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ZOOTAXA
ISSN 1175-5326 (print edition)
ISSN 1175-5334 (online edition)
Accepted by V. Deepak: 21 Dec. 2021; published: 17 Mar. 2022 1
Zootaxa 5116 (1): 001–039
https://www.mapress.com/zt/
Copyright © 2022 Magnolia Press Article
https://doi.org/10.11646/zootaxa.5116.1.1
http://zoobank.org/urn:lsid:zoobank.org:pub:9BF4E28B-2B86-4141-8E90-5F64AD346B7B
On the distribution of the species of the genus Hebius Thompson, 1913 (Squamata:
Natricidae) in northern Thailand, including the description of a new species and
a discussion on snake diversity of this region
SJON HAUSER1, TON SMITS2 & PATRICK DAVID3
1Mu Ban Inthanurak, Wiang Phing Road, Chiang Mai 50100, Thailand.
�
sjonhauser@gmail.com; https://orcid.org/0000-0002-5225-1800
2105 Mu, 4 Nong Puen Taek, Song Phi Nong, Kaeng Krachan, Phetchaburi 76170, Thailand.
�
tonsmitswildlife@gmail.com; https://orcid.org/0000-0002-7467-3748
3Institut de Systématique, Évolution et Biodiversité (ISYEB), Muséum National d’Histoire Naturelle, Sorbonne Université, École Pra-
tique des Hautes Études, Université des Antilles, CNRS, CP 30, 57 rue Cuvier, F-75005 Paris, France.
�
patrick.david@mnhn.fr; https://orcid.org/0000-0001-7562-684X
Abstract
We examined and identified preserved specimens, skins, and photographs from a collection of 83 snakes from northern
Thailand presenting the characters of the genus Hebius Thompson, 1913. They belong to at least six different taxa divided
into five species including a new one described here, namely H. bitaeniatus (Wall, 1925), H. deschauenseei (Taylor,
1934), H. igneus David, Vogel, Nguyen, Orlov, Pauwels, Teynié & Ziegler, 2021, Hebius khasiensis (Boulenger, 1890),
and a series of specimens with strong similarities to H. khasiensis that are here preliminary identified as “Hebius cf.
khasiensis”. Furthermore, we obtained a series of 21 different specimens in the most western strip of the region that we
could not refer to any presently known species. We refer these specimens to a new species that we describe here. For
each of these taxa, we provide the list of localities and specify the geographic range in northern Thailand. Lastly, we also
discuss the diversity of the snake fauna of northern Thailand.
Key words: biogeography, Hebius bitaeniatus, Hebius deschauenseei, H. igneus, H. khasiensis, H. terrakarenorum sp.
nov., mountain streams, northern Thailand, snake diversity, taxonomy
Introduction
The speciose genus Hebius Thompson consists of small- to medium-sized semi-aquatic snakes that are widely dis-
tributed across southern, eastern, and south-eastern Asia, from India to China, and mainland and insular Southeast
Asia, as far east as Japan and as far south as Sulawesi. Interspecific similarities and intraspecific variation in their
morphology have been the cause of considerable taxonomic confusion and numerous misidentifications (see e.g.
David et al. 2013; David et al. 2021).
Before the present work, eight species of the genus Hebius were known to occur in Thailand, namely H. bi-
taeniatus (Wall), H. boulengeri (Gressitt), H. deschauenseei (Taylor), H. groundwateri (Smith), H. igneus David,
Vogel, Nguyen, Orlov, Pauwels, Teynié & Ziegler, H. inas (Laidlaw), H. khasiensis (Boulenger) and H. leucomystax
(David, Bain, Nguyen, Orlov, Vogel, Vu & Ziegler, 2007). Only seven species were cited from this country in the
Reptile Database (Uetz et al. 2021; accessed on 2 December 2021) but this website overlooks the presence of He-
bius boulengeri in Thailand. All Thai species have 19 rows of dorsal scales at midbody, except H. groundwateri
(Smith, 1922) that has only 17 rows.
This paper mostly deals with populations and species of Hebius present in northern Thailand (here abridged as
NT). Various different definitions of the northern Thai region are currently in common use. We herein consider the
region as consisting of the nine most northern provinces, namely Chiang Mai, Chiang Rai, Lampang, Lamphun,
Mae Hong Son, Nan, Phayao, Phrae and Uttaradit as well as the more southernly provinces of Kamphaeng Phet,
Nakhon Sawan, Phetchabun, Phichit, Phitsanulok, Sukhothai, Tak, and Uthai Thani. In other divisions, these eight
HAUSER ET AL.
2 · Zootaxa 5116 (1) © 2022 Magnolia Press
latter provinces are considered to belong to other regions (see, for example, Anonymous 1991; Cox 1991; Gardner
et al. 2000).
The list of species of the genus Hebius currently known from Thailand is as follows:
1. Hebius bitaeniatus (Wall, 1925) was first described from the northern Shan State, Myanmar. In Thailand, it is
known only from Doi Inthanon, the highest mountain in Chiang Mai Province, in northwestern NT. The photograph
of an unidentified living Hebius observed on this mountain was published in Chan-ard et al. (1999) and was later
identified as H. bitaeniatus in David & Pauwels (2000). Subsequent records were all from high elevations (above
1,400 m) on Doi Inthanon. David et al. (2005) provided an expanded description of the species. Notable characters
are the distinct and well-defined pale ochre-yellow dorsolateral stripe edged, with a narrow black line that contrasts
conspicuously with the dark brown ground color; the strong keels in the median dorsal rows; the strongly notched
scales on the posterior part of the body; and the short black stripes in the corners of the ventral plates.
2. Hebius boulengeri (Gressitt, 1937) is an ‘Indo-Chinese species’. In Thailand, it is known only from northeast
and central Thailand (David et al. 2013; our data). Characteristics of this species are the distinct white blotches on
the supralabials that are to some degree fused with each other. In the past, this species has been confused with other
species, in particular Hebius khasiensis, to which it is morphologically similar but this situation has been clarified
considerably by David et al. (2013).
3. Hebius deschauenseei (Taylor, 1934) is widespread in northwestern NT but also occurs in the Phu Hin Rong
Kla National Park in southeastern NT. This species was first described from northern Thailand and has hitherto not
been recorded outside the country. A notable character of this species is a dark pattern made of three parallel rows
of more or less fused dark blotches covering much of the venter in adult specimens. The supralabials are pale ochre-
brown and lack white blotches. The dorsal scales are moderately keeled. The number of ventral plates is relatively
low (148–163 + 1–2 preventrals) and the number of divided subcaudals is high (116–139).
4. Hebius groundwateri (Smith, 1922) is known from only five specimens collected in the Thai province of
Chumphon in 1919 (Smith, 1922), just south of the Isthmus of Kra on the Thai Peninsula. No new records have been
reported from this locality or elsewhere since its discovery. It differs from all other hitherto known Hebius species
from Thailand in having 17 rows of dorsal scales at midbody.
5. Hebius igneus David, Vogel, Nguyen, Orlov, Pauwels, Teynié & Ziegler, 2021 is a recently described dark-
bellied species from southern China and northern Vietnam. David et al. (2021) published the first Thai record of this
species based on a specimen collected in Doi Phu Kha National Park in Pua District, Nan Province, in northeastern
NT. This species has subsequently been found around Phu Chi Fa, Chiang Rai Province. As for H. deschauenseei, a
notable character of this species is the dark color almost entirely covering the venter in adult specimens. Therefore,
its uniformly dark venter, rather than three parallel rows of dark blotches, distinguish it from H. deschauenseei.
Other characteristics are the relatively high number of ventral plates (159–169), the very strong keels on the dorsal
scales near the tail base in both sexes, including in the sole known juvenile, and a dorsolateral series of bright or-
ange, coral or rusty red blotches, distinctly enlarged behind the neck which separate H. igneus from H. deschauen-
seei (David et al. 2021).
6. Hebius inas (Laidlaw, 1901) is a rather rare snake only known from Peninsular Malaysia (West Malaysia)
and southern Thailand. Like H. boulengeri it has white blotches on the supralabials. Two Thai records are described
in Taylor (1965), one originating from Nakhon Si Thammarat Province, the other ‘presumed to have been taken’ in
Prachuap Khiri Khan Province. Localities in northeastern Thailand given in Cox et al. (2012) are in error and most
likely result from a confusion with H. boulengeri. David et al. (2013) demonstrated that a number of specimens of
Hebius khasiensis from Thailand had been erroneously identified as H. inas in the recent past.
7. Hebius khasiensis (Boulenger, 1890) is widespread and common throughout the western and central part
of NT. This species is widely distributed in the Indo-Himalayan region (David et al. 2013). Many records from
Khasi Hills, in northeastern India, were reported by Wall (1908). Wall (1925a) described Natrix gilhodesi and Wall
(1925b) identified as such nineteen specimens from the Kachin Hills (northern Myanmar) but this taxon was later
synonymized with Hebius khasiensis (e.g. Smith, 1943). Smith (1940) confirmed the presence of H. khasiensis in
Upper Burma and Smith (1943) extended the range of the species to include localities in Myanmar’s Shan State and,
by all evidence erroneously, northern Vietnam. No records of this species for Thailand were reported until the end of
the millennium, neither in Taylor and Elbel (1958) or Taylor (1965), nor in Cox (1991), Cox et al. (1998), Jintakune
(2000) and Nutphand (2001). The photograph of a Hebius specimen from Phu Luang (Mountain) in Loei Province
DISTRIBUTION OF THE HEBIUS SPECIES IN NORTHERN THAILAND Zootaxa 5116 (1) © 2022 Magnolia Press · 3
was published in Chan-ard et al. (1999) who identified it as “Amphiesma inas”. Two years later, Chanhome et al.
(2001) claimed that the photo was the first record of Hebius khasiensis for Thailand. Pauwels et al. (2009) reported
additional records from Doi Inthanon Mountain (Chiang Mai Province) and the mountains of Wiang Pa Pao District
(Chiang Rai Province), both in northern Thailand. Cox et al. (2012) mentioned the provinces of Chiang Mai, Chi-
ang Rai and Loei as the range of this species in Thailand. A photograph of a specimen from Umphang District, Tak
Province, was published in David et al. (2013), who considered the species rare throughout its range.
A recent source of these misidentifications is probably a popular pocket guide book (Cox et al. 1998) in which
several species are misidentified. On page 45 of this book, the specimen of “Amphiesma modesta” (now Hebius
modestus) is a Hebius khasiensis, a species not treated in Cox et al. (1998). This photograph depicts a specimen
probably originating from northeastern India. However, the text mentions a venter “almost entirely black on Thai
snakes” and is in conflict with the definition of Hebius modestus, which has a largely pale venter (David et al.
2021). A photograph of probably the same specimen illustrated a popular work of snakes in India (Das, 2002) and
was also misidentified as Hebius modestus in that latter work (David et al. 2013). The subtle morphological differ-
ences between H. khasiensis, H. boulengeri and H. inas have been outlined in David et al. (2013), but the authors
emphasize that ‘they are morphologically so close that they can be positively identified only by using a combination
of characters’. However, H. khasiensis is best defined by (1) its 19 rows of dorsal scales at midbody, (2) its strongly
keeled median dorsal scale rows, (3) the more or less ovoid or subtriangular ivory-white blotches on the posterior
supralabials, which are usually hardly or not fused, (4) the vague reddish brown dorsolateral stripe with a series of
regularly spaced pale spots, (5) the relatively low number of ventral plates (140–155 + 1–3 preventrals), and (6) its
divided subcaudals (85–102) (see David et al. 2013).
Furthermore, specimens with strong similarities to H. khasiensis are here preliminary identified as “Hebius cf.
khasiensis”. They were found in Doi Phu Kha National Park and Phu Hin Rong Kla National Park in eastern NT.
8. Hebius leucomystax (David, Bain, Nguyen, Orlov, Vogel, Vu & Ziegler, 2007) is another “Indo-Chinese” spe-
cies also known from Vietnam and Laos. The first specimen recorded from Thailand originated from Roi Et Prov-
ince, Northeast Thailand, and was discovered in the collection of the Thailand Natural History Museum (THNHM)
in Pathum Thani, where it was mislabeled as Rhabdophis chrysargos (see Pauwels et al. 2015). Subsequently, a
photograph of a snake resembling H. leucomystax was shared on a website (www.norththailandbirding.com). The
specimen was photographed in Phu Langka National Park, Nakhon Phanom Province, in Northeast Thailand. The
most conspicuous characteristic of this species is that all the white blotches on the supralabials are fused into a broad
streak that extends from the snout to below the eye and further to the corner of the mouth and the centre of the neck,
thus creating a distinct ‘white moustache’ (David et al. 2007).
Our field work over the past fifteen years in northern Thailand has resulted in a large collection of snakes,
mostly found dead on the road, which show the diagnostic characters of the genus Hebius. Most of them could be
identified relatively easily as they belong to one of the four species already known to occur in northern Thailand.
Ten specimens from the eastern part resembled both H. khasiensis and H. boulengeri and were tentatively ‘identi-
fied’ as Hebius cf. khasiensis. In contrast, we could not refer a group of more than twenty specimens to any of the
species of Hebius presently considered valid. They differ from all described species through a number of characters,
and we herein refer these specimens to a new species.
Materials and methods
We examined a total number of 82 specimens of the genius Hebius (see Appendix I). The first author collected more
than seventy specimens of road-killed specimens (DOR) referable to the genus Hebius during the period 2010–
2020, as well as photographs were taken of five specimens that were not collected. The second author and others
added photographs of a dozen of living specimens that were not collected, including a few specimens photographed
beyond the northern Thai region. The road-killed specimens were documented with photographs, skins, and/or
specimens preserved completely in 70% ethanol, after fixating them in 10% formalin for a week, or with body parts,
e.g. tail, head with part of the neck and pieces of muscle tissue, preserved in 95% ethanol after examination of the
fresh material and skinning the remaining of the body. All materials originated from northern Thailand.
The localities from where the specimens originated were recorded during collection, and were usually fixed as
the distance in ‘road kilometers’ from a well-known place (road junction, bridge, district border, centre of a village)
HAUSER ET AL.
4 · Zootaxa 5116 (1) © 2022 Magnolia Press
with an accuracy of about 200 meters for recent records, and about 1 kilometer for most records before 2017. During
collection, we recorded the type of the surrounding habitat (e.g. forest type, or nearby presence of a stream). Snakes
were photographed in situ, and usually one to ten hours later examined and photographed again, and subsequently
stored in preservative or skinned. Between collection time and examination, the snakes were temporarily stored in
a cool box with ice.
