Journal of Threatened Taxa | www.threatenedtaxa.org | 26 April 2025 | 17(4): 26803–26813

 

ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print) 

https://doi.org/10.11609/jott.9436.17.4.26803-26813

#9436 | Received 26 September 2024 | Final received 26 February 2025 | Finally accepted 06 March 2025

 

 

Comments on the systematics and morphology of Smithophis bicolor (Blyth, 1855) (Reptilia: Squamata: Natricidae) based on topotypical specimens from Meghalaya, India

 

Jayaditya Purkayastha 1, Bipin Meetei Asem 2, Hmar Tlawmte Lalremsanga 3, Madhurima Das 4 ,

Holiness Warjri 5, Goldenstar Thongni 6  & Sanath Chandra Bohra 7        

 

1,4,7 Help Earth, 16, Raghunath Choudhury Path, Lachitnagar, Guwahati, Assam 781007, India.

2 Zoological Survey of India, Northeastern Regional Centre, Shillong, Meghalaya 793014, India.

3 Developmental Biology and Herpetology Laboratory, Department of Zoology, Mizoram University, Tanhril, Mizoram 796004, India.

4,5 Department of Zoology, Assam Don Bosco University, Sonapur, Assam 781027, India.

6 Rohbah, South West Khasi Hills District, Mawkyrwat, Meghalaya 793114, India.

1 mail.jayaditya@gmail.com, 2 abmeetei@gmail.com, 3 htlrsa@yahoo.co.in, 4 madhurima.das@dbuniversity.ac.in, 5 holiness12345@gmail.com, 6 golden2394@gmail.com, 7 sreptilian6@gmail.com (corresponding author)

 

 

Editor: S.R. Ganesh, Kalinga Foundation, Agumbe, India.                Date of publication: 26 April 2025 (online & print)

 

Citation: Purkayastha, J., B.M. Asem, H.T. Lalremsanga, M. Das, H. Warjri, G. Thongni & S.C. Bohra (2025). Comments on the systematics and morphology of Smithophis bicolor (Blyth, 1855) (Reptilia: Squamata: Natricidae)   based on topotypical specimens from Meghalaya, India. Journal of Threatened Taxa 17(4): 26803–26813. https://doi.org/10.11609/jott.9436.17.4.26803-26813

 

Copyright: © Purkayastha et al. 2025. Creative Commons Attribution 4.0 International License. JoTT allows unrestricted use, reproduction, and distribution of this article in any medium by providing adequate credit to the author(s) and the source of publication.

 

Funding: Rufford Small Grants for Nature Conservation.

 

Competing interests: The authors declare that there are no conflicts of interest regarding the publication of this paper. All authors have participated in the research, design and drafting of this manuscript, and have reviewed and approved the final version. They have no financial or personal relationships that could inappropriately influence or bias the content of this work.

 

Author details: Jayaditya Purkayastha is a wildlife biologist at Help Earth NGO. Bipin Meetei Asem is an assistant zoologist at Zoological Survey of India, North Eastern Regional Centre. Hmar Tlawmte Lalremsanga is a professor at the department of Zoology, Mizoram University. Madhurima Das is an assistant professor at the department of Zoology, Assam Don Bosco University. Holiness Warjri is a research scholar at the department of Zoology, Assam Don Bosco University. Goldenstar Thongni is a naturalist with interest in biodiversity of Meghalaya. Sanath Chandra Bohra is a wildlife biologist at Help Earth.

 

Author contributions: JP—conceptualization and paper writing; BMA—provided morphological data; HTL—provided morphological data and helped in paper writing; MD—molecular analysis; HW—collection of specimens and field study; GT—collection of specimens and field study; SCB—paper writing and securing funds.

 

Acknowledgements: We would like to thank chief wildlife warden (Environment, Forest and Climate Change) and Government of Meghalaya (Permit No.FOR.7/2021/216) for issuing the collection permit. We are also very thankful to the local community for supporting us in our field surveys. We are also thankful to MegLIFE and Rufford Small Grants Foundation for supporting this work. Finally we would like to thank the reviewers and the editor for substantially improving the manuscript through their inputs.

