Coelognathus (Helfenberger, 2001)

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 : 22

Coelognathus

Key to Philippine species and subspecies.

1a. Number of subcaudal scales 87–107; number of ventral body scales + subcaudal scales <330; adults lack distinctive black-edged white bars on side of body; juveniles usually with whitish crossbands present............................................................ 2

1b. Number of subcaudal scales 102–114; number of ventral body scales + subcaudal scales> 325; adults and juveniles with a series of short black-edged white bars on side of body................................................................. Coelognathus philippinus

2a. Adults with tail much lighter than posterior portion of body.......................................................................... Coelognathus erythrurus erythrurus

2b. Adults without a distinct change in dorsal color between posterior portion of body and tail; posterior portion of body may or may not be darker than anterior portion of body............ 3

3a. Adults uniform light brown to reddish brown throughout the length of body and tail; no darkening posteriorly................................ Coelognathus erythrurus manillensis

3b. Adults become darker posteriorly along length of body and tail.................................................................... Coelognathus erythrurus psephenourus