Key to Afrotropical species of Hercostomus (males)

1. R4+5 and M1+2 inconspicuously or slightly convergent; fore tarsomere 3 neither flattened nor widened; fore tarsomeres 4–5 simple ............................................................................................... 2

– R4+5 and M1+2 distinctly convergent; fore tarsomere 3 compressed and widened, rarely simple; if fore tarsomere 3 simple, then fore tarsomeres 4–5 flattened and widened ....................................... 4

2. Lower postocular setae black; cercus regularly subtriangular, black (Grichanov 2004: fig. 24); body 2.3–2.6 mm [Republic of the Congo, Equatorial Guinea] ............... H. intercedens Grichanov, 2004

– Lower postocular setae white; cercus elongate, narrow, with basoventral lobe yellow (Fig. 1A; Grichanov 1999: fig. 19) ................................................................................................................... 3

3. Mid and hind femora each with ventral row of erect cilia, about as long as diameter of femur (Fig. 1 С); body 3.6 mm [Namibia] .......................................................... H. brandbergensis sp. nov.

– Mid and hind femora without long ventral cilia; body 3.0– 4.5 mm [Cameroon, DR Congo, South Africa, Tanzania, Uganda] ............................................................... H. nectarophagus Curran, 1924

4. Fore tarsomere 3 simple, fore tarsomeres 4–5 flattened and widened, fore tarsomere 4 white and fore tarsomere 5 deep black (Fig. 2 С); body 2.4 mm [Tanzania] ............................ H. fedotovae sp. nov.

– Fore tarsomere 3 compressed and widened, fore tarsomere 4 usually black and fore tarsomere 5 usually white ..................................................................................................................................... 5

5. Fore tarsomere 2 as long as fore tibia; fore tarsomere 3 equal to tarsomere 5 (Grichanov 2004: fig. 22); body 4.3 mm [Tanzania] ........................................................ H. heinrichi Grichanov, 2004

– Fore tarsomere 2 much shorter than fore tibia; fore tarsomere 3 usually not equal to tarsomere 5 ... ........................................................................................................................................................... 6

6. Fore tarsomeres 3–4 shortened; tarsomere 3 not longer than tarsomere 5; cercus with large basolateral lobe bearing several short setae; cercus with long narrow apex bearing several long setae ............ 7

– Fore tarsomeres 4–5 shortened; tarsomere 3 longer than tarsomere 5; cercus various, rarely with drawn-out apex ............................................................................................................................... 10

7. Fore tarsomere 4 with short dorsal lobe; tarsomere 3 nearly equal to tarsomere 5 (Grichanov 1999: fig. 39); body 5.0 mm [Tanzania, Zimbabwe] .................................... H. patellitarsis (Parent, 1934)

– Fore tarsomere 4 without lobe; tarsomere 5 at least twice longer than tarsomere 3 ......................... 8

8. Fore tibia mostly brown, white and swollen in distal ¼; fore tarsomere 2 white (Grichanov 2004: fig. 18); body 5.1 mm [Tanzania] .............................................................. H. freidbergi Grichanov, 2004

– Fore tibia yellow; fore tarsomere 2 mostly black [Tanzania] ........................................................... 9

9. Fore tarsomere 2 with row of hooked cilia; tarsomere 5 3 times longer than tarsomere 3 (Grichanov 1999: fig. 40); body 3.8 mm ................................................................. H. enghoffi Grichanov, 1999

– Fore tarsomere 2 with simple setulae; tarsomere 5 2 times longer than tarsomere 3 (Grichanov 1999: fig. 41); body 3.7 mm ..................................................................... H. selikhovkini Grichanov, 1999

10. Cercus with long basolateral lobe, longer than cercus (Figs 3F, 4F) [South Africa] .......................11

– Cercus with short basolateral lobe, shorter than cercus .................................................................. 12

11. Male face 2.7 times as high as wide in middle; fore tarsomere 3 strongly widened, 2 times longer than wide (Fig. 3C); body 4.9–5.5 mm ............................................................... H. sanipass sp. nov.

– Male face 4.9 times as high as wide in middle; fore tarsomere 3 weakly widened, at least 4 times longer than wide (Fig. 4C); body 3.6–4.1 mm ............................................... H. koshelevae sp. nov.