 

 

 

Abstract: The Natricid Snake Smithophis bicolor has been poorly studied and understood since its initial description in the mid-1800s. This study presents a detailed morphological description of S. bicolor based on five examined specimens including a freshly collected mutilated specimen from Meghalaya State, India. For the first time, genetic data has been obtained and analysed, providing novel insights into the species’ phylogenetic position within its genus Smithophis. Morphological comparisons and molecular analyses using cytochrome b mitochondrial gene reveal subtle variations that contribute to a clearer understanding of the species’ taxonomic identity. This study allows us to conclude that currently S. bicolor is restricted to the higher elevations of Meghalaya indicating that literature records mentioning the presence of this species from Mizoram actually represents a distinct, new unnamed lineage.

 

Keywords: Cytochrome b, hemipenis, herpetofauna, Khasi hills, Mairang, northeastern india, phylogeny, re-description, shillong plateau, taxonomy, type locality.

 

 

 

Introduction

 

Blyth (1855) described Smithophis bicolor in the genus Calamaria Boie, 1827 based on a single specimen (holotype ZSI 7030) provided by Mr. Robinson with the type locality recorded as Assam, India. In the same piece of work, Blyth (1855: p. 287) mentioned that the specimens provided by Mr. Robinson might be from Khasya Hills (present day Khasi Hills, Meghalaya State, India) or other upland territories. The holotype ZSI 7030 was mentioned to be with a dusky-plumbeous dorsal surface and a buffy white ventral surface, 17 mid-dorsal scale rows, 210 ventrals and 75 pairs of subcaudals, snout-vent length of 495 mm and a tail length of 111 mm. Boulenger (1893) allocated bicolor to the genus Rhabdops Boulenger and stated its distribution from Khasi Hills, Assam and Yunnan. Rhabdops olivaceus (Beddome 1863) with distribution in the Western Ghats, India is the type species of Rhabdops along with the recently described Rhabdops aquaticus Giri et al. 2017 also known from the Western Ghats, India whereas Rhabdops bicolor was the only species known from northeastern India. Based on genetics and disjunct distribution in Western Ghats and northeastern side, Giri et al. (2019) erected the genus Smithophis to accommodate northeastern populations (bicolor) and also described a new species in the genus namely Smithophis atemporalis noting that the genus Smithophis is more closely related to Opisthotropis and Sinonatrix than to Rhabdops. Furthermore, Giri et al. (2019) in their genetic assessment of Smithophis bicolor used data based on materials from Mizoram State, northeastern India. Since then, three more species were added to the genus, namely, Smithophis arunachalensis Das et al., 2020; S. linearis Vogel et al., 2020 and S. mizoramensis Mirza et al., 2024 (Mirza et al. 2024a). Chandramouli et al. (2021) provided a morphological description of an adult male topotypic specimen of S. bicolor from Shillong, in the Khasi Hills. Giri et al. (2019) in their genetic assessment of S. bicolor used data based on materials from Mizoram, India but missed out the typical population from the Khasi Hills of Meghalaya. In this study, based on fresh collection and museum specimens (Zoological Survey of India, Northeastern Regional Centre, Shillong, Meghalaya State, India) we provide additional morphological and molecular insights for Smithophis bicolor from its type locality and point to the possibility of existence of an undescribed Smithophis from Mizoram State, India, treated as Smithophis cf. bicolor by Giri et al. (2019).

 

 

Materials and Methods

 