Generally, examination of a snake included measuring snout–vent and tail length, and sexing it by squeezing
the base of the tail toward the vent to evert the hemipenes, if present. In specimens that seemed to be of particular
interest, head scalation or the keeling of the rows of dorsal scales were examined in the fresh or preserved materials.
However, many data were later taken from the photographs, such as the number of ventral scales, counted according
to Dowling 1951, subcaudals and the head scalation. Freshly removed skins from the tip of the snout to the vent (or
from the neck to vent) were pinned on plastic board for one or two hours to dry, and subsequently stored in plastic
zip bags. Many skins were later photographed to facilitate counting DSR (dorsal scale rows), rows with keeled
dorsal and study the coloration pattern. A good number of DOR specimens were found completely dried up on a
road. Following treatment with pesticides against mites they were preserved in plastic clip bags. Ventral plates and
subcaudals could be counted quite accurately in some of them, and a good part of the head scalation was sometimes
revealed, but details of keeling and coloration were usually obscured. Measurements of the parameters of the head
were taken with a slide-calliper to the nearest 0.1 mm; all measurements of the body were recorded to the nearest
millimetre. For more on the methodology and examination see Hauser (2017; 2019). Reliable data on infralabials
were almost completely lacking because in road-killed specimens the posterior infralabials are nearly always sev-
ered and twisted and could not be counted accurately. Neither do we have data on the maxillary teeth, as we have
refrained from cutting the skulls of the already very damaged specimens, in order to expose the dentition.
Data were compared with the literature. One of us (PD) has examined many Hebius specimens over the past
twenty years and their data are summarized in more than a dozen articles authored by him (e.g. David et al. 2007,
2013, 2021 and Purkayastha and David, 2019) and we will refer to the material cited in these papers. Most speci-
mens on which the present paper is based, including voucher pictures, have been deposited at the Queen Saovabha
Memorial Institute (QSMI), Thai Red Cross Society in Bangkok, Thailand, while some are still in the private col-
lection of the first author in Chiang Mai, Thailand (SHPC), and the second author in Kaeng Krachan, Phetchaburi,
Thailand (TSPA). All type specimens of the new species, including skins, tissue samples and voucher photographs
have been deposited at QSMI.
Abbreviations related to scalation and morphometry, and condition of specimen: CP = cloacal plate; div. =
divided; DOR = Dead On Road specimen; DSR = dorsal scale formula; F = frontal shield; HL = head length; IN
= internasal shield; InLa = infralabial; Lo = loreal ; Pa = parietal shield; PF = prefrontal; PoOc = postocular; PrOc
= pre-ocular; R = ratio TaL/TOTL; Ro = rostral shield; SupLa = supralabial; SVL = snout vent length; TaL= tail
length; TOTL = total length; V = ventral (plate) or number of ventral plates.
Abbreviation of private and museum collections used in this study:
IDPPA= Ian Dugdale’s Private Photo Archives; JHPPA= Jonathan Hakim’s Private Photo Archive, United
States; QSMI= Queen Saovabha Memorial Institute, Thai Red Cross Society, Bangkok, Thailand; SHPC= Sjon
Hauser’s Private Collection, Chiang Mai, Thailand; TSPA= Ton Smits’ Photo Archive, Kaeng Krachan, Thailand.
Abbreviations related to geography and habitat: asl. = above sea level; Hw = Highway.
Results
Geographic distribution
■ Hebius bitaeniatus (Wall, 1925) was shown to be widely distributed in Doi Inthanon National Park, which cov-
ers most of Doi Inthanon, the region’s highest mountain. We recorded it at high elevations (1550–1700 m) in Mae
Chaem and Mae Wang districts of Chiang Mai Province that make up most of the national park. Within that range,
the species seems to be syntopic with H. khasiensis and H. deschauenseei. A photograph shared on the website
https://www.inaturalist.org/observations/84811914, and taken on “Doi Pha Hom Phok” without other details given,
shows a snake that we identify as H. bitaeniatus. As Doi Pha Hom Pok, in Fang District, Chiang Mai Province, is
northern Thailand’s second highest mountain, with the habitat near the top similar to habitats at high elevations on
DISTRIBUTION OF THE HEBIUS SPECIES IN NORTHERN THAILAND Zootaxa 5116 (1) © 2022 Magnolia Press · 5
Doi Inthanon, it is most likely another locality where this species occurs. Three records from Mae Chaem and five
from Mae Wang District are listed with details of their locality and the date of the record in Appendix 1. The locali-
ties in Fang, Mae Chaem and Mae Wang District are shown in the Figure 1.
■ Hebius deschauenseei (Taylor, 1934) occurs throughout Chiang Mai Province, where we have documented it
in seven districts at elevations of 1,000 to 1,700 m, often in association with fast flowing rocky streams. Its range
certainly extends beyond Chiang Mai into areas of Chiang Rai (Doi Chang in Mae Suai District is mentioned in
Purkayastha & David, 2019) and Mae Hong Son (but we lack valid records), and perhaps Lampang Province. It
was never recorded from Omkoi District in the very south of Chiang Mai Province or further to the south in the
mountains of Tak Province. The records for Uthai Thani Province mentioned in Cox (1991), Cox et al. (2012) and
Chan-ard et al. (2015) are probably based on a misidentification. On the other hand, H. deshauenseei also occurs in
Phu Hin Rong Kla National Park which covers most of a large table mountain in the southeast of the region (part
of it in Phitsanulok, part of it in Phetchabun Province). In Chiang Mai Province we recorded it in Chiang Dao, Doi
Saket, Fang, Mae On, Mae Rim, Mae Taeng, Mae Wang and Mueang District; in Phetchabun in Lom Kao District
and in Phitsanulok in Nakhon Thai District (both in Phu Hin Rong Kla National Park). Thirteen of our records are
listed with details of the locality and the date of the record in Appendix 1. The eleven localities, including the one
from Chiang Rai Province published in Purkayastha & David (2019) are mapped in Fig. 1.
■ Hebius igneus David et al. 2021 was only found in the northeast of the region where it was recorded at elevations
of 1,100 to 1,700 m. The records were often associated with fast flowing rocky streams. Two records were from Phu
Chi Fa, Wiang Kaen District, Chiang Rai Province (new provincial records), four from Pua District, Nan Province,
and two from Bo Kluea District, Nan Province. The eight records are listed with details of the locality and the date
of the record in Appendix 1 and the three localities are mapped in Fig. 1.
■ Hebius khasiensis (Boulenger, 1890). This species was found to occur widely in the west and center of the region,
where it is the most common and widespread of the known Hebius species. It usually occurs in evergreen forest
at an elevation of 900–1,400 m. It has no strong association with fast flowing rocky streams but it prefers wet for-
est where pools are common. Besides Chiang Mai and Tak provinces, we recorded this species in Mae Hong Son
and Lampang (first provincial records). In Chiang Mai we recorded it in the following districts (see Appendix I):
Chomthong, Doi Saket, Kanlayani Watthana, Mae Chaem, Mae On, Mae Rim, Mae Taeng, Mae Wang, Mueang,
Omkoi and Samoeng. In Lampang Province, we only recorded it in Mueang Pan District. In Mae Hong Son Prov-
ince, we only recorded it in Mueang District. In Tak Province, we recorded it in Phop Phra and Umphang District.
Twenty-three records for this species are listed with details of the locality and the date of the record in Appendix
1 and the sixteen known localities at district level (including one reported by Pauwels et al. 2009b) are mapped in
Fig. 1.
■ Hebius cf. khasiensis. In the eastern part of the region, we recorded specimens that resembled H. khasiensis,
but also demonstrated a few atypical characters, such as a narrow horizontal white blotch, edged by black, in the
middle of the large posterior supralabials. As most of our records did not contain enough data, we declined from
positively identifying them as H. khasiensis; the status of this distinct taxon will be addressed elsewhere. These
specimens were found in Nan, Phetchabun and Phitsanulok Province at elevations of 1,100–1,650 m where they are
not strongly associated with fast flowing rocky mountain streams. In Nan Province we recorded it in Doi Phu Kha
National Park in Pua District, in Phetchabun Province in Phu Hin Rong Kla National Park in Lom Kao District, and
in Phitsanulok in Phu Hin Rong Kla National Park in Nakhon Thai District. Ten records are listed with details of the
locality and the date of the record in Appendix 1 and the three known localities are mapped in Fig. 1.
Finally, we collected or photographed more than twenty specimens throughout the west of the region, and the very
northwest of the Central Region, that we could not identify as any of the known Thai species, nor as any other valid
species of the genus Hebius. We herein describe this taxon as a new species. The description of this new species in-
cludes its geographic distribution, and the localities in northern Thailand are mapped in Fig. 1. Twenty-two records
are detailed below.
HAUSER ET AL.
6 · Zootaxa 5116 (1) © 2022 Magnolia Press
FIGURE 1. Localities of the six species of the genus Hebius known to occur in northern Thailand. Hebius terrakarenorum sp.
nov. (white dots). Mae Hong Son Province: 1. Mae Sariang District. Chiang Mai Province: 2. Omkoi District. Tak Province: 3.
Near Mae Wa Luang Village, Tha Song Yang District; 4. 16.5 km north Ban Tha Song Yang (Village), Tha Song Yang District;
5. Phop Phra District; 6. Umpiam Highland, Umphang District; 7. “Ancient Forest” and around, Umphang District.
Hebius bitaeniatus (black triangles) Chiang Mai Province: 1. Fang District (Doi Pha Hom Pok), 2. Mae Wang District (Doi
Inthanon National Park), 3. Mae Chaem District (Doi Inthanon National Park).
Hebius deschauenseei (black dots) Chiang Mai & Chiang Rai Province: 1. Fang District (Doi Ang Khang), 2. Mae Suai District
(Doi Chang), 3. Chiang Dao District. 4. Mae Taeng District. 5. Mae Rim District, 6. Mueang District (Doi Suthep), 7. Mae Wang
District (Doi Inthanon), 8. Mae On and Doi Saket District. Phitsanulok Province: 9. Nakhon Thai District (Phu Hin Rong Kla
N.P). Phetchabun Province: 10. Lom Kao District (Phu Hin Rong Kla N.P).
Hebius igneus (black squares). Chiang Rai Province: 1. Wiang Kaen District (Phu Chi Fa). Nan Province: 2. Pua District (Doi
Phu Kha National Park), 3. Bo Kluea District (Doi Phu Kha National Park).
Hebius khasiensis (white squares). Mae Hong Son Province: 1. Mueang District. Chiang Rai Province: 2. Wiang Pa Pao Dis-
trict (in Pauwels et al., 2009). Chiang Mai Province: 3. Kanlayani Watthana District, 4. Mae Taeng District, 5. Samoeng District,
6. Mae Rim District, 7. Mae On District, 8. Doi Saket District, 9. Mueang District, 10. Mae Wang District, 11. Mae Chaem
District, 12. Chomthong District, 13. Omkoi District. Tak Province: 14. Phop Phra District, 15. Umphang District. Lampang
Province: 16. Mueang Pan District.
Hebius cf. khasiensis. (white squares). Nan Province: 17. Bo Kluea District (Doi Phu Kha National Park). Phitsanulok Prov-
ince: 18. Nakhon Thai District (Phu Hin Rong Kla National Park.). Phetchabun Province: 19. Lom Kao District (Phu Hin Rong
Kla National Park).
Details of the localities of the 22 specimens of Hebius terrakarenorum sp. nov. are listed in the description of the species. The
localities of two specimens from Kanchanaburi Province are about 150 km south of Umphang (white dot number 7) and could
not be shown in this map.
Details of the localities for specimens of four other Hebius species are given in Appendix 1.
DISTRIBUTION OF THE HEBIUS SPECIES IN NORTHERN THAILAND Zootaxa 5116 (1) © 2022 Magnolia Press · 7
Hebius terrakarenorum sp. nov.
Figs. 2–9, 11A, 12–18
Amphiesma deschauenseei (juvenile), Plate 76 in Cox (1991).
Holotype. QSMI 1686, an adult male DOR from “Hw1090, 8.2 km northeast of the bridge over the Mae Klong
Khi River at Mae Klong Khi Village” (16.23661°N, 98.96871°E), elevation about 1,209 m, Umphang District, Tak
Province, northwestern Thailand. Collected by Sjon Hauser on 17 October 2020. Status. Initially, the holotype was
a relatively intact DOR specimen but part of its tail was missing. After complete examination and taking of photo-
graphs, the head was cut off and preserved in 95% ethanol, the rest of the body from neck to vent was skinned and
the dried skin preserved dry. Parts of the tail and some muscle samples were also preserved in 95% ethanol.
Paratypes (7 specimens). 1. QSMI 1687. Male DOR from “Hw1090, 16.4 km northeast of the bridge over
the Mae Klong Khi River at Mae Klong Khi Village”, Umphang District, Tak Province; elevation about 1,200 m.
Collected by Sjon Hauser on 5 October 2019. 2. QSMI 1688. Male DOR from “Hw1090, 16.3 km northwest to the
bridge over the Mae Klong Khi River at Mae Klong Khi Village”, Umphang District, Tak Province; elevation about
1, 200 m. Collected by Sjon Hauser on 5 October 2019. 3. QSMI 1689. Male DOR from “Hw1090 at the village of
Rom Klao 4”, Phop Phra District, Tak Province; elevation about 1,100 m. Collected by Sjon Hauser on 3 October
2019. 4. QSMI 1690. DOR from “Hw1099 near the Stupa Monument and Viewpoint north of the village of Ban
Musoe Pak Thang”, Omkoi District, Chiang Mai Province; elevation about 1,372 m. Collected by Sjon Hauser on
25 June 2019. 5. QSMI 1691. DOR from “Hw1099 near the southern entrance to the village of Ban Musoe Pak
Thang”, Omkoi District, Chiang Mai Province; elevation about 1,275 m. Collected by Sjon Hauser on 24 June 2019.
6. QSMI 1692. Male DOR from “Hw1090 5.4 km east of police checkpoint near (old) KM 49 marker”, Phop Phra
District, Tak Province; elevation about 1,100 m. Collected by Sjon Hauser on 27 October 2018. 7. QSMI 1693.
Male DOR from “Hw1090 1.9 km south of Highways Depot, near Umpiam Refugee Camp”, Umphang District, Tak
Province; elevation about 1,100m. Collected by Sjon Hauser on 20 October 2018.
