Amphisbaena Linnaeus 1758

Key to the species of Amphisbaena with two precloacal pores

1. Precloacals pores separated for median hiatus............................................................... 2

- Precloacals pores arranged in a continuous series............................................................ 5

2. 4/4 supralabials....................................................................................... 3

- 3/3 supralabials....................................................................................... 4

3. Nasals paired, postmalar row present, less than 170 body annuli, tail with autotomic constriction, less than 19 dorsal segments in midbody half-annulus................................................................. Amphisbaena kiriri

- Nasals separated by rostral, postmalar row absent, more than 215 body annuli, autotomic constriction of tail absent, 20 or more less than 19 dorsal segments in midbody half-annulus........................................... Amphisbaena carli

4. More than 238 dorsal half-annuli, less than 16 tail annuli, postmalar row absent, tail tip compressed.. Amphisbaena absaberi

- Less than 215 dorsal half-annuli, more than 17 tail annuli, postmalar row present, tail tip rounded....... Amphisbaena hiata

5. Postmalar present..................................................................................... 6

- Postmalar absent...................................................................................... 8

6. Body annuli 216–249; tail tip slightly compressed............................................ Amphisbaena leeseri

- Body annuli less than 207, tail tip rounded.................................................................. 7

7. Dorsal and ventral sulci present; 10–12 dorsal and 10–14 ventral segments to a midbody annulus..... Amphisbaena silvestrii

- Dorsal and ventral sulci absent; 13–19 more dorsal and 16–23 ventral segments to a midbody annulus...................................................................................................... Amphisbaena darwini

8. Dorsal half-annuli less than 139, 9 tail annuli................................................. Amphisbaena brevis

- Dorsal half-annuli more than 150, tail annuli more than 12..................................................... 9

9. Dorsal half-annuli less than 186......................................................................... 10

- Dorsal half-annuli more than 202........................................................................ 13

10. 10 dorsal and 10 ventral segments to a midbody annulus........................................ Amphisbaena crisae

- 12–16 dorsal and ventral segments to a midbody annulus..................................................... 11

11. Dorsal and ventral sulci present......................................................... Amphisbaena neglecta

- Dorsal and ventral sulci absent.......................................................................... 12

12. 12–15 tail annuli; tail representing 6.1%–9.3% of snout-vent length; prefrontals relatively long, representing 27.7%–4.1% (33.4% means, n = 28) of head length........................................... Amphisbaena mebengokre sp. nov.

- more than 16 tail annuli, tail representing more than 13% of snout-vent length, prefrontals relatively small, representing 24.7% of head length (holotype date)........................................................ Amphisbaena anaemariae

13. Body annuli 328‾342................................................................ Amphisbaena filiformis

- Body annuli less than 292.............................................................................. 14

14. Tail autotomic constriction absent........................................................................ 15

- Tail autotomic constriction present....................................................................... 17

15. Tail tip strongly compressed............................................................. Amphisbaena roberti

- Tail tip rounded...................................................................................... 16

16. Tail annuli 13–18, dorsal sulci present...................................................... Amphisbaena dubia

- Tail annuli 20–26, dorsal sulci absent.................................................. Amphisbaena lumbricalis

17. 10 dorsal segments to a midbody annulus.................................................... Amphisbaena caiari

- 12–16 dorsal segments to a midbody annulus............................................................... 18

18. Body annuli 203‾220, caudal annuli 26‾29, dorsal sulci absent............................... Amphisbaena mitchelli

- Body annuli more than 229, tail annuli 18‾24, dorsal sulci present.............................................. 19

19. Tail tip rounded................................................................... Amphisbaena miringoera

- Tail tip slightly or strongly compressed................................................................... 20

20. Body annuli 230‾241, nasal well delimited and in contact in dorsal portion.................... Amphisbaena persephone

- Body annuli 283–292, nasal shield partially distinct........................................ Amphisbaena cuiabana