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A revision of the dark-bellied, stream-dwelling snakes of the genus Hebius (Reptilia: Squamata: Natricidae) with the description of a new species from China, Vietnam and Thailand

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Species of the genus Hebius Thompson, 1913 with 17 or 19 dorsal scale rows at midbody and an overall dark venter are reviewed, including the two species previously known as Parahelicops annamensis Bourret, 1934 and Pararhabdophis chapaensis Bourret, 1934. Specimens with 17 scale rows are morphologically similar to Hebius venningi (Wall, 1910), which is here redefined based on external morphological characters such as scalation, and dorsal and ventral patterns. Consequently, Natrix nigriventer Wall, 1925 is resurrected from its synonymy with Hebius venningi, whereas Natrix taronensis Smith, 1940, previously considered a subspecies of H. venningi or a full species by some authors but without justification, is here confirmed to full species status. Another group of species, mostly similar in coloration and pattern to the H. venningi group but with 19 dorsal scale rows, includes H. modestus (Günther, 1875), H. deschauenseei (Taylor, 1934) and a new species which is described herein based on specimens from northern Vietnam, southern China and northeastern Thailand due to distinct morphological differences. We also provide updated taxonomic accounts for the species of this group, including an identification key and distribution maps.
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https://doi.org/10.11646/zootaxa.4911.1.1
http://zoobank.org/urn:lsid:zoobank.org:pub:361E198B-5F04-4E5F-824A-73F488AB4A8B
ZOOTAXA
ISSN 1175-5326 (print edition)
ISSN 1175-5334 (online edition)
Accepted by J. Smid: 29 Oct. 2020; published: 19 Jan. 2021
4911
ZOOTAXA
Magnolia Press
Auckland, New Zealand
Zootaxa 4911 (1): 001–061
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Copyright © 2021 Magnolia Press Monograph
A revision of the dark-bellied, stream-dwelling snakes of the genus Hebius
(Reptilia: Squamata: Natricidae) with the description of a new species from
China, Vietnam and Thailand
PATRICK DAVID 1,*, GERNOT VOGEL2, TRUONG QUANG NGUYEN 3,
NIKOLAI L. ORLOV 4, OLIVIER S. G. PAUWELS 5, ALEXANDRE TEYNIÉ 6
& THOMAS ZIEGLER7
1,*Reptiles & Amphibiens, UMR 7205 OSEB, Département Évolution et Systématique, CP 30, Muséum National d’Histoire Naturelle.
57 rue Cuvier, F-75231 Paris Cedex 05, France.
patrick.david@mnhn.fr; https://orcid.org/0000-0001-7562-684X
2Society for Southeast Asian Herpetology, Im Sand 3, D-69115 Heidelberg, Germany.
Gernot.Vogel@t-online.de; https://orcid.org/0000-0002-4542-518X
3Institute of Ecology and Biological Resources and Graduate University of Science and Technology, Vietnam Academy of Science and
Technology, 18 Hoang Quoc Viet Road, Hanoi, Vietnam.
nqt2@yahoo.com; https://orcid.org/0000-0002-6601-0880
4Laboratory of Herpetology, Zoological Institute, Academy of Sciences, 199034 St. Petersburg, Russia.
azemiops@zin.ru; https://orcid.org/0000-0003-4401-348X
5Département des Vertébrés Récents, Institut Royal des Sciences Naturelles de Belgique, Rue Vautier 29, B-1000 Brussels, Belgium.
osgpauwels@yahoo.fr; https://orcid.org/0000-0002-3265-5496
6Société d’Histoire Naturelle Alcide d’Orbigny, 57 rue de Gergovie, F-63170 Aubière, France.
alexandre.teynie@inrae.fr; https://orcid.org/0000-0002-6588-229X
7AG Zoologischer Garten Köln, Riehler Str. 173, D-50735 Köln, Germany.
ziegler@koelnerzoo.de; https://orcid.org/0000-0002-4797-609X
*Corresponding author
DAVID ET AL.
2 · Zootaxa 4911 (1) © 2021 Magnolia Press
PATRICK DAVID, GERNOT VOGEL, TRUONG QUANG NGUYEN, NIKOLAI L. ORLOV, OLIVIER S.
G. PAUWELS, ALEXANDRE TEYNIÉ & THOMAS ZIEGLER
A REVISION OF THE DARK-BELLIED, STREAM-DWELLING SNAKES OF THE GENUS HEBIUS
(REPTILIA: SQUAMATA: NATRICIDAE) WITH THE DESCRIPTION OF A NEW SPECIES FROM
CHINA, VIETNAM AND THAILAND
(Zootaxa 4911)
61 pp.; 30 cm.
19 Jan. 2021
ISBN 978-1-77688-154-3 (paperback)
ISBN 978-1-77688-155-0 (Online edition)
FIRST PUBLISHED IN 2021 BY
Magnolia Press
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ISSN 1175-5326 (Print edition)
ISSN 1175-5334 (Online edition)
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 3
Table of Contents
Table of Contents ...........................................................................................3
Abstract ...................................................................................................4
Introduction ................................................................................................4
Material and methods ........................................................................................5
Results ...................................................................................................5
A. Specimens with 15 or 17 DSR at midbody; base of the tail with strongly keeled scales. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
B. Specimens with 19 DSR at midbody; base of the tail with feebly keeled scales. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
A. Specimens of the genus Hebius with 15 or 17 dorsal scale rows at midbody . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Hebius venningi (Wall, 1910) ...............................................................................7
2. Hebius nigriventer (Wall, 1925) new comb. ...................................................................13
3. Hebius taronensis (Smith, 1940) ............................................................................19
4. Hebius chapaensis (Bourret, 1934) ..........................................................................23
5. Hebius annamensis (Bourret, 1934) .........................................................................29
B. Specimens of the genus Hebius with 19 dorsal scale rows at midbody ..............................................35
6. Hebius modestus (Günther, 1875) ...........................................................................35
7. Hebius deschauenseei (Taylor, 1934) ........................................................................40
8. Hebius igneus spec. nov. ..................................................................................44
DISCUSSION .............................................................................................52
The artificial Hebius venningi / Hebius modestus groups ..........................................................52
On the contents and etymology of the genus Hebius Thompson, 1913 .................................................54
Status of “Natrix modesta in Guizhou Province, China ............................................................54
CONCLUSION ............................................................................................55
ACKNOWLEDGEMENTS ..................................................................................55
LITERATURE CITED ......................................................................................55
DAVID ET AL.
4 · Zootaxa 4911 (1) © 2021 Magnolia Press
Abstract
Species of the genus Hebius Thompson, 1913 with 17 or 19 dorsal scale rows at midbody and an overall dark venter are
reviewed, including the two species previously known as Parahelicops annamensis Bourret, 1934 and Pararhabdophis
chapaensis Bourret, 1934. Specimens with 17 scale rows are morphologically similar to Hebius venningi (Wall, 1910),
which is here redefined based on external morphological characters such as scalation, and dorsal and ventral patterns.
Consequently, Natrix nigriventer Wall, 1925 is resurrected from its synonymy with Hebius venningi, whereas Natrix
taronensis Smith, 1940, previously considered a subspecies of H. venningi or a full species by some authors but without
justification, is here confirmed to full species status. Another group of species, mostly similar in coloration and pattern
to the H. venningi group but with 19 dorsal scale rows, includes H. modestus (Günther, 1875), H. deschauenseei (Taylor,
1934) and a new species which is described herein based on specimens from northern Vietnam, southern China and north-
eastern Thailand due to distinct morphological differences. We also provide updated taxonomic accounts for the species
of this group, including an identification key and distribution maps.
Keywords. Keelback snakes; taxonomic revision; new species; Hebius venningi
Introduction
The systematics of natricine snakes of the Indochinese and Indo-Himalayan regions is still poorly known, as empha-
sised by recent novelties at both the genus and species levels. On the basis of molecular analyses, Guo et al. (2014)
split the genus Amphiesma Duméril, Bibron & Duméril, 1854 into three genera, i.e., (1) Amphiesma, restricted to
A. stolatum, (2) Hebius Thompson, 1913, for most species previously referred to Amphiesma, and (3) Herpetoreas
Günther, 1860 for the Himalayan species: H. sieboldii Günther, 1860, H. platyceps (Blyth, 1854) and a recently
described species, H. burbrinki Guo, Zhu, Liu, Zhang, Li, Huang & Pyron, 2014. On another side, Kizirian et al.
(2018) synonymized the genera Parahelicops Bourret, 1934 and Pararhabdophis Bourret, 1934 with the genus
Hebius. Ren et al. (2018) came to the same conclusion regarding the genus Pararhabdophis.
Several species of the Asian mainland formerly referred to the genus Amphiesma, now placed in the genus He-
bius, have been described in recent years, i.e., Amphiesma andreae Ziegler & Le, 2006, A. leucomystax David, Bain,
Nguyen, Orlov, Vogel, Vu & Ziegler, 2007, and Hebius lacrima Purkayastha & David, 2019.
Malnate (1960) referred Amphiesma deschauenseei to the group of A. modestum, whereas A. venningi was ten-
tatively placed into the group of A. khasiense (Boulenger, 1890). David et al. (2013) referred the species then known
as A. modestum, A. deschauenseei, A. groundwateri (Smith, 1922) and A. venningi to an informal Hebius venningi
group which is the subject of the present paper. The relationships of H. xenura (Wall) within the genus Hebius are
unclear; this species, easily recognized by its subcaudals being entirely single, is not considered here. Lastly, we did
not examine any specimen of H. groundwateri.
Thanks to recent herpetological surveys in remote areas of Vietnam and Laos by five of the authors of the pres-
ent paper (TQN, NLO, AT, GV and TZ), several specimens of natricid snakes largely unknown before the years
2000 were collected. They are all characterized by their very dark dorsal coloration with yellowish-orange, orange
or rusty blotches in life, and a venter entirely or partly blackish-brown or black. Most of these specimens proved to
be representatives of Parahelicops annamensis Bourret, 1934 and Pararhabdophis chapaensis Bourret, 1934, both
now placed in the genus Hebius. The remaining part of these dark-coloured, dark-bellied Indochinese specimens
share several major characters either with H. venningi (Wall, 1910), such as the strong keel on the scales at the base
of the tail, or with H. modestus (Günther, 1875), an Indo-Himalayan species, and/or with H. deschauenseei (Taylor,
1934), a species known only from northern Thailand. As stated in David et al. (2007, 2013), the genus now known
as Hebius is still badly in need of a complete revision.
Working in this direction, we present here a review of eight members of the genus Hebius, i.e., H. venningi, H.
modestus, H. deschauenseei, H. annamensis and H. chapaensis, as well as two species resurrected from the syn-
onymy of H. venningi, namely H. taronensis (Smith, 1940), previously considered a subspecies of H. venningi, and
Hebius nigriventer (Wall, 1925), plus a new species of the genus Hebius, described below based on morphological
differences. These eight species are included in two informal and artificial subgroups of natricid snakes which we
compare with other members of the genus Hebius and redefine below on the basis of new collections.
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 5
Material and methods
Our revision is based on external morphological characters and dentition regarded as taxonomically significant in
the genus Hebius as defined by Malnate (1960), Malnate & Underwood (1988), Ziegler & Le (2006), David et al.
(2007, 2013, 2015a–b), David & Vogel (2010), Guo et al. (2014) and Kizirian et al. (2018). A total of 110 specimens
of the “dark-bellied” species were examined, divided into 84 specimens of “black-bellied” Hebius, i.e., H. modes-
tus, H. venningi auctorum (including H. taronensis and H. nigriventer), H. deschauenseei, and Hebius spec. nov.,
and 26 specimens of the species previously referred to the genera Parahelicops and Pararhabdophis. Examined
specimens are listed under the respective species accounts.
Maxillary teeth were counted by removing the exterior gum surfaces of the right jaw in situ in adult specimens
only; tooth sockets were included in the counts in cases of tooth loss. Measurements, except body and tail lengths,
were taken with a slide-calliper to the nearest 0.1 mm; all measures on body were measured to the nearest millime-
tre. The number of ventral scales was counted according to Dowling (1951). The numbers of dorsal scale rows were
given at one head length behind head, at midbody (i.e., at the level of half of snout-vent length), and at one head
length before vent respectively. The terminal, pointed scute was not included in the number of subcaudals. Values
for symmetric head characters were given in left/right order.
Abbreviations.—Measures and ratios: HL: head length.—SVL: snout-vent length.—TaL: tail length.—TL: to-
tal length.—TaL/TL: ratio tail length/total length.—Meristic characters: DSR: formula of dorsal scale rows.—
IL: infralabials.—SC: subcaudals.—SL: supralabials. –VEN: ventrals.
Museum abbreviations: AMNH: American Museum of Natural History, New York, USA.—BMNH: Natural
History Museum, London, UK.—BNHS: Bombay Natural History Society, Mumbai, India.—CAS: California
Academy of Sciences, San Francisco, USA.—CIB: Chengdu Institute of Biology, Chinese Academy of Scienc-
es, Chengdu, China.—CUB MZ(R): Museum of Zoology, Chulalongkorn University (Bangkok), Bangkok, Thai-
land.—FMNH: Field Museum of Natural History, Chicago, USA.—IEBR: Institute of Ecology and Biological
Research, Hanoi, Vietnam.—KFBG: Kadoorie Farm and Botanic Garden, Hong Kong.—KIZ: Kunming Institute
of Zoology, Kunming, China.—MNHN: Muséum National d’Histoire Naturelle, Paris, France.—MVZ: Museum of
Vertebrate Zoology, Berkeley, California, USA.—NCSM: North Carolina Museum of Natural Sciences (formerly
North Carolina State Museum of Natural Sciences), Raleigh, North Carolina, USA.—ROM: Royal Ontario Musem,
Toronto, Canada.—YU: Yunnan University, Kunming, China.—ZFMK: Zoologisches Forschungsmuseum Alex-
ander Koenig, Bonn, Germany.—ZISP: Zoological Institute, Russian Academy of Science, St. Petersburg, Rus-
sia.—ZSI: Zoological Survey of India, Kolkata, India.
Results
The analysis of morphological characters of our samples showed that two informal groups may be recognized
among the “dark-bellied” species of Asian natricid snakes. These two groups share the following characters: (1) 15,
17 or 19 dorsal scale rows; (2) a very dark dorsum (dark grey, dark brown, or blackish-brown); (3) dark reticulations
on the back, often with orange or reddish-brown spots or dorsal blotches; (4) venter at least in part blackish-brown
or black; (5) postocular stripe absent or present; and (6) strongly keeled scales at the base of the tail in those spe-
cies with 17 dorsal scale rows. These groups include species not only referable to the genus Hebius, as currently
conceived following Guo et al. (2014), but also the two species formerly placed in the genera Parahelicops Bourret,
1934 and Pararhabdophis Bourret, 1934, respectively.
These two main artificial groups may be distinguished as follows (additional generic or specific diagnostic
characters will be detailed below):
A. Specimens with 15 or 17 DSR at midbody; base of the tail with strongly keeled scales.
Aa. Specimens with a venter either nearly entirely dark along its whole length, or pale mesially on the anterior part
of the body with ventral sides dark.
Aaa. Specimens with a longer tail (ratio TaL/TL > 0.30).
DAVID ET AL.
6 · Zootaxa 4911 (1) © 2021 Magnolia Press
Aaaa. Specimens from western Myanmar and extreme north-eastern India; dark postocular streak present; ven-
ter never entirely dark along its whole length, i.e, pale mesially at least on the anterior part of the body, clouded with
darker hues of brown on the outer parts of ventrals; dark hues extending progressively inwards posteriorly giving a
dark, clouded venter posteriorly; dorsum usually olive-grey, greyish-brown or brown, sometimes dark brown, with
darker grey and brown blotches producing a chequered pattern; no ventrolateral stripe; 115–129 subcaudal scales.
Holotype of Tropidonotus venningi Wall, 1910 included.—Taxon 1.
Aaab. Specimens from eastern and northern Myanmar and southwestern China; dark postocular streak present;
venter either entirely dark along the whole of the body, except the first 10–15 ventrals, or with three parallel narrow
pale stripes; dorsum very dark, blackish-brown or black, on each side with a dorsolateral series of large, orange or
rusty-red blotches, turning to an irregular stripe; often a ventrolateral stripe; 105–143 subcaudal scales. Holotype of
Natrix nigriventer Wall, 1925 included.—Taxon 2.
Aab. Specimens with a short tail (ratio TaL/TL < 0.30).
Aaba. Specimens from northern Myanmar and extreme north-eastern India; postocular streak absent or very
faint; venter pale anteriorly with an irregular dark brown crossband on each ventral, very dark ochre-brown, dark
brown or blackish-brown on its posterior half; dorsum overall dark, brown to blackish-brown with faint paler
blotches and diffuse black spots or blotches forming a complex speckled or irregularly mottled pattern; no ventro-
lateral stripe. Holotype of Natrix venningi taronensis Smith, 1940 included.—Taxon 3.
Aabb. Specimens from Vietnam and Laos with a venter entirely dark with some pale streaks; a strong postocular
streak; upper head surface with strong, yellow vermiculations; large, orange dorsal blotches; a ventrolateral stripe.
Holotype of Pararhabdophis chapaensis Bourret, 1934 included.—Taxon 4.
Ab. Specimens from Vietnam and Laos with a nearly entirely pale venter, only with tips of ventral scales dark.
Holotype of Parahelicops annamensis Bourret, 1934 included.—Taxon 5.
B. Specimens with 19 DSR at midbody; base of the tail with feebly keeled scales.
Ba. Specimens with a venter widely pale in its center, more or less extensively dark on the sides, rarely entirely
dark exept on its most anterior part; a dorsolateral stripe present. Holotype of Tropidonotus modestus Günther, 1875
included.—Taxon 6.
Bb. Specimens with dark coloration present also in the centre of the venter.
Bba. Specimens from Thailand with three parallel rows of dark blotches on the venter; a dorsolateral stripe; a
low number of ventrals (usually < 163); and base of tail with weakly keeled scales. Holotype of Natrix deschauen-
seei Taylor, 1934 included.—Taxon 7.
Bbb. Specimens from northern Vietnam, southern China (Yunnan) and north-eastern Thailand, with a venter ei-
ther uniformly very dark brown or black or with 4 or 5 rows of nearly continuous dark blotches separated by narrow
pale stripes or lines; on each side, a dorsolateral series of large, orange or rusty-red blotches, at least on the anterior
part of the body or throughout its whole length; a high number of ventrals (at least 159, in most specimens > 163);
and base of tail with strongly keeled scales.—Taxon 8, Hebius spec. nov.
We consider these eight lineages to be distinct species in the genus Hebius. Two subgroups can be distinguished.
The first one, referred to as the Hebius venningi subgroup, includes specimens with 15–17 DSR at midbody and
strongly keeled scales at the base of the tail. The second one, the Hebius modestus subgroup, includes specimens
with 19 DSR and feebly or moderately keeled scales at the base of the tail. On the basis of their name-bearing types,
the included taxa can be identified as follows:
Group A.—Hebius venningi group. Taxon 1: Hebius venningi (Wall, 1910).—Taxon 2: Hebius nigriven-
ter (Wall, 1925) status nov.—Taxon 3. Hebius taronensis (Smith, 1940). – Taxon 4. Hebius chapaensis (Bourret,
1934).—Taxon 5. Hebius annamensis (Bourret, 1934).
Group B.—Hebius modestus group. Taxon 6: Hebius modestus (Günther, 1875).—Taxon 7: Hebius deschauen-
seei (Taylor, 1934).—Taxon 8: Hebius spec. nov., described below.
We will first characterize below the five species of group A, i.e., species of the genus Hebius with 17 dorsal
scale rows, including H. annamensis and H. chapaensis, and then the three species of group B with 19 dorsal scale
rows.
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 7
A. Specimens of the genus Hebius with 15 or 17 dorsal scale rows at midbody
1. Hebius venningi (Wall, 1910)
(Figs. 1–2)
Tropidonotus venningi Wall, 1910: 345.—Type locality. “Haka Chin Hills”, now Hakha, Hakha District, Chin State, Myan-
mar.—Holotype. BMNH 1946.1.21.86 (formerly BM 1910.1.4.6), adult male; collected by F. E. W. Venning, September
or October 1908.
Tropidonotus venningi.—Venning 1911: 773; Werner 1929: 15 & 24 (in part).
Natrix venningi.—Wall 1923: 601; Wall 1925c: 921; Wall 1926: 560 (in part); Bourret 1936b: 55 (in part: only the mention of
“Birmanie”); Smith 1943: 285 & 286 (in part).
Amphiesma venningi.—Malnate 1960: 51, 52 & 57; Dowling & Jenner 1988: 9 (in part); Welch 1988: 34; Zhao & Adler 1993:
228 (in part; only for the record from “Burma”); Iskandar & Colijn 2001: 98 (in part: except the mention from China); Cap-
tain & Bhatt 2002: 354, 355, 356: Fig. 1–4; Das 2002: 19 (text: in part; figure: genuine H. venningi depicted); Mathew &
Meetei 2004: 135; Whitaker & Captain 2004: 214 (in part), 215–217 (figures); Whitaker 2006: 112; Zhao 2006: 174 & 175
(in part; only for the record of Myanmar); David et al. 2007: 54 (in part) & 60 (in part: specimens from Chin State, Myan-
mar); Sharma 2007: 206 & 207 (in part); Das 2010: 152: Pl. 68: Fig. 7 (genuine H. venningi depicted) & 335 (in part: at the
exception of the mention of China, Yunnan Province); Das 2012: 118 (text: in part; figure: genuine H. venningi depicted) &
151; Wallach et al. 2014: 33 (in part: only mentions from Arunachal Pradesh, India, and Chin State, Myanmar).
Paranatrix venningi.—Mahendra 1984: 245.
Hebius venningi.—Guo et al. 2014: 431 & 438 (citations on pages 428 and 429 refer to other species; see below); Das & Das
2017: 126 (text: in part; figure: genuine H. venningi depicted) & 168; Boundy 2020: 92.
Amphiesma vinningi [sic]).—Ahmed et al. 2009: 155.
Natrix venningi venningi.—Smith 1940: 483 [as “the typical form”]; Smith 1943: 286 (in part: at the exception of specimens
from “Nam-ti Valley”).
Amphiesma venningi venningi.—Welch 1988: 34; Zhao et al. 1998: 90 (in part); Captain & Bhatt 2002: 354 & 355; Zhao 2006:
175 (in part); Sharma 2007: 207 (in part: mention from Chin State).
Paranatrix venningi venningi.—Mahendra 1984: 245.
Amphiesma cf. modestum (nec Tropidonotus modestus Günther, 1875).—Ahmed et al. 2009: 155.
Specimens examined (14).—Myanmar. Chin State. BMNH 1946.1.21.86 (ex BM 1910.1.4.6; holotype of Tropi-
donotus venningi); BMNH 1946.1.13.42 (ex BM 1910.12.9.1); BMNH 1946.1.13.49, BNHS 1316–1320, “Haka,
Chin Hills”, now Hakha, 22°38’60”N, 93°37’00”E, Hakha District; CAS 235175, Shawn Khyak stream, near Ahone
village, Mindat Township, Mindat District, 21°18’40.3”N, 93°45’31.9”E, 3,255 ft; CAS 233206, Chun Kyone,
Hakha Township, Hakha District, 22°46’38.5”N, 93°33’55.7”E, 5,360 ft; CAS 234777, a small stream, Kanpetlet
town, northern Kanpetlet Township, Mindat District, 21°11’55.7”N, 94°03’34.0”E, 4,062 ft; CAS 235376–235377,
Maw stream, near Myin village, Mindat Township, Mindat District, 21°36’34.8”N, 93°53’07.3”E, 3,040 ft. Naga
Self-Administered Zone (or Sagaing Region). CAS 245379, Laung Nguk village, Lahe Township, 26 090’17.8”N,
95 31’17.3”E, 2,857 ft.
Taxonomic comments.—This species was first mentioned in the literature by Venning (1910: 340) on the
basis of two specimens, “Nos XXXV and XXXVI”, referred to the genus Tropidonotus but which Venning did
not formally name. It was then formally described in a subsequent paper of the same volume by Wall (1910: 345).
Although this species was described on the basis of two specimens, Wall (1910) considered the specimen deposited
in London (specimen BMNH 1946.1.21.86; formerly BM 1910.1.4.6) to be the holotype (“the type”, according to
Wall) whereas the second specimen, considered to be a paratype (the “cotype”) was reported by Wall (1910) to be
deposited in collections of the Bombay Natural History Society. In contrast, Wallach et al. (2014: 34) recognized
three syntypes: (1) BMNH 1946.1.21.86, considered to be the holotype by Wall (1910), (2) BMNH 1946.1.13.49,
a juvenile, considered to be the “co-type” by Wall (1910), previously deposited in the collections of the Bombay
Natural History Society (Mumbai, India), and (3) BMNH 1946.1.13.60. This latter specimen is in fact the holotype
of Natrix nigriventer Wall, 1925, here recognized as a valid species; it has been collected in June 1924 and cannot
belong to the type series of a species described in 1910.
Hebius venningi has long been divided into two subspecies, the nominative one and Natrix venningi taronensis
Smith, 1940. On the basis of the differences in morphology of these two taxa discussed below and of their allopatric
distributions, we consider them to be distinct at the specific level (see below). This position had been previously
adopted in 2009 in the list of snakes of Myanmar provided on the website of the California Academy of Sciences:
(http://researcharchive.calacademy.org/research/herpetology/myanmar/project.html; accessed on July 20th
DAVID ET AL.
8 · Zootaxa 4911 (1) © 2021 Magnolia Press
2014). The validity of Hebius taronensis at full species status was eventually accepted by Das (2010: 335; as Am-
phiesma taronense). Hebius venningi is thus a monotypic species.
FIGURE 1. Hebius venningi Wall, holotype (BMNH 1946.1.21.86)—A: dorsal view; B: ventral view; C: lateral
view of the head, right side; D: close-up dorsal view of the head. Photographs: Gernot Vogel.
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 9
FIGURE 2. Hebius venningi Wall, alive—A & C: specimen from Changlang District, Arunachal Pradesh, India.
Photographs: Ashok Captain.—B: specimen CAS 233206, Chun Kyone, Hakha Township, Hakha District, Chin
State, Myanmar. Photograph: Hla Tun.
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10 · Zootaxa 4911 (1) © 2021 Magnolia Press
Furthermore, Wall (1925: 588) described Natrix nigriventer from the vicinity of Bhamo, in Kachin State, Myan-
mar, but Wall (1926) synonymized it with Natrix venningi. This position was followed by Smith (1943). On the
basis of our specimens at hand, we consider this taxon to be distinct from both H. venningi and H. taronensis and
we resurrect it below at full species status.