The study was conducted in Khasi hills of Meghalaya and throughout Mizoram after obtaining permission for collection within both the states from the chief wildlife warden of Environment, Forests and Climate Change Department, Government of Meghalaya and Mizoram (No. FOR./7/2021/216 for Meghalaya and A.33011/2/99-CWLW/225 for Mizoram). A road killed male specimen of Smithophis bicolor was collected from Mairang (ADBU-HN/HW0210), Eastern West Khasi Hills district (25.559°N, 91.635°E; altitude 1,564 m; see Image 1), Meghalaya, India by Holiness Warjri on 12 August 2024 at around 1230 h and has been deposited in the herpetological museum maintained by the Department of Zoology, Assam Don Bosco University, Sonapur, Assam, India. Furthermore, four samples (V1/ERS/ZSI-444, V1/ERS/ZSI-2592, V1/ERS/ZSI-3052 from Shillong, Meghalaya and VR/ERS/ZSI-725 from Umiam, Meghalaya) were also studied from the collection of Zoological Survey of India, Eastern Regional Station, Shillong, Meghalaya, India. Genomic DNA was extracted from ethanol (100%) preserved liver tissue of the specimen ADBU-HN/HW0210 using tissue kit (Qiagen) following manufacturer’s instructions. Partial sequence of the mitochondrial cytochrome b gene was generated using the primer pair L14910 (GACCTGTGATMTGAAAAACCAYCGTTGT), H16064 (CTTTGGTTTACAAGAACAATGCTTTA)                 (Burbrink et al. 2000). Sequence chromatograms were quality checked, edited and assembled into contigs using Chromas and Sequence Scanner v1.0 (Applied Biosystems). Comparative cytochrome b (Table 1) sequences were used following Mirza et al. (2024) and were obtained from GenBank. Sequence alignment was done using MUSCLE (Edgar 2004) in MEGA7 (Tamura & Nei 1993; Kumar et al. 2016) with default parameter settings. Maximum likelihood (ML) phylogenetic tree was reconstructed using un-partitioned dataset in IQ-TREE (Nguyen et al. 2015) with the substitution model GTR+F+I+G4 selected based on the BIC scores by ModelFinder (Kalyaanamoorthy et al. 2017) implemented in the IQ-TREE (Nguyen et al. 2015). The ML analysis was run with an ultrafast bootstrap option (Minh et al. 2013) for 1000 iterations to assess clade support. The un-corrected pairwise p-distance was calculated in MEGA7 (Kumar et al. 2016) with pairwise deletions of missing data and gaps.

Morphometrics and meristics are taken as follows: HL (Head length taken from the retro articular process of the jaw to the tip of the snout), HW (Head width measured at the widest point of the head), HD (Head depth measured at the greatest depth of the head), ED (Eye diameter taken horizontally at the outer margins of the orbit), ND (Greatest nostril diameter), NS (Nostril to snout distance taken from the anterior portion of nostril to the tip of the snout), EN (Eye to nostril distance taken from the anterior portion of orbit to the posterior margin of nostril openings), IND (Internarial distance measured between the two nostril openings), IOD (Inter orbital distance measured between the minimum distance of two outer orbital margins), PL (Greatest length of the parietal scale), SVL (Snout-vent length measured from the tip of the snout to the vent ventrally), TaL (Tail length measured from the vent to the tip of the tail ventrally), TL (Total length measured from the tip of the snout to the to the tip of the tail ventrally or dorsally), DSR (Dorsal scale rows counted in a row transversely in three sections, i.e., exactly one head length behind the neck, exactly in the midbody and exactly one head length before the vent dorsally), V (Number of ventral scales counted ventrally from the 1st scale just behind pre-ventrals till the last scale just before the anal plate), SC (Number of subcaudal scales beginning just behind the cloaca ventrally till the last scale in the tail excluding the terminal scute), SL (Number of supralabial scales counted on the upper lips), IL (Number of infralabial scales counted on the lower lips), COS (Number of circumorbital scales surrounding the orbit), Temp (Number of anterior plus posterior temporal scales in the lateral portion of the head), and Anal (Condition of the anal plate whether its divided or single).

 

 

Results

 

Based on Cyt b (1109 bp) data generated in this study, the Smithophis bicolor from Mairang, Eastern west Khasi Hills, Meghalaya State was seen to show a sister relationship to S. mizoramensis differing in a low to moderate uncorrected p-distance of 4% whereas S. cf. bicolor from Mizoram State (Giri et al. 2019) was seen to be sister to the clade comprising S. bicolor (Mairang) + S. mizoramensis. Smithophis cf. bicolor from Mizoram differs by an uncorrected p-distance of at least 11.5% from the S. bicolor s. str. of Mairang, Eastern West Khasi Hills, Meghalaya State (nearly thrice as high as the divergence between S. bicolor s. str. and S. mizoramensis) (Figure 1, Table 2). Genetic divergence for the cytochrome b (cyt b) gene reveals that true S. bicolor is 4% to 14.3% divergent from other Smithophis species. Morphologically, the species S. bicolor differs from its sister S. mizoramensis mainly in body coloration as well as carination condition of the sacral scales.

