Hydrophis Latreille 1801
Creators: name: Weinell, Jeffrey L.
name: Hooper, Errol
name: Leviton, Alan E.
name: Brown, Rafe M.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Elapidae
Hydrophis

description: Hydrophis
Key to species reported from or likely to occur in marine waters in the Philippines.
1a. Longitudinal scale rows around thickest part of body> 72.......... Hydrophis annandalei
1b. Longitudinal scale rows around thickest part of body 25–70.......................... 2
2a. Rostral scale fragmented into four or five smaller scales (Fig. 35); dorsal head scales with thickened edges.................................................. Hydrophis anomalus
2b. Rostral scale not fragmented into four or five smaller scales.......................... 3
3a. Ventral body scales large (> 1/4 body width) on anterior part of body and small on posterior part of body.................................................. Hydrophis viperinus
3b. Ventral body scales small on both anterior and posterior parts of body.................. 4
4a. Ventral surface of body uniform yellow or white; dorsal part of body uniform dark brown or black........................................................ Hydrophis platurus
4b. Ventral surface of body not uniform yellow or white; dorsal part of body not uniform dark brown or black............................................................... 5
5a. Mental scale elongate, not triangular (Fig. 36A)................... Hydrophis schistosus
5b. Mental scale triangular, not elongate (Fig. 36B).................................... 6
6a. Enlarged chin shields absent................................................... 7
6b. Enlarged chin shields present, one or two pairs.................................... 8
7a. Midbody scales in> 45 longitudinal rows around body................ Hydrophis stokesii
7b. Midbody scales in <45 longitudinal rows around body................. Hydrophis curtus
8a. Longitudinal scale rows around thickest part of body ≤ 2............... Hydrophis jerdoni
8b. Longitudinal scale rows around thickest part of body ≥ 25........................... 9
9a. Frontal scale and parietal scales more or less fragmented (Fig. 37A)...... Hydrophis peronii
9b. Frontal scale and parietal scales unfragmented (Fig. 37B)........................... 10 10a. Maxillary teeth behind fangs ≥ 9.............................................. 11
10b. Maxillary teeth behind fangs ≤ 8.............................................. 13
11a. Neck width divided by width at widest part of body 0.45–0.56; maxillary teeth behind fangs 14–18.................................................... Hydrophis caerulescens
11b. Neck width divided by width at widest part of body ≥ 0.57; maxillary teeth behind fangs 9–13...................................................................... 12
12a. Interspaces between black transverse dorsal bands thin, less than two scale rows wide..................................................... Hydrophis ornatus or H. inornatus
12b. Interspaces between black transverse dorsal bands broad, more than two scale rows wide.............................................................. Hydrophis lamberti
13a. Width of neck> 1/2 width of widest part of body; anterior temporal scale one......... 14
13b. One or both of the following true: (1) width of neck <1/2 width of widest part of body; (2) anterior temporal scales two................................................ 15
14a. Longitudinal scale rows around midbody 8–18 more than around neck.. Hydrophis belcheri
14b. Longitudinal scale rows around midbody 4–8 more than around neck... Hydrophis spiralis
15a. Head very small, width of neck ≤ 1/3 width of widest part of body; longitudinal scale rows around neck 17–23; ventral body scales of anterior part of body wider than adjacent scale rows; ventral body scales of posterior part of body are divided by a long longitudinal furrow................................................................... Hydrophis gracilis
15b. One or more of the following combinations of characters true: (1) head small or moderate in size, width of neck> 1/3 width of widest part of body; (2) longitudinal scale rows around neck ≥ 23; (3) ventral body scales of posterior part of body not divided by a long longitudinal furrow.......................................................................... 16
16a. Longitudinal scale rows around midbody 29–35; ventral body scales 278–325; dorsal surface of head uniformly dark brown to black............................. Hydrophis coggeri
16b. One or more of the following combinations of characters true: (1) longitudinal scale rows around midbody> 35; (2) ventral body scales> 325; (3) dorsal surface of head has yellow spot behind nostrils and yellow streak behind eye...................................... 17
17a. Anterior temporal scales one................................................. 18
17b. Anterior temporal scales two................................................. 20
18a. Ventral body scales <360; maxillary teeth behind fangs 6–8.... Hydrophis melanocephalus
18b. One or both of the following true: (1) ventral body scales ≥ 360; (2) maxillary teeth behind fangs <6.................................................................. 19
19a. Longitudinal scale rows around midbody 37–45; dorsal body scales on thickest part of body hexagonal or quadrangular........................................ Hydrophis brookii
19b. Longitudinal scale rows around midbody 31–39; dorsal body scales on thickest part of body with rounded or bluntly pointed tips................................. Hydrophis klossi
20a. Width of neck ≤ 1/2 width of widest part of body; longitudinal scale rows around midbody 12–20 more than around neck; anterior surface of body dark with pale oval spots laterally that sometimes connect as crossbands.................................. Hydrophis atriceps
20b. One or both of the following true: (1) width of neck> 1/2 width of widest part of body; (2) longitudinal scale rows around midbody <12 more than around neck; (3) anterior and posterior surface of body dark with distinct white annuli............................ 21
21a. Head yellowish or olive (adults) or black (juveniles); ventral body scales with a black longitudinal stripe that may fade with age; ventral body scales 290–390... Hydrophis cyanocinctus
21b. Head black; ventral body scales usually black; ventral body scales 314–356; [non-marine] endemic to Lake Taal (Luzon).................................... Hydrophis semperi
description: Published as part of Weinell, Jeffrey L., Hooper, Errol, Leviton, Alan E. & Brown, Rafe M., 2019, Illustrated Key to the Snakes of the Philippines, pp. 1-49 in Proceedings of the California Academy of Sciences 66 (1) on pages 25-27, DOI: 10.5281/zenodo.11512680