There has been some confusion about the distribution of this species, especially in India. Gayen (2002) recorded
a specimen from the Jaintia (or Jayanyia) Hills, State of Meghalaya, in Northeast India, a record mentioned by
Whitaker & Captain (2004: 214), but Mathew & Meetei (2004) showed that the specimen was misidentified and
should be referred to Hebius xenura (Wall). Captain & Bhatt (2002) published the first authenticated record of He-
bius venningi from India, on the basis of five specimens collected near Gandhigram (also called Shidi), Changlang
District, State of Arunachal Pradesh. These authors noted that four of these specimens (specimens #2–5) could be
referred to “Amphiesma venningi venningi” as defined by Smith (1940; 1943) whereas specimen #1, with 104 sub-
caudals only, agreed with the description of “Amphiesma venningi taronense (Smith, 1940)”. Nevertheless, Captain
& Bhatt (2002) considered all the specimens to be “the same kind of animal” and referred them to as Amphiesma
venningi venningi.
This mix of specimens of two “subspecies” in a single locality and a comparison of their subcaudal counts with
those of specimens of A. venningifrom Yunnan led Captain & Bhatt (2002) to consider that the number of subcau-
dals was not a reliable character and that the validity of the subspecies taronensis was doubtful. In fact, these authors
were not aware of the description of Hebius nigriventer (Wall, 1925), a species resurrected below after having long
been confused with H. taronensis and which occurs in Yunnan. While females of H. nigriventer may have the same
number of subcaudals than H. taronensis, these species clearly differ from each other by several characters detailed
below. On the basis of data and pictures published by Captain & Bhatt (2002) and Whitaker & Captain (2004), we
agree with these authors in referring four of their five specimens to Hebius venningi sensu stricto as defined here.
Although the ventrolateral blotches depicted in Whitaker & Captain (2004: 356, Fig. 4) and the venter largely pale
(orange in life) along much of its length are not present in the holotype and several other examined specimens, these
characters also appear in specimens from Myanmar, for example, CAS 245379. Furthermore, the dorsal pattern
(including head), the dorsal scalation, the numbers of ventrals, and the number of subcaudals of two specimens with
a complete tail are typical of H. venningi. In contrast, we here refer specimen #1, with 104 subcaudals, to Hebius
taronensis on the basis that (1) its number of subcaudals does not agree with that of H. venningi but perfectly fits
that of H. taronensis, (2) Captain & Bhatt (2002) would have noticed the peculiar dorsal and ventral patterns of H.
nigriventer, and (3) Changlang District is less than 50 kilometres from the region of Putao, type locality of Hebius
taronensis.
Thanks to the courtesy of A. Das, who communicated us additional unpublished pictures and data (pers. comm.,
August 2019), we identify as Hebius venningi the specimen from Mizoram (India) depicted by Ahmed et al. (2009:
154) as Amphiesma cf. modestum. These authors thus published the first record of H. venningi from the State of
Mizoram in Northeast India. Subsequently, Lalbiakzuala & Lalremsanga (2019) also published a record of H.
venningi” from the State of Mizoram. However, this specimen is referable to another species, the status of which
will be discussed elsewhere.
H. venningi has also been recorded from Bangladesh by Reza (2010). However, pictures and morphological
data of their specimen make clear that it is a Hebius xenura. So there is currently no record of this species from Ban-
gladesh. Lastly, other records from Yunnan, China (Kou 1985; Zhao & Adler 1993; Zhao et al. 1998; Zhao 2006),
not cited above in the chresonymy, should now be referred to Hebius nigriventer (Wall, 1925), a species that is res-
urrected below from its synonymy with H. venningi. Lastly, the locality cited by Smith (1943) as Bhamo Valley, in
Kachin State, northern Myanmar, now also refers to Hebius nigriventer. As a consequence, H. venningi is currently
restricted to extreme north-eastern India and western and north-western Myanmar.
Diagnosis.—A moderately to large sized species of the genus Hebius characterized by the combination of (1)
17–18-17-16–17 dorsal scale rows, moderately keeled at midbody, strongly keeled posteriorly but 1st DSR smooth;
(2) scales around the base of the tail strongly keeled; (3) head moderately distinct from the neck; (4) eye rather large;
(5) maxillary teeth 28–30, the last two moderately enlarged; (6) tail long, with a ratio TaL/TL usually > 0.30; (7)
VEN 155–172; (8) SC 115–129; (9) prefrontal scales 2; (10) anterior temporal rectangular, narrowing anteriorly;
(11) venter never entirely dark along the whole length of the body: venter pale yellowish-grey or pale yellowish-
brown (usually pink or coral-red in life, sometimes dark yellow) mesially, at least on the anterior part of the body,
with outer parts of ventrals heavily and broadly clouded with darker hues of brown or dark brown; these dark areas
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extend progressively more widely inwards giving a dark, clouded venter posteriorly; (12) dorsum and sides olive-
brown, olive-grey, dark grey, brown to dark brown or sometimes blackish-brown (same in preservative and in life);
(13) dorsal surface distinctly chequered by the presence on sides and upper part of the body of diffuse, elongate or
rectangular blackish-brown or very dark grey blotches; (14) a dorsolateral series of irregular blotches, yellow-ochre
or yellowish-brown (brighter yellow-ochre or yellowish-brown in life), enlarged and forming a chain on the first
quarter to third of the body, progressively smaller, usually vanishing after midbody; (15) a dark postocular streak
usually present; and (16) an ochre-yellow or yellowish-brown streak on each side of the neck and nape forming an
incomplete collar.
Description.—Body rather slender, stouter in large females, cylindrical; the head is somewhat elongate, sub-
rectangular, moderately distinct from the thick neck, flattened anteriorly; snout elongate, obtuse as seen from above,
oblique seen in profile, flat, 19.5–20.5 % of HL, or 1.6–2.0 times longer than diameter of eye; nostrils placed dor-
solaterally on the snout and directed slightly dorsolaterally, small, round, piercing in the middle of the nasal; eye
rather large, about 1.2–1.8 times greater than the distance between its lower margin and the margin of the lip, with
a round pupil; tail long and tapering.
The maximal known total length is 780 mm (SVL 550 mm; TaL 230 mm; specimen #1 of Captain & Bhatt
[2002], probably a female). The longest known male is 658 mm long (SVL 430 mm, TaL 228 mm long; BMNH
1946.1.21.86, holotype).
Ratio TaL/TL: 0.295–0.347, without sexual dimorphism.
Dentition. 28–30 maxillary teeth gradually enlarging, the last 2 moderately enlarged, without diastema.
Body scalation. DSR: 17–18-17-16–17 rows; scales rhomboedric, moderately keeled at midbody, more strongly
keeled posteriorly; scales of 1st DSR smooth; dorsal scales around the base of the tail strongly keeled.
In our sample of 14 specimens, two have 18 scale rows around the neck; two others have 16 scale rows before
vent; all others have 17–17–17 dorsal scale rows throughout the body.
VEN: 155–172 (plus 1 or 2 preventrals); SC: 115–129, all paired, without sexual dimorphism; cloacal plate
divided.
Ratio VEN/SC 1.24–1.54.
Position of the reduction to 6 scale rows around the tail: SC 6–24, with a strong sexual dimorphism (see below);
ratio: length of the portion of tail with 6 dorsal scale rows/length of the portion of tail with 4 dorsal scale rows:
1.0–2.5 with a sexual dimorphism.
Head scalation. Arrangement of upper head scales complete including 2 internasals, 2 prefrontals, 2 supraocu-
lars, 1 frontal, and 2 parietals. Rostral wider than high, barely visible from above; nasals subrectangular, elongate,
about 1.4–1.6 times longer than high, vertically divided above and below the nostril, with the posterior part equal
to anterior one; internasals subtriangular, in broad contact with each other, about 0.9–1.2 times longer than wide,
moderately narrowing anteriorly with an anterior margin about 0.5–0.6 times the width of the posterior margin; 2
prefrontals, rather small, short but wide, distinctly broader than long, 1.1–1.2 times longer than internasals; frontal
large, shield-like, 1.2–1.3 times longer than wide and 2.0–2.4 times longer than prefrontal; 1 supraocular on each
side, subtriangular, 2.0–2.4 longer than wide, about as wide as internasals; parietals large and broad, 1.4–1.6 times
longer than the frontal, or suture between parietals 1.1–1.2 times longer than frontal; 1/1 loreal, pentagonal, elon-
gate, 1.3–1.5 times longer than high, in broad contact with the nasal; 1 or more commonly 2 preoculars, upper one
larger than lower one; 3 small postoculars in all examined specimens; 9/9 SL (8/8 in one specimen only), the first
five as long as high or longer than high, 1st and 2nd SL small and short, in contact with the nasal, 2nd–3rd SL or 2nd–4th
SL in contact with the loreal, 4th–6th or 5th–6th SL entering orbit, 7th and 8th SL largest; 1 anterior temporal, rectan-
gular, elongate, narrowing anteriorly, followed by 1 or 1+1/1 posterior temporals, the most common formula being
1+1 temporals; 9 or 10 (11 in only 1/18 occurrences, namely in adding the values met on each side) infralabials,
first pair in contact, 1st–5th IL in contact with anterior chin shields, 5th and 6th IL largest; posterior chin shields longer
than anterior ones.
Coloration and pattern. The dorsal surface and sides are olive-grey, olive-brown, greyish-brown, dark grey,
brown, dark brown or sometimes blackish-brown, darker on the top than on the sides of the body, with scales indis-
tinctly edged or speckled with very dark brown; dorsum with a chequered pattern, more distinct on the anterior half
of the body, by the presence on the 2nd to 8th dorsal scale rows and vertebral scale rows of 4 to 5 series of irregular,
diffuse elongate or rectangular blotches, blackish-brown or very dark grey blotches, often fuzzy, larger at the bot-
tom of the sides and on 6th–8th dorsal rows, covering a length of 1.5 to 2.5 dorsal scales; on each side of the body,
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a dorsolateral series of irregular blotches, yellow-ochre or yellowish-brown on the 4th–6th or 5th–6th DSR, enlarged,
and forming a chain on the first quarter to third of the body, progressively smaller, vanishing after midbody or
remaining as very faint pale spots throughout the body. The tail is as the body surface, chequered with small dark
blotches and spots.
The head is olive-brown, greyish-brown, brown to dark brown, paler on the rostral and sides of the snout; ce-
phalic scales scattered with pale brown, yellowish-brown or dark yellow-ochre vermiculations, sometimes produc-
ing short, irregular, parallel streaks or elongate areas on prefrontals and frontal and an oblique streak on the outer
edge of each parietal; often the presence of twin parietal pale spots; anterior supralabials greyish-yellow, pale brown
or ochre yellow, especially on their lower half, more or less strongly powdered with olive-brown or dark brown on
their upper part, and more or less broadly edged with dark or blackish-brown; a broader, dark brown or blackish-
brown, oblique streak on the posterior edge of 6th and 7th SL; 8th or 9th SL, or both, mostly dark brown, with only
the lower part pale; often a faint, poorly-defined, paler area on temporals; usually a dark, oblique postocular streak
extending from eye to the corner of the mouth on the top of the 9th SL and temporals, sometimes poorly defined if
the background colour is dark; an irregular yellow-ochre or brownish-yellow, oblique streak directed upwards and
backwards extending from the corner of the mouth to the nape, forming a short chevron, sometimes faint or nearly
absent; a thin streak of same colour extends from the interparietal suture to the apex of the chevron. Infralabials, chin
and throat yellowish-cream or pale yellow-ochre, often nearly uniform with a few dark brown spots on chin shields
and throat, sometimes heavily spotted with dark brown spots and flecks; infralabials each edged with dark brown on
both edges, sometimes strongly speckled with dark brown.
The venter is never entirely dark along the whole length of the body, i.e., always pale mesially at least on the
anterior fifth, quarter, third or half of the body, sometimes only on the first 20 ventrals, depending on specimens.
This pale colour may be beige, pinkish-brown, yellowish-cream, pale yellowish-ochre or pale brownish-grey in
preservative on the inner half to two-thirds of ventral width, with tips and outer parts of ventrals heavily and broadly
clouded with darker hues, such as dark greyish-brown, brown or dark brown; this dark, clouded area progressively
extends inwards, reducing the pale coloration to a narrow mesial part of ventrals then making the venter entirely
clouded with dark hues on the posterior part of the body; tips of ventrals often with a large black blotch. Tail dark
greyish-brown, dark brown or blackish-brown, uniform or with the edges of subcaudals pale grey or brown.
In life, the dorsal surface and sides are olive-grey, olive-brown, greyish-brown, dark grey, brown, dark brown
or sometimes blackish-brown; the dark dorsal blotches forming the chequered pattern are blackish-brown or very
dark grey blotches; the pale irregular blotches on each side of the body are usually bright and conspicuous, grey-
ish-yellow, yellow-ochre or yellowish-brown, sometimes dark greyish-yellow. Pale markings on the head, such as
vermiculations and streaks, and supralabials are also bright yellow-ochre or yellowish-brown. The pale area of the
venter is pink or bright coral red, sometimes yellow (Fig. 2).
Hemipenes.—In situ, it is single, short and thin, reaching the 8–9th SC, proximal part covered with short spines,
2 or 3 spines much larger and hooked; distal part covered with small, dense spines; sulcus spermaticus short and
with poorly visible lips.
Sexual dimorphism.It is expressed in the following characters:
(1) Weakly by the difference in the number of ventral scales: males: 164–167 (mean = 165.5, SD (standard
deviation) = 1.7); females: 157–165 (mean = 160.0, SD = 4.4).
(2) Strongly by the difference in the position of the reduction from 8 to 6 scale rows around the tail (counted in
number of subcaudals): males: SC 19–24; females: SC 4–9.
(3) Strongly by the difference in length of the portion of tail with 6 dorsal scale rows/length of the portion of tail
with 4 dorsal scale rows: 2.1–2.5 in 4 males, 1.0–1.4 in 2 females.
Distribution (Fig. 3).—India. State of Arunachal Pradesh. Patkai Hills, Changlang District; Tirap District
(Borang et al. 2005). State of Nagaland. Khonoma, Kohima District; Dzulake (or Dzuleke, Kohima District (Ahmed
et al. 2009; M. F. Ahmed, pers. comm., May 2018; A. Das, pers. comm., August 2019). State of Mizoram. Vicinity
of Tamdil Lake, Saitual Sub-Division, Aizawl District, 900 m. a.s.l.—Myanmar. Known only from the west of the
country. Chin State. Chin Hills, near Hakha, Hakha District; Mindat Township and Kanpetlet Township, Mindat
District. Sagaing Region (or Naga Self-Administered Zone). Lahe Township.
Biology.—The specimens for which data are available were collected in pristine or disturbed evergreen or semi-
evergreen submontane forest and mixed or deciduous moist montane forest, between 870 and 1,635 metres a.s.l.
Most snakes were found near hills or montane streams. According to Whitaker & Captain (2004), Hebius venningi
feeds on tadpoles and frogs.
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This species seems to be common in some places (Borang et al. 2005). It is inoffensive and does not attempt to
bite when handled.
FIGURE 3. Distribution map of species with 15 or 17 dorsal scale rows at midbody. Circles: Hebius annamensis
Bourret. Diamonds: Hebius venningi Wall. Inverted triangles: Hebius taronensis Smith. Squares: Hebius nigri-
venter Wall. Triangles: Hebius chapaensis Bourret.
2. Hebius nigriventer (Wall, 1925) new comb.
(Figs. 4–5)
Natrix nigriventer Wall, 1925a: 588.—Type locality. “Huton, Bhamo District (30 miles north-east of Bhamo; circa 4,500
feet; Lat. circa 97°33; Long. Circa 24°24”, now Hutung, Bhamo District, Kachin State, Myanmar.—Holotype. BMNH
1946.1.13.60, adult female; collected by Father Gilhodes, June 1924.
Natrix nigriventer.—Bourret 1936b: 55 (synonymy with Natrix venningi).
Hebius nigriventer.—This work.
Natrix venningi (nec Tropidonotus venningi Wall, 1910).—Wall 1926: 560 (in part); Bourret 1936b: 55 (in part: only the mention
of “Chine”); Smith 1943: 286 (in part).
Tropidonotus venningi (nec Tropidonotus venningi Wall, 1910).—Werner 1929: 24 (in part).
Amphiesma venningi (nec Tropidonotus venningi Wall, 1910).—Kou 1985: 160 (in part); Zhao & Jiang 1986: 239 (?; identifica-
tion uncertain); Zhao & Adler 1993: 228 (in part), 310; Zhao et al. 1998: 89 & 90 (in part); Zhang 1999: 430 (?); Zhao et al.
2000b: 205; Iskandar & Colijn 2001: 98 (mention from China); He & Zhou 2002: 167 (in part); Ji 2002: 184; Zhao 2006:
(Vol. I) 174 (in part), (Vol. II) 97: Fig. 59-2–59-3 (Fig. 59-1 depicts a Hebius bitaeniatus); David et al. 2007: 54 (in part), 55
& 60 (in part: three specimens from Kachin State, Myanmar); Sharma 2007: 207 (in part); Yang & Rao 2008: 268 (text: in
part; Figure: H. nigriventer), 269 (text: in part, Table 58: H. nigriventer); Luo et al. 2010: 74; Zhang 2011: 277 (?); Wallach
et al. 2014: 33 (in part: only mentions from Kachin State, Myanmar, and Yunnan, China).
Amphiesma Venrrinig [sic]).—Kou & Zhang 1987: 364.
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FIGURE 4. Hebius nigriventer Wall, holotype (BMNH 1946.1.13.60)—A: dorsal view; B: ventral view; C: lateral
view of the head, right side; D: close-up dorsal view of the head. Photographs: Gernot Vogel.
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 15
Specimens examined (14).—Myanmar. Kachin State. BMNH 1925.9.17.6, BMNH 1925.12.22.21, BMNH
1946.1.13.60 (holotype of Natrix nigriventer), Huton, now Hutung, Kachin Hills, Bhamo District; CAS 238901–
902, vicinity of Nanmon Village, Indawgyi Lake Wildlife Sanctuary, Moenyin Township, Myitkyina District,
24°57’35”N, 96°20’36”E; CAS 245436, north side of Panwa Town, 25°36’54.1N, 98°22’31.5E, Panwa Township,
Myitkyina District, 7,147 ft.—People’s Republic of China. Yunnan Province. CAS 241960, Kongdang township
in Dulong Valley, along road from hotel (Kongdang) to bridge approx. 3 km N of hotel (Kongdang), 27°54’03.6”N,
98°20’52.0”E, Gongshan County, Nujiang Prefecture; CIB 8278, Jinhong Prefecture; KFBG 14536, Hongbenghe,
Xueli Village, Yingjiang County, Dehong Dai and Jingpo Autonomous Prefecture; YU 844023, YU 845075–076,
Mengla, Mengla County, Jinhong Prefecture. YU 835043–044, Jinhong, Jinhong Prefecture.
Taxonomic comments.—This taxon was described as a valid species by Wall (1925a) but subsequently syn-
onymized with Natrix venningi by Wall (1926: 560), a position accepted by Smith (1943). However, Wall (1926)
put emphasis on the similarities in the numbers of dorsals and maxillary teeth between the two taxa but, with three
specimens at hand from Hutung, Kachin State, failed to notice the strong differences in their dorsal pattern. On the
basis of important and constant differences in the pattern and the other morphological characters detailed below, we
resurrect Natrix nigriventer from the synonymy of Natrix venningi Wall, 1910 and consider it to be a valid species
under the combination Hebius nigriventer new comb. This species is monotypic.
H. nigriventer is undoubtedly related to Hebius venningi, and constitutes the “north-eastern” member in the
informal H. venningi complex. It also occurs near the distributional range of H. taronensis. These species can be
differentiated by the characters given above in the introduction to the informal groups, and by the diagnosis given
below in the account of H. nigriventer. Nevertheless, H. taronensis and H. nigriventer seem to be closely related.
It should also be noted that H. nigriventer is quite similar to H. chapaensis. Variation in this latter taxon are still
imperfectly known, especially the ratio tail length/total length and the number of subcaudals on which is mostly
based the difference between these two species. The values of these characters may be expended when more speci-
mens are available. Furthermore, H. chapaensis is highly variable in both dorsal and ventral colour pattern. Lastly,
H. chapaensis also occurs in Jinhong Prefecture, Yunnan Province (Jinlong Ren, pers. comm., June 2020), just as
does H. nigriventer. Nevertheless, our data suggest that these taxa are indeed distinct at species level.
According to Jinlong Ren (pers. comm., June 2020), the presence of H. nigriventer in both western Yunnan and
Myanmar on the one hand, and southern Yunnan on the other hand, isolated areas with very different herpetofaunas,
may suggest that H. nigriventer is a species complex.
Hebius nigriventer has constantly been cited in the Chinese literature under the combination Amphiesma
venningi, for example by Kou (1985), Kou & Zhang (1987; as Amphiesma Venrrinig [sic]), Zhao et al. (1998), Zhao
(2006) and Yang & Rao (2008).
Diagnosis.—A moderately sized species of the genus Hebius characterized by the combination of (1) 17(ex-
ceptionally 19)-17-15–17 dorsal scale rows, moderately keeled at midbody, strongly keeled posteriorly but 1st DSR
smooth; (2) dorsal scales around the base of the tail strongly keeled; (3) head moderately distinct from the neck; (4)
eye size moderate; (5) maxillary teeth 28–33, the last two moderately enlarged; (6) tail long, with a ratio TaL/TL at
least equal to 0.29 in females, up to 0.37 in males; (7) VEN 155–168; (8) SC 105–143; (9) 2 prefrontal scales, (10)
anterior temporal elongate, rectangular; (11) venter entirely very dark, i.e., blackish–brown or black, sometimes
with two, narrow longitudinal paler stripes, at the exception of a middle stripe pale but heavily blotched with dark
hues anteriorly, extending on 5–15 ventrals; (12) dorsal colour very dark, dark brown, very dark greyish-brown or
blackish-brown; (13) dorsum background either uniform or with a subdued chequered dorsal pattern made of large,
diffuse, rectangular darker blotches on 4th–5th and 7th–8th DSR; (14) on each side, a series of large, cream or pale yel-
lowish-brown (bright orange, rusty-red or reddish-brown in life), rectangular blotches, higher than long anteriorly
then more elongate, forming a conspicuous, dorsolateral chain of blotches on 5th–6th DSR throughout the length of
the body, becoming smaller posteriorly and turning to an irregular stripe posteriorly; (15) a dark postocular streak
usually present; and (16) a short, oblique yellowish-brown or yellow-ochre streak (bright orange or rusty-red in life)
above the corner of the mouth and a large blotch of the same colour on the side of the neck.
Comparison. Hebius nigriventer differs from H. taronensis, with which it might be sympatric in northern
Myanmar (Kachin State) by (1) the dorsal general colour and pattern, i.e, a very dark background colour with a
uniform or weakly and partly chequered pattern vs. a dark background with pale and dark spots or blotches forming
a complex speckled or mottled pattern in H. taronensis; (2) a conspicuous dorsolateral chain or stripe of bright, or-
ange or rusty-brown blotches vs. a series of small pale yellowish-brown or ochre-brown dorsolateral blotches on the
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anterior part of the body; (3) venter nearly entirely very dark, i.e. blackish-brown or black, vs. venter both pale and
dark, i.e., with a pale background on its anterior part with the anterior half of each ventral brown or blackish-brown,
producing a pattern of irregular dark crossbands, and venter nearly uniformly very dark ochre-brown, dark brown or
blackish-brown on its posterior part; (4) a longer tail, ratio TaL/TL 0.29–0.37 vs. 0.25–0.29 in H. taronensis, espe-
cially in males: 0.32–0.37 vs. 0.25–0.29; (5) more subcaudals, 105–143 vs. 92–104 SC; (6) fewer ventrals in males,
156–168 vs. 171–175 VEN; (7) a difference in the ratio VEN/SC: 1.16–1.59 vs. 1.66–2.02; and (8) the number of
postoculars, usually 2, rarely 3 in H. nigriventer vs. always 3 in H. taronensis.
FIGURE 5. Hebius nigriventer Wall, alive—A & B: specimen KFBG 14536, Xueli, Yingjiang County, Yunnan
Province, China. Photograph: Jian-Huan Yang.
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H. nigriventer differs from H. venningi, by (1) the dorsal general colour and pattern: a very dark background
colour vs. dorsum grey, greyish-brown or, more rarely dark brown, with a distinct chequered pattern of darker
blotches in H. venningi; (2) a conspicuous dorsolateral chain or stripe of bright, orange or rusty-brown blotches vs.
a dorsolateral series of irregular blotches, yellow-ochre or yellowish-brown (bright yellow-ochre in life), enlarged
and forming a chain on the first quarter to third of the body, usually vanishing after midbody in H. venningi; (3)
venter entirely very dark, blackish-brown or black, sometimes with two, narrow longitudinal paler stripes vs. venter
widely pale in its middle part along at least the anterior part of the body, laterally clouded or dotted with dark grey
or dark brown, never entirely dark; (4) the position of the reduction to 6 scale rows around the tail in males: SC 9–14
vs. SC 19–24; and (5) the number of postoculars, 2, rarely 3, vs. always 3 in H. venningi.
The list of these characters may not clearly express the visual differences between H. nigriventer, an overally
dark species with highly contrasted bright orange dorsolateral blotches, and H. venningi, a usually paler species,
more “grey”, with a much more subdued chequered dorsal pattern. It should be noted that specimen CAS 233206
has a very dark brown background dorsal colour and a venter pale only along the first 10–15 ventrals. However, the
dorsal chequered pattern and the lack of the conspicuous dorsolateral bright orange or rusty-brown blotches make it
undoubtedly referable to H. venningi.
Lastly, H. nigriventer is morphologically quite similar to H chapaensis. Differences between these two species
are given below in the account of H. chapaensis.
Description.—Body rather slender, elongate, cylindrical, stouter in large females; head elongate, triangular,
moderately distinct from the thick neck, flattened anteriorly; snout elongate, obtuse as seen from above, oblique
seen in profile, flat, amounting for 27.5–31.5 % of HL, or 1.9–2.1 times as long as diameter of eye; nostrils placed
dorsolaterally on the snout and directed dorsolaterally, small, round, piercing in the middle of the nasal; eye average,
about 1.0–1.1 times as large as the distance between its lower margin and the margin of the lip, with a round pupil;
tail long and tapering.
