Key to world species of Ologamasus, based on adult females

1. Most dorsal idiosomal setae spatulate and pilose............................................................. 2

- Most dorsal idiosomal setae aciculate and smooth (Fig. 5)..................................................... 7

2. Anterior margin of epistome with a median extension flanked by one or two pairs of spine-like extensions.............. 3

- Anterior margin of epistome only with a median extension.................................................... 5

3. Dorsal idiosomal shield with 30 pairs of setae................ Ologamasus simplicitus Karg & Schorlemmer, 2009; Brazil

- Dorsal idiosomal shield with 40-41 pairs of setae............................................................ 4

4. Setae J 3 and J 4 as long as distance between their bases and bases of subsequent J setae; seta Z 5 about 1.6 times as long as J 5.................................................... Ologamasus cananeiae Silva, Moraes & Krantz, 2007; Brazil

- Setae J 3 and J 4 at least 1.2 times as long as distance between their bases and bases of subsequent J setae; seta J 5 as long as Z 5..................................................................... Ologamasus foliatus Karg, 1976a; Chile

5. Para-anal seta about twice as long as J v5. ............... Ologamasus trituberculatus Karg & Schorlemmer, 2009; Brazil

- Para-anal seta about as long as Jv5....................................................................... 6

6. Seta Jv 4 about 0.5 times as long as distance between its base and base of Jv 5........................................................................................... Ologamasus brevidigitus Karg & Schorlemmer, 2009; Brazil

- Seta Jv 4 about as long as distance between its base and base of Jv 5.......... Ologamasus aberrans (Berlese, 1888); Brazil

7. Dorsal shield J setae at most 0.8 times as long as distance between their bases and bases of subsequent J setae........... 8

- Dorsal shield J setae at least as long as distance between their bases and bases of subsequent J setae.................. 12

8. Ventrianal shield fused with dorsal shield only by a narrow area posterior to anus..................................................................................... Ologamasus brevisetosus Karg & Schorlemmer, 2009; Ecuador

- Ventrianal shield totally fused with dorsal shield, except anterolaterally.......................................... 9

9. Dorsal idiosomal setae minute (2–4 µm)............................ Ologamasus microcrinis (Karg, 1979); Argentina

- Dorsal idiosomal setae short, but not minute (≥ 10 µm)...................................................... 10

10. Posterior margin of genital shield truncate; ventrianal shield smooth............ Ologamasus distorta (Karg, 1976a); Chile

- Posterior margin of genital shield convex; ventrianal shield striate............................................. 11

11. Ventrianal shield with eight pairs of setae (Jv 2 present)................... Ologamasus lanceolatus (Karg, 1976a); Chile

- Ventrianal shield with seven pairs of setae (Jv 2 absent)..................... Ologamasus cavei Sheals, 1962; Argentina

12. Ventrianal shield fused with dorsal shield only by a narrow area posterior to anus................................. 13

- Ventrianal shield totally fused with dorsal shield, except anterolaterally (Fig. 6)................................... 17

13. Ventrianal shield with seven pairs of setae (Zv 3 present)................. Ologamasus membranosus Karg, 1976a; Chile

- Ventrianal shield with six pairs of setae (Zv 3 absent)........................................................ 14

14. Opisthonotal region of dorsal idiosomal shield with 20 pairs of setae (R 1- R 5 present).............................. 15

- Opisthonotal region of dorsal idiosomal shield with 16 pairs of setae (R 1- R 4 absent)............................... 16

15. Setae j 6 and J 1 respectively at most 0.9 times as long as distance between their bases and bases of J 1 and J 2; ventrianal shield smooth...................................................... Ologamasus striolatus (Berlese, 1916); Argentina

- Setae j 6 and J 1 respectively at least 1.5 times as long as distance between their bases and bases of J 1 and J 2,; ventrianal shield imbricate....................................................... Ologamasus striolatosimilis Karg, 1976a; Chile

16. Reticulation of dorsal idiosomal shield with transversally elongate cells; podonotal region of dorsal idiosomal shield with 21 pairs of setae (s 1, s 4 and r 1 absent); sternal shield reticulate..... Ologamasus postpilus Karg & Schorlemmer, 2009; Brazil

- Reticulation of dorsal idiosomal shield with roundish cells; podonotal region of dorsal idiosomal shield with 20 pairs of setae (s 1, s 4, r 1 and r 2 absent); sternal shield longitudinally striate. Ologamasus latoventer Karg & Schorlemmer, 2009; Paraguay

17. Anterior margin of epistome convex and denticulate; genital shield wider than long (including membranous flap); ventrianal shield with seven pairs of setae (not bearing Jv 5)......................... Ologamasus testudinis (Karg, 1976b); Chile

- Anterior margin of epistome with a median extension variously denticulate (Fig. 3); genital shield as long as wide (including membranous flap) (Fig. 6); ventrianal shield with eight pairs of setae (bearing Jv 5) (Fig. 6)......................... 18

18. Sternal shield imbricate; genital shield striate laterally, smooth elsewhere; unsclerotised strip of integument separating ventria- nal from dorsal shield extending to region between Zv 2 and Zv 3 (Fig. 18)........... Ologamasus delaliberai n. sp.; Brazil

- Sternal shield reticulate near st 1 and with longitudinal and parallel striae elsewhere; genital shield striate; unsclerotised strip of integument separating ventrianal from dorsal shield extending almost to Jv 5..................................... 19

19. Podonotal region of dorsal idiosomal shield with 21 pairs of setae (s 1, s 4 and r 1 absent); opisthonotal region of dorsal idio- somal shield with 20 pairs of setae (Z 4 and R 5 present); setae Jv 3 and Zv 2 at least as long as distance between their bases and bases of Jv 4 and Zv 3 respectively................................. Ologamasus simplicior (Berlese, 1914); Argentina

- Podonotal region of dorsal idiosomal shield with 20 pairs of setae (z 4, s 1, s 4 and r 1 absent); opisthonotal region of dorsal idio- somal shield with 18 pairs of setae (Z 4 and R 5 absent) (Fig. 5); setae Jv 3 and Zv 2 at most 0.7 times as long as distance between their bases and bases of Jv 4 and Zv 3 respectively (Fig. 6)............................ Ologamasus lucasi n. sp.; Brazil