Additional specimens (13). 1. QSMI XX-13.11.01-21. “Hw1090, 16.2 km northwest of the bridge over the
Mae Klong Khi River at Mae Klong Khi Village”, Umphang District, Tak Province; elevation about 1,200 m. Col-
lected by Sjon Hauser on 1 November 2013. 2. QSMI 1694. Living subadult from “south of Mae Wa Luang Vil-
lage”, Tha Song Yang District, Tak Province; elevation about 750 m. Voucher photographs taken by Ton Smits on
24 September 2018. 3. QSMI 1695. DOR from “Hw1090, near KM 53, 4 km east of Police Check Point (near KM
49), Phop Phra District, Tak Province; elevation about 1,100 m. Collected by Sjon Hauser on 10 September 2013.
4. QSMI 1696. DOR from “Hw 1090 3.5 km south of Highways Depot, near Umpiam Refugee Camp”, Umphang
District, Tak Province; elevation about 1,150 m. Collected by Sjon Hauser on 11 September 2013. 5. QSMI 1697.
DOR from “Hw1090, 16.2 km northeast of the bridge over the Mae Klong Khi River at Mae Klong Khi Village”,
Umphang District, Tak Province; elevation about 1,200 m. Collected by Sjon Hauser on 1 June 2015. 6. QSMI
1698. DOR from “Hw 1090 3.2 km south of Highways Depot”, Umphang District, Tak Province; elevation oabout
1,150 m. Collected by Sjon Hauser on 9 July 2016. 7. SHPC09.09.17-04. DOR from “Hw 108, 25 km east of Mae
Sariang Town”, Mae Sariang District, Mae Hong Son Province; elevation about 1,000 m. Photographs taken by
Sjon Hauser on 17 September 2009. 8. SHPC11.10.11-14. DOR from “Hw 1090 8 km south of Highway Depot”,
Umphang District, Tak Province; elevation about 1,050 m. Voucher photographs taken by Sjon Hauser on 11 Oc-
tober 2011. 9. SHPC12.10.13-04. DOR from “Hw1090, 16 km northeast of the bridge over the Mae Klong Khi
River at Mae Klong Khi Village”, Umphang District, Tak Province; elevation of about 1,200 m. Collected by Sjon
Hauser on 13 October 2012. 10. SHPC15.10.21-10. DOR from “a little south of KM 86, near the Umpiam Refugee
Camp”, Umphang District, Tak Province; elevation about 1,150 m. Collected by Sjon Hauser on 21 October 2015.
11. SHPC17.09.09-07. DOR from “Hw105, 25 km north of Mae Salit Luang Village”, Tha Song Yang District, Tak
Province; elevation about 600 m. Collected by Sjon Hauser on 9 September 2017. 12. QSMI 1701. Living sub-
adult/juvenile “next to a small stream in Khao Laem National Park, about 500 m from the park HQ,” Sangkhlaburi
District, Kanchanaburi Province. Elevation about 300 m. Photographs taken by Ian Dugdale on 24 March 2017. 13.
IDPPA 2021-03-09. Living adult resting on “stone in the middle of a stream, about 500 m north of the HQ, Thong
Pha Phum National Park,” Thong Pha Phum District, Kanchanaburi Province. Elevation about 800 m. Photographs
taken by Ian Dugdale on 9 March 2021.
Diagnosis (based on the 21 available specimens). A medium-sized snake of the genus Hebius, defined by the
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8 · Zootaxa 5116 (1) © 2022 Magnolia Press
combination of the following characters: (1) TaL/TOTL ratio 0.32–0.36 (n=12); (2) two preoculars; (3) two post-
oculars (the lower one much smaller than the upper one); (4) usually a single elongate anterior temporal followed
by two posterior temporals, the upper one much larger than the lower one; (5) usually 9 supralabials, 5th and 6th
in contact with eye, 8th largest; (6) 159–171 ventrals plus 1–2 (rarely 3) preventrals; (7) cloacal plate divided; (8)
107–130 divided subcaudals; (9) dorsal scales in DSR 19-19-17 (rarely 19-17-17), dorsal keeling variable, most
often 17 rows (out of 19) distinctly keeled at midbody, the enlarged scales of the 1st DSR smooth; (10) reduction of
dorsal scale rows from 19 to 17 rows by a reduction involving the 3rd and 4th DSR, namely 3rd +4th → 3rd DSR on
both sides within five successive ventral plates between the 79th to 102th ventral scale; (11) supralabials cream to
pale brown broadly edged and dusted with dark grey; white blotches absent; (12) venter immaculate pinkish-cream
except for the pale salmon corners of the ventral plates edged with grey and an adjacent cloudy grey spot; (13)
dorsal coloration pattern variable, most commonly a brown ground color, darker on the top of the dorsum, with a
dorsolateral series of some 80 distinct pale ochre-brown to orange-brown rounded blotches on row 6 extending from
the neck to the tail with less distinct series of dark blotches below them on row 4 and above them on row 8; (14) a
bicolored postocular streak to the corner of the jaw, where a characteristic pale ochre-brown pattern extends to the
first pale blotch of the dorsolateral row.
Description of the holotype. General morphology. A male specimen that weighed 31.4 gram, with SVL 425
mm and incomplete tail (TaL 162 mm). Head distinct from the neck; the body is quite round, not laterally com-
pressed. Head length from tip of the snout to the neck (HL1) 21.4 mm; head moderately elongate (5.0% of SVL);
HL2 from tip of the snout to posterior edges of the parietal shields 13.4 mm. Snout length (rostral tip to posterior
edges of prefrontals) 4.1 mm, 1.8 times as long as horizontal diameter of the eye (of 2.3 mm); nares distinctly di-
rected dorsolaterally on the snout, round, quite large (diameter 2.3 mm), 1.5 times as large as the distance between
its lower margin and the margin of the lip (1.5 mm). Eye medium-sized with a round pupil. Tail broken, remaining
proximal part cylindrical. Base of tail with distinct keels.
Size. SVL: 425 mm; TaL: not available; HL1: 21.4 mm; R: not available.
Dentition. Not available.
Hemipenes. The everted hemipenes are pinkish-white, short, single, not forked and bulbous; the organ is overall
densely covered with tiny, slightly curved spines; spines at the tip of the organ are larger.
FIGURE 2. An adult living specimen of Hebius terrakarenorum sp. nov. (specimen IDPPA 2021.03.24) resting on a stone in a
mountain stream in Kanchanaburi Province. Photo by Ian Dugdale.
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FIGURE 3. Freshly road-killed specimen QSMI 1686, holotype of Hebius terrakarenorum sp. nov. from Umphang District,
Tak Province. A. Dorsal view (part of tail is broken off). B. Ventral view, showing one everted hemipenis. C. Upper side of head
and neck. D. Ventral side of head and neck. E. Lateral view of left side of head and neck. F. Dried skin of body of holotype from
10th ventral plate until cloacal plate. G. Details of skin showing dorsal scale row reductions behind midbody from 19 to 17. On
the left side the 4th row fuses into the 3th row at level V97 to V98. On the right side this reduction occurs at level V96 to V97.
Photos by Sjon Hauser.
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FIGURE 4. A. Dorsolateral view of the right side of the head of paratype 2, specimen QSMI 1688, from Umphang District,
Tak Province. Photo by Sjon Hauser. B. Lateral view of the left side of the head of specimen QSMI 1694 from Tha Song Yang
District, Tak. Photo by Ton Smits.
In both specimens there are 2 preoculars, 2 postoculars, 5 temporals 1+2+2 (the lower first posterior temporal much smaller than
the upper one), 9 supralabials, the 1st to 4th relatively small and rectangular, the 5th and 6th larger and in contact with the eye, the
8th the largest and in broad contact with the elongated anterior temporal. In addition, the broad, bicolored postocular streak is
very similar in both photographs.
FIGURE 5. Examples of dorsal skins at midbody of Hebius terrakarenorum sp. nov. A. Holotype, specimen QSMI 1686, from
Umphang. B. Paratype 2, specimen QSMI 1688, from Umphang. C. Paratype 3, QSMI 1689, from Phop Phra. D. Paratype 4,
specimen QSMI 1690, from Omkoi. Photos by Sjon Hauser.
DISTRIBUTION OF THE HEBIUS SPECIES IN NORTHERN THAILAND Zootaxa 5116 (1) © 2022 Magnolia Press · 11
FIGURE 6. A. Dorsal view of Paratype 7, specimen QSMI 1693 from Umphang District, Tak Province. B. Dorsal view of Ad-
ditional Specimen QSMI 1695 from Phop Phra District, Tak Province. Photos by Sjon Hauser.
FIGURE 7. A. The ventral coloration pattern of the anterior part of the body of Paratype 3 of Hebius terrakarenorum sp. nov.,
specimen QSMI 1689, a male from Phop Phra District, Tak Province. B. Ventral view of the posterior end of the body of Para-
type 3 of Hebius terrakarenorum sp. nov., specimen QSMI 1689, a male from Phop Phra District, Tak Province. The cloudy,
ventral spots are larger, darker and nearly fused with the dark-edged corners of the ventral plates, but never intensely dark and
closely set. Photos by Sjon Hauser.
Body scalation. DSR: 19-19-17 scales, scales rhombohedral, not notched at their distal end, with moderately
strong keels at midbody, except for the smooth, slightly enlarged scales of the 1st DSR; vertebral scales not enlarged;
scales around the base of the tail distinctly keeled, not strongly keeled; the reduction from 19 to 17 dorsal scale rows
takes place between the 95th and 98th ventral plate; at level V96 on the right side, the 3rd scale row fuses with 4th row
fuse to become row 3; and at level V97 on the left side scale row 3 and 4 fuse to become row 3; 168 ventral plates
+ 2 preventrals; SC not available (tail truncated), all paired; cloacal plate divided.
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FIGURE 8. A. Ventral view of the anterior part of the body of DOR Additional Specimen 7, SHPC11.10.11-14 from Umphang
District, Tak Province, showing the ‘golden-salmon’ pigment accumulations along the edges of the first row of dorsal scales and
the corners of the ventral plates, and extending less densely to the edges of the second dorsal row. B. Details of Fig. 11, showing
that the pigment accumulations along the edges of the second dorsal row are less dense compared to the first row and ventral
corners, and broken up into distinct grains. Photos by Sjon Hauser.
FIGURE 9. A partially everted hemipenis of paratype 7 of Hebius terrakarenorum sp. nov., specimen QSMI 1693 from Um-
phang District, Tak Province. Photo by Sjon Hauser.
Head scalation. Arrangement of upper head scales complete, including 2 internasals, 2 prefrontals, 2 supraocu-
lars, 1 frontal, and two parietals. Rostral wider than high, not visible from above; nasals subrectangular, distinctly
elongate, divided above and below the quite large, central naris; internasals subtriangular, in broad contact with
each other, wider than long, narrowing anteriorly; 2 prefrontals, subrectangular, much larger than internasals; frontal
hardly longer than wide, longer than prefrontal, the anterior edge perpendicular to the longitudinal axis. Parietals
large, suture between them barely longer than the frontal; 2/2 preoculars; 2/2 postoculars, upper one much larger
than lower one; left loreal trapezoid, a little longer than high; right loreal rectangular, nearly twice as long as high;
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9/9 supralabials, 5th and 6th in contact with eye, 7th and 8th largest; 5/5 temporals in formula 1 + 2 + 2, anterior tem-
poral elongate, disk-shaped/ flattened hexagonal, upper temporal of second row much larger than lower one (both
sides); infralabials much damaged posteriorly on both sides, 1st to 5th IL in contact with anterior shin shields; poste-
rior shin shields longer than anterior ones.
Coloration of freshly killed holotype and its dried skin.
Head and neck. The upper side of the head and neck is dark brown with some greyish vermiculation. Supralabi-
als are cream or pale ochre-brown with their edges dark grey and surroundings peppered with grey. The eye is round,
quite large, with a round, black pupil with a yellow halo; the iris is pale brown mottled and peppered with black. An
oblique, bicolored postocular streak (upper side pale yellowish-brown or yellow-ochre, lower side dark brown) tra-
verses the anterior temporal shield and the 8th and 9th supralabials, dividing these shields in a pale- and dark-colored
section. At the corner of the upper jaw the dark part of the streak fuses with the dark brown ground color of the neck,
the pale ochre part meanders in the characteristic pattern of a curved bar with knobs towards the midline of the neck
and fuses with the first, most anterior pale blotch of the dorsolateral row of blotches.
Dorsal side of the body and tail. The dorsum is dark brown in the central nine scale rows, gradually a little
lighter greyish-brown in the lateral rows, with the enlarged outermost row distinctly paler, its centre ochre-brown,
edged by grey. A dorsolateral series of roundish pale ochre- or orange-brown blotches the size of one scale (plus
parts of the surrounding scales) stretches from the neck to the tail on row 6, each spot separated from the next one
by one brown scale (see Figs. 3, 5A). These dorsolateral blotches are aligned on a diffuse stripe, slightly paler than
the dark brown ground color; the blotches are all of similar size and distinct until the very posterior end of the body
where they become smaller and indistinct and fade away on the tail; another series of lateral dark brown blotches
on dorsal row 4 below each ochre- or orange-brown spot. About 80 blotches are distinct in each row. The upper side
of the tail is uniformly dark brown.
Lower side of head and neck, body and tail. Infralabials and chin shields are white to cream. The venter immac-
ulate pinkish-white/cream except for the corners of the ventral plates which are salmon, laterally edged or peppered
with grey; there is a cloudy grey spot near the corner. Anteriorly these spots are rather vague, cloudy-amoeboid,
posteriorly they are slightly larger, denser, darker and more distinct.
The lower side of the (incomplete) tail is densely peppered with grey, most densely at the lateral sides of the
(divided) subcaudals.
Habitat. The holotype was collected on a road traversing low montane evergreen forest. Next to the road tiny
streams of rain water run off were hidden in the dense vegetation (Fig. 10A). Some 50 m south of the site, a little
fast-flowing stream cascades into a pool that drains under the road onto a steep mountain slope on the other side.
Around the pool bushes of large, 1–2 m high members of the Zingeriberaceae and Phlogacanthus curviflorus (Wal-
lich), and also stands of bamboo. The forest around the pool is inhabited by numerous other snake species, including
Hebius khasiensis, Psammodynastes pulverulentus (H. Boie in F. Boie), Sibynophis collaris (Gray), Lycodon cha-
paensis (Angel & Bourret), previously Lycodon septentrionalis (Günther) (see Wang et al. 2021), Pareas hamptoni
(Boulenger), Pareas macularius Theobald, Rhabdophis nigrocinctus (Blyth) and Trimeresurus popeiorum Smith.