The maximal known total length is 716 mm (SVL 458 mm; TaL 258 mm; specimen CAS 241960) for a male.
The longest known female is 593 mm long (SVL 391 mm, TaL 202 mm long; KFBG 14536). However, specimen
CAS 238901, with an incomplete tail, has a SVL of 454 mm.
Ratio TaL/TL: 0.291–0.366, with a weak sexual dimorphism (see below).
Dentition. 28–32 maxillary teeth gradually enlarging, the last 2 moderately enlarged, without diastema.
Body scalation. DSR: 17(19)-17-15–17 rows; scales rhomboedric, moderately keeled at midbody, more strong-
ly keeled posteriorly; scales of 1st DSR smooth; scales around the base of the tail very strongly keeled.
In our sample of 13 specimens, only one specimen has 19 scale rows around the neck. Two others have 16 scale
rows before vent, two have 15 rows.
VEN: 155–168 (plus 1 or 2 preventrals); SC: 105–143, all paired, with a weak sexual dimorphism (see below);
cloacal plate divided.
Ratio VEN/SC 1.16–1.59, with a weak sexual dimorphism (see below).
Position of the reduction to 6 scale rows around the tail: SC 7–14, with a distinct sexual dimorphism; ratio:
length of the portion of tail with 6 dorsal scale rows/length of the portion of tail with 4 dorsal scale rows: 2.1–3.1.
Head scalation. Arrangement of upper head scales complete including 2 internasals, 2 prefrontals, 2 supraocu-
lars, 1 frontal, and 2 parietals. Rostral wider than high, barely visible from above; nasals more or less rectangular,
elongate, about 1.5–1.8 times longer than high, vertically divided above and below the nostril, with the posterior
part equal to anterior one; internasals rather small, trapezoid, in broad contact with each other, about 1.1–1.2 times
longer than wide, distinctly narrowing anteriorly with an anterior margin about 0.4–0.5 times the width of the pos-
terior margin; 2 prefrontals rather small, short, wide, wider than long, 0.9–1.1 times as long as internasals; frontal
large, shield-like, 1.1–1.3 times longer than wide and 1.8–2.1 times as long as the prefrontal; 1 supraocular on each
side, subtriangular, 2.0–2.2 times longer than wide, about as wide as internasals; parietals large and broad, 1.5–1.6
times longer than the frontal, or suture between parietals 1.0–1.1 times longer than frontal; 1/1 loreal, pentagonal,
elongate, 1.4–1.5 times longer than high, in broad contact with the nasal; 2 preoculars on each side in all examined
specimens, upper one larger than lower one; 2 (in 8/24 occurrences) or 3 (16/24 occurrences) small postoculars;
9/9 SL in all examined specimens, the first five as long as high or longer than high, 1st and 2nd SL small and short,
in contact with the nasal, 2nd–3rd or more rarely 2nd–4th, 3rd or 3rd–4th SL in contact with the loreal, 4th–6th (5th–6th in
two specimens) SL entering orbit, 7th and 8th SL largest; 1 anterior temporal, elongate, rectangular, followed by 1 or,
rarely 1+1/1 or 2 posterior temporals, the most common formula being 1+1 temporals; 10 infralabials in all exam-
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ined specimens, first pair in contact, 1st–5th IL in contact with anterior chin shields, 5th and 6th IL largest; posterior
chin shields longer than anterior ones.
Coloration and pattern. The upper dorsal surface is dark brown or blackish-brown, either nearly uniform or
with, on each side, two series of subdued, poorly visible large, rectangular darker blotches, about 2–2.5 scales
long and wide, one on the top of the back on the 7th–8th DSR, the other series on the 3rd–4th or 4th–5th DSR forming
altogether a diffuse chequered pattern; on each side throughout the length of the body, a dorsolateral series of con-
spicuous distinctly enlarged, vertically elongate or triangular blotches, pale creamish-brown or pale ochre-brown
in preservative (see below in life), extending on the 4th–6th or 5th–6th DSR, longitudinally separated by 2 or 3 dorsal
scales, about 1.5–2 scales long and 2–3 scales high anteriorly; after midbody, these conspicuous blotches become
smaller and squarish or irregularly-shaped, then elongate posteriorly and forming a discontinuous dorsolateral chain
or an irregular stripe; some small orange spots or blotches on the bottom of the sides. The tail is as dark as the upper
surface of the body, possibly mottled with irregular darker blotches; a dorsolateral series of orange-brown, rusty-red
or brownish-red elongate spots or dashes up to the tip of the tail.
The head is dark brown or blackish-brown, irregularly mottled above with both paler and darker brown vermic-
ulations or diffuse areas; loreal and nasal either dark brown or with a paler area, pale yellowish-brown spotted with
dark brown; 1st–6th or 1st–7th supralabials dirty creamish-yellow or pale yellowish-brown, 1st–3rd SL usually strongly
speckled with dark brown, all broadly edged with dark brown or blackish-brown on their posterior edge, sometimes
the pale coloration being restricted to the forward half of the suparalabial; last supralabial with a large pale blotch
on its upper part, pale creamish-yellow or creamish-brown; a broad, dark postocular streak extending obliquely
from postoculars to the two upper parts of posterior supralabials and to the corner of the mouth; a narrower, oblique
streak or a series of small, elongate blotches, dirty creamish-yellow or pale yellowish-brown, extending above the
dark streak from the upper postocular to the large pale blotch on the 9th SL and to behind the corner of the mouth;
on each side of the neck, an irregular, rather broad streak, pale creamish-yellow or yellowish-brown (see below in
life), obliquely directed upwards and backwards, extends from behind the corner of the mouth to the nape, forming a
short chevron with an apex directed backwards. Infralabials, chin and throat yellowish-cream or pale yellow-ochre,
with scattered dark brown spots on chin shields and throat, sometimes heavily spotted with dark brown; infralabials
strongly edged with dark brown on both anterior and posterior edges, and often strongly speckled with dark brown,
being sometimes more brown than pale.
The venter is dark brown, blackish-brown or black on nearly its whole length at the exception of first 10–20
ventrals, pale in their middle but heavily blotched with dark hues; often, three narrow longitudinal stripes, paler
brown or yellow-ochre, one in the middle of the venter, the other ones on the outer third of each ventral along the
anterior half of the body after the pale central area, vanishing at the level of third to half of the body, making the
venter nearly uniformly dark on its posterior part; tips of ventrals without dark blotch but with a streak of the pale
colour forming an irregular ventrolateral stripe reduced to the anterior part of the body. Tail uniformly dark brown
or blackish-brown below; tip of tail very dark.
In life, the overall coloration is as described above but more constrasted; the dorsal surface is dark or nearly
black, somewhat shining; large and small, elongate dorsolateral blotches are conspicuous, bright orange-brown, red-
ochre, rusty-red or brownish-red, strongly constrasting with dark background colour. Pale markings on the head and
supralabials are dark greenish-yellow, yellowish-ochre or pale yellowish-brown; the narrow, arched streak, or the
series of irregular blotches extending from the upper postocular to the 9th SL and to behind the corner of the mouth
are yellow-ochre, pale yellowish-brown, orange brown or rusty red; the broad streak on each side of the neck has
the same colour than dorsolateral blotches. Pale areas of the venter are yellowish ochre or brownish-yellow, never
in reddish hues.
Hemipenes.—The hemipenis of this species has not been examined.
Sexual dimorphism.It is expressed in the following characters:
(1) strongly by the difference in the ratio TaL/TL: males: 0.348–0.375 (mean = 0.353, SD = 0.019); females:
0.291–0.341 (mean = 0.312, SD = 0.026).
(2) by the difference in the number of subcaudals: males: 124–143 ( = 133.0, s = 7.5); females: 105–126
(mean = 112.0, SD = 9.7).
(3) Strongly by the difference in the position (counted in subcaudals) of the reduction of scale rows around the
tail to 6: males: SC 9–14; females: SC 6–7.
Distribution (Fig. 3).—Myanmar. Kachin State. Bhamo District; Myitkyina District.—People’s Republic of
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 19
China. Yunnan Province. Yingjiang County, Dehong Dai and Jingpo Autonomous Prefecture; Gongshan County,
Nujiang Prefecture; Mengla County, Jinhong Prefecture.
This species may also be present in northern Laos.
Biology.—This species inhabits evergreen or semi-evergreen submontane forest and mixed or deciduous moist
montane forest from 350 up to 1,550 m asl. According to data relative to a few specimens, H. nigriventer is both
diurnal and active at dusk or in the early part of the night, at air temperatures from about 24 to 27 °C. This species
is seemingly largely aquatic. Most snakes were found in hill or montane streams, between or on rocks in the stream
bed. One of the specimens mentioned by Wall (1925) had swallowed two large and four small tadpoles. Another
one, a female collected in June, contained two large eggs, indicating that egg laying would have taken place at the
beginning of the rainy season.
3. Hebius taronensis (Smith, 1940)
(Figs. 6–7)
Natrix venningi taronensis Smith, 1940: 482.—Type locality. “Pangnamdim”, now Pannandin, about 27°43’N, 97°52’E, Nawng-
mun Township, Putao District, Kachin State, Myanmar.—Holotype. BMNH 1946.1.13.55 (originally BM 1940.1.6.93),
adult male; collected and deposited by Ronald Kaulback, 1937–1939.
Natrix venningi taronensis.—Smith 1943: 286.
Amphiesma venningi taronensis.—Captain & Bhatt 2002: 354, 355; Welch 1988: 34; Zhao 2006: 175; Sharma 2007: 208.
Paranatrix venningi taronenis.—Mahendra 1984: 245.
Amphiesma taronense.—Das 2010: 335; Das 2012: 151; Wallach et al. 2014: 33 (in part: mention from Kachin State only).
Hebius taronensis.—Boundy 2020: 92; this work.
Specimens examined (14).—Myanmar. Kachin State. BMNH 1936.7.4.31, “Nam Ti Valley, Upper Burma”, now
Ratnamhti (27°35’N, 97°47’E), north of the village of Alangdunhku, at about mid-distance between Langtao and
Nawngmun, Putao District; BMNH 1946.13.55 (holotype), BMNH 1946.1.7.92–97, “Pangnamdin”, 27°42’N,
97°54’E, now Pannandin, Nawngmun Township, Putao District; BMNH 1974.885–886, “Pangnamdin, 3000 ft,
27°42’N, 97°54’E”, now Pannandin, Nawngmun Township; BMNH 1946.1.13.44, “Aliwang, Taron Valley”, now
Alawang (27°42’N, 98°08’E), near Renam, in the valley of the Nam Taron, Putao District; CAS 221298, between
Alonga and Ahtonga bridge, 27°16’51.3N, 97°45’31.8E, Machanbaw Township, Putao District; CAS 224426–427:
Pannandin Village, Hkakabo Razi National Park, Nawngmun Township, 27°43’28.7”N, 97°52’09.5”E, Putao Dis-
trict.
Taxonomic comments.—This taxon was described as a subspecies of Hebius venningi (Wall, 1910). Subse-
quently, it has rarely been cited as a valid taxon in the literature. It has even been overlooked, for example, by Dowl-
ing & Jenner (1988). However, Das (2010, 2012), Wallach et al. (2014) and Boundy (2020) recognized this taxon at
full species level, although without justification. This species is monotypic.
On the basis of the differences in morphology between Natrix v. venningi and Natrix venningi taronensis dis-
cussed below and of their allopatric distribution, we consider them to be distinct at the specific level. This position
has already been previously adopted in the list of snakes of Myanmar provided on the website of the California
Academy of Sciences, by Das (2010: 335; 2012: 151) and by Wallach et al. (2014: 33); see the details above under
the account of H. venningi. Following Guo et al. (2014), the species taronensis is placed in the genus Hebius.
Hebius taronensis may be confused with H. nigriventer, although the tail length and dorsal pattern in life are
quite different. Our data show that these taxa differ by constant characters and should be considered distinct species;
see above under the account of H. venningi. H. taronensis is now restricted to the north of Kachin State, in northern
Myanmar and, tentatively, north-eastern India.
Diagnosis.—A moderately sized species of the genus Hebius characterized by the combination of (1) 17(18)-
17-17 dorsal scale rows, moderately keeled at midbody, strongly keeled posteriorly but 1st DSR smooth; (2) dorsal
scales around the base of the tail very strongly keeled; (3) head moderately distinct from the neck; (4) eye average;
(5) maxillary teeth 28–32, the last two moderately enlarged; (6) tail moderately long, with a ratio TaL/TL < 0.29; (7)
VEN 158–176; (8) SC 92–104; (9) prefrontal scales 2; (10) 3 postoculars in all examined specimens; (11) anterior
temporal more or less hexagonal, narrowing posteriorly; (12) venter both pale and dark, i.e., with a pale background
on its anterior part, up to the third or half of the body, with the anterior half of each ventral typically brown or black-
ish-brown, producing a mottled pattern of irregular dark crossbands, sometimes reduced to one or two dark blotches
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on some ventrals; on its posterior part, the venter is nearly uniformly very dark ochre-brown, dark brown or black-
ish-brown; (13) dorsum and sides of body dark, i.e. brown, dark greyish-brown, dark brown and blackish-brown;
(14) dorsal pattern made of faint, irregular pale blotches mixed with diffuse, squarish dark brown blotches forming
a complex variegated or reticulate pattern, not distinctly chequered; (15) on each side, a series of small, elongate,
dorsolateral blotches, pale yellowish-brown or ochre-brown (vividly colored in bright orange-yellow or bright yel-
low in life); (16) usually no clearly defined postocular streak; and (17) irregular yellowish-brown or yellow-ochre
streaks or a faint blotch on the neck.
Comparison. Hebius taronensis differs from H. venningi by (1) a shorter tail, ratio TaL/TL 0.25–0.29 vs.
0.30–0.35 in H. venningi; (2) fewer subcaudals, 92–104 vs. 115–129; (3) dorsum brown to blackish-brown with pale
and dark spots or blotches forming a complex speckled or mottled pattern vs. dorsum grey or greyish-brown with
a chequered pattern of darker blotches; (4) on each side, a series of more or less elongate blotches, pale yellowish-
brown or ochre-brown (bright orange or yellowish-red in life) vs. yellow-ochre or yellowish-brown (same in life);
(5) venter both pale and dark, i.e. with a pale background on its anterior part with the anterior half of each ventral
brown or blackish-brown, producing a pattern of irregular dark crossbands, and venter nearly uniformly very dark
ochre-brown, dark brown or blackish-brown on its posterior part vs. venter widely pale in its middle along at least
the anterior part of the body, laterally clouded or dotted with dark grey or dark brown, never entirely dark.
The differences between H. taronensis and H. nigriventer have been given above in the diagnosis of the latter
species.
Description.—Body rather slender, elongate, cylindrical, stouter in large females; head elongate, somewhat
triangular, moderately distinct from the thick neck, flattened anteriorly; snout elongate, obtuse as seen from above,
oblique seen in profile, flat, 24.5–30.5 % of HL, or 1.8–2.1 times as long as diameter of eye; nostrils placed dorsolat-
erally on the snout, small, round, piercing in the middle of the nasal; eye size average, about 1.0–1.2 times as large as
the distance between its lower margin and the margin of the lip, with a round pupil; tail rather long and tapering.
The maximal known total length is 833 mm (SVL 581 mm; TaL 252 mm; specimen CAS 224427) for a female.
The longest known male is 634 mm long (SVL 458 mm, TaL 176 mm long; BMNH 1946.1.13.55).
Ratio TaL/TL: 0.254–0.288, without sexual dimorphism (see below).
Dentition. 27–32 maxillary teeth gradually enlarging, the last 2 moderately enlarged, without diastema.
Body scalation. DSR: 17(18)-17-16–17 rows; scales rhomboedric, feebly or moderately keeled at midbody,
strongly keeled posteriorly; scales of 1st DSR smooth; dorsal scales around the base of the tail very strongly
keeled.
In our sample of 12 specimens, only one has 18 scale rows around the neck.
VEN: 158–175 (plus 1 or 2 preventrals); SC: 92–104, all paired; cloacal plate divided.
Ratio VEN/SC 1.66–2.02.
Position of the reduction to 6 scale rows around the tail: SC 9–14, without sexual dimorphism; ratio: length of
the portion of tail with 6 dorsal scale rows/length of the portion of tail with 4 dorsal scale rows: 1.3–3.1.
Head scalation. Arrangement of upper head scales complete including 2 internasals, 2 prefrontals, 2 supraocu-
lars, 1 frontal, and 2 parietals. Rostral wider than high, barely visible from above; nasals more or less rectangular,
elongate, about 1.4–1.6 times longer than high, vertically divided above and below the nostril, with the posterior
part equal to anterior one; internasals subtriangular, small, in broad contact with each other, about 1.0–1.2 times
longer than wide, distinctly narrowing anteriorly with an anterior margin about 0.4–0.5 times the width of the pos-
terior margin; 2 prefrontals, rather large, distinctly wider than long, 1.2–1.3 times longer than internasals; frontal
large, shield-like, 1.2–1.3 times longer than wide and 1.6–1.9 times as long as the prefrontal; 1 supraocular on each
side, subtriangular, 2.0–2.3 times longer than wide, about as wide as internasals; parietals large and broad, 1.6–1.8
times longer than the frontal, or suture between parietals 1.1–1.3 times longer than frontal; 1/1 loreal, pentagonal,
elongate, 1.4–1.5 times longer than high, in broad contact with the nasal; 2 preoculars on each side in all examined
specimens, upper one larger than lower one; 3/3 small postoculars in all examined specimens; 9 SL (only 8 SL in
1/18 occurrences), the first five as long as high or longer than high, 1st and 2nd SL small and short, in contact with the
nasal, 2nd–3rd SL (3rd–4th in one specimen) in contact with the loreal in all examined specimens, 4th–6th SL entering
orbit, 7th and 8th SL largest; 1 anterior temporal, long, hexagonal, distinctly narrowing posteriorly, followed by 1 or
1+1/1 posterior temporals, the most common formula being 1+1 temporals; 10 infralabials in all examined speci-
mens, first pair in contact, 1st–5th IL in contact with anterior chin shields, 5th and 6th IL largest; posterior chin shields
longer than anterior ones.
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Coloration and pattern. The upper dorsal surface is dark ochre-brown, chestnut brown or dark brown, some-
times blackish-brown, with many scales irregularly edged or entirely covered with dark brown or blackish-brown,
especially on the top of the body, mixed with irregular, diffuse, faint paler areas, pale yellowish-brown or pale
brown, producing a complex, irregularly marbled or reticulate pattern; on each side of the body, a dorsolateral series
of distinctly enlarged, aligned, pale creamish-brown or pale ochre-brown blotches, about 1.5–2 scales long and 2–3
scales high on the 4th–6th or 5th–6th DSR, forming a discontinuous dorsolateral chain; these blotches become quickly
reduced in size, remaining as very faint pale spots in the hinder part of the body and are poorly visible posteriorly,
mixed in the general dorsal pattern. The dorsal surface of the tail is as the upper surface of the body, irregularly
mottled with many darker blotches but without distinct pale areas.
The head is dark brown or blackish-brown above, darker than the sides of body, irregularly mottled with paler
areas and speckled with darker dots or with irregular darker brown areas; side of the snout slightly paler than up-
per head surface; anterior or all supralabials pale brownish-yellow, pale or brown, strongly powdered and more or
less broadly edged with dark brown on their posterior edge; usually no real dark postocular streak, the temporal
region being merely mottled with irregular paler brown; however, in a few specimens (such as CAS 221298), a
pale yellowish-brown elongate blotch on the temporal region defines a lower, broad, dark brown streak, connect-
ing posterior temporals to the corner of the mouth; on each side of the neck an irregular, more or less well-defined,
yellow-ochre or brownish-yellow streak obliquely directed upwards and backwards extends from the corner of the
mouth to the nape forming a short chevron with an apex directed backwards, faint or absent in darker specimens;
infralabials, chin and throat pale yellowish-cream or pale yellow-ochre, with a few scattered dark brown spots on
chin shields and throat, sometimes heavily spotted with dark brown; infralabials strongly edged with dark brown on
their both edges, and often strongly speckled with dark brown.
The venter is both pale and dark: the background colour is beige, pale greyish-brown or pale ochre-brown on its
anterior part, i.e., along the anterior quarter to third, sometimes up to nearly the half of the body, and dark brown or
blackish-brown on its posterior part; the first 10–15 ventrals may be merely speckled with brown blotches but, typi-
cally, the anterior half of each ventral is irregularly covered with dark brown or blackish-brown, producing a pattern
of irregularly-edged, dark crossbands on a paler background; backwards, the dark area progressively expands up to
covering the whole of each ventral, often so irregularly as to leave one or two blotches of pale area on the middle of
ventrals; after midbody the venter is uniformly dark up to the vent, with the posterior margin of each ventral paler
brown; no ventral or ventrolateral pale stripes or streaks. Tail uniformly dark brown or blackish-brown below; tip
of tail as the undersurface of tail.
In life, the pattern is much more vivid and contrasted; the background coloration is as described above, usu-
ally dark brown or nearly black; the faint, dorsal paler areas are dark ochre-brown or yellowish-brown; dorsolateral
blotches are vividly colored in bright lemon-yellow, orange-yellow or yellowish-red, visible throughout the length
of the body. Pale markings on the head, the supralabials, the elongate blotch on the temporal region and the streak
obliquely directed upwards and backwards on the hinder part of the head and the neck are dirty yellow or yellow-
ish-ochre. Pale areas of the venter are yellowish-ochre or yellowish-brown.
Hemipenes.—The hemipenis of this species has not been examined.
Sexual dimorphism.It is expressed in the two following characters:
(1) Difference in the number of ventral scales: males: 171–175 (mean = 172.6, SD = 1.5); females: 158–171
(mean = 165.6, SD = 1.5).
(2) Strongly by the ratio length of the portion of tail with 6 dorsal scale rows/length of the portion of tail with 4
dorsal scale rows: 2.6–3.1 in 4 males, 1.3–2.0 in 2 females.
Distribution (Fig. 3).—Myanmar. Kachin State. Lake Indawgyi, Mohnyin Township; Nawgmung Township
and Machanbaw Township, Putao District.—India. State of Arunachal Pradesh. Changlang District.
In Myanmar, this species is currently endemic to the mountain ranges located north-east of Putao and Mawg-
mung, in the extreme north of the country. Farther south in the same state, it is replaced by Hebius nigriventer.
The presence of H. taronensis in extreme north-eastern India is based on a specimen cited by Captain & Bhatt
(2002). Although we have not seen it, its number of subcaudals and relatively short tail are typical of H. taronensis.
We here add this species to the snake fauna of India.
Biology.—This species inhabits semi-evergreen submontane forest and mixed or deciduous moist montane for-
est from about 1,000 up to at least 1,850 m asl. Most known localities are between 1,100 and 1,800 metres a.s.l. H.
taronensis is seemingly diurnal. According to Smith (1940), most specimens were obtained from small mountain
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streams. One was eating a frog, another specimen had eaten tadpoles. Others were found under rocks near a stream.
Nothing else is known on the biology of this seemingly rare or highly localized species. According to Smith (1940),
this water snake is quiet and harmless.
FIGURE 6. Hebius taronensis Smith, holotype (BMNH 1946.1.13.55)—A: dorsal view; B: ventral view; C: lateral
view of the head, right side; D: close-up dorsal view of the head. Photographs: Gernot Vogel.
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 23
FIGURE 7. Hebius taronensis Smith, alive—Specimen from Lake Indawgyi, Mohnyin Township, Kachin State,
Myanmar. Photograph: Nikolay Poyarkov.
4. Hebius chapaensis (Bourret, 1934)
(Figs. 8–9)
Pararhabdophis chapaensis Bourret, 1934a: 131 (Separate: p. 3), Fig. 2.—Type locality. “Chapa, province de Laokay (Tonkin),
à l’altitude moyenne de 1600 m”, now Sa Pa, Lào Cai Province, Vietnam, ca. 1,600 m elevation.—Holotype. MNHN
1938.0125, adult male (Muséum National d’Histoire Naturelle, Paris, France); collected by René Bourret, Summer 1930
or 1931 and deposited in 1934.
Pararhabdophis chapaensis.—Bourret 1935a: 249; Bourret 1936a: 97, 103, 114 & 121; Bourret 1936b: 121, Fig. 49; Bourret
1939a: 44; Bourret 1939b: 54; Smith 1943: 316; Tran et al. 1981: 382; Welch 1988: 88; Nguyen & Ho 1996: 98; Iskandar
& Colijn 2001: 103; Nguyen et al. 2005a: 93; Nguyen et al. 2009: 363; Das 2010: 296; Bain & Hurley 2011: 104 & 129;
Stuart & Nguyen 2012b: e.T191911A2014449; Pham et al. 2013: 17, 21 & 22: Fig. B; Teynié et al. 2014: 43, 44: Pl. 7B;
Wallach et al. 2014: 522; David et al. 2015b: 203, 209, 215, 216 & 219; Le et al. 2018: 103, 106: Fig. 3A & 107.
Hebius chapaensis.—Kizirian et al. 2018: 2, 3 & 5; Ren et al. 2018: 31, 37 & 40; Boundy 2020: 92; T. V. Nguyen et al. 2020:
234: Fig. 8 (A); Wang et al. 2020: 205; Appendix 2: 15.
Specimens examined (10).—People’s Republic of China. Yunnan Province. CIB 110718, Menglun, 21°58’5”N,
101°11’51.46”E, Mengla County, Xishuangbanna Dai Autonomous Prefecture. elev. 567 m.—Vietnam. Lao Cai
Province. IEBR 2907–2909, Cat Cat, I Ninh Ho, Sa Pa; MNHN 1938.0125 (holotype of Pararhabdophis cha-
paensis), Sa Pa, ca. 1,600 m a.s.l.; ROM 38195, Lao Cai. Cao Bang Province. ROM 28636, Cao Bang.—Laos.
Houaphan Province. NCSM 77924, Phou Louey National Protected Area, near Tad Loi Waterfall, 20.23253°N,
103.2108°E, Viengthong District, elev. 1,186 m; 1 non preserved specimen, near Viengthong, Viengthong District,
elev. 1,050m. Louangphabang (or Louang Prabang) Province; NCSM 77925, Hoay Tala 1, branch of the Nam
Madao, 19.30189°N, 102.5736°E, Phoukhoume District, elev. 1,269 m.