 

Morphology of topotypical, Meghalaya specimens

(V1/ERS/ZSI-2592, V1/ERS/ZSI-725, V1/ERS/ZSI-3052, V1/ERS/ZSI-444, ADBU-HN/HW0210; Images 2–4): Smithophis bicolor is mainly characterized by having 17 smooth dorsal scale rows across the body without having any keeled sacral scales in males. It possesses temporal scales (1+1) and features 5 circum-orbital scales along with a single internasal and a single prefrontal scale. Tail is relatively short and ends with a short spine like scale. The examined specimens from Meghalaya exhibit an elongated body with a head slightly distinct from neck, little longer than broad (HW/HL 0.58–0.75), slightly flattened dorsoventrally (HL/HD 0.41–0.57). The eyes are moderately sized (ED/HL 0.12–0.19); nostrils are placed closer to snout than to the eye (NS/EN 0.69–0.88), relatively small in size (ND/ED 0.50–0.71); a pair of parietals, each parietal scale is relatively large, half or slightly more than half of head length (Parietal/HL 0.50–0.61); SVL ranges from 360–535 mm; TaL ranges from 110–160 mm; tail relatively short (TaL/SVL 0.30–0.44; TaL/TL 0.22–0.25); TL ranges from 470–690 mm. The meristic characteristics of the specimens are consistent across the examined specimens. All individuals possess 17–17–17 dorsal scale rows; Ventrals 209–212 in males and 192 in females; subcaudals 75–80 in males and 68 in females; SL usually 5 and IL usually 6 or 7. One unsexed individual has 212 ventrals and 71 subcaudals, SL 5 on each side and IL 6 on each side. The circum-orbital scale count is uniform across all specimens, with five scales surrounding each eye. The temporal scales are arranged in a 1+1 pattern in all individuals and anal plate is divided in all specimens.

 

Sexual dimorphism

Based on our data, males of this species have ventrals ranging from 209 to 212 (versus 192 in a female), Sc ranging from 75 to 80 (versus 68 in a female) and Tal/TL ratio of 0.23 to 0.25 (versus 0.22 in a female).

 

Coloration in preservative (Image 2)

The specimens in ZSI, especially V1/ERS/ZSI 444 and 3052, have become completely faded in comparison to their coloration in life (read below), such that there is barely much difference between their dorsal and ventral colours, indicating bleaching of dorsal colour. Eyes became paler and pupil became light grey.  

 

Coloration in life (based on live uncollected snakes; Image 3)

Smithophis bicolor we encountered had a dorsal region with uniformly shiny black above with a slightly violet tinge, whereas the ventral is uniformly (mostly) gambodge yellow in life. In the posterior half of the lateral region, a prominent, broad gambodge yellow stripe runs along the body, covering the ventrals. The dorsal and ventral coloration meet somewhat at the middle of the lateral region, giving it a typical bicoloured appearance which begins from the snout and extends up to the tip of the tail in life.

 

Hemipenial description (based on ADBU-HN/HW0210; Image 4)

Short and stout, characterized by heavy spinosity over the distal three-quarters, with the proximal one-quarter, near the base, exhibiting a somewhat calyculate texture. The spines are more pronounced and larger towards the intermediate region and the base, gradually becoming smaller and conspicuous, somewhat hair or serrations like towards the tip. The spines in hemipenis of Smithophis bicolor are much more pronounced than its sister taxa S. mizoramensis.

 

Comparisons

Smithophis bicolor has well defined temporal scales (1+1) vs. absent in S. atemporalis; Smithophis bicolor does not have keeled sacral scales in males vs. presence of keeled sacral scales in S. arunachalensis and S. mizoramensis. The dorsum is immaculate in Smithophis bicolor vs. either blotched or striped in all the other congeners. Furthermore, Smithophis bicolor has 4–5 circumorbital scales vs. 6–7 in S. linearis.

 

Natural history and distribution (Image 5)

Based on our current data, Smithophis bicolor is a terrestrial to semi-aquatic species which mainly prefers to live in close proximity to streams and other water bodies surrounded by semi-evergreen, evergreen, moist deciduous, montane forests and at times even moderately disturbed hilly areas. Based on the specimens, the species is found in areas of higher elevation ranging 1,000–1,700 m. All the freshly observed specimens from Meghalaya State were seen near streams, boulders with or without mosses, loose soils or roadside edges with or without mosses within wet montane or wet semi-evergreen or evergreen forests, particularly during the day. It has been observed that this species (just like other congeners) is often seen or becomes active during heavy rainfall. The current understanding based on the available data allows us to conclude that Smithophis bicolor is currently restricted to the higher elevations of Meghalaya State, particularly in the Khasi Hills and its adjacent areas, i.e., Garo hills whereas those reported as S. bicolor s. lat. from regions outside Meghalaya State might represent a different species.

