Trilepida Hedges, 2011

Luna, Igor Veronese de, Ugalde, Miguel Relvas, Guimarães, Mariana Rocha Santos, Hoffmann, Kauann, Citeli, Nathalie, Kiefer, Mara Cintia & Hamdan, Breno, 2025, Fig. 3 in Positive association between PTN polymorphisms and schizophrenia in Northeast Chinese Han population., Zoological Studies 64 (20), pp. 141-149 : 3-5

Trilepida Hedges, 2011

1. Dorsal scales counted along dorsal midline between rostral and terminal tail scale 217–232; subcaudal scales 18–23; supralabials 2+1; uniformly dark brown colour pattern above and light brown with widely white bordered scales on belly ... Trilepida salgueroi

Key for Typhlopidae (Merrem, 1820)

1. Preocular separated from anterior nasal; preocular contacts second and third supralabials; dorsal scales counted along dorsal midline between rostral and terminal tail scale never exceeding 441 ........................................................................ Amerotyphlops

Amerotyphlops Hedges et al., 2014

1. Scale rows usually 20/20/20 or 20/20/18; dorsal scales counted along dorsal midline between rostral and terminal tail scale 195–287; nasal suture incomplete, not contacting rostral; dorsum generally yellowish brown ........ Amerotyphlops brongersmianus

Key for Alethinophidia families

1. Loreal pit absent; non-solenoglyphous dentition ....................... 2

- Loreal pit present; solenoglyphous dentition ................................ ................................................................... Viperidae ( Crotalinae )

2. Proteroglyphous dentition, absence of loreal scale, short maxila; coral-like colouration (dorsal colour pattern with black, red and white rings) ..................................................................... Elapidae

- Aglyphous or opisthoglyphous dentition, elongated maxilla; varied colouration (if coral-pattern, then usually with loreal and/ or eye diameter greater than its distance from the mouth) ......... 3

3. Internasals + prefrontals counting more than 6 scales ...... Boidae

- Internasals + prefrontals counting 6 or less ................................ 4

4. Four prefrontals .................................................... Tropidophiidae

- Prefrontals in 2 or less ....................... Colubridae and Dipsadidae

Key for Boidae Gray, 1825

1. Labial pits present; top of the head with some plates in the anterior region, larger than the scales on the posterior region ... 2

- Labial pits absent; top of the head entirely covered with small scales ...................................................................................... Boa

2. Shallow labial pits; supralabial in contact with the eye; a single plate between the posterior nasal and preocular; large supraocular present ........................................................................... Epicrates

- Deep labial pits; subocular pits present; more than one loreal between the posterior nasal and preocular pits; supraocular region covered by several small scales ...................................... Corallus

Boa Linnaeus, 1758

1. Posterior dorsal spots not blotched; posterior dorsal saddle spots shape similar to the anterior spots; last lateral ocelli dark brown, black or dark red; tail spots black; tail interspots absent ............... .................................................................................. Boa atlantica

Epicrates Wagler, 1830

1. Lateral stripe absent; dorsal ground colour pale to yellow reddish ......................................................................... Epicrates cenchria

Corallus Daudin, 1803

1. Dorsal scale in almost always over 50 rows; subcaudals 94–137; nasals in contact; supralabials touch the orbit ............................... ........................................................................ Corallus hortulana

Key for Colubridae Oppel, 1811 and Dipsadidae Bonaparte, 1838

1. Nostrils (and usually eyes) facing the top of the head, single internasal ........................................................................ Helicops

- Nostrils and eyes laterally set up; 2 internasals .......................... 2

2. The 2nd supralabials contacting eyes ......................................... 3

- The 2nd supralabial not contacting eyes .................................... 4

3. Parietal scales without yellow ring; dorsum olive-brown or yellowish; body slender posteriorly ...................... Elapomorphus

- Parietal scales with a yellow ring; dorsum pinkish red; body not slender posteriorly ...................................................... Coronelaps

4. Dorsal scales rows in an even number; vertebral row absent .... 5

- Dorsal scale rows in an odd number; vertebral row present ...... 6

5. Dorsal scales in 10 or 12 rows ..................................... Chironius

- Dorsal scales in 14 or 16 rows ......................................... Spilotes

6. Anterior dorsal scales oblique .................................................... 7

- Not as above ............................................................................... 8

7. Dorsal scales keeled; body laterally compressed ............. Spilotes

- Dorsal scales smooth; body dorsoventrally compressed ............... ......................................................................................... Xenodon

8. Dorsal scale rows are typically in different numbers of 21 or 23; but if 21 or 23, the pupil may be elliptical ................................. 9

- Dorsal scales in 21 rows; rounded pupil ................. Tropidodryas

9. Anal plate entire ....................................................................... 10

- Anal plate divided .................................................................... 21

10. One only pair of chinshields ............................................ Atractus

- 2 or more pairs of chinshields .................................................. 11

11. Rounded pupil .......................................................................... 20

- Elliptical or subelliptical pupil ................................................. 12

12. Dorsal scales in 17–19 rows ..................................................... 13

- Dorsal scales in 13–15 rows .............................................. Dipsas

13. Long and slender tail, with more than 100 subcaudal scales ........ ...................................................................................... Siphlophis