Taxonomic comments.—Bourret (1934a) erected the genus Pararhabdophis for the sole included species Para-
rhabdophis chapaensis Bourret, 1934, described from a single specimen, on the basis of the following characters:
32 subequal maxillary teeth, of which the three last ones are strongly enlarged, and a small eye with a vertical pupil;
other characters included a head well distinct from the neck, 2 internasals and 2 prefrontals, an elongate, slightly
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laterally compressed body, dorsal scales feebly keeled, without apical pits, in 17 rows, tail long, subcaudals paired
and hypapophyses developed throughout along the vertebral column. Smith (1943) accepted the validity of this
genus solely on the basis of the vertical pupils of the holotype. Otherwise, Smith stated that he would have placed
it in the then large genus Natrix Laurenti. In fact, the diagnosis of the genus has been somewhat biased by Bourret
(1934a). The holotype is in bad condition and strongly dessicated. After a careful examination under a powerful
incident light, the pupil of the holotype became visible. It is indeed elliptic at left but nearly circular at right, where
it is much more difficult to see. Most probably, Bourret was misled by the state of his specimen, perhaps found dead
on road. We suspect that the dessication of this specimen may have altered the shape of the eye.
The status of this genus has not been re-evaluated between 1934 and 2018 and it has been constantly considered
to be valid (see the references cited above), probably by lack of additional specimens. Indeed, for long, this species
has been known from its sole holotype, collected in north-western Vietnam. Subsequently, three specimens were
obtained from Laos (Teynié et al. 2014). David et al. (2015b) examined a total of nine specimens of Pararhabdophis
chapaensis and confirmed the validity of the species. All these specimens agree in all points with the holotype but
have a round pupil. The posterior maxillary teeth are strongly enlarged. In the family Natricidae, this condition is
met in the genus Rhabdophis and in Amphiesma stolatum (Duméril, Bibron & Duméril), sole species of the genus
Amphiesma following the revision of Guo et al. (2014). It appears also in the Himalayan species currently referred
to the genus Herpetoreas Günther by Guo et al. (2014).
Eventually, on the basis of molecular data, Kizirian et al. (2018) showed that Pararhabdophis chapaensis
is nested within the genus Hebius Thompson, 1913. Barely one month later, Ren et al. (2018) reached the same
conclusions on the basis of both morphological and molecular data. We here follow these authors in referring Para-
rhadophis chapaensis to the genus Hebius. The dentition of the upper maxilla, made of subequal small teeth fol-
lowed by two enlarged posterior teeth, the average-sized eye with a round pupil, the dorsolateral nostrils, the keeled
dorsal scales, the long, keeled tail, the supralabials longer than high and the general pattern, are typical of the genus
Hebius as defined by Guo et al. (2014). This species is monotypic.
Furthermore, Ren et al. (2018) reported the occurrence of this species in China on the basis of a single specimen
collected from Pingbian Miao Autonomous County, Honghe Hani and Yi Autonomous Prefecture, Yunnan Province,
at about only 21 kilometres from the Sino-Vietnamese border along the Vietnamese province of Lào Cai. These
authors also examined seven additional specimens from north-western Vietnam (Sa Pa, Lao Cai Province).
Diagnosis.—A moderately sized species of the genus Hebius characterized by the combination of (1) a body
elongate in both sexes; (2) head distinct from the neck; (3) 17–18 (rarely 19)-17-17 dorsal scale rows, distinctly
keeled at midbody, strongly keeled posteriorly, especially before vent but smooth or feebly keeled on the 1st dorsal
scale row; (4) scales around the base of the tail very strongly keeled; (5) eye average with a pupil variable in shape,
i.e., usually round but also elliptic or even asymmetrically and irregularly shaped, 1.0–1.2 times the distance be-
tween the lower margins of eye and of lip; (6) 29–34 maxillary teeth, progressively increasing in size in a continu-
ous series, the last two or three abruptly and strongly enlarged, not separated from anterior teeth by a diastema; (7)
nostrils piercing laterally or slightly dorsolaterally; (8) tail long but with a ratio Tal/TL lower than 0.30; (9) 159–177
VEN; (10) 90–114 subcaudals, paired; (11) internasals abruptly truncated; (12) 2 prefrontal scales, (13) 1 anterior
temporal, (14) venter dark, blackish-brown or black, with some paler, more or less faint longitudinal streaks and
sometimes a pale blotch or streak on the outer margin of ventrals; (15) background colour dark brown or blackish-
brown; (16) dorsal pattern made of more or less elongate cream, pale yellow or pale orange-brown blotches on a
faint dorsolateral stripe; (17) an elongate, cream or pale ochre-yellow blotch, or isolated blotches on the nape; (18)
a strong postocular streak; (19) upper head surface with strong, yellow vermiculations; and (20) supralabials cream,
ochre-yellow or pale yellowish-brown, edged with dark brown, or divided into a pale and dark area.
Comparison. Among species with 17 dorsal scale rows, Hebius chapaensis readily differs from H. annamensis
by (1) internasals abruptly truncated (vs. distinctly narrowing); (2) its venter nearly entirely dark vs. entirely pale
with only tips of ventral scales dark in H. annamensis; (3) a distinct dorsal pattern; and (4) a shorter tail, ratio TaL/
TL 0.28–0.30 vs. 0.30–0.34 in H. annamensis; see also below in the account of H. annamensis.
Hebius chapaensis differs from H. venningi by the characters given in the key above, especially (1) a shorter
tail, ratio TaL/TL 0.28–0.30 vs. 0.30–0.35 in H. venningi; (2) the number of postoculars, mostly 2 (exceptionally
3) vs. 3 in all examined specimens of H. venningi; (3) venter entirely dark with some pale streaks vs. venter pale
mesially at least on the anterior part of the body, clouded with darker hues of brown on the outer parts of ventrals
in H. venningi.
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Hebius chapaensis differs from H. taronensis especially by (1) its venter entirely dark with some pale streaks
vs. venter pale anteriorly with an irregular dark brown crossband on each ventral, dark brown on its posterior half in
H. taronensis; (2) dorsum with large, orange dorsal blotches vs. dorsum overally dark with faint paler blotches and
diffuse black spots or blotches forming a complex speckled or irregularly mottled pattern.
Lastly, H. chapaensis is morphologically quite similar to H. nigriventer. These species may be distinguished
by (1) a shorter tail in H. chapaensis, 0.28–0.30 vs. 0.29–0.37 in H. nigriventer; (2) 90–114 subcaudals in H. cha-
paensis vs. 105–143 SC in H. nigriventer; (3) dorsal scales strongly keeled on the body (smooth or feebly keeled
on the 1st dorsal scale row) vs. moderately keeled at midbody, strongly keeled posteriorly, but with scales of 1st
DSR smooth; (4) dorsal pattern made of more or less elongate, cream, pale yellow or pale orange-brown blotches
(orange or rusty-red in life) on a faint dorsolateral stripe vs. rectangular blotches of the same colours, higher than
long anteriorly then more elongate, forming a conspicuous, dorsolateral chain of blotches. Other characters may be
found in the account of H. nigriventer.
Description.—Body elongate, slightly laterally compressed, somewhat thicker in females; head elongate,
somewhat triangular, distinct from the thick neck, strongly flattened anteriorly; snout elongate, flat, blunt or slightly
round seen from above, subrectangular seen in profile, 25.0–31.0 % of HL, or 1.8–2.0 times longer than diameter
of eye; nostrils small, round, placed slightly dorsolaterally on the snout and directed dorsolaterally, piercing in be-
tween the two parts of divided nasal; eye size average, about 1.0–1.2 times as large as the distance between its lower
margin and the margin of the lip, with a pupil variable in shape, i.e., usually round but also elliptic or even asym-
metrically and irregularly shaped, according to our specimens and Ren et al. (2018); tail long, thin and tapering.
The maximal known total length is 742 mm (SVL 534 mm; TaL 208 mm; specimen ROM 38195) for a male.
The longest known female is 730 mm long (SVL 522 mm, TaL 208 mm long; ROM 28636).
Ratio TaL/TL: 0.280–0.296, without sexual dimorphism (see below).
Dentition. 29–34 maxillary teeth, gradually enlarging in a continuous series, the last 2 or 3 teeth abruptly and
strongly enlarged, without diastema.
Body scalation. DSR: 17(or 18)-17-17 rows; scales rhomboedric, keeled on 2nd–10th, moderately on the anterior
part of the body, strongly posteriorly, very strongly in the region of the vent and along the base of the tail; scales of
1st row smooth anteriorly, feebly keeled posteriorly.
In a sample of 11 specimens, the dorsal scale row formulas are: 17–17–17 (7 specimens), 18–17–17 (3 speci-
mens) and 19–17–17 (1 specimen).
VEN: 159–177 (plus 1 or 2 preventrals); SC: 90–114, all paired, with a weak sexual dimorphism (males:
103–114; females 90–111); cloacal plate divided.
Ratio VEN/SC 1.47–1.77.
Position of the reduction to 6 scale rows around the tail: SC 8–19, with a sexual dimorphism (males: 15–19th
subcaudal; females: 8–13th subcaudal); ratio: length of the portion of tail with 6 dorsal scale rows/length of the por-
tion of tail with 4 dorsal scale rows: 0.39–0.55.
Head scalation. Arrangement of upper head scales complete including 2 internasals, 2 prefrontals, 2 supra-
oculars, 1 frontal, and 2 parietals. Rostral hexagonal, wider than high, well visible from above; nasals more or less
rectangular, elongate, vertically divided above and below the nostril by a furrow with the fore and hind parts similar
in size, altogether about 1.2–1.6 times longer than high; internasals subtriangular, 1.1–1.2 times longer than wide,
abruptly truncated with their anterior margin about 0.7–0.58 times the width of the posterior margin, elongate,
in broad contact with each other, shorter than the prefrontal; 2 prefrontals, rather large, wide but short, distinctly
broader than long, 1.1–1.3 times longer than internasals; in broad contact with loreal; frontal hexagonal, large,
shield-like, 1.1–1.3 times longer than wide and 1.7–1.9 times as long as the prefrontals; on each side 1 supraocular,
subtriangular slightly narrower than internasals, 1.6–1.8 longer than wide, about 0.5 times as wide as frontal; pari-
etals long and broad, 1.7–2.1 times longer than frontal, or suture between parietals as great as the frontal length; 1/1
loreal, rectangular, elongate, 1.5–1.8 times longer than high, in broad contact with the nasal; 2 (rarely 1) preoculars
on each side, 2 subequal preoculars on each side in all specimens examined by us, 1 or 2 scales in specimens exam-
ined by Ren et al. (2018); 2 or rarely 3 small postoculars on each side, upper one largest; 9 (rarely 10) supralabials,
1st–5th SL longer than high, other supralabials as long as high, 1st–2nd SL small and short, 1st–3rd SL in contact with
nasal, 2nd–3rd or 3rd–4th SL in large contact with the loreal, 4th–6th or rarely 5th–6th SL entering orbit, 7th–8th supralabi-
als largest; 1 anterior temporal, narrow and elongate, in all known specimens; complete temporal formulas as 1+1
or more rarely 1+2; 9–10 (rarely 8) infralabials, first pair in contact with each other behind the mental, 1st–5th (rarely
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26 · Zootaxa 4911 (1) © 2021 Magnolia Press
1st–4th) IL in contact with anterior chin shields, 5th IL largest; mental triangular; anterior pair of chin shields equal to
or slightly longer than posterior shields.
Coloration and pattern. In preservative, upper dorsal surface and body sides are dark brown, dark chestnut
brown or deep blackish-brown, with sides below the 5th dorsal scale row either variegated with cream or yellow, or
with most scales of the 1st to 4th scale rows marked with irregular longitudinal streaks, cream, ochre or pale brown
(see below in life), reduced to dots posteriorly; a large, elongate, crescentic blotch or smaller, isolated cream, pale
yellow or pale orange-brown blotches on the nape; a faint or irregular dorsolateral stripe, yellowish-ochre or pale
brown, extending from the neck to vent on the 5th–7th dorsal scale rows, often barely distinct or even absent; on the
dorsolateral stripe (when present), a series of cream or yellow, elongate, blotches 2 or 3 scale long; the first four to
six blotches behind the neck largest, covering scales of the 5th–7th dorsal scale rows, others progressively narrower
and forming a chain of vertically narrow, irregular, strongly elongate blotches then turning into a narrow stripe pos-
teriorly. Dorsal surface of tail is the same than the upper body surface, with a row of dorsolateral blotches of same
colour as those of the body.
The head is dark brown or blackish-brown as the body above, irregularly but strongly variegated above with
paler brown, yellow or yellowish-ochre; sides of the snout distinctly paler, greyish-brown or greyish- or brownish-
yellow or brown-ochre; anterior supralabials rather brown, others ochre-yellow or pale brown, more or less strongly
edged with dark brown or blackish-brown, last three supralabials ochre-yellow on their lower part, dark brown or
blackish-brown on much of their middle, pale above, this pattern forming a lower, dark postocular streak; above,
a narrow, oblique, more or less distinct cream, pale ochre-yellow or pale brown postocular streak on anterior and
lower posterior temporals and top of the 8th and 9th supralabials, reaching the neck behind the corner of the mouth
but not connected with the large blotch on the nape. The throat, chin and infralabials are cream or pale yellowish-
ochre, more or less heavily spotted with dark brown spots; infralabials heavily marbled or spotted with dark brown.
Eye dark golden brown in life.
The venter is dark brown or blackish-brown, with some paler, more or less faint longitudinal streaks; a more or
less conspicuous cream spot or streak on the outer part of each ventral, with dark brown or blackish-brown tips. The
under surface of tail has the same colour than the venter.
In life, the colour and pattern are much more vivid, some specimens being especially colourful (see Fig. 9); the
dorsal background colour is dark greyish-brown, dark reddish-brown, dark brown or blackish-brown; scales of the
sides below the 5th dorsal scale row variegated with yellow or orange, or scales of the 1st to 4th scale rows marked
with yellow or bright coral-red longitudinal streaks or dots posteriorly; the large crescentic blotch or the smaller
blotches on the nape are yellowish-ochre or reddish-brown; the dorsolateral stripe is yellowish-red, rusty-red or red-
dish-brown; the dorsolateral blotches, anteriorly, and stripe, posteriorly, are vividly and conspiscuously colored in
bright yellowish-red, orange or bright rusty-red. Pale markings on the head, the supralabials, the elongate blotch on
the temporal region and the streak obliquely directed upwards and backwards on the hinder part of the head and the
neck are yellowish-ochre or yellowish-red. Pale areas of the venter are yellowish-ochre.
Hemipenes.—Based on morphological data of the specimen IEBR2908 and Ren et al. (2018), in everted condi-
tion the organ is single, short and subcylindrical, not forked, reaching the 5–6th SC, spinose throughout; spines more
or less uniform in size; sulcus spermaticus simple, reaching the tip of the organ.
Sexual dimorphism.It is expressed in two characters:
(1) Position of the reduction to 6 scale rows around the tail: males: 15–19th SC; females: 8–13th SC.
(2) Number of subcaudals: males: 103–114; females 90–111.
Distribution (Fig. 3).—Vietnam. Cao Bang Province. Cao Bang. Hanoi Municipality. Ba Vi National Park.
Dien Bien Province. Muong Nhe Nature Reserve, Muong Nhe District. Lao Cai Province. Lao Cai; Hoang Lien Na-
tional Park, Sa Pa District; Bat Xat Nature Reserve, Bat Xat District. Son La Province. Copia Nature Reserve, Thuan
Chau Dsitrict; Sop Cop Nature Reserve, Sop Cop District. Thanh Hoa Province. Xuan Lien, Thuong Xuan District.
Yen Bai Province. Mu Cang Chai Species and Habitat Conservation Area, Che Tao Commune (Le et al. 2018).—
Laos. Houaphan Province. Phou Louey National Protected Area, Viengthong District. Louangphabang Province.
Hoay Tala, Phoukhoume District. Xaisomboun Province. Longcheng District (T. V. Nguyen et al. 2020).—People’s
Republic of China. Yunnan Province. Daweishan National Nature Reserve, Pingbian Miao Autonomous County,
Honghe Hani, Yi Autonomous Prefecture, and Jinhong Prefecture. This distribution includes data from Ren et al.
(2018; pers. comm., June 2020).
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FIGURE 8. Hebius chapaensis Bourret, holotype (MNHN 1938.0125)—A: dorsal view; B: lateral view of the
head, right side. Photographs: Patrick David.
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28 · Zootaxa 4911 (1) © 2021 Magnolia Press
FIGURE 9. Hebius chapaensis Bourret, alive—A: specimen from Yen Bai Province, Vietnam. Photograph: Niko-
lai Orlov. B: specimen from Thanh Hoa Province. Photograph: Truong Quang Nguyen. C: specimen from Tuyen
Quang Province. Photograph: Truong Quang Nguyen.
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Biology.—This species inhabits regions covered with tropical and subtropical evergreen montane forests be-
tween 900 and 2,046 m a.s.l. (Ren et al. 2018). All specimens for which data are available were collected in mon-
tane, wet evergreen forests and in close association with forest streams. This species is nocturnal and both semi-
aquatic and terrestrial; no specimen was collected at more than a few meters from water. One specimen from Laos
was swimming in submerged vegetation along the bank of a 3 meter wide stream with moderate current; another
specimen was seen perched on a tree at 1 meter from a stream. A specimen observed by Ren et al. (2018) was ac-
tively preying upon tadpoles of a treefrog species (Rhacophorus duboisi) on the edge of a pool. Other data of the
biology of Hebius chapaensis, such as reproductive habits, are still unknown. Specimens from Laos did not prove
to be aggressive when handled.
5. Hebius annamensis (Bourret, 1934)
(Figs. 10–11)
Parahelicops annamensis Bourret, 1934c: 167 (Separate: p. 3) & 170 (Separate: p. 6), Fig. 2.—Type locality. “Bana, station
d’altitude située à 1 500 m d’altitude au bord de la Baie de Tourane”, now Ba Na Nature Reserve, Da Nang City, Vietnam,
1,500 m a.s.l.—Holotype. MNHN 1938.0117, adult male (Muséum National d’Histoire Naturelle, Paris, France); collected
and deposited by René Bourret in 1934.
Parahelicops annamensis.—Bourret 1936a: 97, 104, 114 & 125; Bourret 1936b: 122, Fig. 50; Bourret 1939b: 54; Taylor &
Elbel 1958: 1158; Campden-Main 1970: 46, Fig.; Welch 1988: 88; Nguyen & Ho 1996: 98; Orlov et al. 1998: 61 & 63; Le
2000: 161; Iskandar & Colijn 2001: 102; Orlov et al. 2003: 232; Nguyen et al. 2005a: 93; Stuart 2006: 167–171; Stuart &
Chuaynkern 2007: 35 (implicitely, only generic name cited); Murphy et al. 2008: 180; Stuart & Heatwole 2008: 97; Ziegler
et al. 2008: 197, 200, 201; Nguyen et al. 2009: 362; Das 2010: Plate 51 (p. 118), 296; Yang et al. 2011: 62, 65–67; Stuart
& Nguyen 2012a: e.T192102A2040117; Teynié et al. 2013: 166, 167, 169, 178 & 182; Wallach et al. 2014: 520; David
et al. 2015b: 203–205, 209–213; Kizirian et al. 2018: 1–3; Ren et al. 2018 (implicitely, only generic name cited): 37, 46
(Table 5), 47 & 51.
Opisthotropis annamensis.—Smith 1943: 331 & 334; Bain & Hurley 2011: 104 & 128.
Amphiesma annamense.—Teynié et al. 2013: 178 (generic allocation in error).
Hebius annamensis.—Kizirian et al. 2018: 5; Boundy 2020: 91.
Specimens examined (16).—Vietnam. Da Nang City. MNHN 1938.0117 (holotype of Parahelicops annamensis),
“Bana”, now Ba Na Nature Reserve, elev. 1,500 m; ZISP NLO-2831, Ba Na Nature Reserve, elev. 1,400 m. Ha
Tinh Province. AMNH 147129, Po Mu forest, Rao An, Huong Son District (18°20’26”N 105°14’13”E, 870 m);
ZISP NLO-2478, Rao An, Huong Son District, elev. 300 m. Kon Tum Province. IEBR 371, ZISP NLO-3435, Mang
Canh village (14°41’950N, 108°14’642E), Kon Plong District, elev. 1,200–1,250 m. Quang Binh Province. IEBR
4580 (Field number QB.2015.377), Dong Chau Forest, 16°58.104’N, 106°35.579’E, elevation 696 m, Thuy
District; ZFMK 86457, ZISP NLO-2714, Phong Nha - Ke Bang National Park, 17°42.654’N, 105°52.708’E, elev.
527 m, Hoa Son Commune, Minh Hoa District. Quang Tri Province. ZISP NLO-3257, Ban Cup, Huong Hoa Dis-
trict, 16°57.434’N, 106°35.329’E, elev. 490 m a.s.l. Thua Thien-Hue Province. ZFMK 83513, Bach Ma National
Park; ZISP NLO-2790, Bach Ma National Park, elev. 1,350 m.—Laos. Champasak Province. NCSM 77919. Houay
Tad Seua stream, Dong Hua Sao NPA, Pakxong District, 1,245 m a.s.l. Xékong Province. FMNH 258637, Xe
Sap National Biodiversity Conservation Area, 16°04’10’’N, 106°58’45”E, Kaleum District, elev. 1,280–1,500 m;
NCSM 78630, Phou Ajol, 15.68239°N, 107°1942°E, Dakchung District, elev. 1,475 m; NCSM 78632, Phou Ajol,
15.68516°N, 107°1981°E, Dakchung District, elev. 1,450 m.
Taxonomic comments.—Bourret (1934c) erected the genus Parahelicops for the sole included species Para-
helicops annamensis Bourret, 1934, described in the same paper from a single specimen, on the basis of the fol-
lowing characters: 25 subequal maxillary teeth, of which the two last ones are enlarged, a small eye with a round
pupil, nostrils directed upwards, and a single prefrontal; other characters included a head distinct from the neck, 2
internasals, body elongate, slightly laterally compressed, dorsal scales keeled, without apical pits, in 15 rows, tail
long, subcaudals paired and hypapophyses developped throughout the vertebral column. The position of the genus
Parahelicops has long been controversial (David et al. 2015b). Bourret (1934c) stated that this genus was similar
to members of the genus Opisthotropis Günther, 1872 but differed by its dentition, its head clearly distinct from the
neck and its more elongate body.
Smith (1943: 334), although recognizing the validity of the characters on which Bourret (1934c) based his de-
scription, synonymized Parahelicops with the genus Opisthotropis in extending the definition of this latter one. In
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30 · Zootaxa 4911 (1) © 2021 Magnolia Press
contrast, Taylor & Elbel (1958: 1156) accepted the validity of Parahelicops on the basis of Bourret’s characters and
placed in this latter genus a new species from north-eastern Thailand, Parahelicops boonsongi. David et al. (2015b)
showed that this species is obviously not congeneric either with P. annamensis, or with any other natricid genera. As
a consequence, P. boonsongi was referred to the new genus Isanophis David, Pauwels, Nguyen & Vogel, 2015.
Stuart (2006), although recognizing the validity of the genus Parahelicops, also suggested a close relationship
with Opisthotropis. In contrast, David et al. (2015b), on the basis of morphological characters, considered the genus
Parahelicops to be valid and distinct from Opisthotropis. Although “Parahelicops annamensis has usually a single
prefrontal, as in most species of Opisthotropis, it differs from the latter genus, as defined by Boulenger (1893a),
Pope (1935), Smith (1943), Bourret (1936b) and Brown & Leviton (1961), by several morphological characters
such as (1) 2 distinctly enlarged maxillary teeth vs. subequal teeth in Opisthotropis, (2) dorsolateral nostrils vs.
directed distinctly upwards in Opisthotropis, and (3) supralabials longer than high vs. distinctly higher than long in
Opisthotropis. In contrast, some characters of the genus Parahelicops, i.e., the dentition of the upper maxilla, made
of subequal small teeth followed by two enlarged posterior teeth, the average eye with a round pupil, the dorsolat-
eral nostrils, the keeled dorsal scales, the long, keeled tail, the supralabials longer than high and the general pattern,
were obviously typical of the genus Hebius as defined by Guo et al. (2014), and especially the “H. modestus spe-
cies group”, the group of Indo-Himalayan species which is treated in the present paper. Eventually, Kizirian et al.
(2018), on the basis of molecular data, showed that Parahelicops annamensis was nested in the genus Hebius and a
synonym thereof. We here follow these authors in referring Parahelicops annamensis to the genus Hebius.
For long, Hebius annamensis has been known from its sole holotype collected in central Vietnam. The sec-
ond known specimen, and first record from Laos, was described by Stuart (2006). Subsequently, more specimens
became available, especially from central Vietnam. David et al. (2015b), in the genus Parahelicops, expanded the
description of H. annamensis. This species is monotypic.
Diagnosis.—A moderately sized species of the genus Hebius characterized by the combination of (1) body
elongate in males and females; (2) head distinct from the neck; (3) 15 or 17 dorsal scale rows at midbody, moder-
ately keeled at midbody, strongly keeled posteriorly, usually smooth on the 1st dorsal scale row; (4) scales around
the base of the tail very strongly keeled; (5) eye moderate with a round pupil, 1.2–1.4 times the distance between
the lower margins of eye and of lip; (6) maxillary teeth 28–34, progressively increasing in size in a continuous
series, the last two moderately enlarged and not separated by a diastema from anterior teeth; (7) nostrils piercing
dorsolaterally; (8) tail long with a ratio Tal/TL equal to 0.30 and above; (9) VEN 158–172; (10) SC 116–146; (11)
internasals distinctly narrowing anteriorly; (12) prefrontal single in most known specimens, (13) 8 or 9 supralabi-
als; (14) 1 anterior temporal, (15) venter pale on its inner three quarters, with tips of ventral scales very dark; (16)
background colour chestnut brown, dark brown or dark greyish-brown; (17) dorsal pattern made of isolate, cream
or yellowish-ochre blotches (bright orange or rusty-red blotches in life), usually transversally elongate as crossbars
anteriorly, then becoming irregular, broken spots posteriorly; (18) a short and narrow, oblique postocular streak
reaching the neck behind the corner of the mouth, sometimes extending on the nape as a broad, oblique and elongate
cream or yellowish-ochre streak (orange or rusty-red in life); and (19) supralabials dark as the upper head surface,
without defined spots or blotches.
Comparison. In preservative, specimens of Hebius annamensis may be easily misidentified as H. modestus
(Günther, 1875), an Indo-Himalayan species unknown east of Myanmar. However, H. modestus has 19 scale rows
at midbody vs. 17, 143–163 ventrals vs. 158–172, and a ochre or pale brown venter.
