Gerrhopilidae

Weinell, Jeffrey L., Hooper, Errol, Leviton, Alan E. & Brown, Rafe M., 2019, Illustrated Key to the Snakes of the Philippines, Proceedings of the California Academy of Sciences 66 (1), pp. 1-49 : 14-15

Gerrhopilidae

Represented by a single genus...................................... Gerrhopilus (p. 24)

Homalopsidae Key to Philippine genera.

1a. Supralabial scales do not border eye; frontal scale fragmented into multiple smaller scales; internasal scales paired, positioned posterior to a pair of nasal scales; nasal scales in contact with each other medially ( Fig. 9A )....................................... Cerberus (p. 21)

1b. One or more supralabial scales usually border eye; frontal scale not fragmented; internasal scale single, not paired, and is positioned medially between a pair of nasal scales; nasal scales not in contact with each other medially..................................... Gerarda (p. 24)

Lamprophiidae Key to Philippine genera.

1a. Nasal scale large, round and undivided (Fig. 13A)............... Psammodynastes (p. 31)

1b. Nasal scale divided (Fig. 13B)................................................. 2

2a. Snout broad ( Fig. 18B ); anterior chin shields smaller than or similar in size to posterior chin shields; subcaudal scales unpaired (Fig. 14B)...................................... 3

2b. Snout narrow ( Fig. 18A ); anterior chin shields much larger than posterior chin shields; subcaudal scales paired or unpaired (Fig. 14)....................................... 4

3a. Maxilla not strongly angled; no maxillary diastema, although anterior and posterior maxillary teeth are much larger than intervening teeth; posterior maxillary tooth grooved; five infralabial scales in contact with chin shields, and fourth infralabial scale broadly in contact with the anterior and posterior chin shields for about an equal length ( Fig. 19A )..... Hologerrhum (p. 24)

3b. Maxilla strongly angled; large diastema between anterior and posterior maxillary teeth; posterior maxillary teeth not grooved; one of the following is also true: (1) five infralabial scales in contact with chin shields, and fourth infralabial scale either not in contact with or barely in contact with posterior chin shield ( Fig. 19B ), or (2) four infralabial scales in contact with chin shields, and third infralabial scale either not in contact with or barely in contact with posterior chin shield ( Fig. 19C )........................................... Cyclocorus (p. 22)

4a. Five supralabial scales; subcaudal scales unpaired................ Unnamed genus (p. 35)

4b. Six or more supralabial scales; subcaudal scales paired.............................. 5 5a. Parietal scales in contact with supralabial scales ( Fig. 20A )............ Myersophis (p. 30)

5b. Parietal scales not in contact with supralabial scales ( Fig. 20B )....... Oxyrhabdium (p. 31)

Figures

FIGURE 9. Dorsal view of head of (A) Cerberus schneideri (KU 305489), (B) Opisthotropis typica (KU 327424), (C) Calamaria gervaisii (KU 322329), (D) Liopeltis philippinus (KU 327731). Frontal scale (reddish brown), prefrontal scales (blue), internasal scales (purplish-gray), nasal scales (green).

FIGURE 18. Dorsal head shape and scalation of (A) Oxyrhabdium modestum (KU 311301): narrow snout, (B) Hologerrhum philippinum (KU 330056): broad snout.

FIGURE 19. Ventral view of head of (A) Hologerrhum philippinum (KU 330065): five infralabial scales in contact with chin shields; anterior chin shields broadly contact infralabial scales 1–4; posterior chin shields broadly in contact with fourth and fifth infralabial scales; (B) Cyclocorus lineatus lineatus (KU 346571): five infralabial scales in contact with chin shields; anterior chin shields broadly in contact with infralabial scales 1–4; posterior chin shields broadly in contact with fifth infralabial scale; (C) Cyclocorus nuchalis nuchalis (KU 327765): four infralabial scales in contact with chin shields, anterior chin shields broadly in contact with infralabial scales 1–3; posterior chin shields broadly in contact with fourth infralabial scale.

FIGURE 20. Lateral view of head of (A) Myersophis alpestris (KU 308684), (B) Oxyrhabdium modestum (KU 311301). Parietal scale (blue), temporal scales (green), posterior supralabial scales (purplish-gray).