- Medium tail, with less than 100 subcaudal scales .................... 14

14. Banded or coral pattern (juveniles or adults), some adults may have gray-darkened dorsum ........................................ Oxyrhopus

- Dorsal lateral bands absent in adults, juveniles may have a white neck collar ................................................................................ 15

15. Subcaudal scales entire; snout slim and moderately prominent .... ..................................................................................... Pseudoboa

- Subcaudal scales divided; snout short and large ...................... 16

16. Rostral spatulate, with a sharp upward tip and a horizontal edge ...................................................................................... Phimophis

- Not as above ............................................................................. 17

17. Ventre blotched or darkened ................................. Paraphimophis

- Ventre uniformly white and immaculate in juveniles and adults .. ................................................................................................... 18

18. Dorsum uniform or with vertebral black stripe from the neck until the tip of the tail; dorsal scales in 19 rows; prefrontal scales paired ........................................................................................ 19

- Dark transversal dorsum spots or blotches; dorsal scales in 17 rows; 1 only prefrontal scale ...................................... Xenopholis

19. Dorsum uniform in juveniles; generally 7 supralabial scales; adults usually have fully black-darkened dorsum .............. Clelia

- Dorsum with longitudinal black stripe from the neck until the tip of the tail in juveniles; generally 8 supralabial scales; dorsum not fully darkened in adults, longitudinal black stripe gets larger in shape ........................................................................... Mussurana

20. Number of subcaudal scales is not much smaller than ventral scales; anterior chinshields are shorter than posteriors ................. .................................................................................... Drymoluber

- Number of subcaudal scales considerably smaller than ventral scales; anterior chinshields equal or longer than posteriors .......... ................................................................................... Drymarchon

21. Nasal scale entire; loreal scale absent ........................... Tomodon

- Nasal scale divided or semi-divided ......................................... 22

22. Loreal scale absent ................................................................... 23

- Loreal scale present or if loreal is fused with prefrontals, there is preocular dark stripe ................................................................. 25

23. Eyes smaller than its distance to the mouth; head indistinct from the neck; small tail; apical pits absent .............................. Tantilla

- Eyes larger than its distance to the mouth; head well distinct from the neck; tail extremely elongated; apical pits present ............. 24

24. Snout slightly elongated and not acuminated; light oral lining; dorsum green to bluish or silver-grey, with a clear metallic shine, at least anteriorly; ventre pale green or whitish ........... Leptophis

- Snout extremely elongated and acuminated, dark oral lining; dorsum brownish or light brown, sometimes with a yellow predominance anteriorly; ventre white or yellowish ...... Oxybelis

25. Rounded pupil .......................................................................... 28

- Elliptical or subelliptical pupil ................................................. 26

26. Eyes are not large and not round; tail not large; cylindrical body and slight cervical constriction; longitudinal stripes or blotches that extended the ventre, well defined or not ................................ .......................................... Dryophylax / Mesotes / Thamnodynastes

- Eyes large and round; large tail; slender neck with head strongly distinct; body slightly or strongly compressed laterally; ventre with no stripes or blotches ........................................................ 27

27. Body not elongated and slightly compressed laterally; dorsal scales in 19 to 23 rows; less than 100 subcaudal scales ................ ...................................................................................... Leptodeira

- Body extremely elongated and strongly compressed laterally; scales of vertebral rows can be highly different from paravertebral rows; dorsal scales in 15 or 17 rows; more than 100 subcaudal scales ............................................................................ Imantodes

28. Number of subcaudal scales equal to or larger than the number of ventral scales ............................................................................ 29

- Number of subcaudal scales smaller than the number of ventral scales ........................................................................................ 30

29. Scales of vertebral row larger than paravertebrals; nasal scale entire; apical pits absent; dorsal scales smooth; 22–26 maxilary teeth .............................................................................. Cercophis

- Dorsal scales uniform; nasal scale divided; apical pits present; scales keeled; 33–36 maxilary teeth ............................. Leptophis

30. Double anterior temporal scale ................................................ 31

- Single anterior temporal scale .................................................. 32

31. Loreal scale separated from prefrontal; dorsal scales in 15 rows ..................................................................................... Palusophis

- Loreal scale fused with prefrontals; dorsal scales in 17 rows ....... ..................................................................................... Caaeteboia

32. More than 85 subcaudal scales ................................................. 33

- Less than 85 subcaudal scales .................................................. 36

33. Immaculate ventre, without stripes or blotches ........................ 34

- Ventre with longitudinal black stripe usually present .............. 35

34. Light oral lining ................................... Philodryas / Pseudablabes

- Dark oral lining ......................................................... Chlorosoma

35. Dorsal line absent or discreet ................................... Amnisiophis

- Dorsal line present .................................................. Echinanthera

36. Pattern of midventral colouration without longitudinal stripe ...... ................................................................................................... 37

- Midventral pattern of colouration with a black longitudinal continuous stripe .......................................................... Sordellina

37. Belly with no continuous series of lateral black dots .................... .............................................................................. Erythrolamprus

- Two continuous series of lateral black dots on the belly .......... 38

38. Dorsal scales in 15 rows ....................................... Adelphostigma

- Dorsal scales in 17 rows ........................................... Dibernardia