With its typical dorsal and ventral pattern and its long tail, Hebius annamensis cannot be confused with any
species of the genus Hebius with 17 dorsal scale rows, from which it differs as follows:
Hebius annamensis readily differs from H. chapaensis by the characters given above in the account of this latter
species. The main characters are (1) internasals distinctly narrowing anteriorly (vs. abruptly truncated); (2) number
of subcaudals, 116–146 vs. 90–114 subcaudals in H. chapaensis; (3) venter largely pale, with only tips of ventral
scales dark vs. nearly entirely dark in H. chapaensis; (4) a distinct dorsal pattern, consisting of pales blotches, usu-
ally arranged as crossbars anteriorly in H. annamensis vs. bright, pale blotches on a faint dorsolateral stripe in H.
chapaensis; and (5) head with short and narrow postocular streak in H. annamensis, as well as with dark supralabi-
als, without defined blotches vs. strong postocular streak in H. chapaensis, with pale supralabials, edged with dark,
or divided into a pale and a dark areas.
Hebius annamensis differs from both H. taronensis and H. nigriventer by its venter largely pale vs. entirely
black or so in these species, plus by characters given in the key above.
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FIGURE 10. Hebius annamensis Bourret, holotype (MNHN 1938.0117)—A: dorsal view; B: lateral view of the
head, right side. Photographs: Patrick David.
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FIGURE 11. Hebius annamensis Bourret, alive—A: specimen from Quang Tri Province, Vietnam. Photograph:
Nikolai Orlov. B: specimen from Quang Binh Province. Photograph: Nikolai Orlov. C: specimen from Kon Tum
Province. Photograph: Truong Quang Nguyen.
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 33
FIGURE 12. Distribution map of species with 19 dorsal scale rows at midbody. Circles: Hebius modestus Günther.
Squares: Hebius deschauenseei Taylor. Black triangle: Type locality of Hebius igneus spec. nov. White triangles:
Hebius igneus spec. nov.
Hebius annamensis differs from H. venningi especially by (1) a prefrontal usually single vs. always double; (2)
the number of postoculars, 2 (rarely 3) in H. annamensis vs. usually 3 (rarely 2) in H. venningi; (3) venter largely
pale, with only tips of ventral scales dark vs. venter pale mesially, at least on the anterior part of the body, clouded
with darker hues of brown on the outer parts of ventrals in H. venningi; (4) dorsal pattern made of isolate, bright
orange or rusty-red blotches, usually horizontally elongate or vertically elongate as crossbars anteriorly vs. dorsal
surface distinctly chequered by the presence on sides and upper part of the body of diffuse blackish-brown or very
dark grey blotches, and with a dorsolateral series of irregular blotches, yellow-ochre or yellowish-brown (bright
yellowish-ochre in life), enlarged and forming a chain on the first quarter to third of the body; (5) the distribution
range, Vietnam and southern Laos vs. Northeast India and North Myanmar for H. venningi.
Description.—Body moderately robust but elongate, somewhat thinner in males, and cylindrical; head oval,
rather short, moderately distinct from the thick neck, flattened anteriorly; snout long, flat, blunt or slightly round
seen from above, subrectangular seen in profile, 2.0–2.2 times as long as horizontal diameter of eye; no canthus
rostralis; nostril directed dorsolaterally, small, round, piercing in the middle of the divided nasal; eye moderately
sized or small, its diameter about 1.2–1.4 times the distance between the lower margins of eye and of lip, with a
round pupil; tail long, thin and tapering.
The maximum known length is 796 mm for a male (SVL 528 mm, TaL 268 mm; specimen ZISP NLO 3257).
The longest known female is 685 mm long (SVL 465 mm, TaL 220 mm; ZISP NLO 2831).
Ratio TaL/TL 0.297–0.337, without clear sexual dimorphism (6 males: 0.301–0.337; 3 females: 0.297–0.321).
Dentition. 28–34 maxillary teeth, gradually enlarging in a continuous series, the last 2 teeth moderately en-
larged, without diastema.
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Body scalation. DSR: 17–19-15–17-15–17 rows; scales rhomboedric, normal in shape, distinctly keeled on
2nd–10th, moderately on the anterior part of the body, strongly posteriorly, very strongly in the region of the vent and
along the base of the tail; scales on 1st row smooth anteriorly, feebly keeled posteriorly.
The number of dorsal scale rows is quite variable in this species. In our sample of 15 specimens, the dorsal
scale row formulas are: 18–15–15 (1 specimen), 19–15–15 (4), 17–17–17 (1), 18–17–15 (2), 18–17–17 (2), and
19–17–17 (5).
VEN: 158–172 (plus 1 or 2 preventrals), with a sexual dimorphism (see below); SC: 116–146, all paired, with
a sexual dimorphism; cloacal plate divided.
Ratio VEN/SC 1.18–1.44.
Position of the reduction to 6 scale rows around the tail: SC 4–16, with a strong sexual dimorphism (see below);
ratio: length of the portion of tail with 6 dorsal scale rows/length of the portion of tail with 4 dorsal scale rows:
0.10–0.64.
Head scalation. Arrangement of upper head scales complete but prefrontals modified, including 2 internasals,
1 or 2 prefrontals (see below), 2 supraoculars, 1 frontal, and 2 parietals. Rostral hexagonal, wider than high, barely
visible from above; nasal subrectangular, elongate, vertically divided by a furrow, with the fore and hind parts of
similar size, altogether about 1.3–1.5 times longer than high; internasals distinctly subtriangular, elongate, in broad
contact with each other, 1.2–1.4 times longer than wide, distinctly narrowing anteriorly with anterior margin about
0.4–0.5 times the width of the posterior margin; 1 prefrontal (in 12/15 specimens), shield-like and broad, or 2 pre-
frontals (3/15), subrectangular, in both cases broader than long and 0.9–1.2 times as long as internasals, in broad
contact with loreal; frontal hexagonal, shield-like, rather wide but short, its apex directed posteriorly, 1.0–1.2 times
longer than wide, 1.7–2.0 times longer than prefrontals; on each side 1 entire, subtriangular supraocular, rather
broad, 1.8–2.2 times longer than wide, slightly narrower than internasals, about 0.5 times as wide as frontal; pari-
etals large, long and wide, 1.7–2.1 times longer than frontal and in contact for a length 1.2 times as long as the fron-
tal length; large, rectangular loreal scale, elongate, 1.5–1.8 times longer than high, in broad contact with the nasal; 2
subequal preoculars on each side in all examined specimens; 2 or rarely 3 small postoculars, the upper one largest;
8 or 9 supralabials, 1st as long as high, 2nd–5th longer than high, other supralabials as long as high, 1st–2nd supralabi-
als, small and short or, exceptionally 1st–3rd supralabials, in contact with nasal, 2nd–3rd or 3rd–4th supralabials in large
contact with the loreal, 4th–5th supralabials, or exceptionally solely 4th, solely 5th, 4th–6th or 5th–6th supralabials, enter-
ing orbit; 6th–7th or 7th–8th supralabials largest; 1 anterior temporal, narrow and elongate, in all known specimens
with complete temporal formulas as 1+1+2 or rarely 1+2+2 or 1+3 (this latter condition only in the type); 10 (rarely
8 or 9) infralabials, 1st pair in contact with each other behind the mental, 1st–5th infralabials in contact with anterior
chin shields, 5th infralabial largest; mental triangular; anterior pair of chin shields equal to or slightly longer than
posterior shields.
Coloration and pattern. In preservative, the dorsal and lateral surfaces of body are dark chestnut brown, dark
brown or dark greyish-brown, darker above than on the sides, either nearly uniform or, more usually, profusely var-
iegated with diffuse, darker brown blotches, larger on the upper parts of the sides than on the vertebral region; scales
of the lower lateral scale rows usually spotted or marked with diffuse, yellowish-grey blotches or streaks; in 3 out
of 13 specimens, a faint dorsolateral stripe is present on 5th–7th dorsal rows, barely paler than the background color
and poorly distinct; on each side, a series of about 50 to 70 distinct dorsolateral blotches, cream, ochre, yellowish-
brown, pinkish-brown or orange-brown on 5th–7th dorsal rows, separated from each other by 2–3 dorsal scales, form-
ing a discontinuous dorsolateral stripe; the first few blotches are usually vertically elongate and form a few vertical
crossbars extending outwards and reaching downwards the level of the 3rd scale row on the anteriormost part of the
body, quickly followed by thick and horizontally elongate blotches extending up to the first anterior quarter to third
of the body; progressively these blotches are reduced to irregular or broken spots or even disappear posteriorly; a
short, cream ventrolateral stripe on the anterior part of the body, up to 20th to 30th ventrals. The upper surface of tail
is as the body, either uniform or with only a few pale dots.
The head is dark chestnut-brown, more or less variegated above with ochre yellow or pale yellowish-brown,
often with numerous minute scattered dark dots; a ochre yellow or pale yellowish-brown sagittal line present, but
faint, or absent; last three posterior supralabials irregularly and faintly edged with ochre-yellow anteriorly; a short,
narrow or relatively broad, oblique, more or less distinct postocular streak on anterior and lower posterior temporals,
and on top of 8th and 9th supralabials, reaching the neck behind the corner of the mouth and extending as a large,
cream or yellowish-ochre oblique, elongate blotch on the nape, connecting the posterior end of the postocular streak
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with the first dorsolateral blotch. The throat, chin and infralabials are cream or pale yellowish-ochre, more or less
heavily spotted with dark brown spots; infralabials heavily marbled or spotted with dark brown. Eye deep black in
life.
The venter is cream, pale yellowish-ochre or pale brown on the inner half to two thirds of its width, with tips of
ventrals dark brown or dark greyish-brown, this dark surface progressively widening posteriorly; often some irregu-
lar dark spots scattered on the pale part. The under surface of tail is as the venter but the pale central part is narrower
than the dark, outer parts anteriorly, the tail becoming progressively entirely dark below.
In life, the background coloration is chestnut-brown, dark olive-brown or dark brown, more or less iridescent;
the upper dorsal dark blotches are blackish-brown or very dark grey whereas the lower lateral scale rows are marked
with yellowish-ochre blotches or streaks; when present, the dorsal stripe is rusty-brown; the main dorsolateral
blotches are yellowish-ochre, orange or reddish-brown, a colour often still seen in recently preserved specimens;
the short ventrolateral stripe is pale yellowish-ochre. Pale markings on the head are yellowish-ochre or dirty, grey-
ish-yellow; the elongate blotch on the temporal region and on the hinder part of the head is yellowish-ochre or
sometimes reddish-ochre; behind the head, the streak obliquely directed upwards and backwards on the neck is of
the same colour or turns to bright orange or yellowish-red. The background colour of the throat and venter is cream
or pale yellowish-grey.
Hemipenes.—In situ, the organ is single, short and subcylindrical, not forked, reaching the 10th SC, spinose
throughout.
Sexual dimorphism.It is expressed in three characters:
(1) by the difference in the number of ventrals: males: 168–172 (mean = 167.7, s = 1.7); females: 158–167
(mean = 164.2, SD = 3.4).
(2) by the difference in the number of subcaudals: males: 126–146 (mean = 138.7, s = 6.9); females: 116–126
(mean = 119.7, SD = 5.5).
(3) by the position of the reduction to 6 scale rows around the tail: males: 12–16th SC; females: 4–7th SC.
Distribution (Fig. 3).—This species has been recorded only from central Vietnam and southern Laos.Vietnam.
Da Nang City. Ba Na Nature Reserve. Ha Tinh Province. Huong Son District. Kon Tum Province. Ngoc Linh Nature
Reserve, Kon Plong District. Quang Binh Province. Dong Chau Forest, Lê Thuy District; Phong Nha - Ke Bang
National Park, Minh Hoa District. Quang Tri Province. Huong Hoa District. Thua Thien-Hue Province. Bach Ma
National Park—Laos. Champasak Province. Dong Hua Sao National Biodiversity Conservation Area, Pakxong
District. Xékong Province. Sap National Biodiversity Conservation Area, Kaleum District; Dakchung District.
Biology.—This species inhabits regions covered with tropical wet evergreen forest and subtropical montane
evergreen forests between about 300 and 1,500 m a.s.l., although most specimens for which elevation data are
available were collected between 1,200 and 1,400 m a.s.l. (see also Stuart & Nguyen 2012a). All were collected in
primary montane evergreen forests and in close association with fast-running, rocky forest streams.
This species seems to be mainly nocturnal and aquatic, although one specimen was found on the ground. Ac-
cording to Stuart (2006), specimen FMNH 258637 was collected at night (20.30 h) in steep terrain covered by wet
evergreen forest between 1,280–1,500 m elevation. The snake was first observed on land 50 cm from a small, swift,
rocky stream, then it dove into the water and swam under a rock on the stream bottom. Specimen ZFMK 86457 was
captured at night (20.00–21.00h) in the leaf litter of a forest stream at 510 m a.s.l., with only the snout tip protruding
from the surface of the water (David et al. 2015b). Other biological data of Hebius annamensis, such as its diet and
reproductive habits, are still unknown.
B. Specimens of the genus Hebius with 19 dorsal scale rows at midbody
6. Hebius modestus (Günther, 1875)
(Fig. 13)
Tropidonotus modestus Günther, 1875: 232.—Type locality. “The Himalayas”, specified as being the “Khasi Hills”, State
of Meghalaya, India, according to Boulenger (1893a: 229) and the BMNH’s collection catalogue.—Syntypes. BMNH
1946.1.13.40 and BMNH 1946.1.13.41, two adult males; collected by Dr. Thomas C. Jerdon.
Tropidonotus modestus.—Anderson 1879: 817; Theobald 1882: 302; Boulenger 1890: 343; Sclater 1891: 36; Boulenger 1893a:
229; Boulenger 1893b: 308 & 322; Werner 1929: 15 & 25.
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Nerodia modesta.—Wall 1923: 603; Wall 1925b: 809; Wall 1926: 560.
Natrix modesta.—Mell 1929: 5, 16, 145 (in part: mention from “Osthimalaya” only), 147 (in part: mention from “Osthimalaya”
only) & 157; Mell 1931a: 203 (species with 19 DSR), 1931b: 231; Pope 1935: 90 (discussion about the species cited by
Anderson 1879); Bourret 1936a (in part): 94, 103 (only mentions from “Assam & Bengale” and “Yunnan”; the mention
given on p. 113 refers to Hebius boulengeri); Bourret 1936b: 72 & 73 (in part; mentions from Assam and Yunnan); Smith
1943: 290–291 (in part, except specimens from “Upper Laos”, “Cambodia”, “South Annam [Langbian Plateau]”, and
“Pen[insular] Siam”); Deuve 1970: 84 & 88 (in part: except specimens from “Xieng Khoang”); Anonymous 1977: 62; Hu
et al. 1980: Pl. 38, 11 (in part) & 70 (in part); Yang et al. 1983: 43 (in part).
Natrix modista [sic].—Yang et al. 1978: 67 (in part).
Amphiesma modesta.—Malnate 1960: 50, 52 & 57; Whitaker 1978: 117; Murthy 1986: 72; Tian et al. 1986: 116 & 149; Yang
& Inger 1986: 7; Zhao & Jiang 1986: 239; Welch 1988: 31 (in part: except mentions from Laos, Vietnam and Cambodia);
Murthy 1990: 72; Zhao & Adler 1993: 227 (in part: only mentions of Yunnan, India and northern Burma) & 310 (in part:
Yunnan); Mathew 1995: 437 & 438 (in part: except mentions from Thailand, Cambodia, and Laos); Das 1996: 53; Nguyen
& Ho 1996: 69 (in part: not the specimens from Vietnam and localities herein); Zhao & Yang 1997: 205 (in part), 206: Fig.
62; Cox et al. 1998: 45 (in part: only the mention from Assam, the figure depicts a Hebius khasiensis); Mathew 1998: 132;
Sharma 1998: 94; Zhao et al. 1998: 51 & 65 (in part), 66: Fig. 19; Zhang 1999: 430 (in part); Orlov et al. 2000: 71 (in part,
only the mentions of south-western China, Myanmar and India); Iskandar & Colijn 2001: 96 (in part: except mentions from
Cambodia, Laos and Vietnam); Das 2002: 18 (text: in part, except mentions of Thailand, Laos and Vietnam; figure: Hebius
khasiensis); Hallermann et al. 2002: 150; He & Zhou 2002: 167 (in part); Ji 2002: 178 & 179; Sharma 2003: 132 & 133;
Stotz et al. 2003: 100; Borang et al. 2005: 22; Sanyal & Gayen 2006: 271 (in part) & 283; Sharma 2007: 209 (in part: except
mentions from Thailand, Cambodia, Laos and “Annam”); Yang & Rao 2008: 259 (in part); Luo et al. 2010: 74 (in part);
Murthy 2010: 33; Zhang 2011: 277 (in part); Guo et al. 2014: 431.
Amphiesma modestum.—Zhao et al. 2000b: 205; Das 2003: 473; David et al. 2005: 175; Whitaker 2006: 112; Zhao 2006: (Vol.
I) 167 (in part; only for mentions from Yunnan; the status of the specimen depicted in Vol. II: p. 89: Fig. 51 is addressed
below in the Discussion); Zhang 2009: 82 (in part: Fig. 81 does not depict this species); David et al. 2007: 41, 42, 54, 56,
57 & 59; Das 2010: 333 (in part: except mentions of northern Laos, south-central Cambodia and central Vietnam); Bain &
Hurley 2011: 104 & 128 (in part); David et al. 2013: 302, 308, 310, 312: Fig. 4C, 314, 324, 325, 326 & 335.
Amphiesma modestus.—Guo et al. 2014: 432.
Hebius modesta.—Guo et al. 2014: 428 (specimen CAS 234262).
Hebius modestum.—Guo et al. 2014: 437 & 438.
Hebius modestus.—Boundy 2020: 92; Wang et al. 2020, Appendix 2: 15; this work (see below in the Discussion).
Natrix modesta modesta.—Bourret 1936b: 73 (in part: mentions from Assam and Yunnan; Fig. 30 on p. 74 refers to another
species; see below).
Specimens examined (14).—India. State of Meghalaya. BMNH 76.2.16.1–2, “Cherra Punji, Khasi Hills”, now
Cherrapunji; BMNH 1946.1.13.40–41 (syntypes), Khasi Hills; ZSI 4276, “Cherrapunji, Assam”; ZSI 15263, “As-
sam”, no specified locality.—Myanmar. Kachin State. BMNH 1925.4.2.16, “Hutong, Bhamo District”, now Hu-
tung; BMNH 1925.9.17.2, BMNH 1925.12.22.22–23, “Huton, Kachin Hills”, now Hutung, Kachin Hills, Bhamo
District. Shan State. MNHN 1893.0400, “Mts Carin, 1200–1300 m”, now Mts. Karen, locality specified by Bou-
lenger (1893b: 322) as “Thao, District of Karin Bia-po”, now Tahò, 19°23’N, 96°54’E, Tauggyi District in extreme
south-western Shan State.—People’s Republic of China. Yunnan Province. CAS 234262, Fangma Qiao River,
15–16 km from Longshan (Longling County, Baoshan Prefecture), 24°32’38.1”N, 98°38’49.2”E, Mangshi County,
Dehong Dai and Jingpo Autonomous Prefecture, 1,140 m a.s.l.; CIB 81II0366 (Nr 8275), Baoshan, Baoshan Prefec-
ture; KIZ 75II0238, Tongbiguan, Yingjiang County, Dehong Dai and Jingpo Autonomous Prefecture.
Taxonomic comments.—This species was described on the basis of two specimens, as clearly stated by Gün-
ther (1875) in the original description. Boulenger (1893a: 229) also recognized two types. Wallach et al. (2014: 30)
stated that Nguyen et al. (2009: 356) had designated specimen BMNH 1946.1.13.41 as the lectotype of the spe-
cies. We consider this assertion to be erroneous as Nguyen et al. (2009: 356) only stated that this specimen was the
“type”; this brief mention contravenes Art. 74.7 of the Code and cannot be construed as the valid designation of a
lectotype.
The chresonymy given above includes only those citations dealing with Hebius modestus as currently con-
ceived, although some refer to this species only in part. Tropidonotus modestus Günther, 1875 has been one of the
most confused species in the genera Natrix and Amphiesma. Whereas Anderson (1879; genuine specimens from
Yunnan) and Boulenger (1890, 1893a) correctly described the species as conceived here, the confusion arose from
Smith (1943: 290) who adopted a large, and quite erroneous, definition of Natrix modesta and included under this
name no less than four currently valid species, i.e., Hebius modestus, H. deschauenseei (Taylor), H. groundwateri
(Smith) and H. inas (Laidlaw). Hebius boulengeri Gressitt, 1937 was not explicitly cited as a synonym by Smith
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 37
(1943) but has been confused by this latter author and, more widely subsequently in the literature with Hebius
modestus for populations of Laos, Cambodia and Vietnam. The chresonymy of H. boulengeri can be found in David
et al. (2013), with a list of the numerous citations of Amphiesma modestum or Natrix modesta referring to Hebius
boulengeri. As shown by David et al. (2013), most records of Hebius modestus from southern China and Vietnam,
and all those from Cambodia and Laos should refer to Hebius boulengeri (for example, in Mell 1922; Angel 1929;
Smith 1943 [see above in the chresonymy]; Campden-Main 1970; Deuve 1970; Saint Girons 1972 [in part]; Zhao
& Adler 1993; Nguyen et al. 1995, 2009; Daltry & Chheang 2000; Grismer et al. 2007, 2008; Das 2010 [in part;
see above in the chresonymy]; and Daltry & Traeholt 2003; list not exhaustive; see David et al. 2013 for a more
complete list). However, David et al. (2013) erroneously considered citations by Mell (1929: 5, 16, 145 [in part],
147 [in part ] & 157) to belong to the chresonymy of Hebius boulengeri. In fact, as Mell mentioned specimens
from “Osthimalaya” (i. e. Eastern Himalaya), he most likely made reference to Hebius modestus or, perhaps to the
new species described below. Furthermore, Nabhitabhata (1987) listed, without comments nor voucher specimens,
Amphiesma modestum from Doi Suthep-Pui National Park, Chiang Mai Province, northern Thailand. This record
may refer to Hebius khasiensis (see David et al. 2013), or, more likely, to Hebius deschauenseei (see below). Lastly,
it should be noted that the treatise of Natrix modesta modesta” in Bourret (1935b: 259 & 261 [Reprint p. 1 & 3]),
Bourret (1936b: 73–74 [in part], 74: Fig. 30) and Bourret (1937: 27 & 29) refer to the new species, related to Hebius
modestus, described below.
Mahendra (1984: 244) erected the genus Paranatrix (type species: Tropidonotus modestus Günther, 1875, now
Hebius modestus, by original designation) for six species of the genus Hebius present in India. Furthermore, Ma-
hendra (1984: 247) synonymized H. khasiensis with H. modestus. This synonymy is erroneous as these species are
morphologically distinct from each other. These two species differ by (1) the shape of their internasals, abruptly
truncated vs. distinctly narrowing in H. modestus, (2) the number of subcaudals, 87–111 vs. 104–122, (3) the pattern
of supralabials, with distinct white, round, blotches vs. speckled with dark brown and scales edged with dark brown
or blackish-brown, and (4) venter entirely pale vs. pale ochre-brown or pale brown on a wide central area, edged
with dark brown. Additional characters can be found in David et al. (2013). However, the generic nomen Paranatrix
is an available name if the genus Hebius has to be further split.
As conceived here, Hebius modestus is a well defined, purely Indo-Himalayan species that has a much more
restricted range than that given by Smith (1943) or, for example by Nguyen et al. (2009) and Wallach et al. (2014)
who considered H. modestus to be widespread from India to South Vietnam. This species is monotypic.
Diagnosis.—A moderately sized species of the genus Hebius characterized by the combination of (1) 19-19-17
dorsal scale rows, barely or weakly keeled at midbody and on the posterior part of the body, smooth on 1st DSR;
(2) dorsal scales around the base of the tail weakly keeled; (3) head moderately distinct from the neck; (4) eye
large; (5) maxillary teeth 27–30, the last two moderately enlarged; (6) tail long, with a ratio TaL/TL at least equal
to 0.28 in females, up to 0.32 in males; (7) VEN 143–163; (8) SC 104–122; (9) prefrontal scales 2; (10) 1 or rarely
2 anterior temporals, rectangular and elongate; (11) venter pale ochre-brown or pale brown on a wide central area,
broadly edged with dark brown or blackish on the outer quarter of ventrals, rarely entirely dark except on its most
anterior part; (12) dorsal colour dark greyish-brown, brown or dark brown; (13) dorsum usually scattered with
blackish-brown or black spots or blotches; (14) on each side, a more or less conspicuous, ochre-yellow, ochre-red,
orange-brown or reddish-brown stripe, often reduced to a succession of elongate blotches on the anterior part of the
body, extending from the nape to the base of the tail on 4th–7th or 5th–7th DSR, often but not always irregularly edged
below and above by a series of large blackish-brown blotches; (15) no postocular streak; and (16) a short but broad,
horizontal, pale yellowish-brown streak on the sides of the neck before the dorsolateral stripe, plus a streak on the
nape behind the parietals.
Comparison. Hebius modestus differs from the group of H. venningi, i.e., H. venningi, H. taronensis and H.
nigriventer, with which it might be sympatric in northern India and Myanmar (Kachin State) by (1) the number
of 19 DSR at midbody; (2) the general dorsal pattern, usually striped and with dark blotches above and below the
dorsolateral stripe vs. not striped but chequered or, in H. nigriventer, with conspicuous, large dorsolateral blotches;
(3) venter usually widely pale along its whole length, edged with blackish-brown, rarely entirely dark except on its
most anterior part vs. (a) venter pale (coral red in life) mesially, on the anterior part of the body and dark, clouded
posteriorly in H. venningi; (b) venter both pale and dark, i.e. with a pale background on its anterior part with irregu-
lar dark crossbands and nearly uniform on its posterior part in H. taronensis and (c) venter nearly entirely very dark
in H. nigriventer; and (4) a conspicuous yellow streak on the sides of the neck.
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FIGURE 13. Hebius modestus (Günther), syntype (BMNH 1946.1.13.41)—A: dorsal view; B: ventral view; C:
close-up dorsal view of the head; D: lateral view of the head, right side. Photographs: Gernot Vogel.