Description of the paratypes and variation. A summary of morphological and meristic data of the seven paratypes
is given in Table 1. For photographs of these paratypes, see Figures 12–18. Morphological data, often incomplete,
of twelve additional, much damaged DORs or living specimens are summarized in Appendix 2.
Variation of the head scalation and coloration of the head
The head scalation of the paratypes is similar to that of the holotype. Differences occur in the number of supra-
labials, of temporals and the shape of the loreal.
There are always 2 preoculars (on both sides); there are nearly always 2 postoculars (on both sides) but in a
few cases (3 out of 18 occurrences) it appeared that the two were fused to one; in a few specimens (3 out of 17) a
side of the head has 10 supralabials (vs. 9 in the holotype and in most of the paratypes); the loreal is rectangular,
usually longer than high, the ratio length/height varying from 1.2 to 2.0. In one specimen, the loreal is slightly
trapezoid-shaped; there is mostly 1 elongated anterior temporal followed by 2 posterior temporals (in 14 out of 17
occurrences), the upper one much larger than the lower one. However, the second row of posterior temporals shows
more variation (2, 3 or 4) or damage means the number of shields hard to count accurately.
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TABLE 1. Data on the morphology of the holotype and seven paratypes of Hebius terrakarenorum sp. nov.
Data Holotype QSMI
1686
Paratype 1
QSMI 1687
Paratype 2
QSMI 1688
Paratype 3
QSMI 1689
Paratype 4
QSMI 1690
Paratype 5
QSMI 1691
Paratype 6
QSMI 1692
Paratype 7
QSMI 1693
Origin Umphang Umphang Umphang Phop Phra Omkoi Omkoi Phop Phra Umphang
Sex male male male male n.a. n.a. male male
SVL (mm) 425 306 408 360 239 277 319 263
TaL (mm) 162+* 75+* 195 172 118 155 179 131
TOTL (mm) 587+* 381+* 603 532 347 432 498 394
TaL/TOTL (%) 27.6+* 19.7+* 32.3 32.3 34.0 35.9 35.9 33.2
Ventral plates (preventrals) 168 (2) 168 (1) 170 (2) 160 (1) 160 (1) 171 (1) 165 (2) 166 (2)
Cloacal plate (CP) divided ?? divided divided divided divided divided divided
SC (pairs) 80+* 62+* 107 111 116 130 126 119
DSR 19-19-17 19-19-17 19-19-17 19-19(18)-17 19-17(18)-17 19-19-17 19-19-17?? 19-19-17
19 >> 17 between Vx-Vy V98-V103 n.a.* V93-V97 V79-V83 V70-V74 V102-V103 n.a. V95-V100
Keeled r. at MB (tot. r.) 17 (19) distinct 17 (19) weak 17 (19) distinct 7 weakly 9 (17) very weak 17 (from 19) not distinct 9 weakly
Sup.lab.L;contact eye; largest 9; 4-5-6; 7 or 8 n.a.* 9; 5-6; 7 or 8 10; 5-6-7; 8 9; 5-6; 8 9; 5-6; 8 10; 5-6-7; 9? 9; 5-6-7; 8
Sup.lab.R;contact eye; largest 9; 4-5-6; 8 9; 5-6; 7 or 8 9; 5-6; 7 or 8 9(10); 5-6; 7 9; 5-6-7; 7, 8 or 9 9; 4-5; 7 9; 5-6; 8? 9; 5-6-7; 8
Sup.lab. edged or dusted grey L-yes; R-yes L-yes; R-yes L-yes; R-yes L-yes; R-yes L-yes; R-yes L-yes; R-yes yes L-yes; R-yes
Sup.lab. cream or pale brown L-yes; R-yes L-yes; R-yes L-yes; R-yes L-yes; R-yes L-yes; R-yes L-yes; R-yes yes L-yes; R-yes
Sup.lab. with white blotches L-no; R-no L-no; R-no L-no; R-no L-no; R-no L-no; R-no L-no; R-no not distinct L-no; R-no
temporals (AT,PT1,PT2) L-123; R-12x* L-123; R-123 R-122;L-113 L-122;R-122 L-122?;R-122 L-123;R-124 L-222*;R-113? L-123,R-123
Preoculars (left and right) 2 and 2 2 and 2 2 and 2 2 and 2 2 and 2 2 and 2 2 and 2 2 and 2
Postoculars (left and right) 2 and 2 2 and 2 2 and 2 1 and 1 (?) 2 and x? 2 and 2 1 and 2 2 and 2
Loreal .. x longer than high 1.3 and 1.7 1.3; pentag. 1.5 and 1.5 2 and 2 1.5 and 1.5 2 and 1.5 1.5 and x? x? and 1.5
Ant. edge frontal straight? yes yes yes yes yes yes damaged yes
Venter pinkish cream yes yes yes yes yes yes yes yes
Corners V pale orange-brown yes yes yes yes yes yes ?? yes
Spots corners V cloudy grey yes yes yes yes yes yes yes yes
Ground colour dorsum dark brown dark brown dark brown dark brown brown brown dark brown dark brown
Dorsolat.series pale blotches distinct disctinct distinct vague very vague distinct distinct no
r1,19 pale orange-brown edged, clouded
with grey
yes yes yes ant. vague yes yes yes no
SC-pairs clouded with grey yes yes, laterally mottled only distally densely densely densely yes
Postocular bicolored streak distinct distinct distinct very vague distinct distinct distinct? no
tailbase keeled? distinctly strongly strongly distinctly distinctly distinctly distinctly strongly
* = broken, much damaged
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The supralabials are nearly always edged or peppered with grey, but there is considerable variation in the degree
of this pigmentation between the specimens, e.g. sometimes the peppering extends to cover nearly half of the shield.
The postocular streak and its characteristic extension towards dorsal row 6 of the neck is distinct and conspicuous
in more than half of the specimens, but in other specimens (pale morphs) it was vague or could not be clearly dis-
tinguished.
Variation of the dorsal scale row reduction of 19 to 17 rows
The skins of seven specimens were quite complete and the dorsal scale row reductions of from 19 to 17 rows
could be determined accurately. In two specimens this reduction was on one or on both sides aberrant in the sense
that a reduction was reversed by a division to the original rows, and subsequently two or three scale lengths posteri-
orly there was again a fusion which resulted in the stable lower number of rows. These reductions and divisions are
summarized below.
QSMI 1686 (holotype) left side : V097-V098=3+4→3
right side : V096-V097=3+4→3
QSMI 1688 (paratype 2) left side : V093-V094=3+4→3
right side : V093-V094=3+4→3
QSMI 1689 (paratype 3) left side : V079-V080=4+5→4
right side : V082-V083=3+4→3
QSMI 1690 (paratype 4) left side : V070-V071=3+4→3
right side : V073-V074=3+4→3 V075-V076=3→3+4 V078-V079=3+4→3
QSMI 1691 (paratype 5) left side : V102-V103=3+4→3
right side : V102-V103=3+4→3
QSMI 1693 (paratype 7) left side : V094-V095=3+4→3 V095-V096=3→4+5 V096-V097=4+5→4
right side : V095-V096=4+5→4 V096-V097=4→4+5 V097-V098=4+5→4
QSMI 1698 (additional 7) left side : V089-V090=3+4→3
right side : V088-V089=3+4→3
Variation of the dorsal pattern of coloration
The dorsolateral row of pale ochre/orange blotches on the 6th DSR is by far the most conspicuous pattern in a
majority of specimens. This row extends from the neck to the tail without fusing into a stripe, but it is situated on
a vague continuous stripe darker than the blotches but lighter than the background color. Adjacent contrasting dark
blotches on the 4th and 8th dorsal scale rows, distinctly darker than the brown ground color, accentuate the pale
blotches on both sides. In some specimens, these dark blotches become more conspicuous, while at the same time
the pale blotches have faded to a considerable degree (see Fig. 5D of the skin of specimen QSMI 1690 from Omkoi).
In other specimens, the overall color is much paler, such as pale greenish bronze-brown, without any conspicuous
pale blotches on the paler dorsolateral stripe, which remains clearly visible, and with only numerous, rather incon-
spicuous darker spots present, as is illustrated in Fig. 6A for specimen QSMI 1693 from Umphang District. In a few
specimens, the dorsum is nearly uniformly pale greyish-brown without distinct spots and with only a remnant of the
pale dorsolateral stripe, as is illustrated in Fig. 6B for specimen QSMI 1695 from Phop Phra District. In both pale
morphs, however, traces of the full-developped coloration pattern of a series of blotches can be seen. In these pale
morphs the postocular streak is generally either vague or absent, whereas the underside of the tail is nearly white
(vs. dark grey in the more colorful specimens with pronounced blotches). However, in these pale morphs the cloudy
spots near the corners of the ventral plates are always distinct.
Coloration pattern of the venter
The color of the ventral plates is pinkish-white with the corners of these plates pale salmon. The pale salmon
color of the corners usually extends to the first dorsal row (adjacent to the ventral plates). At the border of the pale
salmon corner of the ventral plate and their pinkish-white central part is an inconspicuous greyish-brown spot that
is cloudy and usually amoeboid-shaped or a vague short streak (see Fig. 7A). This pattern is best shown anteriorly,
whereas posteriorly the pinkish-white background color of the spots may change to a very pale brownish-white and
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the spots often become darker, denser and more closely set in the corner of the ventral plate, but never intensely dark
(see Fig. 7B).
Salmon pigment accumulations. A peculiar characteristic of the coloration pattern of the species consists of the
salmon (pale orange) color covering the corners of the ventral plates and the first row of dorsal scales, sometimes
extending to the second row, in the ventrolateral area of the anterior part of the body. This pigmentation is strongly
concentrated along the edges of these plates and scales. We recorded these accumulations in a good number of the
DOR-specimens, but they are particularly conspicuous in specimen SHPC11.10.11-14 (see Fig. 8A and 8B).
These pigment accumulations also appear to be present in specimen QSMI 1694, a living individual from Tha
Song Yang District, Tak Province.
FIGURE 10: Habitat of Hebius terrakarenorum sp. nov. A. Habitat of the holotype, specimen QSMI 1686. Run offs of rain
water and tiny streams were hidden in the dense vegetation of partly degraded evergreen forest at 1,250–1,300 m. B: A little
stream amidst ‘ancient’ evergreen forest in Tak’s Umphang District, at an elevation of 1,230 m. The picture shows the site where
the stream enters a large concrete drain under the road to re-emerge on the other side. Over the past ten years, some eight road-
killed specimens of H. terrakarenorum were found within a distance of 100 m from this site. C. A fast flowing forest stream
amidst evergreen forest in Tak’s Tha Song Yang District, at an elevation of 600 m, habitat of specimen SHPC17.09.09-07.
Photos by Sjon Hauser.
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FIGURE 11. A. Hebius terrakarenorum sp. nov. A1–3: Specimen QSMI 1694 from Tha Song Yang District, Tak Province.
Photos by Ton Smits. B. Hebius igneus. B1–3: Specimen QSMI 1713 from Bo Kluea District, Nan Province. Photos by Ton
Smits. C. Hebius deschauenseei. C1–2. Specimen SHPC14.05.14-01, a subadult from Doi Suthep, Mueang District, Chiang Mai
Province. C3. Subadult DOR specimen SHPC11.06.28-05 Mae Taeng District, Chiang Mai Province. Photos by Sjon Hauser.
D. Hebius khasiensis. D1–2. Specimen SHPC11.10.15-05 from Umphang District, Tak Province. D3. Ventral view of specimen
SHPC20.06.24-09 from Omkoi District, Chiang Mai Province. Photos by Sjon Hauser. E. Hebius cf. khasiensis. E1–3 Specimen
QSMI 1727 from Bo Kluea District, Nan Province. Photos by Ton Smits. F. Hebius bitaeniatus. F1–F3: Specimen QSMI XX-
14.09.29-06 from Mae Wang District, Chiang Mai Province. Photos by Sjon Hauser.
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FIGURE 12. Paratype 1 of Hebius terrakarenorum sp. nov., specimen QSMI 1687 from Umphang District, Tak Province. A.
Dorsal view. B. Ventral view. C. Upper side of head and neck. D. Lateral view of head and neck. E. Ventral side of head and
neck. Photos by Sjon Hauser.
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FIGURE 13. Paratype 2 of Hebius terrakarenorum sp. nov., specimen QSMI 1688 from Umphang District, Tak Province. A.
Dorsal view B. Ventral view, showing two everted hemipenes. C. Upper side of head. D. Dorsolateral view of right side of head.
E. Dried skin of body from neck until cloacal plate. F. Details of skin showing dorsal scale row reductions behind midbody from
19 to 17. On the left side the 4th row fuses into the 3th row at level V93 to V94. On the right side this reduction also occurs at
level V93 to V94. Photos by Sjon Hauser.
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FIGURE 14. Paratype 3 of Hebius terrakarenorum sp. nov., specimen QSMI 1689 from Phop Phra District, Tak Province. A.
Dorsal view B. Ventral view, showing one everted, damaged hemipenis. C. Upper side of head and neck. D. Ventral side of head
and neck. E. Lateral view of left side of head and neck. F. Dried skin of body from neck until cloacal plate (2 pieces). G. Details
of skin showing dorsal scale row reductions behind midbody from 19 to 17. On the left side the 5th row fuses into the 4th row at
level V78 to V79. On the right side the fourth row fuses into the 3rd row at level V82 to V83. Photos by Sjon Hauser.
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FIGURE 15. Paratype 4 of Hebius terrakarenorum sp. nov., specimen QSMI 1690 from Omkoi District, Chiang Mai Province.
A. Dorsal view. B. Ventral view, showing one partly everted hemipenis. C. Upper side of head and neck. D. Ventral side of head
and neck. E. Dried skin of body from neck until cloacal plate. F. Details of skin showing dorsal scale row reductions just before
midbody from 19 to 17. On the left side the 4th row fuses into the 3th row at level V70 to V71. On the right side this reduction
occurs at level V73 to V74 and following an inversion this reduction occurs again at level V78 to V79. Photos by Sjon Hauser.
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FIGURE 16. Paratype 5 of Hebius terrakarenorum sp. nov., specimen QSMI 1691 from Omkoi District, Chiang Mai Province.
