Sacken)

- Cell bm hyaline in apical half (Fig. 23) .......................................................................................21. translucens, n. sp.

7 Cell r1 and r2+3 entirely infuscated or hyaline just at tip (Fig. 18) ........................................... 16. pleuralis (Williston)

- Cell r1 or cell r2+3 with some hyaline areas ................................................................................................................... 8

8 Cell r1 entirely infuscated except for a hyaline area near tip; half of cell r2+3 infuscated with a color spot at tip (Figs. 3, 13 & 22) .................................................................................................................................................................... 9

- Pigment on cell r1 never reaching wing margin; cell r2+3 with at most basal half infuscated..................................... 11

9 Without a crossvein between R4 and R2+3 (Fig. 22)................................................................ 20. sinuosa (Wiedemann)

- A crossvein between R4 and R2+3 (Fig. 3 and 13)........................................................................................................ 10

10 Cell r5 infuscated beyond R4 vein with just a hyaline area near wing margin (Fig. 3) .... 3. blanchardiana (Jaennicke)

- Cell r5 infuscated at or slightly beyond R4 vein, apical third hyaline (Fig. 13) ........ 12. jaennickeana (Osten Sacken)

11 Cell a hyaline or infuscated just at base (Figs. 9, 10 & 24) ....................................................................................... 12

- Cell a with at least basal half infuscated .................................................................................................................... 14

12 Margin of color in wing smooth and straight not sinuose; cell r1 infuscated at most at its basal half (Fig. 9)............... ............................................................................................................................................................... 8. curta (Loew)

- Margin of color in wing sinuose forming right angles not straight; basal half of cell r1 infuscated (Figs. 10 & 24)..... .................................................................................................................................................................................... 13

13 First abdominal tergite with yellow scales, not dense, not forming a band; second to fourth abdominal tergites with black and yellow scales............................................................................................................... 22. webberi (Johnson)

- First abdominal tergite with a band of white scales; second to fourth abdominal tergites with fulvous scales ............. .................................................................................................................................................9. edwardsii (Coquillett)

14 Hyaline aureoles around bases of cells r4, r5, m2 and cup (Fig. 17) ............................................... 15. morioides (Say)

- Wings without aureoles............................................................................................................................................... 15

15 Fourth abdominal tergite with a stripe of white scales; color in cell a not reaching hind margin of wing (Figs. 2, 7 & 8) ................................................................................................................................................................................. 16

- Fourth abdominal tergite without a stripe of white scales, some white scales may be present but scattered not form- ing a stripe; color in cell a reaching hind margin of wing (Figs. 4, 5, 6, 11, 15, 21 & 25)........................................ 18

16 Face bluntly projecting; mesopleuron and proepimeron black pilose; coxae with black tomentum.............................. ........................................................................................................................................... 6. chimaera (Osten Sacken)

- Face rounded or bluntly projecting; mesopleuron and proepimeron black and yellow pilose; coxae with black and yellow or yellow tomentum ....................................................................................................................................... 17

17 Face bluntly projecting; fifth abdominal tergite with abundant white scales covering the whole tergite ......................

.....................................................................................................................................................7. comanche (Painter) - Face rounded; fifth abdominal tergite with black scales, some white scales may be present scattered at tergite side... ...................................................................................................................................................... 2. bigradata (Loew)

18 Margin of color in wing smooth and straight (Figs. 5, 6, 11 & 15) not sinuose......................................................... 21

- Margin of color in wing sinuose forming right angles (Figs. 4, 21, & 25) not straight.............................................. 19

19 Abdomen with black tomentum overall, not dense ....................................................................... 23. wilcoxi (Painter)

- Abdomen with at least some white or pale yellow scales scattered or forming bands............................................... 20

20 Sides of first, second and anterior half of third abdominal tergites with abundant white hair, abundant black mix with some yellow hairs on rest ............................................................................................................ 19. seminigra (Loew)

- Sides of abdomen with first and basal half of second tergites whitish pilose, rest black pilose... 4. castanipes Bigot

21 Sides of first abdominal tergite white or yellow pilose .............................................................5. celeris (Wiedemann)

- Sides of first abdominal tergite black pilose.............................................................................................................. 22

22 Face rounded; fifth abdominal tergite with white scales; mesopleuron entirely black pilose ........................................ ................................................................................................................................................ 14. martinorum (Painter)

- Face bluntly projecting; fifth abdominal tergite with black scales; mesopleuron mixed black and yellow pilose ........ ...................................................................................................................................................... 10. incisiva (Walker)