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 39
Description (based on our specimens).—Body rather slender, elongate, cylindrical, barely stouter in large
females; head elongate, subtriangular, moderately distinct from the thick neck, flattened anteriorly; snout elongate,
obtuse or rectangular as seen from above, oblique seen in profile, flat, amounting for 25.2–28.6 % of HL, or 1.8–2.0
times as long as diameter of eye; nostrils placed dorsolaterally on the snout and directed dorsolaterally, small, round,
piercing in the middle of the nasal; eye rather large, about 1.3–1.7 times as large as the distance between its lower
margin and the margin of the lip, with a round pupil; tail long and tapering.
The maximal known total length is 648 mm (SVL 440 mm; TaL 208 mm; specimen ZSI 15263) for a male. The
longest known female is 618 mm long (SVL 433 mm, TaL 185 mm long; BMNH 76.2.16.1).
Ratio TaL/TL: 0.288–0.326, with a weak sexual dimorphism (see below).
Dentition. 27–29 maxillary teeth gradually enlarging, the last 2 moderately enlarged, without diastema.
Body scalation. DSR: 19-19-17 rows in all examined specimens; scales rhomboedric, feebly or moderately
keeled at midbody; scales of 1st DSR smooth; scales around the base of the tail only weakly keeled.
VEN: 143–163 (plus 1 or 2 preventrals); SC: 104–122, all paired, with a strong sexual dimorphism (see below);
cloacal plate divided.
Ratio VEN/SC 1.36–1.52, without sexual dimorphism (see below).
Position of the reduction to 6 scale rows around the tail: SC 21–29, without sexual dimorphism; ratio: length of
the portion of tail with 6 dorsal scale rows/length of the portion of tail with 4 dorsal scale rows: 1.7–2.5.
Head scalation. Arrangement of upper head scales complete including 2 internasals, 2 prefrontals, 2 supraocu-
lars, 1 frontal, and 2 parietals. Rostral wider than high, barely visible from above; nasals more or less rectangular,
not elongate, about 1.6–1.7 times longer than high, vertically divided above and below the nostril, with the posterior
part equal to anterior one; internasals rather small, short, subtriangular, in broad contact with each other, about 1.0–
1.1 times longer than wide, distinctly narrowing anteriorly with an anterior margin about 0.35–0.45 times the width
of the posterior margin; 2 prefrontals rather small, short, wider than long, 0.9–1.2 times as long as internasals; fron-
tal large and wide, shield-like, 1.4–1.6 longer than wide and 2.0–2.4 times as long as the prefrontal; 1 supraocular on
each side, subtriangular, 2.0–2.2 times longer than wide, about as wide as internasals; parietals large, elongate and
broad, 1.6–1.9 times longer than the frontal, or suture between parietals 1.1–1.2 times longer than frontal; 1/1 loreal,
pentagonal, short and high, 1.2–1.3 times longer than high, in broad contact with the nasal; 1/1 (in 4/12 specimens)
or 2/2 preoculars, upper one larger than lower one; 2/2 (in 2/12 specimens) or 3/3 small postoculars; 9/9 SL in all
examined specimens, the first five as long as high or longer than high, 1st and 2nd SL small and short, in contact with
the nasal, 2nd–4th SL or more rarely 2nd–3rd SL (in 1/24 occurrences) or 3rd–4th SL (2/24 occurrences) in contact with
the loreal, 4th–6th (5th–6th in two specimens) SL entering orbit, 7th and 8th SL largest; 1 anterior temporal, elongate,
rectangular, followed by 1, or rarely 2, posterior temporals, the most common formula being 1+1 temporals; 10/10
(9/9 in 1 specimen) infralabials, first pair in contact, 1st–5th IL in contact with anterior chin shields, 5th and 6th IL
largest; posterior chin shields longer than anterior ones.
Coloration and pattern. The upper dorsal surface is overall dark, namely dark greyish-brown, chestnut-brown
or dark brown, often distinctly darker on the back than on the lower sides; dorsum and lower sides ranging from
nearly uniform, with only poorly defined very dark and paler areas, to distinctly scattered with very dark brown,
blackish-brown or black spots; a broad dorsolateral stripe, ochre-yellow, yellowish-brown, ochre-red, orange-brown
or reddish-brown extends on the 4th–7th or 5th–7th DSR from behind the neck to the base of the tail but is usually
reduced to a succession of elongate blotches on the anterior part of the body, or is faint and entirely reduced to a
succession of blotches along the whole length of the body, this dorsolateral stripe may be absent in nearly unpat-
terned specimens and is replaced by a series of ill-defined, paler reddish-brown areas; a series of darker brown or
blackish-brown elongate blotches, on the top of the back on the 8th DSR, next to the dorsolateral stripe or series of
blotches, 1 scale long and high and longitudinally separated by 2 or 3 dorsal scales, sometimes absent; another series
of irregular, elongate, darker brown or blackish-brown blotches below the dorsolateral stripe or series of blotches,
on the 2nd to 4th DSR; these series of blotches are sometimes absent. The tail is brown as the upper surface of the
body, with irregular darker blotches; if present on the body, the dorsolateral stripe or blotches are present on its
dorsolateral part, or replaced by paler reddish-brown areas.
The head is dark greyish-brown or dark brown, irregularly mottled with diffuse darker brown areas; loreal
and nasal sometimes with irregular pale brown areas; 1st–7th or 1st–8th supralabials usually creamish-yellow, yel-
lowish-brown or pale brown, usually speckled with dark brown and all edged with dark brown or blackish-brown
on their posterior edge, sometimes entirely dark with their central part barely paler; last supralabial either entirely
DAVID ET AL.
40 · Zootaxa 4911 (1) © 2021 Magnolia Press
dark or with its lower part pale; no postocular streak; a conspicuous horizontal, creamish-yellow, ochre-yellow or
yellowish-brown streak often present on the side of the neck, extending from behind the corner of the mouth up to
the beginning of the dorsolateral stripe or its first blotch around the 10th ventral; this streak may be entirely absent
in poorly patterned specimens without dorsolateral stripe; a short median streak behind parietals; no oblique streak
behind the head forming a chevron on the nape; infralabials, chin and throat cream, pale yellow-ochre or pale
brown, with scattered dark brown spots along the outer edges of chin shields and throat, sometimes heavily spotted
with dark brown; infralabials strongly edged with dark brown on their both anterior and posterior edges, and often
strongly speckled with dark brown, sometimes entirely brown.
The venter is always pale, i.e., beige, creamish-brown, pale yellow-ochre or pale brown on its whole length,
nearly uniform or speckled with dark or blackish-brown dots along its middle, more heavily on its posterior part,
progressively making the venter entirely dark on its last quarter in some specimens; outer part of each ventral with
an irregular dark or blackish-brown blotch, progressively widening posteriorly, tips of ventrals usually pale as the
inner part of the venter, producing an irregular, discontinuous ventrolateral stripe. Lower surface of tail either pale
as the venter, heavily spotted with dark or blackish brown, or entirely dark brown or blackish-brown depending on
the colour of the posterior part of the body; tip of tail very dark.
We have not seen any genuine specimen of Hebius modestus alive or depicted in life in the literature. As stated
above, the specimen from Mizoram (India) depicted by Ahmed et al. (2009: 154) as Amphiesma cf. modestum is
indeed a specimen of Hebius venningi.
Hemipenes.—In situ, the hemipenis is short and thin, reaching the 8th SC and forked near its tip, proximal part
covered with short spines, 2 or 3 much larger; distal part covered with small, dense spines; sulcus spermaticus short
and with small lips.
Sexual dimorphism.It is expressed in the following characters:
(1) Strongly by the difference in the ratio TaL/TL: males: 0.320–0.326 (mean = 0.323, s = 0.003); females:
0.288–0.307 (mean = 0.299, s = 0.007).
(2) Strongly by the difference in the number of subcaudals: males: 113–122 (mean = 117.0, s = 3.2); females:
104–109 (mean = 107.0, s = 2.2).
Distribution (Fig. 12).—India. State of Meghalaya. Definitely known only from the Khasi Hills. State of
Arunachal Pradesh. Tirip District; Lohit District (Borang et al. 2005).—Myanmar. Kachin State. Bhamo District.
Shan State. Tahò, 19°23’N, 96°54’E, Tauggyi District.—People’s Republic of China. Yunnan Province. Mangshi
County and Yingjiang County (Dehong Dai and Jingpo Autonomous Prefecture), in the extreme western part of the
province.
This species is probably also present in some other states of India, such as Nagaland, and in other districts of
Kachin State in Myanmar, but it has yet to be found there.
As explained above, previous records of Hebius modestus from eastern Thailand, Cambodia, Laos, and Vietnam
should be referred to other species, mostly Hebius boulengeri.
Biology.—This species inhabits evergreen or semi-evergreen submontane forest up to 1,600 m a.s.l. where it is
seemingly associated with hill or montane forest streams. It inhabits the forest litter near these streams or in other
riparian areas. Very little has been recorded about the biology of Hebius modestus. It probably feeds on tadpoles
and frogs. Wall (1926) recorded a female, preserved between June and August, that contained three large eggs in its
oviducts. This species is either secretive or rare.
7. Hebius deschauenseei (Taylor, 1934)
(Fig. 14)
Natrix deschauenseei Taylor, 1934: 300, 301: Figs. 2–4, Pl. 17: Fig. 5.—Type locality. “Chieng Mai, North Siam”, now Chiang
Mai, Chiang Mai Province, Thailand.—Holotype. ANSP 19927, adult male; collected by R. M. de Schauensee, Janu-
ary–March 1933.
Natrix deschauenseei.—Bourret 1936a 103 (in part; the wide range given for this species is obviously erroneous); Taylor &
Elbel 1958: 1151; Taylor 1965: 825, 826: Fig. 52.
Macropophis deschauenseei.—Bourret 1936b: 105.
Amphiesma deschauenseei.—Malnate 1960: 50, 52 & 56; Welch 1988: 30; Cox 1991: 234, 268: Pl. 76; Chan-ard et al. 1999:
30; Chanhome et al. 2001: 58; Nabhitabhata et al. 2004: 124; David et al. 2007: 41, 54, 56 & 59 (in part: specimens from
Thailand only); Pauwels et al. 2009: 77 & 78; Das 2010: 331 (in part: mention of Thailand only); Bain & Hurley 2011 (in
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 41
part): 104 & 128; Iskandar & Colijn 2001: 95; Cox et al. 2012: 365 & 366, 367 (in part: mentions of Thailand only); Das
2012: 113 (in part: mention of Thailand only); Chan-ard et al. 2015: 230.
Hebius deschauenseei.—Guo et al. 2014: 438 (implicitely); Boundy 2020: 92.
Natrix modesta (nec Tropidonotus modestus Günther, 1875).—Mell 1929: 5, 16, 145 (in part: mention from “Nordsiam” only),
147 (in part: mention from “Nordsiam” only) & 157; Smith 1943: 285, 290 & 291.
Amphiesma modesta.—Nabhitabhata 1987: 42.
Specimens examined (17).—Thailand. Chiang Mai Province. BMNH 1969.1721–1725, “Pa Meang, Me Nga, N.
Siam”, BMNH 1974.5193, “Pa Meang, Me Nga, N. Thailand”, now in the vicinity of Pa Muang (or Pamuang); CUB
MZ(R)5, Forestry Station, Doi Suthep, 3,000 ft; CUB MZ(R)36118, Doi Suthep; FMNH 178396–178398, Chiang
Mai. Chiang Rai Province. BMNH 1969.1719, “Doi Chang”, now Doi Chang (Mt. Chang), Chiang Rai District.
Unspecified locality. BMNH 1921.4.1.6–9, “Hills of North Siam”; CUB MZ(R)1999.63, “Thailand”.
Taxonomic comments.—This species was recognized as valid in the genus Natrix by Bourret (1936a) but
Bourret (1936b) placed it in the genus Macropophis Boulenger, 1893, a genus that was considered a synonym of
Tropidonophis Jan, 1863 which includes natricid species of the Philippines, eastern Indonesia and Australasia (Mal-
nate & Underwood 1988). Subsequently Natrix deschauenseei was synonymized with N. modesta (Günther, 1875)
by Smith (1943: 290), along with three other species now considered to be valid (see above under the account of
Hebius modestus). Subsequently, the validity of Natrix deschauenseei was recognized by Taylor & Elbel (1958) and
Taylor (1965), and accepted by all subsequent authors, although H. deschauenseei has not always been correctly
identified, for example by Nabhitabhata (1987) who confused it with H. modestus (see above). Hebius deschauen-
seei is monotypic.
Diagnosis.—A moderately to large sized species of the genus Hebius characterized by the combination of (1)
19-19-17 dorsal scale rows, moderately or weakly keeled at midbody, more strongly keeled posteriorly excepted
scales of the 1st DSR, all smooth; (2) dorsal scales around the base of the tail weakly keeled; (3) head moderately
distinct from the neck; (4) eye rather large; (5) 29–30 maxillary teeth, the last two moderately enlarged; (6) tail long
and tapering, with a ratio TaL/TL at least equal to 0.33; (7) VEN 149–168; (8) SC 115–141; (9) prefrontal 2; (10)
usually 5th–6th SL entering orbit; (11) 1 anterior temporal; (12) venter never entirely dark: along its whole length,
creamish-yellow or pale yellowish-grey with three parallel rows of dark blotches, one on the outer part of each
ventral, and one on the central part of the venter producing three irregular, parallel stripes separated from each other
by a narrow, pale area; (13) dorsum and sides olive-brown, olive-grey or greyish-brown, sometimes dark brown;
(14) dorsal surface with irregular, blackish-brown or very dark grey blotches, not producing a chequered pattern;
(15) a dorsolateral series of large, elongate blotches, yellow-ochre, rusty red or yellowish-brown, enlarged on the
first quarter to third of the body, progressively smaller and united, forming a dorsolateral stripe, usually extending
along the whole of the body on the 4th–5th or 5th–6th dorsal scale rows; (16) postocular streak present, not visible in
dark specimens; and (17) an ochre-yellow or yellowish-brown streak on each side of the neck and nape forming an
incomplete collar.
Description.—Body rather slender, stouter in large females, cylindrical; head moderately elongate, triangular,
moderately distinct from the thick neck, flattened anteriorly; snout elongate, obtuse or squarish as seen from above,
oblique seen in profile, flat, 25.9–31.3 % of HL, or 1.7–2.1 times as long as diameter of eye; nostrils small, round,
placed dorsolaterally on the snout and directed slightly dorsolaterally; eye rather large, about 1.5–1.8 times as large
as the distance between its lower margin and the margin of the lip, with a round pupil; tail long and tapering.
The maximal known total length is 553 mm (SVL 368 mm; TaL 185 mm; specimen BMNH 1969.1721, female)
but specimen BMNH 1969.1719, with an incomplete tail and a SVL 556 mm long, should have reached a total
length of ca. 850 mm. The longest known male is 484 mm long (SVL 312 mm, TaL 172 mm long; CUB MZ(R)
36118).
Ratio TaL/TL: 0.327–0.378, without sexual dimorphism.
Dentition. 29–36 maxillary teeth gradually enlarging, the last 2 to 4 moderately enlarged, without diastema.
Body scalation. DSR: 19-19-17 rows; scales rhomboedric, weakly or moderately keeled; scales of 1st DSR
smooth; dorsal scales around the base of the tail not strongly keeled.
VEN: 149–168 (plus 2 or 3 preventrals); SC: 115–141, all paired, with a weak sexual dimorphism; cloacal plate
divided.
Ratio VEN/SC 1.11–1.32.
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FIGURE 14. Hebius deschauenseei Taylor, alive—A & B: specimens from Doi Inthanon National Park, Chiang
Mai Province, Thailand. Photographs: Parinya Pawangkhanant. C: specimen from Mt. Doi Inthanon, Chiang Mai
Province. Photograph: Nikolay Poyarkov.
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Position of the reduction to 6 scale rows around the tail: SC 5–22, with a strong sexual dimorphism (see below);
ratio: length of the portion of tail with 6 dorsal scale rows/length of the portion of tail with 4 dorsal scale rows:
1.2–2.4 with a sexual dimorphism.
Head scalation. Arrangement of upper head scales complete including 2 internasals, 2 prefrontals, 2 supraocu-
lars, 1 frontal, and 2 parietals. Rostral wider than high, barely visible from above; nasals subrectangular, elongate,
about 1.4–1.6 times longer than high, vertically divided above and below the nostril, with the posterior part equal
to anterior one; internasals subtriangular, in broad contact with each other, about 1.0–1.2 times longer than wide,
distinctly narrowing anteriorly with an anterior margin about 0.4–0.5 times the width of the posterior margin; 2
prefrontals, rather small, short but wide, distinctly broader than long, 1.0–1.3 times longer than internasals; frontal
large and elongate, shield-like, 1.2–1.6 longer than wide and 1.8–2.4 times longer than prefrontal; 1 supraocular
on each side, subtriangular, 2.0–2.2 times longer than wide, about as wide as internasals; parietals large and broad,
1.8–2.2 times longer than the frontal, or suture between parietals 1.2–1.4 times longer than frontal; 1/1 loreal, pen-
tagonal with its apex directed backwards, distinctly elongate, 1.4–1.8 times longer than high, in broad contact with
the nasal; 2/2 preoculars in all examined specimens, upper one larger than lower one; 2/2 or more rarely 3/3 small
postoculars; usually 9/9 SL (8/9 in 1/18 specimens, 10/9 in 1/18 and 10/10 in 2/18), the first five as long as high or
longer than high, 1st and 2nd SL small and short, in contact with the nasal, 2nd–4th SL or 3rd–4th SL (2nd–3rd SL in 1/18
specimens) in contact with the loreal, mostly 5th–6th SL entering orbit (in 29/36 occurrences), also 4th–6th SL (3/36),
5th–7th or 6th–7th (in 2/36 occurrences each), 7th and 8th SL largest; 1 anterior temporal, rectangular, elongate, narrow-
ing anteriorly, followed by 2 or 1+1/1 posterior temporals, the most common formula being 1+2 temporals; 10/10
(in 17/18 occurrences) or 9/10 (1/18) infralabials, first pair in contact, 1st–5th IL in contact with anterior chin shields,
5th and 6th IL largest; posterior chin shields longer than anterior ones.
Coloration and pattern. This species is quite variable. The dorsal surface and sides are pale olive-brown, olive-
grey, pale greyish-brown, bronze-brown, dark reddish-brown or dark brown; scale rows of the upper dorsal surface
distinctly darker, up to blackish-brown; on the sides, scales may be pale centered and indistinctly edged with minute
dark brown blotches; two or three series of small, irregular dark blotches on the sides; dorsal surface with usually
two or three series of irregular, elongate, blackish-brown or very dark grey blotches, rather faint in darker specimens
but conspicuous in paler ones, the series just above the dorsolateral stripe more conspicuous; another series of dark,
elongate blotches just below the dorsolateral stripe; a faint dorsolateral stripe, reddish-brown or brown, extending
from the neck to the base of the tail barely visible, on which is superposed a conspicuous series of dorsolateral bright
yellow, yellow-ochre, rusty red or yellowish-brown blotches on the 4th–6th then 5th–6th DSR, much enlarged, dis-
tinctly elongate or X-shaped, or as high as long on the first fifth to quarter of the body, 2 to 2.5 scales high and long,
progressively smaller and more elongate, forming a chain, then united and forming a narrow, dorsolateral stripe
posteriorly, 1.5 to 2 scales high; lower part of scales of the 1st dorsal row largely dark brown or blackish-brown,
forming an irregular, ventrolateral dark stripe. The tail is as the body surface, speckled with small dark blotches and
spots and with a yellow-ochre, rusty red or yellowish-brown narrow, irregular dorsolateral stripe, no more than 1
scale high, progressively vanishing around the posterior half of the tail.
The head is olive-brown, olive-grey or brown, upper head surface with irregular darker vermiculations or ir-
regular areas; rostral and sides of the snout paler; an oblique streak on the outer edge of each parietal present or
absent; 4 or 5 anterior supralabials strongly powdered with olive-brown, greyish-brown or pale brown, edged with
dark brown or blackish-brown; a broader suture, dark brown or blackish-brown, on the posterior edge of 6th and 7th
SL; 7th, 8th and 9th SL (when present) pale yellowish-brown or yellowish-grey, also edged with blackish-brown; a
dark postocular streak, oblique or Z-like, i.e., straight, then strongly oblique then straight, extends from behind the
eye or from postoculars to the corner of the mouth on the top of the 8th and 9th SL and temporals; a poorly-defined,
paler area on temporals above the dark postocular streak; an irregular yellow-ochre or brownish-yellow, oblique
streak directed upwards and backwards, extending from the corner of the mouth and the pale area on the temporals
to the nape, forming a short chevron, sometimes faint or nearly absent; a thin streak of same colour extending from
the interparietal suture to the apex of the chevron. Infralabials, chin and throat yellowish-cream or pale yellowish-
brown, often nearly uniform with a few dark brown spots on chin shields and throat, sometimes heavily spotted with
dark brown spots; infralabials more or less broadly and distinctly edged with dark brown on both their anterior and
posterior edges.
The venter is never entirely dark but contains dark blotches in its middle: background colour creamish-yellow,
yellowish-brown, beige ochre-brown, or olive-grey, darker posteriorly; tips and extreme outer part of ventrals dark
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brown; 3 parallel series of blotches or spots, olive-grey, dark grey, brown, dark brown or blackish-brown, extending
from the neck to the vent: one located on the mesial part of the ventrals, the two outer ones located at the level of
the outer third of each ventral, not in contact with the dark hues of the ventral tip; usually only the two outer series
begin at the neck, the central one beginning at level of the 10th–15th ventral, or, in an opposite way, the central stripe
begins first, the two lateral ones farther back; these blotches are more or less enlarged, those of the outer series
triangular with their apex directed posteriorly, those of the central one wider, looking as a flat, irregular triangle or
more irregular; the three series may be close but never united, or even distinctly separated when they are made of
rather small spots, widening posteriorly; sometimes, these series are barely visible in specimens with a rather dark
venter. Tail dark greyish-brown, dark brown or blackish-brown, covered with 3 series of irregular blotches narrowly
separated by a thin, pale line, turning to entirely dark on its posterior half; outer edge of subcaudals pale, forming
a narrow line.
In life, the background coloration is as described above in preservative; the upper dorsal surface, between the
dorsolateral stripes, is distinctly darker than the lateral sides; the various upper lateral and dorsolateral dark blotches
are very dark grey, dark brown or blackish-brown; the dorsal stripe, rusty-brown or reddish-brown, is more visible
than in preservative; the main dorsolateral blotches are bright yellowish-ochre, orange or reddish-brown; the dark
ventrolateral stripe is dark brown or blackish-brown. Pale markings on the head are yellowish-ochre, greyish-yellow
or reddish-brown; the elongate blotch on the temporal region, on the hind part of the head and on the neck is yellow-
ish-ochre, reddish-ochre or reddish-brown. The background colour of the throat and venter is pale greyish-yellow,
yellowish-grey or pale reddish-brown; the dark blotches forming the three parallel series of blotches or spots are in
various shades of brown.
Hemipenes.—The hemipenis of this species has not been examined.
Sexual dimorphism.It is expressed in the following characters:
(1) Strongly by the difference in the number of subcaudal scales: males: 124–141 (mean = 130.0, s = 6.4); fe-
males: 113–124 (mean = 117.8, s = 4.8).
(2) Strongly by the difference in the position (counted in subcaudals) of the reduction to 6 scale rows around the
tail: males: SC 14–22 (mean = 17.9, s = 2.5); females: SC 5–13 (mean = 9.6, s = 3.0).
(3) Strongly by the difference in length of the portion of tail with 6 dorsal scale rows/length of the portion of tail
with 4 dorsal scale rows: 1.2–1.8 in 8 males, 2.0–2.4 in 5 females.
Distribution (Fig. 12).—Thailand. According to our specimens and Chan-ard et al. (2015): Chiang Mai Prov-
ince. Chiang Mai; Doi Inthanon; Doi Suthep; Pa Muang (or Pamuang). Chiang Rai Province. Doi Chang (Mt.
Chang), Chiang Rai District. Uthai Thani Province. Huai Kha Khaeng Wildlife Sanctuary.
Cox et al. (2012: 367) mentioned the occurrence of this species in Loei Province, North-east Thailand. Accord-
ing to M. J. Cox (personal communication, June 2018), this record merely results from a lapsus. There is not any
record to support the occurrence of H. deschauenseei in this province.
Biology.—According to Chan-ard et al. (2015), this species inhabits semi-evergreen and mixed deciduous sub-
montane and montane forest. It is nocturnal and terrestrial and occurs in the vicinity of forest streams. Nothing else
is known of the biology of this rare species.
8. Hebius igneus spec. nov.
(Figs. 15–16)
Tropidonotus modestus (nec Tropidonotus modestus Günther, 1875).—Bourret 1927: 237 (?).
Natrix modesta (nec Tropidonotus modestus Günther, 1875).—Bourret 1936b: 72 (in part), 73 (in part: mention from “Tonkin”
and description of the venter as “Dessous ... presque entièrement noirâtre”); Bourret 1939a: 42 (by inference); Bourret
1939b (in part: mention from Tam Dao, by inference): 53; Tran et al. 1981: 380 (?; tentatively but this mention does not
refer to Hebius boulengeri).
Amphiesma modesta.—Dao 1981: 7; Dao 1982: 8 (species with 19 DSR); Nguyen et al. 1995: 32; Zhao et al. 1998: 66 (in part:
only specimens of Table 14 listed below in the non-type specimens); Orlov et al. 2000: 71 (in part: mention of Tam Dao);
Le et al. 2001: 27; Bain & Nguyen 2004: 7; Ho et al. 2005: 99 (?); Nguyen et al. 2005a: 75 (in part: mentions from Vietnam
except that from Gia Lai); Nguyen et al. 2005b: 120; Orlov 2005: 33 (in part).
Amphiesma modestum.—Ziegler & Le 2006: 40, 41 & 49; Nguyen et al. 2009: 354 (in part: probably the mentions from the
provinces of Cao Bang and Ha Giang); Ziegler et al. 2007: 20, 22 & 23.
Natrix modesta modesta (nec Tropidonotus modestus Günther, 1875).—Bourret 1935b: 259 & 261 (Reprint p. 1 & 3); Bourret
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 45
1936b: 73 & 74 (in part: mention from “Tonkin” and description of the venter as “Dessous ... presque entièrement noirâtre],
74: Fig. 30 (specimen from Tam Dao); Bourret 1937: 27 & 29; Bourret 1939b (in part: mention from Tam Dao, by infer-
ence): 53.