A. Dorsal view. B. Ventral view, distinctly showing the divided cloacal plate. C. Upper side of head and neck. D. Lateral view
of right side of head and neck. E. Ventral side of head and neck. F. Dried skin of body from neck until cloacal plate. G. Details
of skin showing dorsal scale row reductions behind midbody from 19 to 17. On the left side the 4th row fuses into the 3th row at
level V102 to V103. On the right side this reduction also occurs at level V102 to V103. Photos by Sjon Hauser.
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FIGURE 17. Paratype 6 of Hebius terrakarenorum sp. nov., specimen QSMI 1692 from Phop Phra District, Tak Province. A.
Dorsal view. B. Ventral view, showing two partly everted hemipenes. C. Ventral view of the tail. D. Dorsolateral view of head
and neck. E. Ventral side of head and neck. Photos by Sjon Hauser.
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FIGURE 18. Paratype 7 of Hebius terrakarenorum sp. nov., specimen QSMI 1693 from Umphang District, Tak Province. A.
Dorsal view. B. Ventral view, showing one completely everted hemipenis. C. Upper side of head and neck. D. Ventral side of
head and neck. E. Dried skin of body from neck until cloacal plate. F. Details of skin showing dorsal scale row reductions behind
midbody from 19 to 17. On the left side the eduction is complicated at level V94 to V96. On the right side the reduction is also
complex and occurs at level V94 to V98. Photos by Sjon Hauser.
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Hemipenes. We everted specimens of specimens QSMI 1686 and QSMI 1693. They show that the hemipenis of
this species is short, single, not forked and bulbous; the proximal part is short (or less prone to be everted follow-
ing pressure on the base of the tail) with some large basal spines; the distal part is slightly pear-shaped and densely
covered with many short, curved spines, their tip pointing downwards in the direction of the vent; among these tiny
spines may be seen a number of much larger spines similarly curved and directed downwards; spines at the tip of the
organ are larger. The sulcus is divided near the base but this forking is just short and cannot be distinguished more
proximally where it seems to “disappear” amidst the spines (Fig. 9). Lips of the sulcus are not prominent.
Etymology. The species nomen terrakarenorum is a modern Latin noun meaning “Land of the Karen”. It refers
to the Karen People, the major inhabitants of the mountains throughout the hitherto known range of the new species.
This species nomen is a noun at the plural genitive case, not an adjective.
We suggest the colloquial names: Karenland Keelback (English), Hébius du Pays Karen (French), Karenland
Wassernatter (German) and Ngu Lai Sap Thin Kariang (Thai). It is likely that the species also occurs in ‘Karen
country’, namely in the mountainous part of eastern Myanmar adjacent to the Thai-Myanmar border, which remains
a herpetologically extremely under-explored region.
Distribution and habitat. This species is definitely known from the provinces of Chiang Mai, Mae Hong Son,
Tak and Kanchanaburi (see Fig. 1). Mae Sariang District, Mae Hong Son Province, is the northernmost locality
where we have recorded a specimen. Nevertheless, it is possible that the range extends further northward in Mae La
Noi, Khun Yuan and even Mueang districts of Mae Hong Son Province, which still are herpetologically poorly sur-
veyed areas. The type locality of the species is at the edge of the mountains just north to Umphang valley. It is most
likely that the species occurs in mountain streams south of that valley. The most southern localities are 120 to 150
km to south in Kanchanaburi Province, in central Thailand, beyond the northern Thai region. A picture of a juvenile
Hebius taken by Jarujin Nabhitabhata and identified as H. deschauenseei in Cox (1991) is probably a misidentifica-
tion and instead is a juvenile H. terrakarenorum sp. nov. This specimen might have originated from Uthai Thani
Province (south of Umphang) as Uthai Thani was mentioned both in Cox (1991), Cox et al. (2012) and Chan-ard
et al. 2015 (see also David et al. 2021) as part of the range of H. deschauenseei, without reference to a preserved
specimen or voucher photographs. To us Uthai Thani Province seems unlikely as home of H. deschauenseei as we
have never come across it to the south of Doi Inthanon National Park, in spite of quite extensive field surveys in
Chiang Mai’s Omkoi District and in much of Tak Province.
Biology. Nearly all specimens were found next to fast-flowing mountain streams. For examples of three dif-
ferent habitats, see Fig. 10. A majority of the road-killed specimens were male and many of them were collected in
October, which suggests that the main mating season might be at the end of the rainy season in October. This might
indicate that beyond the mating season these snakes rarely venture beyond the direct surroundings of the streams.
A living specimen captured and handled by the second author was docile and did not strike or bite, which is in line
with the behavior of other Hebius species known from Thailand and elsewhere.
Comparisons of Hebius terrakarenorum spec. nov. with other species.
In many characters, Hebius terrakarenorum sp. nov. is similar to H. igneus David, Vogel, Nguyen, Orlov, Pau-
wels, Teynié & Ziegler, 2021. It can be distinguished from the latter by (1) the immaculate pinkish-cream venter ex-
cept for the grey-edged corners of the ventral plates and a modest, cloudy grey dot in or near that corner (vs. three or
four parallel rows, often fused, of very distinct blackish blotches largely darkening the ventral surface in H. igneus),
(2) the distinctly but moderately keeled scales at the tail base (vs. strongly keeled in H. igneus), (3) the row of pale
ochre dorsal blotches that remain separate posteriorly (vs. usually fused into a lateral stripe posteriorly of midbody
in H. igneus), and (4) the reduction of 19 → 17 DSR in H. terrakarenorum follows a different pattern to that of
H. igneus. In H. terrakarenorum the reduction of DSR 3+4 → 3 is on both sides within a space of no more than 5
ventral plates, so there is only a short section of less than 3 ventral plates of the total body length that is spanned by
18 dorsal rows, but in H. igneus the reduction implies DSR 4+5 → 4 at V85–98 on the left and at V100–103 on the
right, so the part of the body spanned by 18 dorsal scale rows can be as long as 15 successive ventral plates, see Da-
vid et al. (2021). The number of ventrals of the new species (159–171, n=19) is not significantly different from the
Chinese and Vietnamese populations of H. igneus (159–165, n=9, David et al. 2021), but lower than in the Hebius
igneus population of eastern North Thailand (168–178, n=5, see results).
H. terrakarenorum sp. nov. resembles H. deschauenseei (Taylor) but can be distinguished from the latter by
(1) the pattern of two rows of modest, cloudy dots on the otherwise immaculate cream belly (vs. three parallel rows
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of very distinct dark blotches partly blackening the venter in H. deschauenseei), (2) the higher number of 159–171
ventral plates (vs. 148–163 in H. deschauenseei) and (3) the usual 2 rows of ochre- or orange-brown dorsal spots
extending towards the tail (vs. only spotted anteriorly).
H. terrakarenorum sp. nov. superficially resembles Hebius clerki (Wall) from Northern India and North Myan-
mar, as the dorsum of both species is usually adorned with two rows of distinct pale brown blotches and both have
a postocular streak that extends to the neck in a characteristic way. However, there are many differences that easily
distinguish these species apart, as follows: (1) Hebius terrakarenorum sp. nov. has a longer tail with a relative tail
length R of 0.32–0.36 (vs. 0.26–0.33 in H. clerki), (2) a higher number of subcaudal pairs of 107–130 (vs. 63–77 in
H. clerki), (3) a usual number of 9 supralabials (vs. mostly 8 in H. clerki), (4) the presence of 1 anterior temporal
(vs. 1 or 2 in H. clerki), and (5) the cloudy amoeboid spots in/near the corner of the ventral plates (vs. dark streak-
like spots in H. clerki).
H. terrakarenorum sp. nov. can be distinguished from its sympatric congener Hebius khasiensis (Boulenger)
by (1) its pale brown/cream supralabials (vs. supralabials with large ovoid or triangle-shaped, ivory blotches in
H. khasiensis), (2) the greyish-brown cloudy, amoeboid spots in/near the corners of the ventral plates (vs. dark
brown, rectangular and closely set in the corners in H. khasiensis), (3) the much higher number of ventral plates of
159–171 (vs. 139–149, in western Thailand) and (4) upper dorsal scales moderately keeled (vs. strongly keeled in
H. khasiensis).
H. terrakarenorum sp. nov. can be distinguished from Hebius bitaeniatus (Wall) by (1) most usually spotted
dorsal pattern (vs. two distinct unbroken ochre-brown lateral stripes edged with black in H. bitaeniatus), (2) its
modest keeling (vs. nearly all rows strongly keeled in H. bitaeniatus), (3) the cloudy, amoeboid ventral spots adja-
cent to the corners of the ventral plates (vs. dark brown short stripes in H. bitaeniatus) and (4) its higher number of
subcaudal pairs (107–130 vs. 80–100 in H. bitaeniatus).
H. terrakarenorum sp. nov. can be distinguished from Hebius groundwateri (Smith) by (1) its higher number of
159–171 ventral plates (vs. 147–154 in H. groundwateri), (2) its divided cloacal plate (vs. entire in H. groundwateri)
and (3) the number of 19 rows of dorsal scales at midbody (vs. 17 in H. groundwateri).
Among other species, H. terrakarenorum sp. nov. can be distinguished from Hebius boulengeri (Gressitt), He-
bius leucomystax (David, Bain, Nguyen, Orlov, Vogel, Vu & Ziegler), and Hebius inas (Laidlaw) by its pale brown
supralabials (vs. supralabials with ivory white blotches in H. boulengeri and H. inas, and entirely white in H. leuco-
mystax) and moderately strong dorsal keels (vs. strong dorsal keels in H. boulengeri, H. leucomystax and H. inas).
The pinkish-white belly and the 19 rows of dorsal scales at midbody distinguish H. terrakarenorum sp. nov.
from Hebius venningi (Wall), Hebius nigriventer (Wall), Hebius taronensis (Smith), Hebius chapaensis (Bourret)
and Hebius annamensis (Bourret) that have 17 or 15 dorsal rows at midbody) and a dark venter, except H. annamen-
sis in which the venter is largely pale. These species have recently been revised by David et al. (2021).
H. terrakarenorum sp. nov. can be distinguished from Hebius modestus (Günther) by its higher number of
159–171 ventral scales (vs. 143–163 in H. modestus), a distinct postocular streak (vs. absent in H. modestus) and the
light-colored pinkish-white belly (vs. a mostly pale brown, edged with dark grey venter in H. modestus).
H. terrakarenorum sp. nov. can be distinguished by its 19 rows of dorsal scales at midbody from H. atemporalis
(Bourret), H. sauteri (Boulenger), H. arquus (David and Vogel), H. frenatus (Dunn), H. sarawacensis (Günther), all
with 17 rows at midbody.
H. terrakarenorum sp. nov. can be distinguished from Hebius metusia (Inger, Zhao, Shaffer & Wu) by the ab-
sence of sharp, well-defined dorsolateral stripes (vs. present in H. metusia)
H. terrakarenorum sp. nov. can be distinguished from Hebius andreae (Ziegler and Le) from Vietnam by its
lower number (159–171) of ventral plates (vs. 179–180 in H. andreae) and higher number (107–130) of subcaudal
pairs (vs. 99–103 in H. andreae). Moreover, the new species has 2 pre- and 2 postoculars (vs. 1 and 3 respectively
in H. andreae), and it lacks a conspicuous dorsal pattern of pale, black-edged crossbars on the anterior body (vs.
present in H. andreae).
H. terrakarenorum sp. nov. can be distinguished from Hebius octolineatus (Boulenger), H. septemlineatus
(Schmidt) and Hebius parallelus (Boulenger) by the absence of distinct dorsolateral stripes (vs. present in H. octo-
lineatus and H. parallelus).
H. terrakarenorum sp. nov. is differentiated from Hebius flavifrons (Boulenger) and Hebius nicobariensis
(Sclater) by its divided cloacal plate (vs. entire in H. flavifrons and H. nicobariensis).
H. terrakarenorum sp. nov. differs from Hebius sangzhiensis Zhou, Qi, Lu, Lyu & Li in Zhou, Sun, Qi, Lu,
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Lyu, Wang, Li & Ma by its larger number (107–130) of subcaudal pairs (vs. 81–82 in H. sangzhiensis), higher
(0.32–0.36) relative tail length (vs. 0.24–0.27 in H. sangzhiensis) and the number of 9 supralabials (vs. 8 or 7 in H.
sangzhiensis).
H. terrakarenorum sp. nov. can be separated from Hebius beddomei (Günther), H. kerinciensis (David & Das),
Hebius petersii (Boulenger) and Hebius viperinus (Schenkel) by having more ventral scales, 159–171, vs. 140–150
in H. beddomei, 140 in H. kerinciensis, 134–150 in H. petersii, and 101 in H. viperinus.
H. terrakarenorum sp. nov. can be distinguished from Hebius concelarus (Malnate), Hebius ishigakiensis (Mal-
nate & Munsterman) and Hebius optatus (Hu and Zhao) by the absence of dorsal crossbars (vs. distinct crossbars in
H. concelarus, H. ishigakiensis and H. optatus).
H. terrakarenorum sp. nov. is different from Hebius celebicus (Peters & Doria) and H. sarasinorum (Bouleng-
er) by its number of DSRs of 19-19(17)-17 (vs. 15-15-15 in both H. celebicus and H. sarasinorum), higher number
(159–171) of ventral plates (vs. 125–150 in H. celebicus and 137–146 in H. sarasinorum) and much higher number
(107–130) of subcaudal pairs (vs. 45–75 in H. celebicus and 64–75 in H. sarasinorum).
H. terrakarenorum sp. nov. can be distinguished from Hebius craspedogaster (Boulenger) by its dorsolateral
series of pale brown blotches (vs. a series of small, black-edged, white spots in H. craspedogaster) and cloudy, dis-
tinctly spaced ventral spots (vs. ventral spots that are almost in contact with each other in H. craspedogaster).
H. terrakarenorum sp. nov. is different from Hebius johannis (Boulenger) by its usual pattern of two rows of
dorsolateral blotches and the moderate but distinct keels of the dorsal scales (vs. a variegated or reticulated dorsal
pattern and smooth or weakly keeled scales in H. johannis).
H. terrakarenorum sp. nov. is different from Hebius lacrima Purkayastha & David by the absence of distinct
white blotches on the supralabials (vs. present in H. lacrima).
H. terrakarenorum sp. nov. is different from Hebius miyajimae (Maki) by a series of distinct pale blotches (vs.
well-defined dorsolateral stripes in H. miyajimae).
H. terrakarenorum sp. nov. is different from Hebius popei (Schmidt) by the absence of distinct dorsolateral
stripes and the relatively high number of 159–171 ventral plates (vs. presence of dorsolateral stripes and 130–142
ventral plates).
