Hebius, Thompson, 1913

Hauser, Sjon, Smits, Ton & David, Patrick, 2022, On the distribution of the species of the genus Hebius Thompson, 1913 (Squamata Natricidae) in northern Thailand, including the description of a new species and a discussion on snake diversity of this region, Zootaxa 5116 (1), pp. 1-39 : 30-31

The nine species currently known from Thailand can be separated by the following key:

1A. 17 dorsal scale rows at midbody......................................................... Hebius groundwateri

1B. 19 dorsal scale rows at midbody......................................................................... 2

2A. Dorsal scales strongly keeled and notched posteriorly; dorsal pattern made of a pale dorsolateral stripe, edged above and below by a dark stripe; broad, black postocular streak extending from the corner of the mouth onto the neck..... Hebius bitaeniatus

2B. Dorsal scales not strongly keeled or notched posteriorly; dorsal pattern not made of longitudinal stripes; no black postocular streak............................................................................................... 3

3A. A broad, white stripe from the tip of the snout to the corner of the mouth, extending on the nape and forming a conspicuous chevron............................................................................. Hebius leucomystax

3B. Supralabials not covered with a white stripe, more or less patterned or overall dark................................. 4

4A. Venter largely black; on each side, a dorsolateral series of large, elongate blotches, yellow-ochre, or yellowish-brown, orange or rusty red, enlarged on the first quarter to third of the body, progressively smaller and united, forming a dorsolateral stripe. ................................................................................................... 5

4B. Venter largely pale, with only tips of ventral plates ornate with pink, grey or black; pattern not made of large, elongate blotches, yellow-ochre, or yellowish-brown, orange or rusty red........................................................ 6

5A. Venter with three parallel rows of dark blotches separated by narrow pale lines; usually less than 163 ventral plates; base of tail with weakly keeled scales............................................................. Hebius deschauenseei

5B. Venter either uniformly very dark brown or black or with 4 or 5 rows of nearly continuous dark blotches separated by narrow pale stripes or lines; usually more than 163 ventral plates; base of tail with strongly keeled scales........... Hebius igneus

6A. Supralabials cream to pale brown broadly edged and dusted with dark grey, without white blotches or streaks; dorsolateral pattern made of a series of about 80 distinct pale ochre-brown to orange-brown rounded blotches with less distinct series of dark blotches below them and above them; 159–171 ventrals.............................. Hebius terrakarenorum sp. nov.

6B. Supralabials with distinct white or cream blotches or streaks; dorsolateral pattern not as above; most usually less than 160 ventral plates......................................................................................... 7

7A. Each posterior supralabial with a round or oval, central cream blotch, not forming a stripe; 1 st dorsal scale keeled, throughout or at least on the posterior part of the body................................................................. 8

7B. Posterior supralabials dark brown or black, each with a median, horizontal and longate, thin cream blotch or streak, usually united as a narrow stripe, extending on the neck as a continuous stripe; scales of 1 st DSR entirely smooth...................................................................................................... Hebius boulengeri

8A. Dorsal pattern made of a series of reddish-brown or rusty (cream in preservative) dots or small blotches usually aligned on a faint dorsolateral stripe; usually isolated pale blotches on the side of the neck, sometimes partly connected by a narrow pale line, not reaching the dorsolateral stripe (if present) or dorsolateral spots; frontal 2.0–2.5 times longer than prefrontals........................................................................................... Hebius khasiensis

8B. Dorsal pattern made of a series of relatively large yellow or ochre (cream or yellow in preservative) dorsolateral spots on a more or less visible dorsolateral stripe, the first two to four of them enlarged and connected by a yellow or grey stripe; usually on the side of the neck a conspicuous, pale stripe or series of large pale, connected spots, reaching the dorsolateral stripe; frontal 1.7–1.9 times longer than prefrontals............................................................. Hebius inas