Amphiesma deschauenseei (nec Natrix deschauenseei Taylor, 1934).—Nguyen et al. 2009: 354 (in part); Bain & Hurley 2011:
104 & 128; Guo et al. 2014: 428: Table 1, 434: Fig. 2A, 435: Fig. 2B–C (specimen AMNH 148575 from Vietnam).
Holotype.—IEBR 2295, an adult female, from Ban Cai, 21°51’714N, 106°58’063E, elevation: 350–450m, Duc
Xuan, Na Hang District, Tuyen Quang Province, Vietnam. Collected by Truong Quang Nguyen, Kien Van Doan and
Cuc Thu Ho, 21 May 2004.
Paratypes (8 specimens).—Vietnam. IEBR A.2018.2 (Field number ROM 28638), a stream on the east side
of the village of Tam Dao (21°27’31”N, 105°38′61”E), elevation 925 m, Tam Dao Hill Station; collected by Cuc
Thu Ho, Sergei A. Ryabov and Nikolai L. Orlov, July 2001. Lào Cai Province. IEBR A.2018.3 (Field number
ROM 03474), Fan Si Pan mountain range (22°19’N, 103°47’ E), elevation 1,900 m, Sa Pa District; collected by
Cuc Thu Ho, Sergei A. Ryabov and Eugenyi Rybaltovsky, July 2001.—PeoPles RePublic of china. Yunnan
Province. CIB R579003 (Nr 8278), Xishuangbanna, Xishuangbanna Dai Autonomous Prefecture. - KIZ 75I324,
Lafu, Menglian, Pu’er Prefecture; KIZ 75I423, Menglian, Menglian Dai, Lahu and Va Autonomous County, Pu’er
Prefecture; KIZ 79I195, KIZ 79I300, Manlai, Daxueshan, Yongde County, Lincang Prefecture.
Additional specimens (2).—Vietnam. Ha Giang Province. AMNH 148575, Mt. Tay Con Linh II, Cao Bao
Commune, Vi Xuyen County; collected by Raoul Bain & Truong Quang Nguyen, May 2000. Vinh Phuc Province.
thailand. Nan Province. FMNH 271591, Amphoe Pua (i.e, Pua District).
Taxonomic note. This species has long been known in the literature, at least since Bourret (1935b: 259 & 261
[Reprint p. 1 & 3]), under the combination Natrix modesta modesta, and appeared again in Bourret (1936b: 73–74
[in part], 74: Fig. 30), Bourret (1937: 27 & 29) and Bourret (1939b: 53, by inference) under the same combination.
Hebius igneus spec. nov. was even depicted by Bourret (1936b: 74: Fig. 30). Subsequently, this species has been
identified as Amphiesma deschauenseei or A. modesta, now Hebius deschauenseei and Hebius modestus, respec-
tively; see the chresonymy given above.
Diagnosis.—A moderately to large sized species of the genus Hebius, defined by the combination of the follow-
ing characters: (1) 19-19-17 dorsal scale rows, feebly or moderately keeled at midbody, more strongly keeled poste-
riorly at the exception of the scales of the 1st DSR, all smooth; (2) dorsal scales around the base of the tail strongly
keeled; (3) head moderately distinct from the neck; (4) eye rather large; (5) maxillary teeth 29–30, the last two
moderately enlarged; (6) tail long, with a ratio TaL/TL at least equal to 0.295; (7) VEN 159–169; (8) SC 115–129;
(9) prefrontals 2; (10) one anterior temporal; (11) venter overall dark, i.e., dark brown, blackish-brown or black,
with either pale irregular streaks or with several parallel, connected rows of dark blotches separated from each other
by a narrow, irregular pale area; (12) dorsal surface and sides dark brown, dark chestnut-brown or blackish-brown,
irregularly spotted by the presence of blackish-brown or black scales, darker than the background colour; (13) a
dorsolateral series of bright orange, coral or rusty red blotches (yellow in preservative), distinctly enlarged behind
the neck and at least on the anterior half of the body, then progressively smaller but always visible; these blotches
may be connected and form a distinct dorsolateral line; (14) a dark postocular streak present; and (15) an ochre-yel-
low or yellowish-brown streak on each side of the neck and nape forming an incomplete collar.
Morphological comparisons of Hebius igneus spec. nov. with other species.—Because of its peculiar dorsal
pattern made of distinct, aligned bright dorsolateral blotches combined with an overall dark venter, we here put
emphasis on the colour and patterns in comparing the new species with other species.
Hebius igneus spec. nov. differs from H. annamensis (Bourret), H. atemporalis (Bourret), H. chapaensis (Bour-
ret), H. groundwateri (Smith), H. nigriventer (Wall) new. comb., H. sauteri (Boulenger) (including the subspecies
H. s. bourreti and H. s. maximus), H. taronensis (Smith), and H. venningi (Wall), as well as three species present in
Borneo, i.e., H. arquus (David & Vogel), H. frenatus (Dunn) and H. sarawacensis (Günther), in having 19 DSR vs.
17 rows in all these species and sometimes 15 in H. annamensis. Furthermore, by its largely black venter, Hebius
igneus spec. nov. further differs from the mainland species H. annamensis, H. atemporalis, H. groundwateri, H.
sauteri, and H. venningi which have a large part of the venter pale.
Among the numerous species with 19 dorsal scale rows, Hebius igneus spec. nov. differs by its dorsal pattern
from a number of distinctly striped species such as Amphiesma stolatum (Linnaeus), and Hebius bitaeniatus (Wall),
H. clerki (Wall), H. metusia (Inger, Zhao, Shaffer & Wu), H. octolineatus (Boulenger) and H. parallelus (Bouleng-
er) (see David et al. 2005) which display pale and dark dorsal stripes. Furthermore, these species have a pale venter
and a lower number of subcaudals.
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FIGURE 15. Hebius igneus spec. nov., holotype (IEBR 2295)—A: dorsal view; B: ventral view; C: lateral view of
the head, right side. Photographs: Patrick David.
Also by its dorsal and ventral patterns, Hebius igneus spec. nov. differs from species with 19 DSR of the Hebius
khasiensis-group, hence containing H. khasiensis (Boulenger), H. boulengeri (Gressitt), H. craspedogaster (Bou-
lenger), H. inas (Laidlaw), H. johannis (Boulenger), H. kerinciensis (David & Das), and H. leucomystax (David,
Bain, Nguyen, Orlov, Vogel, Vu & Ziegler). All these species have dorsolateral spots and stripes but the blotches are
smaller and all these species have a pale venter at the exception of the tips of ventrals. Furthermore, both H. khasien-
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 47
sis and H. inas differ from Hebius igneus spec. nov. by the pattern of their supralabials, composed of distinct, pale
blotches in H. khasiensis and H. inas, at least on the posterior supralabials. Furthermore, Hebius igneus spec. nov.
differs from H. leucomystax (David, Bain, Nguyen, Orlov, Vogel, Vu & Ziegler) and H. lacrima Purkayastha & Da-
vid by its overall dark supralabials vs. supralabials largely white in these two latter species, plus by its venter largely
dark, and its different dorsal pattern.
In the same way, Hebius igneus spec. nov. differs from H. optatus (Hu & Zhao) and H. andreae (Ziegler & Le)
by its dorsal pattern made of conspicuous dorsolateral blotches vs. patterns made of vertical, narrow or wide cross-
bars, without longitudinal dorsolateral stripes or series of dots in these two latter species. Malnate (1962) referred
Hebius craspedogaster, H. popei, H. pryeri, H. sauteri and H. vibakari in a distinct species group, named as the
Amphiesma vibakari-group”. Besides H. sauteri, which has 17 DSR at midbody, Hebius igneus spec. nov. differs
from these species by its dorsal and ventral patterns and by its higher number of subcaudals.
Hebius igneus spec. nov. obviously shares one or more characters with other species of “dark-bellied” Hebius,
as treated here. However, for summarizing, Hebius igneus spec. nov. differs from H. annamensis, H. chapaensis,
H. deschauenseei, H. modestus, H. nigriventer, H. taronensis and H. venningi by the combination of the following
characters: (1) 19 DSR at midbody, (2) scales near vent and the base of the tail strongly keeled, (3) at least 159
ventrals, (4) a dorsolateral series of bright orange, coral or rusty red elongate blotches, larger anteriorly but extend-
ing behind half of the body, and (5) several parallel series of dark blotches on the venter more or less separated by
narrow pale stripes. Tentatively included in this group but not addressed here, Hebius xenura (Wall), which has also
19 DSR at midbody and dorsal blotches, differs from Hebius igneus spec. nov. by (1) its undivided subcaudals (vs.
divided in H. igneus), (2) fewer subcaudals, i.e., 92–105 vs. 115–129, and (3) its ventral pattern, pale with tips of
ventrals dark vs. venter overall dark.
As shown above, Hebius annamensis, H. chapaensis, H. nigriventer, H. venningi, and H. taronensis have 17
DSR at midbody (or 15 in H. annamensis) vs. 19 in Hebius igneus spec. nov. Furthermore, H. annamensis and
H. venningi have a venter largely pale mesially or, in H. venningi, pale mesially on the anterior part of the body,
clouded with darker hues of brown on the outer parts of ventrals and entirely clouded posteriorly.
Among the other two species of this group with 19 DSR at midbody, Hebius igneus spec. nov. differs from H.
modestus by (1) dorsal scales before the base of the tail and supracaudal scales just after strongly keeled vs. weakly
keeled in H. modestus, (2) slightly more ventrals, 159–169 VEN vs. 143–163, (3) venter overall dark brown, black-
ish-brown or black, with either pale irregular streaks or with several parallel, connected rows of dark blotches sepa-
rated from each other by a narrow, irregular pale area vs. venter pale ochre-brown or pale brown on a wide central
area, broadly edged with dark brown or blackish-brown on the outer quarter of ventrals, rarely nearly overally dark
except on its anterior part, (4) a dorsolateral series of bright orange, coral or rusty red blotches, distinctly enlarged
behind the neck and at least on the anterior half of the body, then progressively smaller but always visible vs. a more
or less conspicuous, ochre-yellow, ochre-red, orange-brown or reddish-brown stripe, often reduced to a succession
of elongate blotches on the anterior part of the body, and (5) a dark postocular streak present vs. no such streak.
Lastly, Hebius igneus spec. nov. is more similar to H. deschauenseei, from which it differs as follows: (1) supra-
caudal scales around the base of the tail strongly keeled vs. weakly keeled in H. deschauenseei, (2) Ratio TaL/TL,
0.30–0.33 vs. 0.33–0.38, (3) venter overally dark after the 5th–8th ventrals, i.e., dark brown, blackish-brown or black,
with 4 or 5 parallel, connected rows of dark blotches separated from each other by a narrow, irregular pale area vs.
venter never entirely dark along its whole length, creamish-yellow or pale yellowish-grey with three parallel stripes
of aligned dark blotches separated from each other by a pale area in H. deschauenseei, (4) dorsal surface and sides
dark brown, dark chestnut-brown or blackish-brown vs. olive-brown, olive-grey or greyish-brown, (5) dorsolateral
blotches, distinctly enlarged behind the neck and at least on the anterior half of the body, then progressively smaller
but always distinct vs. dorsolateral blotches not as enlarged anteriorly and progressively smaller and united, forming
a dorsolateral stripe, and (6) a dark postocular streak present vs. postocular streak absent or barely visible.
Although it is a juvenile with a rather pale venter anteriorly, specimen FMNH 271591 from Nan Province,
Thailand, is here referred to Hebius igneus spec. nov., and not to H. deschauenseei. Its strongly keeled scales in the
region of the base of the tail (vs. weakly keeled), its ventral pattern, overally black, and its dorsal pattern are typical
of H. igneus spec. nov.
Etymology.—The specific nomen is the Latin adjective igneus (a, um) which means “in fire”. This specific
name was coined by analogy to the large bright orange dorsolateral blotches on the forepart of the body.
We suggest the following common names: Fire-back Keelback (English), Hébius igné (French), Feuerfleckige
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Wassernatter (German), Huo Wen Fu Lian She (火纹腹链蛇) (Chinese), Ngu Lai-sab Fai (Thai) and Rắn sãi lửa
(Vietnamese).
FIGURE 16. Hebius igneus spec. nov., alive—A: specimen from Yen Bai Province, Vietnam. Photograph: Nikolai
Orlov. B: specimen from Ha Giang Province. Photograph: Truong Quang Nguyen. C: specimen from Lao Cai Prov-
ince. Photograph: Truong Quang Nguyen.
Description of the holotype (Fig. 15).—General morphology. Body rather robust but elongate; head moder-
ately elongate (4.0% of SVL), moderately distinct from the thick neck, flattened anteriorly in front of the eyes; snout
elongate, subrectangular as seen from above, oblique seen in profile, 30.4% of HL, or 2.2 times as long as horizontal
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 49
diameter of the eye; nostrils distinctly placed dorsolaterally on the snout and directed slightly dorsolaterally, round,
quite large, piercing the middle of nasal; eye rather large, diameter 1.4 times as large as the distance between its
lower margin and the margin of the lip, with a round pupil; tail cylindrical, long and tapering.
Size. - SVL: 534 mm; TaL: truncated; HL: 21.4 mm; ratio TaL/TL: not available.
Dentition. - Maxillary teeth: 28 gradually increasing in size + 2 distinctly enlarged teeth, without diastema.
Body scalation. - DSR: 19-19-17 scales, scales rhomboedric, not notched at their distal end, weakly keeled at
midbody, more strongly keeled posteriorly at the exception of the scales of the 1st DSR, all smooth; scales before
vent and around the base of the tail strongly keeled.
Dorsal scale row reduction:
4+5 → 4 (9) 4+5 → 4 (98)
21 ——————— 19 ——————— 17
4+5 → 4 (10) 4+5 → 4 (101)
165 VEN (+ 2 preventrals); > 50 SC (incomplete tail), all paired. Cloacal plate divided.
Position of the reduction to 6 scale rows around the tail: 13th SC. Length, in number of subcaudals spanned, of
the portion of tail with 6 caudal scale rows (see Malnate & Underwood 1988): 26; length of tail with 4 caudal scale
rows: unavailable, tail truncated; ratio: length with 6 dorsal scale rows/length of the portion of tail with 4 dorsal
scale rows: unavailable.
Head scalation. - Arrangement of upper head scales complete including 2 internasals, 2 prefrontals, 2 supra-
oculars, 1 frontal, and 2 parietals. Rostral wider than high, barely visible from above; nasals subrectangular, nearly
pentagonal, distinctly elongate, about 2.0 times longer than high, vertically divided above and below the nostril,
with the posterior part equal to anterior one; internasals subtriangular, in broad contact with each other, about
1.0–1.2 times longer than wide, distinctly narrowing anteriorly, the width of the anterior margin about 0.5 times of
the posterior margin; 2 prefrontals, rather small, short but wide, distinctly broader than long, 1.1 times longer than
internasals; frontal large and elongate, shield-like, 1.45 times longer than wide and 2.0 times longer than prefrontal;
1/1 supraocular, subtriangular and elongate, 2.0/1.8 times longer than wide, about as wide as internasals; parietals
large and broad, 1.9 times longer than the frontal, or suture between parietals 1.3 times longer than frontal; 1/1 lo-
real, pentagonal, moderately elongate, 1.4 times longer than high, in broad contact with the nasal; 2/2 preoculars,
upper one larger than lower one; 2/2 small postoculars; 9/9 SL, 1st longer than high, 2nd–6th slightly higher than long,
7th–9th large and longer than high, 1st and 2nd SL in contact with the nasal, 2nd–4th SL in contact with the loreal, 4th–6th
(left) and 5th–6th (right) SL entering orbit, 7th and 8th SL largest, 9th rather short; 1/1 anterior temporal, rectangular,
elongate, slightly narrowing anteriorly, followed by 1+1/1 (left) and 1+1 (right) posterior temporals; 10/10 infralabi-
als, first pair in contact, 1st–5th IL in contact with anterior chin shields, 5th and 6th IL largest; posterior chin shields
longer than anterior ones.
Coloration in alcohol. - Body blackish-brown, slightly darker on the top of the body than on its sides; many
scales of the sides edged with blackish-brown or black and, also, somewhat paler in their middle; some scales of
the sides of the body darker than the dorsal background colour, producing darker spots; a series of conspicuous,
elongate dorsolateral, yellow blotches on 6th and 7th dorsal scale rows (66 at left, 68 at right), 2 to 2.5 DSR long and
1.5 to 2 scales high on the neck, distinctly enlarged, then 1 to 1.5 scale long and 1.5 to 2 scale high, often irregularly
split into two parts on fore third of the body, progressively smaller, irregularly split after midbody and reduced to a
spot posteriorly but always visible; no dorsolateral stripe.
The tail is of the same background colour than the body but without any spot or other mark on its top and
sides.
Head blackish-brown above with some scattered beige dots on internasals, prefrontals and cephalic region; a
short, faint, cream sagittal line just behind the suture between parietals; rostral and nasals slightly paler than upper
head surface; a very thin and faint (barely visible at right), yellowish-brown, postocular streak extending obliquely
downwards from the upper postocular along the anterior outer edge of each parietal then across upper temporals up
to the upper edge of the 9th SL; supralabials with a blackish-brown background colour; 1st to 6th supralabials some-
what paler near their anterior suture, more conspicuous on the edge of 6th SL; 7th SL yellowish-cream on a large
oblique part of its central area with only the top and bottom of the scale blackish-brown; a small area near the lower
anterior margin of 8th SL also yellowish-cream, forming with the central area of 7th SL a conspicuous, elongate and
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50 · Zootaxa 4911 (1) © 2021 Magnolia Press
oblique marking; posterior part of 9th SL pale yellowish-brown; in contrast, the upper parts of 7th, 8th and 9th SL, and
anterior temporal uniformly black, forming a large, oblique postocular streak extending from behind the eye to the
corner of the mouth and slightly beyond; sides of the neck yellowish-cream, strongly spotted with blackish-brown,
from which extends a yellowish-cream, oblique streak directed upwards and backwards at left, and two connected
blotches at right, forming an irregular, yellowish-brown V-like mark just behind the head with its branches not in
contact on the neck.
Infralabials blackish-brown with lower parts of posterior infralabials irregularly marked with yellowish-cream;
mental scale dark brown; chin and throat yellowish-cream with dark brown spots on anterior chin shields and a few
other scattered spots on the back of the throat; lower sides of the neck yellowish-cream with four irregular dark
brown streaks on each side.
Venter overall dark due to numerous blackish-brown, connected blotches on a yellowish-cream background
colour arranged as follows: venter yellowish-cream on the first seven ventrals, with a mesial row of dark blotches
and tips of ventrals dark, then, on the next three or four ventrals, 3 or 4 rows of dark blotches, one or two mesially
plus one on the tip of each ventral, separated by pale background colour, then 4 or 5 parallel, elongate blotches
(not three as in H. deschauenseei), extending from the anterior margin of the ventral and not or barely reaching its
posterior margin, these blotches becoming progressively wider and connected, reducing the background colour to
short, pale irregular streaks separating the rows of dark blotches; after the first third of the body, the blotches are
entirely connected, forming dark transversal blotches on much of each ventral, leaving a narrow, pale area along the
posterior edge of each ventral.
Tail blackish-brown below, with only the posterior edge of each subcaudal narrowly edged with beige brown.
The coloration in life was rather similar, but more bright, at the exception of the dorsolateral spots which were
orange and the apex of the chevron on the neck that was bright yellow.
Description of the paratypes and variation.—A summary of morphological and meristic data of the paratypes
is given in Table 1. Other important characters agree with features of the holotype and are mentioned below in the
variation.
TABLE 1. Morphological characters of the paratypes of Hebius igneus spec. nov.
Collection number Sex Teeth SVL
(mm)
TaL
(mm)
TaL/ TL VEN SC SL PreOc PostOc IL
CIB110718 M 26+3 282 - - 164 - 10/10 2/2 2/2 10/10
KIZ 75I324 M - 595 - - 159 - 9/9 2/2 2/2 9/9
KIZ 79I195 M - 391 165 0.297 163 115 9/9 2/2 2/2 10/10
KIZ 75I423 M - 455 - - 165 - 9/9 2/2 3/3 10/10
IEBR A.2018.2 F 28+2 409 193 0.321 165 129 9/9 2/2 2/2 10/10
IEBR A.2018.3 F 27+2 490 - - 163 - 9/9 2/2 2/2 10/10
KIZ 79I300 F - 512 - - 163 - 9/9 2/2 2/2 10/11
CIB R579003 F - 397 196 0.331 163 124 9/9 2/2 2/2 10/10
General morphology. The maximal known total length is 602 mm long (SVL 409 mm, TaL 193 mm; specimen
IEBR A.2018.2, female). Specimen KIZ 75I324 (male), with an incomplete tail, has a SVL = 595 mm, a value
which would give a total length of ca. 860 mm.
Body relatively slender in males, more robust but elongate in females. Head both moderately elongate and dis-
tinct from the neck, amounting (in adults above SVL 300 mm) for 3.7–4.3 % of SVL (x = 4.0 %); snout elongate,
rather flat, subrectangular as seen from above, oblique seen in profile, amounting (in adults) for 27.6–30.4 % (x =
29.0 %) of HL in both sexes, or 2.1–2.7 (x = 2.4) times as long as diameter of eye; eye large, amounting for 1.4–1.7
(x = 1.5) times the distance eye–lip. Tail progressively tapering. Ratio TaL/TL: 0.297–0.331, without sexual dimor-
phism, but this ratio is based on only three values as most specimens have truncated tails.
Body scalation. DSR: 19–21-19-17, feebly or moderately keeled at midbody, more strongly keeled posteriorly,
always smooth on 1st DSR; dorsal scales immediately before vent and around the base of the tail strongly keeled.
In our sample of 11 specimens, only one has 21 DSR behind neck while another has 20 DSR.
The reduction 19 → 17 DSR, as DSR 4 + 5 → 4, appears at VEN 85–98 at left, at VEN 100–103 at right.
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VEN: 159–169 (plus 1–2 preventrals); SC: 115–129, all paired; cloacal plate divided.
Length in number of subcaudals spanned, of 6 caudal scale rows (see Malnate & Underwood 1988): 13–30 (in
females); length in number of subcaudals spanned, of 4 caudal scale rows: 38–68. Ratio: length 4 rows/length 6
rows: 1.86–2.92 (in females).
Dentition: 29–30 maxillary teeth in a continuous series, gradually enlarged with posterior two teeth slightly
enlarged, without diastema.
Head scalation. It is as described for the holotype and paratypes, with the following variation: internasals
subtriangular and narrowing forward, 1.1–1.4 times as long as wide and 0.35–0.45 times as wide anteriorly than
posteriorly; prefrontals subrectangular, broader than long; frontal hexagonal, large and elongate, 1.15–1.45 times as
long as wide, 1.6–2.0 times longer than the prefrontals; parietals long and wide, in contact for a length 1.2–1.3 times
as great as the frontal length; 1/1 pentagonal loreal, horizontally elongate, 0.6–0.7 times as high as long, in broad
contact with the nasal; 2/2 preoculars in all examined specimens; 2 or 3 postoculars (2/2 in 7/11 specimens, 3/3 in
4/11), the upper one larger than the two lower ones; 9/9 supralabials in all examined specimens, 1st–2nd SL (in 7/11
specimens) or 1st–3rd SL (in 4/11) in contact with the nasal, 2nd–3rd SL (in 6/22 occurrences), 2nd–4th SL (12/22) or
3rd–4th SL (4/22) in contact with the loreal, usually 5th–6th SL entering orbit (14/22 occurrences), or 4th–6th SL (7/22),
rarely 4th–5th SL (1/22); 7th–8th SL largest ones, much enlarged; 1/1 anterior temporal in all examined specimens, fol-
lowed by 1, 1/1+1 or 2 posterior temporals; usually 10 infralabials (in 17/22 occurrences), also 9 IL (in 4/22) or 11
IL (1/22), first pair in contact behind the mental, 1st–5th IL in contact with anterior chin shields, 5th and 6th IL largest;
posterior chin shields longer than anterior ones.
Coloration and pattern. Dorsal surface and sides dark or very dark brown, even blackish-brown or deep black,
more rarely dark chestnut-brown, nearly uniform or irregularly spotted by the presence of blackish-brown or black
scales, darker than the background colour; in some specimens, many scales of the sides edged with blackish-brown
or black and also somewhat paler in their middle; in all examined specimens, a series of 65 to 75 conspicuous,
elongate dorsolateral blotches on 5th and 6th or 6th and 7th dorsal scale rows, yellow, pale yellowish-brown or pale
reddish-brown in preservative, distinctly enlarged on the neck where they are about 2 to 2.5 DSR long and 1.5 to
2 scales high, then progressively smaller, often split into two parts on fore third of the body, irregularly split after
midbody and reduced to a spot or a dash posteriorly but always visible; dorsolateral stripe usually absent but a faint,
ochre-brown or reddish-brown stripe, may be present between the blotches along the posterior part of the body. The
upper surface of tail is dark coloured as the body, either with a dorsolateral series of horizontally elongate pale spots
in preservative or uniformly dark.
Head as described for the holotype: upper surface, parietal region and background colour of supralabials dark
brown or blackish-brown, with scattered beige or pale brown dots on internasals, prefrontals and cephalic region; a
short, cream sagittal line just behind the suture between parietals present but more or less faint; rostral and sides of
the snout slightly paler than upper head surface; a yellowish-brown or yellowish-ochre line on the outer edge of each
parietal and onto upper temporals very thin or often absent; usually (rarely completely absent) a yellowish-brown
or yellowish-ochre postocular streak, varying from barely visible or even reduced to a few dots, to quite broad and
distinct, extending from upper postocular downwards to 9th SL and the corner of the mouth; 1st to 6th supralabials
more or less distinctly paler, i.e., dark brown or dark ochre-brown, near their anterior edge, also often in their central
part or even the anterior half of the scale; 6th SL usually more distinctly paler in its anterior half; 7th SL yellowish-
cream or ochre-brown on a large part, either as a triangular pale area, wider at its base on its anterior half or on its
central area with only the top and bottom of the scale blackish-brown; 8th SL also yellowish-cream or ochre-brown
on its lower anterior part, sometimes forming with the central area of 7th SL a conspicuous, elongate and oblique
marking, or when the paler areas of the 7th and 8th are disjunct, forming two pale, parallel triangles; posterior part
of 9th SL creamish-yellow or pale yellowish-brown; upper parts of 7th, 8th and anterior part or middle of 9th SL, and
anterior temporal uniformly black or very dark blackish-brown, forming a large, irregular, oblique postocular streak
extending from behind the eye to the corner of the mouth and slightly beyond in some specimens; sides of the neck
yellowish-cream, strongly spotted with blackish-brown, from which extends a yellowish-cream, more or less wide
oblique streak directed upwards and backwards, forming an irregular, yellowish-brown V-like mark just behind the
head with its branches not in contact on the neck.