 

 

Discussion

 

Despite being one of the earliest described species of the genus Smithophis, S. bicolor lacked any new information until recent times (Chandramouli et al. 2021). This study not only gives genetic data from the type locality of S. bicolor but also provides expanded morphological description of the species based on multiple specimens. The examination of additional topotypic specimens of S. bicolor from Meghalaya resulting in this expanded morphological description makes the species better characterised in terms of its morphology. This provides a concrete dataset for researchers to describe as well as compare new and previously described species with the nominal taxon in the future. Furthermore, the population previously identified as S. bicolor from Mizoram (Giri et al. 2019) which represents a genetically and morphologically distinct lineage, will be formally described as a new species in our forthcoming publication in preparation.

Meghalaya State, which is rich in terms of biodiversity forms a part of the Indo-Burma biodiversity hotspot which lies on the southern bank of river Brahmaputra and has been relatively well surveyed historically, particularly during the time of British India. Since then, after a long time the state has witnessed a significant increase in the number of new herpetofaunal species descriptions in the past two decades alongside range extensions regarding certain species (e.g., Das et al. 2010; Mahony et al. 2011, 2013, 2018, 2020; Purkayastha & Matsui 2012; Datta-Roy et al. 2013; Kamei et al. 2013; Agarwal et al. 2018b; Purkayastha et al. 2020a,b; 2021; 2022; Rathee et al. 2022; Mirza et al. 2024b). Despite being a described species, further research and field work are necessary to properly understand the accurate distribution range, ecology, reproductive biology and conservation biology of S. bicolor. The Khasi Hill is the “type locality” for snake species like Stoliczkia khasiensis Jerdon, 1870 which is known just from a single specimen and since its description in 1870, the species was never reported for the second time as a result of which it has been considered as a lost species. This highlights the importance of conducting continuous as well as comprehensive herpetofaunal surveys throughout Khasi Hills and its adjoining hill ranges before the depletion of forest cover due to anthropogenic pressures.

We suggest further field investigations involving wide samplings throughout the given range of the genus Smithophis to understand the potential reason behind the diversification of these natricids that will definitely help to uncover further new unnamed populations in the region.

 

Table 1. List of cytochrome b sequences used in this study. New sequence entry in bold.

Species

Voucher

Genbank accession number

Location

Opisthotropis andersonii

SYS r001383

KY594735

Mt. Maofeng, Guangzhou, Guangdong, China

Opisthotropis cheni

YBU 071040 (=GP383)