H. terrakarenorum sp. nov. can be distinguished from Hebius pryeri (Boulenger) by its brown dorsal ground
color with a dorsolateral series of pale blotches (vs. blackish with pale crossbars in H. pryeri).
H. terrakarenorum sp. nov. is different from Hebius sanguineus (Smedley) from West Malaysia by its dorsal
color pattern of brown with dorsolateral rows of pale blotches (vs. brick red flanks and brown reticulated upper part
of the dorsum in H. sanguineus ) and higher number (159–171) of ventral plates (vs. 140–155 in H. sanguineus)
H. terrakarenorum sp. nov. is different from H. vibakari (H. Boie) by its pale brown supralabials (vs. large
white roundish blotches in H. vibakari) and the dorsum with series of blotches (vs. nearly unpatterned in H. viba-
kari)
H. terrakarenorum sp. nov. is distinguished from Hebius yanbianensis Liu, Zhong, Wang, Liu & Guo by the
presence of 2 postoculars (vs. 3 in H. yanbianensis), its long tail with a TaL/TOTL ratio of 0.32–0.36 (vs. 0.26 in
H. yanbianensis), its high number of 107–130 subcaudals pairs (vs. 90 in H. yanbianensis) and its rows of cloudy
ventral spots (vs. intense dark, closely set blotches in H. yanbianensis).
Three species placed until recently in the genus Hebius have now be referred to two other genera (see Das et
al. 2020; Lalronunga et al. 2020; Deepak et al. 2021). H. terrakarenorum sp. nov. differs from Herpetoreas pealii
(Sclater) by having more (159–171) ventral scales (vs. 142–144 in Herpetoreas pealii. Hebius terrakarenorum sp.
nov. differs from Herpetoreas xenura (Wall) by its paired subcaudals (vs. single subcaudals in Herpetoreas xenura).
Finally, Hebius terrakarenorum sp. nov. differs from Amphiesma monticola (Jerdon) by its number of ventral
plates, 159–171 vs. 136–144 in A. monticola, and a much distinct dorsal pattern.
Morphological data used in the comparisons above have been taken from Boulenger (1890; 1893), Das et al.
(2020), David et al. (2005; 2007; 2013; 2015a-b, 2021), Deepak et al. (2021), De Lang & Vogel (2005), Kaitio &
Mamoru (2016), Lalronunga et al. (2020), Liu et al. (2018), Purkayastha & David (2019), Smith (1943), Zhou et
al. (2019), and Ziegler et al. (2019).
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Discussion
Summarized variation of Hebius terrakarenorum. Hebius terrakarenorum sp. nov. is a slender, brown semi-
aquatic snake reaching a total length of 650 mm and a relative tail length of 32–36%. It is further characterized by
DSR 19-19-17, 159–171 ventral plates (and 1–2 preventral plates), and 107–130 subcaudal scales, all paired, and
nearly always two pre- and two postoculars. The nine supralabials are cream or pale brown and around the sutures
dusted with greyish brown pigment or edged with brown and lack white blotches. In most specimens, a distinct,
broad bicolor postocular streak traverses the anterior temporal and the large, posterior supralabials; from the corner
of the upper jaw a highly characteristic pattern connects it with the first pale blotch on the neck. A dorsolateral series
of distinct pale ochre-brown blotches on row 6; a series of dark brown blotches below the pale ones on dorsal scale
row 4 and a series of dark brown blotches above the pale ones on dorsal scale row 8 adorn the body from the neck
to the tail, but this typical pattern may be vague or absent in the pale color morphs that occur frequently.
The venter is white or cream with a pinkish hue, but the corners of the ventral plates are pale ochre brown.
Throughout the length, there is a row of sometimes vague but always distinct amoeboid greyish cloudy or mottled
spots close to the corner of the ventral plates, more distinct posteriorly than anteriorly, but never intensely black or
dark brown or closely set. The underside of the tail is usually grey, but this coloration may be poorly expressed or
absent in the pale morphs.
Coloration. The variable coloration pattern is perhaps the most remarkable aspect of the new species. Pale
morphs are common (in six out of 21 specimens), the two rows of pale ochre-brown dorsal blotches and the char-
acteristic bicolored postocular streak being expressed poorly in them. Similar polymorphism is unusual in snake
species of the region. In northern Thailand, the ground color of the pseudaspidid Psammodynastes pulverulentus
(H. Boie in F. Boie, 1827) ranges from dark brown to pale ochre-brown, but usually there is little or no correlation
between the shade of the ground color and the degree the pattern of little dark brown widely spaced little triangle-
shaped spots is expressed. In the natricid Trimerodytes yunnanensis (Rao and Yang, 1998), the ground color varies
from bright pinkish-red and pale brick red to greyish-brown and dark brown. This snake is rare in northern Thailand,
but our data of six specimens suggest that juveniles are reddish and become dark brown when maturing (Hauser,
unpublished data). Graded polymorphism of the dorsal ground color and the suppression of the patterning is known
in the colubrid Boiga siamensis Nootpand 1971. In central northern Thailand, about 5–10 per cent of the specimens
show a pale pinkish-brown (normally: greyish-brown) ground color, while the patterning is reddish-brown (nor-
mally: dark brown), but in some of the most pale morphs the patterning is hard to distinguish from the ground color
(Hauser & Smits, in preparation). This pale morphism seems to be somewhat localized and may partly depend on
ontogenetic and environmental factors. A similar relationship may also hold true for the pale morphs of H. terra-
karenorum sp. nov. The occurrence of golden-salmon pigment accumulations along the edges of the scales near the
ventrolateral area of the anterior part of the body is seen in less than 40% of the specimens of H. terrakarenorum
sp. nov., but there seems to be no correlation with a distinctly spotted pattern, pale color morphism or the sex of the
specimen. We guess that this coloration is functionally similar to the bright yellow or orange necks and chins often
seen in other Southeast Asian snake species, such as the natricids Amphiesma stolatum (Linnaeus, 1758) and Fowlea
flavipunctatus (Hallowell, 1860) and the colubrids Dendrelaphis subocularis (Boulenger, 1888) and Sibynophis col-
laris (Gray, 1853). These ‘bright-necked’ morphs are quite common but there appears to be no relationship with sex,
age or season of the year.
Finally, it appears that juveniles of H. terrakarenorum sp. nov. differ slightly from the adults by their bright
pale ochre and dark brown reticulated pattern on the flanks of the neck. Whether or not pale morphism occurs in
juveniles is not yet known.
Distribution. Hitherto, the new species is only known from a relatively small strip of the northern part of the
Tenasserim Range that stretches along the Myanmar border from Mae Sariang and Omkoi in the north, through Tha
Song Yang district to Phop Phra and Umphang districts in southern Tak Province, with a southern extension to Kan-
chanaburi Province. The new species has not been recorded from Tak’s Mae Ramat and Mae Sot districts, but it is
expected that it also occurs in these districts and will be eventually discovered within this ‘gap’. Hitherto, two other
snake species seem to be confined to this part of the Tenasserim Range, Protobothrops kelomohy Sumontha, Vasa-
ruchapong, Chomngam, Suntrarachun, Pawangkhanant, Sompan, Smits, Kunya & Chanhome, 2020, known within
a small area in Tha Song Yang and Omkoi districts, and Dendrelaphis nigroserratus Vogel, Van Rooijen & Hauser,
2012, occurring in a much larger area stretching from Phop Phra, Umphang and Kanchanaburi provinces to the
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south in Phetchaburi Province. Recently it was shown that the range of the latter species extends as far to the south
as Surat Thani Province in the Thai peninsula, but throughout this southern extension, it seems restricted to moun-
tains or foothills of the Tenasserim Range (Hauser et al. 2021). These mountains are the natural border between
Thailand and Myanmar over more than 2,000 kilometres and are watershed area of the Salwene River in Myanmar
to the west, and the Chao Phraya, Mae Klong and a number of relatively short rivers that flow into the Gulf of Siam
to the east. It appears that the range is a major geographic barrier between the lowlands in Myanmar and Thailand.
On the other hand, the Isthmus of Kra, somewhat in the middle of its full range from northern Thailand to Singapore,
is known to have been one of the major biogeographic bottlenecks, barriers and filters of the region throughout the
past two million years and possibly longer (Pauwels et al. 2003; Voris, 2006). The range is home to another natricid
species, possibly endemic, Hebius groundwateri (Smith), only known from its type locality just south of the Kra
Isthmus in Chumphon Province, with no specimens recorded since its discovery a century ago. Throughout the
mountains of the Tenasserim Range, karst outcrops abound, and karst habitats might be favored by the new species
H. terrakarenorum. Unfortunately, the herpetofauna of the Tenasserim Range within Myanmar remains, as is also
true for many other parts of that country, one of the least studied and poorly known in Asia (Leviton et al. 2008; Platt
et al. 2018).
Northern Thailand’s snake fauna in perspective. Until recently, much of northern Thailand’s ophiofauna had
been seriously understudied, an important issue that was emphasized in only a few studies (Pauwels et al. 2001;
Pauwels et al. 2003; Chuaynkern et al. 2015; Hauser 2019; Hauser et al. 2021). Most fieldwork had been done near
Chiang Mai (City), while much of the region remained terra incognita. For the entire Nan Province, only eight
snake species were listed by Cox et al. (2012), while in Chuaynkern and Chuaynkern (2012), Nan was listed only
twice as home of a snake species! In striking contrast to this poverty at the local level is the list of 86 snake species
recorded in Tam Dao, a much smaller area in northern Vietnam (Orlov et al. 2000). Also the richness of data from
Indochina gathered in Bain and Hurley (2011) contrasts with the poverty in contemporary Thai sources.
Pauwels et al. (2001) predicted that western Thailand, in particular, might reveal a large number of new taxa
in the years to come. Subsequently, intensified surveying of the region resulted in the addition of a several snake
species new for Thailand that originated from the north. The new colubrid Dendrelaphis nigroserratus, the viperid
Protobothrops kelomohy, and the natricid Hebius terrakarenorum sp. nov. (this paper), have first been reported
from northwestern Thailand. The first country record of the pareid Pareas hamptoni (Boulenger) came from Tak
Province (Vogel 2010). From the central northern part of the region (Chiang Mai and Chiang Rai provinces), Pla-
giopholis blakewayi Boulenger (Tillack et al. 2006), and the natricids Hebius khasiensis (Boulenger) (Pauwels et
al. 2009a) and Trimerodytes yunnanensis (Rao & Yang) (Pauwels et al. 2009b; as Sinonatrix yunnanensis) were
reported as new country records or additions to the regional herpetofauna. Surprisingly, a rising interest in the snake
diversity of the eastern provinces resulted in even more ‘new records’. We may mention the natricids Trimerodytes
praemaxillaris (Angel), formerly Paratapinophis praemaxillaris (see Deepak et al. 2021), rediscovered by Murphy
et al. (2008), Opisthotropis spenceri Smith (rediscovered following a hiatus of nearly a century by Chuaynkern et al.
2015) and Hebius igneus (David et al. 2021), the colubrids Ptyas nigromarginata (Blyth) (first country record, Vogel
& Hauser 2013) and Liopeltis frenatus (Günther) (first country record, Hauser 2018), the xenodermid Parafimbrios
lao Teynié, David, Lottier, Le, Vidal & Nguyen (first record, Teynié & Hauser 2017), the viperid Protobothrops mu-
crosquamatus (Cantor) (first record, Vasaruchapong et al. 2017), and the elapid Bungarus slowinskii Kuch, Kizirian,
Nguyen, Lawson, Donnelly & Mebs (first country record, Smits & Hauser 2019), all originating from Nan Province,
and the colubrid Cyclophiops multicinctus Roux (first country record, Hauser 2018) from Uttaradit Province. The
new country records of the colubrid Liopeltis stoliczkae (Sclater) originated from both western and eastern NT
(Hauser 2019), while the first country record of the colubrid Dendrelaphis walli Vogel & Van Rooijen, 2011 from
both NT, central and northeastern Thailand is in preparation (Smits et al. unpublished data). Moreover, a number of
subspecies of the Oligodon cinereus-complex are expected to be upgraded to species level in the near future (David
and others, in preparation), among them a specimen much similar to Oligodon (cinereus) pallidocinctus, which has
been recorded from NT (Hauser, unpublished data). Hitherto, most of these new additions to the snake fauna of NT
are (still) unknown from other regions of the country.
Recent reports on new snake species from southern China have an impact on the diversity of northern Thai-
land’s ophiofauna. All populations of Pareidae of the region formerly identified as Pareas carinatus (Boie) will be
assigned to a different species so this “new addition” is, in fact, no more than a change of name. Similarly, all or
most of the northern Thai specimens earlier identified as Dendrelaphis cyanochloris (Wall) will likely be re-allo-
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30 · Zootaxa 5116 (1) © 2022 Magnolia Press
cated to the new species Dendrelaphis vogeli Jiang, Guo, Ren & Li, and many of the crotalid specimens identified
as Trimeresurus albolabris (Gray) to the new species Trimeresurus guoi Chen, Shi, Vogel & Ding in Chen, Shi, Gao,
Vogel, Song, Ding & Dai. In a similar vein, all northern Thai specimens of the colubrid species previously identified
as Gonyosoma prasinum (Blyth) should now be assigned to Gonyosoma coeruleum Liu, Hou, Ye Htet Lwin, Wang
& Rao (see Liu et al. 2021).
Many of these latest studies were in the wake of the rise of gene sequencing research and the breakthrough
of De Queiroz’ unified species concept (De Queiroz 2005, 2007), which propelled many researchers’ ambition to
identify and describe new taxa. However, several of these studies coupled DNA sequencing with poor morphologi-
cal research, e.g. by relying for the morphology on outdated sources (or even popular works), or taking the identi-
fication of specimens of which gene sequences were deposited at gene banks for granted. In a recent, mega study
on dark-bellied Hebius species (David et al. 2021) it was concluded that ‘many phylogenetic trees and data bases
are plagued with misidentifications,’ and it was emphasized that systematic links between sequences and voucher
specimens available for morphological examination will be crucial in future research. In the recent description of
the new pareid species Pareas geminatus Ding, Chen, Suwannapoom, Nguyen, Poyarkov & Vogel from Indochina,
southern China and northern Thailand, such crucial links are completely absent.