Venter overall dark as in the holotype, with numerous dark greyish-brown, dark brown or blackish-brown
blotches on a yellowish-cream background colour; venter largely yellowish-cream anteriorly on the first 5 to 8
ventrals, with a mesial row of dark blotches or a solid streak and tips of ventrals dark, then, from 3 to 5 rows of
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parallel, elongate dark blotches, one to three mesially plus one on the tip of each ventral, separated by pale back-
ground colour, extending from the anterior margin of the ventral and not or barely reaching its posterior margin,
these blotches becoming progressively wider and connected, reducing the background colour to short, pale irregular
streaks separating the rows of dark blotches; after the first third to half of the body, depending on specimens, the
blotches are entirely united and form dark, transversal blotches on much of each ventral, leaving a narrow, pale area
along the posterior edge of each ventral.
Tail blackish-brown below, with only the posterior edge of each subcaudal narrowly edged with beige brown
or yellowish-ochre.
In life, the coloration and pattern are quite similar to the conditions in preservative but more bright; the dorsal
background coloration is chestnut-brown, dark brown, blackish-brown or even deep black, more or less iridescent;
many scales of the sides are marked with yellow or yellowish-ochre; the dorsolateral blotches are conspicuous,
bright yellow, orange, rusty red or bright reddish-ochre. Pale markings and vermiculations on the head are more
conspicuous, more bright yellow, golden yellow or yellowish-ochre; when present, the large blotch on the 7th supra-
labial is cream, yellowish-ochre or ochre-brown; the elongate blotch on the temporal region and on the hind part of
the head is pale yellow, golden yellow, or yellowish-ochre, the branch obliquely directed upwards and backwards
on the neck being often more orange colored; the background colour of the venter between dark blotches is cream
or pale yellowish-grey.
Sexual dimorphism. According to our sample of 11 specimens, it is only weakly expressed in a single charac-
ter:
Position of the reduction to 6 scale rows around the tail, expressed in the number of subcaudals: males: 14–21
vs. females 8–15.
Our limited sample does not show any difference in the numbers of ventrals and subcaudals or in the ratio
TaL/TL.
Hemipenes.—The everted hemipenis (AMNH 148575) is short, single, cylindrical, reaching only the 7th SC. It
is entirely covered with spines, of which a few are largest at the base of the organ near the sulcus spermaticus; a few
isolated large spines at the distal end of the organ.
Distribution (Map 12).—Hebius igneus spec. nov. occurs over the eastern part of the range of the informal
group of the “dark-bellied” Hebius species.
People’s Republic of China. Yunnan Province. Baoshan Prefecture; Pu’er Prefecture; Xishuangbanna Dai Au-
tonomous Prefecture.—Vietnam. North of the country: Ha Giang Province. Vi Xuyen District. Lao Cai Province.
Sa Pa, Van Ban. Tuyen Quang Province. Na Hang District. Vinh Phuc Province. Tam Dao National Park. –Thai-
land. Nan Province. Pua District.
Based on its currently known distribution, Hebius igneus spec. nov. may obviously be expected in northern and
north-western Laos. It may also be expected from other parts of north-eastern Thailand such as Loei Province.
Biology.—This species inhabits regions covered with tropical evergreen forest and subtropical montane ever-
green and deciduous forests between 300 and 1,900 m a.s.l. All specimens were collected in close association with
rocky, fast-moving mountain streams in forested areas. This species is crepuscular and nocturnal. It feeds on frogs
of the families Megophryidae and Ranidae.
DISCUSSION
The artificial Hebius venningi / Hebius modestus groups
Guo et al. (2014) placed Amphiesma venningi auctorum in the genus Hebius Thompson, 1913. As conceived by Guo
et al. (2014), the genus Hebius contained then 39 species, of which 16 were included in the molecular phylogeny
and confidently placed in the genus by these authors. Guo et al. (2014) tentatively placed there the remaining 23
species on the basis of their morphological characters and their similarities with the 16 species of the phylogeny.
Guo et al. (2014) stated that Hebius venningi was not monophyletic. This point is apparent in Guo et al. (2014:
434–435: Fig. 2A–C). Species treated in the present paper appear at three different positions in the phylogeny pro-
posed by Guo et al. (2014: 434, Fig. 2A), as follows:
(1) A clade containing Hebius khasiensis and H. boulengeri, and “Amphiesma modesta”, this latter species be-
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 53
ing represented by specimen MVZ 226514. However, this latter specimen belongs to a series of specimens from
Tam Dao Hill Station (Vietnam) which were all identified as Hebius boulengeri by David et al. (2013).
(2) A small, distinct clade containing Amphiesma venningi”, specimen CAS 233206 and Amphiesma sp.”,
specimen GP 1618. As stated above, CAS 233206 is identified as Hebius venningi. We did not examine specimen
GP 1618 (Guo Peng’s private collection; from Myanmar) but we tentatively identify it as representing H. venningi.
(3) A larger clade containing four taxa: (a) “Amphiesma deschauenseei”, specimen AMNH 148575; (b) “Am-
phiesma venningi”, specimen GP 1300; (c) Amphiesma venningi”, specimen GP 2468; (d) “Amphiesma modesta”,
specimen CAS 234262; and (e) “Amphiesma atemporalis”, specimen GP 2318.
We examined only two of these five specimens. Specimen AMNH 148575 is a specimen of Hebius igneus
spec. nov. Specimen CAS 243262 (not 24262 as written in the tree) is a genuine Hebius modestus. On the basis of
Guo et al. (2014: 428–429) and of their phylogenetic tree, we refer specimen GP 1300 (Yunnan, China), closely
related to AMNH 148575, also to Hebius igneus spec. nov. Specimen GP 2468, from “Thailand” is placed on a dif-
ferent branch. The locality of this specimen being in Chiang Mai Province (Peng Guo, pers. comm., July 7th 2019),
we tentatively assign it to Hebius deschauenseei.
From this phylogenetic tree published in Guo et al. (2014: Fig. 2A), it appears that species identified as Am-
phiesma venningi” auctorum are only distantly related, with Clade (2) containing Hebius venningi (CAS 233206)
and Amphiesma GP 1618”, Clade (3) containing Hebius modestus (CAS 243262) + true H. deschauenseei (GP
2468) + Hebius igneus spec. nov. (AMNH 148575 and GP 1300). Quite interestingly, Guo et al.’s tree shows that
Hebius atemporalis (Bourret) also belongs to this group. We provide on Fig. 17 a reproduction of the phylogenetic
tree showing the relationships between the Hebius species based on the trees published by Guo et al. (2014) and Ren
et al. (2018) with the species names as we identified them.
FIGURE 17. Reproduction of the phylogenetic tree published by Ren et al. (2018) with modified species names and
their codes based on our identifications.
As stated by Guo et al. (2014: 437), misidentifications are an apparent problem for the identification of speci-
mens of the genus Hebius used in phylogenies. Guo et al. (2014: 437) stated that “A sample of H. modestum from
Yunnan, China (CAS 234262) is much distinct from another one from Vietnam (MVZ 226514)”. Indeed, whereas
specimen CAS 234262 (examined) is a genuine Hebius modestus, MVZ 226514 (examined) is referable to Hebius
boulengeri. In fact, according to the list of specimens used in their phylogeny, it appears that Guo et al. (2014) had
at hand only one specimen of Hebius venningi, CAS 233206, which we examined and of which we confirmed the
identification, although it is very dark in both dorsal and ventral patterns.
A more recent phylogeny of the genus Hebius was published by Ren et al. (2018: 38, fig. 2). It is in part based
on the same specimens used by Guo et al. (2014) but Ren et al. (2018) added samples of Pararhabdophis cha-
paensis” to their analyses. If we examine the phylogenetic tree published by these authors, species treated in the
present paper also appear at three different positions as follows:
(1) A clade containing H. boulengeri and specimen MVZ 226514, identified as Hebius modestum [sic]”. As
explained above, this latter specimen belongs to a series of specimens from Tam Dao Hill Station (Vietnam) which
were all identified as Hebius boulengeri by David et al. (2013).
(2) A distinct clade containing “Hebius venningi”, specimen CAS 233206 and “Hebius sp.” but without men-
DAVID ET AL.
54 · Zootaxa 4911 (1) © 2021 Magnolia Press
tion of the collection number given as specimen GP 1618 in Guo et al. (2014). As stated above, CAS 233206, ex-
amined by us, was identified as Hebius venningi. So, we tentatively identify the other specimen as representing H.
venningi.
(3) A larger clade, closely related to the previous one, containing five taxa: (a) Amphiesma venningi”, specimen
GP 2468; (b) “Hebius modestum”, specimen CAS 234262; (c) “Hebius deschauenseei”, specimen AMNH 148575;
(d) “Hebius venningi”, specimen GP 1300; and (e) a series of four specimens of Pararhabdophis chapaensis. Taxa
(c) to (e) are referred to Clade B by Ren et al. (2018).
The identification of specimens MVZ 226514 of clade (1) above (H. boulengeri) and CAS 233206 + “Hebius
sp.” of clade (2) above (H. venningi) do not change. In clade (3) according to our data as given above, we confirm
the identifications of specimens GP 2468 (H. deschauenseei), CAS 234262 (H. modestus), and AMNH 148575 (He-
bius igneus spec. nov.). However, the identity of specimen GP 1300, from Yunnan (China) is more problematical. It
is obviously close to AMNH 148575 (H. igneus spec. nov.) in Guo et al. (2014) but in Ren et al. (2018), the same
specimen is close to Hebius chapaensis. Without having seen the specimen deposited in a private collection, it is
impossible to take a decision, so we here refer this specimen as Hebius sp.
So, as a conclusion, misidentications in the phylogenetic tree of Ren et al. (2018) are similar to those found in
Guo et al. (2014), at the exception of specimen GP 1300. This point shows that a sound identication of specimens
included in phylogenies, based on their examination, is mandatory.
Lastly, Kizirian et al. (2018) published an expanded phylogeny of the genus . Their results somewhat differed
from those of Guo et al. (2014) and Ren et al. (2018) by the position of Hebius atemporalis, more closely related to
H. venningi sensu stricto, and the addition of Hebius annamensis, related to species of Clade (3) as defined above.
However, the trees of Kizirian et al. (2018) show that Clade (3) as defined above constitutes a rather distinct clade
within the genus Hebius.
On the contents and etymology of the genus Hebius Thompson, 1913
The genus Hebius was erected by Thompson (1913: 423) for the Japanese species Tropidonotus vibakari Boie, 1826
on the basis of anatomical differences presented by this species compared with other members of the genera Tropi-
donotus as then conceived. The etymology of Hebius was not discussed either by Thompson (1913) or by Guo et al.
(2014). As it was coined for a Japanese species, Thompson Latinized the Japanese noun Hebi (), literally meaning
“a snake”. The ending of the Latinized noun, -us, suggests a noun of masculine gender in classical Latin. Guo et
al. (2014: 438) also stated that Hebius was masculine but these authors variously treated it as neutral (for example:
Hebius modestum, p. 437 & 438) or feminine (Hebius modesta, p. 428). We here treat this genus as masculine. As a
consequence, the correct endings of the 47 species (as of 1st July 2019) included in the genus Hebius by Guo et al.
(2014: 437–438), modified by David et al. (2015a), Kizirian et al. (2018), and Purkayastha & David (2019), are as
follows:
H. andreae, H. annamensis, H. arquus, H. atemporalis, H. beddomei, H. bitaeniatus, H. boulengeri, H. cha-
paensis, H. celebicus, H. clerki, H. concelarus, H. craspedogaster, H. deschauenseei, H. flavifrons, H. frenatus, H.
groundwateri, Hebius igneus spec. nov., H. inas, H. ishigakiensis, H. johannis, H. kerinciensis, H. khasiensis, H.
lacrima (this specific name is a noun in apposition, not an adjective), H. leucomystax, H. metusia (this specific name
is a noun in apposition, not an adjective), H. miyajimae, H. modestus, H. monticola, H. nicobariensis, H. nigriventer
new. comb., H. octolineatus, H. optatus, H. parallelus, H. pealii, H. petersii, H. popei, H. pryeri, H. sanguineus,
H. sarasinorum, H. sarawacensis, H. sauteri, H. taronensis, H. venningi, H. vibakari, H. viperinus, H. xenura (this
specific name is a noun in apposition, not an adjective), and H. yanbianensis.
Status of “Natrix modesta” in Guizhou Province, China
Zhao et al. (1998: 66) and Wu et al. (1985: 180) mentioned Amphiesma modesta and Natrix modesta, respectively,
from Guizhou Province, in south-western China. This record was based upon two specimens, CIB 8276 (Field
number 63III6129) and CIB 8277 (Field number 63III6122), both from Bamao, Luodian County, Qiannan Buyei
and Miao Autonomous Prefecture, Guizhou Province. We examined these specimens. Although they have 19 DSR
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 55
at midbody, dorsolateral nostrils and numbers of ventrals and subcaudals similar to those of Hebius modestus, they
differ by (1) their dorsal scales before vent, much more keeled than in H. modestus sensu stricto, (2) their dorsal
pattern with two broad, conspicuous dorsolateral stripes, (3) the presence of a postocular streak, and (4) their ventral
pattern, with a venter largely cream becoming progressively clouded.
Scalation characters between these two specimens and our sample of H. modestus being identical, we refrain
from concluding here about the systematic status of these specimens from Guizhou Province but their status needs
to be evaluated.
CONCLUSION
Thanks to a number of recent resurrections of synonyms and of descriptions of new species, including the present
one, the genus Hebius currently includes 47 recognized species, and is by far the most speciose genus of Asian natri-
cid snakes. The status of several populations is still awaiting evaluation, leading most probably to additional taxa
recognitions. Most Hebius species are restricted to mountain streams and their direct forested surroundings, simi-
larly to many members of Opisthotropis and of the scincid genus Tropidophorus Duméril & Bibron and numerous
other aquatic and semi-aquatic reptiles. Our new species discovery stresses once again the importance of preserving
these fragile environments.
Our study also stresses again how important it is to make a maximal use of types and other museum-preserved
specimens and to properly characterize them morphologically and chromatically. For instance, a proper re-exami-
nation of Hebius specimens used in recent phylogenetic studies allowed us to correct taxa misplacements within
phylogenetic trees due to misidentifications. Many phylogenetic trees and databases are plagued with misidentifi-
cations, and systematic links between sequences and voucher specimens available to the scientific community for
morphological examination are crucial, especially for speciose groups like Hebius, comprising numerous species
which are distinguished based on relatively subtle characters.
ACKNOWLEDGEMENTS
We thank Kien Van Doan and Cuc Thu Ho (Hanoi), Sergei A. Ryabov, and Evgenyi Rybaltovsky (Saint Petersburg)
as well as Roman Nazarov (Moscow), for their assistance in the field, as well as E. Sterling (New York) and K. Koy
(Berkeley) for providing the background of maps used in the present paper.
We are also indebted to Ashok Captain (Pune, India), Abhijit Das (Dehradun, India), Peng Guo (Yibin, China),
Hla Tun (Yangon, Myanmar), Parinya Pawangkhanant (Phayao, Thailand), Nikolay “Nick” Poyarkov Jr. (Moscow,
Russia), Jing Long Ren (Chengdu, China), and Jian-Huan Yang (Hong Kong, China) for having readily shared their
data and photographs on specimens that they collected and authorized their publication in our paper.
Research of Truong Quang Nguyen is supported by the Vietnam Academy of Science and Technology (Project
Code QTBY01.01/19-20). Research of Nikolai Orlov is partly supported by grants RFBR 19-04-00119 and 19-54-
54003 Vietnam under the State theme of Zoological Institute AAAAA19-119082990107-3.
We are grateful to David A. Kizirian and Linda S. Ford (AMNH), Colin J. McCarthy and Patrick Campbell
(BMNH), Varad Giri (BNHS), Robert C. Drewes and Jens V. Vindum (CAS), Yuezhao Wang, Xiaomao Zeng and
Ermi Zhao (CIB), Kumthorn Thirakhupt (CUB), Alan Resetar (FMNH), Canh Xuan Le and Sinh Van Nguyen
(IEBR), Michael W. Lau (KFBG), Dingqui Rao (KIZ), Ivan Ineich, Nicolas Vidal and Annemarie Ohler (MNHN),
Bryan L. Stuart (NCSM), Bob Murphy (ROM), Dennis Rödder and Wolfgang Böhme (ZFMK), Dingqi Rao (YU),
and Channakesava Murphy (ZSI) for the possibility to examine specimens deposited in the collections of their re-
spective institutions.
LITERATURE CITED
Ahmed, M.F., Das, A. & Dutta, S.K. (2009) Amphibians and Reptiles of Northeast India. A photographic guide. Aaranyak,
Guwahati, Assam, 169 pp.
Anderson, J. (1879) Anatomical and zoological researches: comprising an account of the zoological results of the two expedi-
DAVID ET AL.
56 · Zootaxa 4911 (1) © 2021 Magnolia Press
tions to western Yunnan in 1868 and 1875; and a monograph of the two cetacean genera, Platanista and Orcella. Vol. 1.
Text. B. Quaritch, London, xxv + 985 pp.
https://doi.org/10.5962/bhl.title.55401
Angel, F. (1929) Liste des Reptiles et Batraciens du Haut-Laos recueillis par M. Delacour. Description d’un genre de deux es-
pèces et d’une variété d’Ophidiens. Bulletin du Muséum d’Histoire naturelle de Paris, Series 2, 1 (1), 75–81.
Anonymous (Sichuan Biological Research Institute) (1977) Systematic key to the Reptiles of China. Science Press, Beijing, vi +
111 pp., pls. 1–22 + col. pls. 1–6. [in Chinese]
Bain, R.H. & Hurley, M.M. (2011) A biogeographic synthesis of the Amphibians and Reptiles of Indochina. Bulletin of the
American Museum of Natural History, 360, 1–138.
https://doi.org/10.1206/360.1
Bain, R.H. & Nguyen, T.Q. (2004) Herpetofaunal diversity of Ha Giang Province in Northeastern Vietnam, with descriptions of
two new species. American Museum Novitates, 3453, 1–42.
https://doi.org/10.1206/0003-0082(2004)453<0001:HDOHGP>2.0.CO;2
Borang, A., Bhatt, B.B., Bordoloi Chaudhury, S., Borkotoki, A. & Bhutia, P.T. (2005) Checklist of the snakes of Arunachal
Pradesh, Northeast India. Journal of the Bombay Natural History Society, 102 (1), 19–26.
Boulenger, G.A. (1890) The Fauna of British India, including Ceylon and Burma. Reptilia and Batrachia. Taylor & Francis,
London, xviii + 541 pp.
https://doi.org/10.5962/bhl.title.57017
Boulenger, G.A. (1893a) Catalogue of the snakes in the British Museum (Natural History), Vol. I., containing the families Typh-
lopidae, Glauconiidae, Boidae, Ilysiidae, Uropeltidae, Xenopeltidae, and Colubridae Aglyphae, part. British Museum of
Natural History, London, xiii + 448 pp., 28 pls.
Boulenger, G.A. (1893b) Viaggio di Leonardo Fea in Birmania e regioni vicine. LII. Concluding report on the Reptiles and Ba-
trachians obtained in Burma by Signor L. Fea, dealing with the collection made in Pegu and the Karin Hills in 1887-1888.
Annali del Museo Civico di Storia Naturale di Genova, (2), 13, Vol. 33, 304–347, pls. 7–12.
Boundy, J. (2020) Snakes of the World. A Supplement. CRC Press, Boca Raton - London - New York, vii + 273 pp.
Bourret, R. (1927) Inventaire général de l’Indochine. La Faune de l’Indochine. Vertébrés. Société de Géographie de Hanoi,
Hanoi, 453 pp., pls. 1–9.
Bourret, R. (1934a) Notes herpétologiques sur l’Indochine française. I. Ophidiens de Chapa. Bulletin général de l’Instruction
Publique, 13e Année (1933–1934), 7 Mars 1934, 129–138. [Separate reprint: 1–10]
Bourret, R. (1934b) Notes herpétologiques sur l’Indochine française. II. Sur quelques Serpents des montagnes du Tonkin. Bul-
letin Général de l’Instruction Publique, Hanoi, 13e Année (1933–1934), 8 Avril 1934, 149–157. [Separate reprint: 3–11]
Bourret, R. (1934c) Notes herpétologiques sur l’Indochine française. III. Ophidiens d’Annam et du Moyen Laos. Bulletin gé-
néral de l’Instruction Publique, 13e Année (1933–1934), 9 Mai 1934, 167–176. [Separate reprint: 3–12]
Bourret, R. (1935a) Notes herpétologiques sur l’Indochine française. IX. Les Serpents de Chapa. Bulletin général de l’Instruction
publique, 14e Année (1934–1935), 7 Mars 1935, 239–251. [Reprint: 5–17]
Bourret, R. (1935b) Notes herpétologiques sur l’Indochine française. X. Les Serpents de la station d’altitude du Tam-dao. Bul-
letin général de l’Instruction publique, 14e Année (1934–1935), 8 Avril 1935, 259–271. [Reprint: 1–13]
Bourret, R. (1936a) Les Serpents de l’Indochine. Tome I. Études sur la faune. Henri Basuyau et Cie, Toulouse, 141 pp.
Bourret, R. (1936b) Les Serpents de l’Indochine. Tome II. Catalogue systématique descriptif. Henri Basuyau et Cie, Toulouse,
505 pp.
Bourret, R. (1937) Notes herpétologiques sur l’Indochine française. XIII. Serpents récemment récoltés au Tonkin et en Annam.
Bulletin général de l’Instruction Publique, 16e Année (1936–1937), 9 Mai 1937, Annexe, 27–36.
Bourret, R. (1939a) Notes herpétologiques sur l’Indochine française. XIX. La faune herpétologique des stations d’altitude du
Tonkin. Bulletin général de l’Instruction Publique, 19e Année (1939–1940), 4 Décembre 1939, Annexe, 41–47.
Bourret, R. (1939b) Notes herpétologiques sur l’Indochine française. XX. Liste des Reptiles et Batraciens actuellement connus
en Indochine Française. Bulletin général de l’Instruction Publique, 19e Année (1939–1940), 4 Décembre 1939, Annexe,
49–60.
Brown, W.C. & Leviton, A.E. (1961) Discovery of the snake genus Opisthotropis in the Philippine Islands, with description of
a new species. Occasional Papers of the Natural History Museum of Stanford University, 8, 1–5.
Campden-Main, S.M. (1970) A field guide to the Snakes of South Vietnam. Smithsonian Institution, Washington, D.C., 114 pp.
Captain, A. & Bhatt, B. (2002) First record of Amphiesma venningi (Wall, 1910) (Serpentes, Colubridae, Natricinae) from India,
with remarks on its subspecies. Hamadryad, 26 (2), 354–358. [2001]
Chan-ard, T., Grossmann, W., Gumprecht, A. & Schulz, K.-D. (1999) Amphibians and Reptiles of Peninsular Malaysia and
Thailand. An illustrated checklist Amphibien und Reptilien der Halbinsel Malaysia und Thailands. Eine illustrierte
Checkliste. Bushmaster Publications, Würselen, 240 pp.
Chan-ard, T., Parr, J.W.K. & Nabhitabhata, J. (2015) A field guide to the Reptiles of Thailand. Oxford University Press, New
York, xxix + 314 pp.
Chanhome, L., Pauwels, O.S.G., Jintakune, P. & David, P. (2001) Catalogue of the herpetological collection of the Queen Saov-
abha Memorial Institute, Thai Red Cross Society, Bangkok. Part I. Snakes (except Elapidae and Viperidae). Bulletin of the
Maryland Herpetological Society, 37 (2), 49–72.
Cox, M.J. (1991) The snakes of Thailand and their husbandry. Krieger Publishing Co., Malabar, Florida, xxx + 526 pp.
A REVISION OF THE DARK-BELLIED SPECIES OF THE SNAKE GENUS HEBIUS Zootaxa 4911 (1) © 2021 Magnolia Press · 57
Cox, M.J., Hoover, M.F., Chanhome, L. & Thirakhupt, K. (2012) The snakes of Thailand. Chulalongkorn University Museum
of Natural History, Bangkok, xx + 844 pp.
Cox, M.J., van Dijk, P.P., Nabhitabhata, J. & Thirakhupt, K. (1998) A photographic guide to snakes and other reptiles of Penin-
sular Malaysia, Singapore and Thailand. New Holland Publishers (UK) Ltd, London, Cape Town, Sydney and Singapore,
144 pp.
Daltry, J.C. & Chheang, D. (2000) Reptiles. In: Daltry, J.C. & Momberg, F. (Eds.), Cardamom Mountains Biodiversity Survey
2000. Fauna & Flora International, Cambridge, pp. 101–110 + 230–233 (Appendix VI. Part A: Reptiles known to occur in
the Cardamom Mountains) + 234–237 (Appendix VI. Part B: Reptiles expected to occur in the Cardamom Mountains).
Daltry, J.C. & Traeholt, C. (2003) Reptile and Amphibian survey. In: Daltry, J.C. & Traeholt, C. (Eds.), Biodiversity assessment
of the southern Cardamons and Botum-Sakor Peninsula. Final report on surveys carried out during the 2002–2003 dry
season. WildAid: Cambodia Program & Department of Forestry and Wildlife, Phnom Penh, pp. 82–100, Appendix III: pp.
aa–hh and Appendix IV: pp. ii–mm.
Dao, T.V. (1981) List of the Vietnamese snakes at present known in Vietnam. Tap chi Sinh Vat Hoc, 3 (1), 6–10. [in Vietnam-
ese]
Dao, T.V. (1982) Key to the species of Vietnamese snakes. Part II. Tap chi Sinh Vat Hoc, 4 (1), 5–9. [in Vietnamese]
Das, I. (1996) Biogeography of the Reptiles of South Asia. Krieger Publishing Company, Malabar, Florida, vii + 87 pp.
Das, I. (2002) A photographic guide to snakes and other reptiles of India. New Holland Publishers (UK) Ltd, London, Cape
Town, Sydney and Auckland, 144 pp.
Das, I. (2003) Growth of knowledge on the Reptiles of India, with an introduction to systematics, taxonomy and nomenclature.
Journal of the Bombay Natural History Society, 100 (2 & 3), 446–501.
Das, I. (2010) A field guide to the Reptiles of South-east Asia