GQ281779

Nanling NR, Guangdong, China

Opisthotropis daovantieni

FMNH 252009

OK315831

An Ke, Gia Lai, Vietnam

Opisthotropis durandi

NCSM 80739

MK941137

Nam Lan, Phosaly, Laos

Opisthotropis guangxiensis

GP746

GQ281776

Guangxi, China

Opisthotropis haihaensis

SYS r000537

MN890017

Quang Ninh, Vietnam

Opisthotropis hungtai 1

SYSr000538

MN890018

Mt. Wuhuang, Guangxi, China

Opisthotropis hungtai 2

SYS r000946

KY594748

Heishiding NR, Fengkai, Guangdong, China

Opisthotropis jacobi

ZFMK 100818

MG545602

Tam Dao NP, Vinh Phuc, Vietnam

Opisthotropis kuatunensis

SYS r000998

KY594745

Qixiling NR, Yongxin County, Jiangxi, China

Opisthotropis lateralis

ZMMU NAP-08678

OK315832

Xuan Son NP, Phu Tho, Vietnam

Opisthotropis latouchii

GP647

GQ281783

Fujian, China

Opisthotropis laui

SYS r001161

KY594738

Shangchuan Í., Taishan, Guangdong, China

Opisthotropis maxwelli

SYS r000841

KY594736

Nan'ao Is., Nan'ao, Guangdong, China

Opisthotropis shenzhenensis

SYS r001032

KY594729

Mt. Tiantou, Shenzhen, Guangdong, China

Opisthotropis typica

HT0794

LC325343

Malaysia

Opisthotropis voquyi

ZMMU R-16681

OK315833

Tay Yen Tu NR, Bac Giang, Vietnam

Opisthotropis zhaoermii

CIB110000

MG012801

Guzhang, Hunan, China

Smithophis atemporalis

BNHS 2366

MK350262

Mizoram, India

Smithophis cf. bicolor

BNHS 2369

MK350261

Mizoram, India

Smithophis cf. bicolor

MZMU 1798

PP996090

Aizawl, Mizoram, India

Smithophis bicolor

ADBU-HN/ HW0210

PQ727125

Mairang, Eastern West Khasi Hills, Meghalaya, India

Smithophis linearis

KIZ 059110

MT185677

Yunnan, China

Smithophis mizoramensis

BNHS 3766

PP996092

Suangpuilawn, Saitual, Mizoram, India

Smithophis mizoramensis

BNHS 3767

PP996093

Suangpuilawn, Saitual, Mizoram, India

Smithophis mizoramensis

BNHS 3768

PP996094

Suangpuilawn, Saitual, Mizoram, India

Smithophis mizoramensis

MZMU 2602

PP996091

Suangpuilawn, Saitual, Mizoram, India

Trimerodytes percarinata

ZMMU R-16444

OK315846

Pu Mat NP, Nghe An, Vietnam

 

 

Table 2. Uncorrected p-distance between the members of the genus Smithophis.

PQ727125_S._bicolor

 

 

 

 

 

 

 

 

PP996092_S. mizoramensis

0.040

 

 

 

 

 

 

 

PP996093_S._mizoramensis

0.040

0.000

 

 

 

 

 

 

PP996094_S._mizoramensis

0.040

0.000

0.000

 

 

 

 

 

PP996091_S._mizoramensis

0.040

0.000

0.000

0.000

 

 

 

 

MK350262_S._atemporalis

0.107

0.096

0.096

0.096

0.096

 

 

 

MK350261_S._cf.  bicolor

0.115

0.098

0.098

0.098

0.098

0.125

 

 

PP996090_S._ cf.  bicolor

0.115

0.098

0.098

0.098

0.098

0.125

0.000

 

MT185677_Smithophis_linearis

0.143

0.138

0.138

0.138

0.138

0.156

0.169

0.169

 

 

Table 3. Morphometric and meristic data of Smithophis bicolor from eastern and western Khasi Hills, Meghalaya State, India (-- indicates missing data). Measurements in mm.

Museum no.

V1/ERS/

ZSI-2592

V1/ERS/

ZSI-725

V1/ERS/

ZSI-3052

V1/ERS/

ZSI-444

ADBU-HN/

HW0210

Location

Fruit garden, Shillong

Tripura Castle Road, Shillong

Risa Colony, Shillong

Umiam, Umsaw, NEPA Campus

Mairang, Eastern West Khasi hills

Sex

Unsexed

Male

Female

Male

Male

HL

12.54

10.9

14.74

9.8

11

HW

8.28

7.52

9.79

7.48

7.5

HD

7.09

5.8

7.51

5.5

5.1

ED

1.8

1.9

1.51

1.62

1.7

ND

1.27

0.9

0.9

1.18

0.9

NS

1.94

1.6

1.9

1.43

1.8

EN

2.17

1.87

2.6

2.15

2.2

IND

3.48

3.4

3.45

3.2

3.4

IOD

5.8

5.34

5.77

5.2

4.8

PL

7.63

6

7.21

6.8

6.5

SVL

520

385

535

360

360

TaL

160

113

155

120

110

TL

680

498

690

480

470

DSR

17/17/17

17/17/17

17/17/17

17/17/17

17/17/17

V 

212

209+

192

212

209

SC

71

75

68

80

76

SL (L/R)

5/5

5/5

5/5

5/5

5/--

IL (L/R)

6/6

6/6

6/6

7/6

--

COS

5

5

5

5

5

Temp 

1+1

1+1

1+1

1+1

1+1

Anal

Divided

Divided

Divided

Divided

Divided

 

 

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