Conclusion
Before the present work, 48 species were recognized in the genus Hebius in the Reptile Database (Uetz et al. 2021;
accessed on 2 December 2021), which took into account the placements of Hebius pealii (Sclater) and Hebius
xenura (Wall) in the genus Herpetoreas (see Das et al. 2020 and Lalronunga et al. 2020). With the description of
Hebius terrakarenorum sp. nov. from Thailand and the assignement of Hebius monticola (Jerdon) to the genus Am-
phiesma by Deepak et al. (2021), the total number of valid species in the genus Hebius is remains of 48, whereas
the number of Hebius species known from Thailand has increased to nine.
The nine species currently known from Thailand can be separated by the following key:
1A. 17 dorsal scale rows at midbody .........................................................Hebius groundwateri
1B. 19 dorsal scale rows at midbody .........................................................................2
2A. Dorsal scales strongly keeled and notched posteriorly; dorsal pattern made of a pale dorsolateral stripe, edged above and below
by a dark stripe; broad, black postocular streak extending from the corner of the mouth onto the neck . . . . .Hebius bitaeniatus
2B. Dorsal scales not strongly keeled or notched posteriorly; dorsal pattern not made of longitudinal stripes; no black postocular
streak ...............................................................................................3
3A. A broad, white stripe from the tip of the snout to the corner of the mouth, extending on the nape and forming a conspicuous
chevron ............................................................................. Hebius leucomystax
3B. Supralabials not covered with a white stripe, more or less patterned or overall dark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4A. Venter largely black; on each side, a dorsolateral series of large, elongate blotches, yellow-ochre, or yellowish-brown, orange
or rusty red, enlarged on the first quarter to third of the body, progressively smaller and united, forming a dorsolateral stripe .
...................................................................................................5
4B. Venter largely pale, with only tips of ventral plates ornate with pink, grey or black; pattern not made of large, elongate blotches,
yellow-ochre, or yellowish-brown, orange or rusty red . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5A. Venter with three parallel rows of dark blotches separated by narrow pale lines; usually less than 163 ventral plates; base of tail
with weakly keeled scales .............................................................Hebius deschauenseei
5B. Venter either uniformly very dark brown or black or with 4 or 5 rows of nearly continuous dark blotches separated by narrow
pale stripes or lines; usually more than 163 ventral plates; base of tail with strongly keeled scales . . . . . . . . . . . Hebius igneus
6A. Supralabials cream to pale brown broadly edged and dusted with dark grey, without white blotches or streaks; dorsolateral pat-
tern made of a series of about 80 distinct pale ochre-brown to orange-brown rounded blotches with less distinct series of dark
blotches below them and above them; 159–171 ventrals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Hebius terrakarenorum sp. nov.
6B. Supralabials with distinct white or cream blotches or streaks; dorsolateral pattern not as above; most usually less than 160
ventral plates .........................................................................................7
7A. Each posterior supralabial with a round or oval, central cream blotch, not forming a stripe; 1st dorsal scale keeled, throughout
or at least on the posterior part of the body .................................................................8
7B. Posterior supralabials dark brown or black, each with a median, horizontal and longate, thin cream blotch or streak, usually
united as a narrow stripe, extending on the neck as a continuous stripe; scales of 1st DSR entirely smooth . . . . . . . . . . . . . . . . .
.....................................................................................Hebius boulengeri
8A. Dorsal pattern made of a series of reddish-brown or rusty (cream in preservative) dots or small blotches usually aligned on a
faint dorsolateral stripe; usually isolated pale blotches on the side of the neck, sometimes partly connected by a narrow pale
line, not reaching the dorsolateral stripe (if present) or dorsolateral spots; frontal 2.0–2.5 times longer than prefrontals . . . . . .
.....................................................................................Hebius khasiensis
DISTRIBUTION OF THE HEBIUS SPECIES IN NORTHERN THAILAND Zootaxa 5116 (1) © 2022 Magnolia Press · 31
8B. Dorsal pattern made of a series of relatively large yellow or ochre (cream or yellow in preservative) dorsolateral spots on a more
or less visible dorsolateral stripe, the first two to four of them enlarged and connected by a yellow or grey stripe; usually on
the side of the neck a conspicuous, pale stripe or series of large pale, connected spots, reaching the dorsolateral stripe; frontal
1.7–1.9 times longer than prefrontals ............................................................. Hebius inas
The explosive increase over the past ten years of our understanding of the diversity and complexity of northern
Thailand’s ophiofauna suffers to some extend from the shortcomings outlined above. Moreover, for the field worker
it has become more difficult or impossible to identify new species, as keys often include anatomical characters such
as number of maxillary teeth or the hemipenial structure, which are hard to verify in the field. The recent identifica-
tion of four species of the Bungarus candidus complex resulted largely from gene sequencing and dental or hemi-
penial morphology (Chen et al. 2021b), characters of little use in the field. Interestingly, an earlier gene sequencing
study concluded that, in China, the Bungarus candidus (Linnaeus) and Bungarus multicinctus multicinctus Blyth,
could not be distinguished by the number of their black-and-white crossbars (traditionally the major key), whereas
B. candidus was shown to occur in southern China and that the (sub)species Bungarus multicinctus wanghaotingi
Pope was considered invalid (Xie et al. 2018). In a Chinese study just three years later (Chen et al. 2021b) DNA
gene sequencing was combined with the analysis of more morphological characters, including dentition and hemi-
penial structure. This resulted in the resurrection of B. wanghaotingi as a full species, while the Chinese snakes
identified as B. candidus by Xie et al. (2018) were identified as the resurrected B. wanghaotingi; moreover, a new
species, Bungarus suzhenae, was added to the complex.
It is amidst these turbulent waters of present day snake taxonomy in the Oriental Region that our modest study,
a revaluation of just five or six related species within the relatively small northern Thai region and restricted to
morphology, should be appreciated.
Acknowledgements
We are grateful to Lawan Chanhome, head of the Snake Farm, Queen Saovabha Memorial Institute, Bangkok,
for receiving our materials and voucher photographs of our Hebius specimens in the QSMI collections. Thanks to
Jonathan Hakim, USA, for sharing with us photos taken of Hebius khasiensis on Doi Suthep. A big thanks to Ian
Dugdale in Kaeng Krachan, Phetchaburi, for his permission to publish one of the photographs he took of two He-
bius specimens observed in Kanchanaburi. We thank Parinya Pawangkhanant in Bangkok for sharing his immense
knowledge on the herpetofauna of Tak Province. TS is grateful to his family of Tan, Toy and little Ravel for their
company during his long trips to Tak, Nan and Chiang Rai for fieldwork in 2018 and 2019. SH thanks Yot Tha
Paeng, former Park Ranger stationed at the Doi Phu Kha National Park, Nan Province, for his help with collecting
road-killed snake specimens in 2015 (including two Hebius igneus specimens avant la lettre) and his assistance
during field work at night.
Lastly, we thank V. Deepak (Senckenberg Museum, Dresden, Germany) for his assistance with recent literature
on the family Natricidae, and two anonymous reviewers who greatly contributed to improve this paper.
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DISTRIBUTION OF THE HEBIUS SPECIES IN NORTHERN THAILAND Zootaxa 5116 (1) © 2022 Magnolia Press · 35
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APPENDIX 1. Examined specimens of Hebius species from Thailand
Hebius bitaeniatus (n=8). Chiang Mai Province. Mae Chaem District: QSMI 1702: Adult DOR from “Hw 1192, about 1.5 km
from junction with Hw 1009, Doi Inthanon National Park”. Elevation about 1,625 m. Collected by Sjon Hauser on 20 May
2012; SHPC13.05.16-09: DOR from “Hw 1192, 5 km from junction with H1009”. Elevation about 1,500 m. Collected by
Sjon Hauser on 16 May 2013 (preserved dry); QSMI 1703: DOR from “Hw 1192, 400 m from junction with Hw 1009, Doi
Inthanon National Park”. Elevation about 1,700 m. Collected by Sjon Hauser on 5 July 2013. Mae Wang District: QSMI
XX-12.08.04-09: DOR from “Rural Road Chiang Mai 4016, 1 km south of Mae Wang Exit, Doi Inthanon National Park”.
Elevation about 1,650 m. Collected by Sjon Hauser on 4 August 2012; QSMI XX-13.07.05-11: DOR from “Rural Road
Chiang Mai 4016, about 1 km south of Mae Wang Exit, Doi Inthanon National Park”. Elevation about 1650 m. Collected
by Sjon Hauser on 5 July 2011; QSMI XX-14.09.29-06: DOR from “Rural Road Chiang Mai 4016, 200 m south of Mae
Wang Exit, Doi Inthanon National Park”. Elevation about 1,700 m. Collected by Sjon Hauser on 29 September 2014;
SHPC15.05.20.05B: Juvenile DOR from “local road, 1.5 km east of Khun Mae Wak Village”. Elevation about 1,550 m.
Collected by Sjon Hauser on 20 May 2015; SHPC19.06.23-15: Juvenile DOR from “Rural Road Chiang Mai 4016, 2.9
km south of Mae Wang Exit, Doi Inthanon National Park”. Elevation about 1,600 m. Collected by Sjon Hauser on 23 June
2019.
Hebius deschauenseei (n=13). Chiang Mai Province. Chiang Dao District: QSMI 1705: DOR from “Hw1322, east of Khun
Khong Village.” Elevation about 1,200 m. Collected by Sjon Hauser on 19 April 2007; Doi Saket District: QSMI 1704:
DOR from “Hw 1252, 10 km southeast of junction with Hw 118 (near Kiu Tam Village)”. Elevation about 1,200 m. Col-
lected by Sjon Hauser on 1 June 2004; Fang District: SHPC05.06.08-08: Dry DOR on “road to Ban Kum Village, 3 km
from village, Doi Ang Khang National Park”, Elevation about 1,550 m. Collected by Sjon Hauser on 8 June 2005 (pre-
served lacquered); Mae On District: SHPC07.04.30-02: DOR from “RR4063, near Wat Pang Hai”, Elevation about 800 m.
Photos taken by Sjon Hauser on 30 April 2007 (photos only); Mae Rim District: SHPC21.05.20-03: Flat dry juvenile DOR
from “Hw 1096 500 m east of border Samoeng and Mae Rim District.” Elevation about 1,100 m. Collected by Sjon Hauser
on 20 May 2021; Mae Taeng District: QSMI 1706: DOR from “Hw 1095, 2 km west of Mae Sae Village.” Elevation about
1,300 m. Collected by Sjon Hauser on 17 October 2005; SHPC11.06.28-05: DOR from “Hw 1095, 1.5 km east of Mae Sae
Village.” Elevation about 1,200 m. Photos taken by Sjon Hauser on 28 June 2011. (Photos only); Mae Wang District: QSMI
XX-14.09.29-05: DOR from “Hw 1284, about 2 km south of Mae Wang exit of Doi Inthanon National Park”, Doi Inthanon,
(near mountain stream)”. Elevation about 1,600 m. Collected by Sjon Hauser on 29 September 2014; SHPC10.11.20-14:
Large adult DOR “from RR near Mae Wang Village (near stream).” Elevation about 1,400 m. Collected by Sjon Hauser
on 20 November 2010; Mueang District: QSMI 1707: Living juvenile from “Hw 1004, a little downhill from Wat Phrathat
Doi Suthep.” Elevation about 1,150 m. Photos and collected by Sjon Hauser on 6 September 2010; QSMI 1708: Living
subadult “about 3 km north of Phuphing Palace, Doi Suthep-Pui National Park.” Elevation about 1,550 m. Photos taken by
Sjon Hauser on 14 May 2014 (only photos); Phetchabun Province: Lom Kao District: QSMI 1709: Juvenile intact DOR
from “Hw 2331, 19.1 km east of HQ Phu Hin Rong Kla National Park,” Elevation 1,603 m. Collected by Sjon Hauser on
22 June 2017. Phitsanulok Province. Nakhon Thai District: SHPC16.11.10-07: Juvenile DOR from “Hw 2331, 1.4 km east
of HQ Phu Hin Rong Kla National Park.” Elevation about 1,200 m. Collected by Sjon Hauser on 10 November 2016.
Hebius igneus (n=8). Chiang Rai Province. Wiang Kaen District: QSMI 1714. Living adult from “Phu Chi Fa.” Elevation
about 1,200 m. Photos by Ton Smits on 14 August 2019; TSPA2019-08-13: Dead adult specimen found “in mountain
stream near Phu Chi Fa.” Elevation about 1,200 m. Photos by Ton Smits on 13 August 2019; Nan Province. Bo Kluea
District: SHPC15.07.23-01: Adult DOR from “Hw 1256, 1 km east from border Pua-Bo Kluea,” Elevation about 1,650
m. Collected by Sjon Hauser on 23 July 2015; QSMI 1713: Living specimen “at forest stream about 5 km east of Doi Phu
Kha Viewpoint 1,715 m, Hw 1256.” Elevation about 1250 m. Photos by Ton Smits on 3 August 2019; Pua District: QSMI
1699: DOR adult from “Hw 1256.” Elevation about 1,100-1,500 m. Collected by Yot Tha Paeng in August 2015; QSMI
1710: DOR juvenile from “Hw 1256 near KM31 and Lan Du Dao,” Pua District. Elevation 1,550 m. Collected by Sjon
Hauser on 5 October 2015; QSMI 1711: Adult DOR from “Hw 1252” Elevation about 1,100-1,500 m. Collected by Yot
Tha Paeng in July 2015 (only photographs); QSMI 1712: Living specimen from “Hw 1256, near Lua Village, 2.5 km west
of junction with road to Ton Tong Waterfall.” Elevation about 1,000 m. Photos by Sjon Hauser on 10 and 11 June 2018.
HAUSER ET AL.
36 · Zootaxa 5116 (1) © 2022 Magnolia Press
Hebius khasiensis (n=23). Chiang Mai Province: QSMI 1716. Intact DOR from “Hw 1095, 6 km west of Pa Pae Village,” Mae
Taeng District. Elevation about 850 m. Collected by Sjon Hauser on 27 May 2006. SHPC15.06.27-07. Freshly killed DOR
from Rural Road 4051, 1 km uphill from/south of Mae Khi Village, Mae Rim District. Elevation about 1000 m. Collected
by Sjon Hauser on 27 June 2015. QSMI 1717. Living adult from “Hw 1252, 2.5 km east of junction with Rural Road 4063,”
Doi Saket District. Elevation about 1,400 m. Photographs by Sjon Hauser on 29 April 2019. SHPC21.06.04-12. DOR from
“RR 4063, 8.4 km from junction with RR 3005,” Mae On District. Elevation about 800 m. Collected by Sjon Hauser on 4
June 2021. QSMI 1718. Doi Suthep-Pui National Park,” Mueang District. Elevation about 1,200 m. Photos by Jon Hakim
on 26 March 2015. QSMI 1719. DOR from “Hw 1349, 16.2 km west of the centre of Bo Kaeo Village,” Samoeng District.