12. Cercus with large mushroom-like process bearing fan of at least 5 long strong setae; setae at least as long as cercus .................................................................................................................................. 13

– Cercus with short narrow process or low prominence at base, bearing at most 3 strong setae ...... 18

13. Anal lobe of wing with broad and deep postero-proximal emargination (e.g., Fig. 5A; Grichanov 2004: fig. 15) ................................................................................................................................... 14

– Posterior wing margin evenly convex ............................................................................................ 16

14. Postpedicel 2.5–3 times longer than high; fore tarsomeres 4–5 with mostly black accumbent setulae; body 3.4–3.5 mm [Ethiopia] ............................................................... H. kefaensis Grichanov, 2004

– Postpedicel slightly longer than high .............................................................................................. 15

15. Fore tarsomeres 4 and 5 dark, with fringe of white erect hairs, 1.5–2 times longer than diameter of tarsomeres (Grichanov 2004: fig. 14); body 3.6 mm [Ethiopia] ........... H. balensis Grichanov, 2004

– Fore tarsomere 4 with strong basodorsal black spine formed of 3 mostly fused bristles, with brush of white erect hairs; fore tarsomere 5 clear white, with dorsal fringe of white erect hairs, not longer than diameter of tarsomere (Fig. 5 C); body 4.9 mm [Kenya] ............................ H. vikhrevi sp. nov.

16. Fore tarsomere 3 ¼ or 2 ⁄ 5 length of tarsomere 2 (Grichanov 1999: Fig. 42); cercus with only several long cilia in distal part; basolateral process of cercus comparatively small, ¼ length of cercus, with 5–6 long setae (Grichanov 1999: fig. 13); body 4.3 mm [Kenya] ...... H. yakovlevi Grichanov, 1999

– Fore tarsomere 3 3 ⁄ 5 – ¾ length of tarsomere 2; cercus densely covered with long hairs in distal part; basolateral process of cercus large, with at least 10 long setae ...................................................... 17

17. Fore tarsomere 3 strongly widened, about 3 times longer than wide (Grichanov 1999: fig. 44); basolateral process of cercus with about 20 long setae (Grichanov 1999: fig. 12); body 4.6 mm [Yemen] ...................................................................................................... H. scotti Grichanov, 1999

– Fore tarsomere 3 weakly widened, at least 4 times longer than wide (Grichanov 1999: fig. 46); basolateral process of cercus with about 10 long setae (Grichanov 1999: fig. 11); body 3.5–4.1 mm [Ethiopia, Kenya, Uganda] ..................................................................... H. ozerovi Grichanov, 1999

18. Cercus with 2 lateroventral processes; fore tarsomere 3 strongly widened; segment 7 of abdomen at least ¼ longer than epandrium ........................................................................................................ 19

– Cercus with one basolateral prominence; fore tarsomere 3 usually weakly widened; segment 7 of abdomen equal to or shorter than epandrium ................................................................................. 20

19. Fore tarsomere 3 nearly equal in length to tarsomere 2 (Grichanov 1999: fig. 45); distoventral process of cercus narrow, as wide as basoventral process (Grichanov 2011b: fig. 72); body 3.0 mm [South Africa] ...................................................................................................... H. perturbus Curran, 1924

– Fore tarsomere 3 approximately half as long as tarsomere 2 (Grichanov 1999: fig. 48); mid-ventral process of cercus wide, 2 times wider than basoventral process (Grichanov 1999: fig. 15); body 3.5 mm [DR Congo, Kenya, Tanzania] ..................................................... H. wittei Grichanov, 1999

20. Fore tarsomere 3 half as long as tarsomere 2 or shorter; fore tarsomere 1 shorter than tarsomere 2; epandrium slightly projected apicoventrally; cercus with long and narrow distal part .................. 21

– Fore tarsomere 3 ¾ length of tarsomere 2; fore tarsomere 1 longer than tarsomere 2; epandrium strongly projected apicoventrally; cercus relatively broad ............................................................. 22

21. Fore tarsomere 2 slightly longer than tarsomere 1 and 2 times longer than tarsomere 3 (Grichanov 1999: fig. 43); mid tibia without ventral seta; body 4.6 mm [Cameroon] .......................................... .................................................................................................................. H. tobiasi Grichanov, 1999

– Fore tarsomere 2: 2 times longer than tarsomere 1 and 4 times longer than tarsomere 3 (Grichanov 2004: fig. 30); mid tibia with ventral seta at ¾; body 4.5 mm [Tanzania] .......................................... .................................................................................................................... H. ngozi Grichanov, 2004

22. Cercus truncated at apex, with distinct basolateral prominence bearing 2–3 strong setae (Grichanov 1999: fig. 17); body 3.4 mm [Uganda] ............................................. H. mostovskii Grichanov, 1999

– Cercus somewhat projected apicoventrally, with dorsal subapical tubercle and indistinct basolateral prominence (Grichanov 1999: fig. 16); body 3.4 mm [Cameroon, Uganda] .......................................................................................... H. krivosheinae Grichanov, 1999