Key to species of Sphaerobelum (based mainly on male characters):

1. Femur of legs at mesal margin extended, with teeth (Fig. 13A). Apical margin of prefemur modified, extended into a process..................................................................................................... 2

- Femur of legs not extended, well-rounded (Fig. 17B). Prefemur unmodified........................................ 9

2. Teeth on femur only at apex: 4–6 (Fig. 8A). Anterior telopod consisting of 3 podomeres............................. 3

- Teeth on whole mesal margin of femur:>10. Anterior telopod always consisting of 4 telopoditomeres................... 4

3. Female vulval operculum strongly projecting in two processes. Posterior telopod with telopoditomere 4 tip curved towards immovable finger like a small hook..................................................... S. bicorne Attems, 1938

- Female vulva projecting in a mesal process (Fig. 8B). Posterior telopod: telopoditomere 4 straight, not hooked (Fig. 10E)......................................................................................... S. bolavensis n. sp.

4. Posterior telopod: telopoditomere 4 apex weakly curved towards and overlapping immovable finger. Anterior side of immovable finger with sclerotized spots opposite to tip of telopoditomere 4 (Fig. 12E). Immovable finger in anterior view with a large sclerotized spine...................................................................................... 5

- Posterior telopod: telopoditomere 4 straight, not curved. No sclerotized spots or a spine at immovable finger (Fig. 16E)......................................................................................................... 6

5. Male antennae with 30–35 apical cones. Tergites covered with short setae. Legs orange. Prefemur mesal margin rounded (Fig. 11B)................................................................................... S. phouloei n. sp.

- Male antennae with 65–70 apical cones. Tergites glabrous. Legs light brown. Prefemur mesal margin with indentations like the femur (Fig. 13A)..................................................................... S. denticulatum n. sp.

6. Male antennae red or brown, with>70 apical cones. Tergites matte. First laterotergite weakly projecting posterior-laterally. ...................................................................................................... 7

- Male antennae yellow, with 50–55 apical cones. Tergites shiny, with setae. First laterotergite strongly projecting posterior-laterally................................................................................. S. spinatum n. sp.

7. Tergites glabrous, matte. Endotergum bristles only protruding slightly midway towards margin. Anterior telopod: telopoditomeres 3 and 4 not well-separated in posterior view (Figs 21 B–D)..................................... S. nigrum n. sp.

- Tergites hairy, with pits. Endotergum bristles long, protruding above tergite margin. Anterior telopod: telopoditomeres 3 and 4 well separated........................................................................................ 8

8. Colour dark olive, posterior tergal margins with a broad, light-brown band, antennae and legs conspicuously orange. Prefemur without lateral projection. Apical margins of vulval operculum equally converging towards a mesal tip. Tip of laterotergite 1 slightly extended, well-rounded. Male antennomere 6 thickened...................... S. cattiense Semenyuk et al., 2018

- Colour dark chestnut brown, posterior tergal margins black, legs dark brown, tips light brown. Lateral margin of prefemur with a sharp projection juxtaposed to coxal process. Apical margin of vulval operculum recessed centrally. Tip of laterotergite 1 slightly extended, sharp. Male antennomere 6 axe-shaped....................... S. konkakinhense Semenyuk et al., 2018

9. Posterior telopod without 'hook'......................................................................... 10

- Posterior telopod: telopoditomere 4 apically always with a short recurved 'hook' (Fig. 21E)........................... 13

10. Tergites covered with very long setae. Setae longer than width of tergites (Fig. 6E). Immovable finger of posterior telopod with very long mesal extension (Fig. 18C). Antennae green. Anterior telopod suture between telopoditomeres 3 and 4 weak, not visible in anterior view (Figs 18A, B).......................................................... S. lachneeis n. sp.

- Tergites covered with short setae. Immovable finger of posterior telopod swollen, but not with such a long lateral extension. Anterior telopod: telopoditomeres 3 and 4 well separated...................................................... 11

11. Podomere 3 of anterior telopod distally with a lateral extension. Posterior telopod: telopoditomere 4 distally with an incurved process overlapping with process of podomere 2. Marginal setae of terga not reaching posterior margin. Tergite posterior margin well-rounded, not tesselated..................................................... S. separatum Attems, 1953

- Podomere 3 of anterior telopod cylindrical, without lateral extension. Posterior telopod: telopoditomere 4 without incurved process, but with 3 separate spines. Marginal setae of terga reaching posterior margin. Tergite posterior margin tesselated...................................................................................................... 12.

12. Antennae with>80 apical cones. Legs: femur 2x longer than wide. Tarsi with 7 or 8 ventral spines. Antennae and legs yellow. Vulval operculum well-rounded, not extending............................. S. truncatum Wongthamwanich et al., 2012

- Antennae with <70 apical cones. Legs: femur 1.7 times longer than wide. Tarsi with 7–10 ventral spines. Antennae and legs orange-red............................................................................ S. peterjaegeri n. sp.

13. Tergites glabrous, at least posterior 2/3 of each tergite....................................................... 14.

- Tergites covered with short setae. Dirty olive-brown. Head punctured and densely hirsute........ S. hirsutum Verhoeff, 1924

14. Anal shield with a short, or completely reduced locking carina. Posterior telopod: immovable finger, swollen at inner and mesal margin. Telopoditomere 4 at mid-point strongly curved and overlapping immovable finger (Fig. 22G)............ 15

- Anal shield with long locking carina,> 3X length of tergite carina. Posterior telopod: immovable finger, swollen only at inner margin; mesal margin straight..................................................... S. clavigerum Verhoeff, 1924

15. Anterior telopod: telopoditomeres 3 and 4 clearly separated (Figs 21 B–D). Antennae and legs brown......................................................................................................... S. splendidum n. sp.

- Anterior telopod: telopoditomeres 3 and 4 separation only partly visible in anterior view (Fig. 22D). Antennae and legs red..................................................................................................... 16

16. Process of telopoditomere 2 projecting as high as basal 1/3 of telopoditomere 3+4 (Fig. 22F). Anal shield with a single short locking carinae. Palpi of gnathochilarium, sensory cones located in single field........................ S. laoticum n. sp.

- Process of telopoditomere 2 projecting as high as basal 3/4 of telopoditomere 3+4 (Fig. 25E). Anal shield without locking carinae. Palpi of gnathochilarium, sensory cones located in several clusters........................ S. schwendingeri n. sp.