Elevation about 1,100 m asl. Collected by Sjon Hauser on 1 July 2021; SHPC18.08.11-10. DOR from “RR 4053, 3 km
south of Bo Kaeo Village,” Samoeng District. Elevation about 900 m. Collected by Sjon Hauser on 11 August 2018; QSMI
1720: Juvenile DOR from “Hw 1349 9.4 km west of border Kanlayanawatthana-Samoeng District”, Kanlayani Watthana
District. Elevation about 1,200 m. Collected by Sjon Hauser on 1 September 2020. QSMI 1721. Juvenile DOR from “Hw
1349, 18.4 km west of border Samoeng-Kanlayani Watthana districts,” Kanlayani Watthana District. Elevation about 1,100
m. Collected by Sjon Hauser on 4 September 2020. QSMI 1722. DOR adult from “Hw 1263, 3 km east of Pang Ung Vil-
lage (5 km east of border with Mae Hong Son Province),” Mae Chaem District. Elevation about 1,200 m. Collected by
Sjon Hauser on 12 July 2005; SHPC05.07.12-03. DOR from “Hw1009, 5 km south of Khun Klang Village, Doi Inthanon
National Park,” Chomthong District. Elevation about 1,000 m. Collected by Sjon Hauser on 12 July 2005. SHPC16.06.28-
09. Subadult DOR from “rural road road 2.5 km south of Mae Wak Village,” Mae Wang District. Elevation about 1500 m.
Collected by Sjon Hauser on 28 June 2016. SHPC18.06.19-01. DOR from “Hw 1099, 2.1 km north of Viewpoint-Chedi
Monument,” Omkoi District. Elevation about 1,300 m. Collected by Sjon Hauser on 19 June 2018. QSMI 1723. Living
adult from “Hw 1099, about 3 km north of Ban Musoe,” Omkoi District. Elevation about 1,200 m. Photos by Sjon Hauser
on 17 September 2019. Chiang Rai Province. Wiang Pa Pao District, in Pauwels et al. (2009). Lampang Province: QSMI
1724. Large DOR from “Hw 1252, 400 m west of Mae Chaem Village,” Mueang Pan District. Elevation 1,100 m. Collected
by Sjon Hauser on 29 June 2019. Mae Hong Son Province Mueang District: QSMI 1715: DOR from “Rural Road 4001, 5.3
km south of Rak Thai Village.” Elevation 1,025 m. Collected by Sjon Hauser on 5 September 2020. Tak Province: QSMI
XX-11.08.24-13. DOR on “Hw 1090, near KM 116 (old), Ancient Forest,” Umphang District. Elevation 1,250 m. Collected
by Sjon Hauser on 24 August 2011; QSMI XX-13.08.06-08, DOR on “Hw 1090, near KM 93 (old), about 7 km south of
Highways Depot,” Umphang District. Elevation 1,100 m. Collected by Sjon Hauser on 6 August 2013; QSMI 1725. Liv-
ing adult from “Hw 1090, 13.1 km northeast of bridge at Mae Klong Khi Village, Ancient Forest,” Umphang District.
Collected by Sjon Hauser on 15 October 2011. Also in David et al. 2013; SHPC15.06.01-06. DOR from “Hw 1090, 4 km
north of Mae Klong Khi Ranger Station, Ancient Forest,” Umphang District. Elevation about 1,250 n. Collected by Sjon
Hauser on 1 June 2015; QSMI 1726. DOR from “Hw 1090, 4 km north of Highways Depot, ” Phop Phra District. Elevation
1,150–1.200. Collected by Sjon Hauser on 15 July 2005. SHPC07.05.03-06. DOR from “Hw 1090 about 10 km north of
Highways Depot,” Phop Phra District. Tak Prov. Elevation about 1,050 m. Collected by Sjon Hauser on 3 May 2005.
Hebius cf. khasiensis (n=10) Nan Province: SHPC15.07.07-03. DOR from “Hw 1256, 4 km east of Summit 1715 m,” Bo Kluea
District. Elevation about 1450 m. Collected by Sjon Hauser on 7 July 2015. SHPC19.11.05-11. DOR from “Hw 1256,
1.4 km east of Ko Kuang Village,” Bo Kluea District. Eelvation about 1400 m. Collected by Sjon Hauser on 5 November
2019. QSMI 1727. Living adult from “Doi Phu Kha National Park,” Bo Kluea District. Photographs taken by Ton Smits
on 10/11 August 2019. Phitsanulok Province: QSMI 1728. Juvenile DOR from “Hw 2331 close to junction with road to
Lom Lo (Hmong) village, Phu Hin Rong Kla National Park,” Nakhon Thai District. Elevation about 1,200 m. Collected
by Sjon Hauser on 23 October 2019. QSMI 1729. Living adult from “Phu Hin Rong Kla National Park,” Nakhon Thai
District. Photographs by Ton Smits on 31 July 2018. Phetchabun Province: SHPC11.07.14-04. DOR from “Hw 2331, Phu
Hin Rong Kla National Park,” Lom Kao District. Elevation 1,500 m. Photographs by Sjon Hauser on 14 July 2011. QSMI
1730. Juvenile DyOR from “Hw 2331, Phu Hin Rong Kla National Park,” Lom Kao District. Elevation about 1,500 m.
Collected by Sjon Hauser on 4 June 2012. SHPC17.05.21-17. DOR from “Hw 2331, 3.7 km west of Phu Phaeng Ma,” Lom
Kao District. Elevation 1600. Collected by Sjon Hauser on 21 May 2017. SHPC17.05.22-12. DOR from “Hw 2331, 8.7
km east of border Phitsanulok-Phetchabun,” Lom Kao District. Elevation about 1,600 m. Collected by Sjon Hauser on 22
May 2017. SHPC17.05.22-14. DOR from “Hw 2331, 11.8 km east of border Phitsanulok–Phetchabun,” Lom Kao District,
Elevation about 1,650 m. Collected by Sjon Hauser on 22 May 2017.
DISTRIBUTION OF THE HEBIUS SPECIES IN NORTHERN THAILAND Zootaxa 5116 (1) © 2022 Magnolia Press · 37
APPENDIX 2. Summary of data of 13 additional specimens of Hebius terrakarenorum sp. nov. from Tak Province,
Thailand.
Hebius terrakarenorum sp. nov. Additional-01
QSMI-XX-
13.11.01-21
Additional-02
QSMI 1694
(18.09.24)
Additional-03
QSMI 1695
(13.09.10-04)
Additional-04
QSMI 1696
(13.09.11-11)
origin Umphang Tha Song Yang Phop Phra Umphang
sex male subadult male ?
SVL (mm) 335 n.a. 263 237
TaL (mm) n.a.* n.a. 130 103
TOTL (mm) n.a.* n.a. 393 340
Ratio= TaL/TOTL (%) n.a.* n.a. 33.1 30.3
Ventral plates (PV) 159(2) 166 162 (2) 167(1)
Cloacal plate (CP) divided divided ? divided
SC-pairs n.a.* n.a.* 117 120+
DSR n.a. 19-19-17 xx-19-xx n.a.
19 >> 17 between Vx-Vy n.a. n.a. n.a. n.a.
keeled rows at midbody keels present n.a. mostly smooth many keeled
Sup.lab.L; touching eye; largest n.a. 9; 4-5-6;8 n.a. 9; 5-6; 8
Sup.lab.R; touching eye; largest n.a. 9; 5-6; 8 n.a. 9; 5-6; 8 or 9
Sup.lab. edged or dusted grey n.a. L-yes; R-yes yes yes
Sup.lab. cream-pale brown yes L-yes; R-yes yes yes
Sup.lab. with white blotches no L-no; R-no no no
infralabials l/r; largest n.a. n.a. 9/10;5or6/5or6
temporals (AT,PT1,PT2) n.a. L-xxx/R-123 n.a. L123/R113
preoculars (left and right) n.a. L2-R2 n.a. L2-R2
postoculars (left and right) n.a. L2-R2 n.a. L2-R2
loreal .. x longer than high n.a.* 1.3 and 1.5 n.a. L-2.0; R-small
ant. edge F straight with spike? yes ? n.a. yes
belly pinkish cream yes yes yes yes
corners V pale orange-brown yes yes yes yes
spots corners V cloudy grey yes yes yes yes
ground colour dorsum grey-brown dark brown grey-brown brown
dorsolat. series pale blotches no yes vague no
row1,19 pale orange brown edged
or clouded with grey
yes yes vague yes
SC-pairs clouded with grey yes yes hardly yes
postocular bicoloured streak no yes very vague R:vague
“salmon throat” yes yes no no
tailbase keeled? n.a. (weakly) distinctly distinctly distinctly
......continued on the next page
HAUSER ET AL.
38 · Zootaxa 5116 (1) © 2022 Magnolia Press
APPENDIX 2. (Continued)
Hebius terrakarenorum sp. nov. Additional-05
QSMI 1697
(15.06.01-07)
Additional-06
QSMI 1698
(16.07.09-05)
Additional-07
SHPC09.09.17-04
Additional-08
SHPC11.10.11-14
origin Umphang Umphang Mae Sariang Umphang
sex ? male male n.a.
SVL (mm) 239 232 medium-sized n.a.
TaL (mm) broken, n.a. 98 n.a. n.a.
TOTL (mm) n.a. 330 about 400 n.a.
Ratio= TaL/TOTL (%) n..a. 29.7 n..a. n.a.
Ventral plates (PV) 161(2) 163(1) 162(1) 161 (3)
Cloacal plate (CP) divided divided divided? n.a.
SC-pairs tail broken 111 126+ 110
DSR n.a. 19-19-17 n.a. n.a.
19 >> 17 between Vx-Vy n.a. V88-V92 n.a. n.a.
keeled rows at midbody post.keels keels many keels many keels
Sup.lab.L; touching eye; largest n..a. n.a. n.a. 9; 5-6; 7 or 8
Sup.lab.R; touching eye; largest n.a. 9; 5-6; 8 n.a. ??
Sup.lab. edged or dusted grey yes yes yes L-yes; R-?
Sup.lab. cream-pale brown yes yes yes yes
Sup.lab. with white blotches no no no no
infralabials l/r; largest n..a. n.a. n.a. n.a.
temporals (AT,PT1,PT2) L123/Rxxx n.a. n.a. n.a.
preoculars (left and right) L2 R2 n.a. n.a.
postoculars (left and right) L2 R2 n.a. n.a.
loreal .. x longer than high n.a. n.a. n.a. n.a.
ant. edge F straight with spike? dislocated yes yes yes
belly pinkish cream yes yes yes yes
corners V pale orange-brown yes yes yes yes
spots corners V cloudy grey yes yes yes yes
ground colour dorsum brown brown brown brown
dorsolat. series pale blotches no no yes yes
row1,19 pale orange brown edged or
clouded with grey
? yes yes yes
SC-pairs clouded with grey yes yes yes yes
postocular bicoloured streak very vague distinctly yes not distinct
“salmon throat” a little a little yes yes
tailbase keeled? distinctly distinctly distinctly? ?
......continued on the next page
DISTRIBUTION OF THE HEBIUS SPECIES IN NORTHERN THAILAND Zootaxa 5116 (1) © 2022 Magnolia Press · 39
APPENDIX 2. (Continued)
Hebius terrakarenorum sp. nov. Additional-09
SHPC12.10.13-
04
Additional-10
SHPC15.10.21-
10
Additional-11
SHPC17.09.09-
07
Additional-
12 QSMI
1701
Additional-
13 IDPPA
2021-03-09
origin Umphang Umphang Tha Song Yang Sangkhla-
buri
Thong Pha
Phum
sex ? male male n.a. n.a
SVL (mm) check 306 >359 mm (dry) n.a. n.a.
TaL (mm) tail broken, n.a. 156 tail broken n.a. n.a.
TOTL (mm) n.a. 462 n.a. about 300 about 500
Ratio= TaL/TOTL (%) n.a. 33.8 n.a. n.a. n.a.
Ventral plates (PV) 160(3) 165(2) 160 (2) n.a. n.a.
Cloacal plate (CP) divided divided divided n.a. n.a.
SC-pairs 77+* 117 tail broken n.a. n.a.
DSR n.a. n.a. n.a. n.a. n.a.
19 >> 17 between Vx-Vy n.a. n.a. n.a. n.a. n.a
keeled rows at midbody indistinct** some
keels,indist.
many dist.keeled n.a. keels visible
Sup.lab.L; touching eye; largest 9?; xx; 7, 8 or 9 9; 5-6 ;7, 8 or 9 9; 5-6; 8 9; 5-6; 8 9; 4-5-6; 8
Sup.lab.R; touching eye; largest 9; 5-6; 7 or 8 9; 5-6 ;7, 8 or 9 9; 5-6; 7 or 8 9; 4-5-6; 8 n.a.
Sup.lab. edged or dusted grey yes yes yes yes yes
Sup.lab. cream-pale brown yes yes yes yes yes
Sup.lab. with white blotches no no no no no
infralabials l/r; largest L-xx; R-8? L-10,R-
10;5,6/5,6
n.a. n.a. n.a.
temporals (AT,PT1,PT2) L123/R123 L123/R-not
clear
damaged L122/ R123 L122
preoculars (left and right) L-2; R-2 R-2 R-2 R2 L2
postoculars (left and right) L-2; R-2 R-2 R-2 R2 L2
loreal .. x longer than high L-2.0; R-1.5 L-elong.;R-
vague
R-2.0 R1.4 L1.5
ant. edge F straight with spike? yes yes yes yes ??
belly pinkish cream yes probably probably yes yes?
corners V pale orange-brown yes probably probably yes yes
spots corners V cloudy grey yes yes yes n.a. n.a.
ground colour dorsum dark brown brown dark brown dark brown dark brown
dorsolat. series pale blotches no no yes yes yes
row1,19 pale orange brown
edged or clouded with grey
yes yes ?? yes yes
SC-pairs clouded with grey yes yes yes n.a. n.a.
postocular bicoloured streak no not distinct yes very dis-
tinct
very distinct
“salmon throat” no no/vague ?? ?? ??
tailbase keeled? vaguely keeled keels quite strongly ?? quite
strongly
* tail(tip) broken
