Research Article |
Corresponding author: Nikolay A. Poyarkov ( n.poyarkov@gmail.com ) Corresponding author: Tan Van Nguyen ( tan.sifasv@gmail.com ) Academic editor: Silke Schweiger
© 2024 Nikolay A. Poyarkov, Andrey M. Bragin, Tan Van Nguyen.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Poyarkov NA, Bragin AM, Nguyen TV (2024) A new endemic insular species of the genus Colubroelaps (Squamata, Serpentes, Colubroidea) from Khanh Hoa Province, Vietnam. Herpetozoa 37: 379-390. https://doi.org/10.3897/herpetozoa.37.e137809
|
A new species of the poorly known genus Colubroelaps Orlov, Kharin, Ananjeva, Nguyen & Nguyen, 2009, is described based on a single female specimen collected from Hon Tre Island, Khanh Hoa Province, Vietnam. The new species, Colubroelaps adleri sp. nov., can be distinguished from its sister species Colubroelaps nguyenvansangi Orlov, Kharin, Ananjeva, Nguyen & Nguyen, 2009 by the following combination of morphological characters: small body size (TL 402 mm); tail relatively short (ratio TaL/TL 0.10); dorsal scales in 14–14–14 rows; supralabials six, third and fourth entering orbit; infralabials seven; loreal present; ventral scales 234; subcaudals 30, all divided; cloacal plate divided; dorsal coloration pale brown, with narrow and interrupted dark stripe along spine; body flanks dark-gray lacking bluish iridescence; ventrally uniform off-white; head black with rostral, nasals, prefrontals, preoculars, loreal, and the two anterior supralabials, as well as anterior parts of supraoculars and frontal dirty yellowish-brown with dark-brown spots. This discovery represents the second known species of the genus Colubroelaps and the first record of the genus in the coastal areas of southern-central Vietnam. The new species is likely micro-endemic to the small island of Hon Tre within Nha Trang Bay in Khanh Hoa Province, Vietnam, at an elevation of 30 m a.s.l., and was recorded only from the heavily disturbed secondary forest area of the island. The new species is under threat due to the intensifying development of tourist infrastructure on Hon Tre Island. We suggest that the new species be considered Endangered (EN) following the IUCN’s Red List categories.
Colubroelaps adleri sp. nov., conservation, Hon Tre Island, morphology, Nha Trang Bay, taxonomy
The monotypic genus Colubroelaps Orlov, Kharin, Ananjeva, Nguyen & Nguyen, 2009, is one of the most mysterious groups of snakes. This genus, colloquially known as lace snakes (
Currently, the genus Colubroelaps is only known for a single species named C. nguyenvansangi Orlov, Kharin, Ananjeva, Nguyen & Nguyen, 2009. The Nguyen Van Sang’s lace snake was described based on a single adult female collected in 2003 from the Loc Bac Forest Enterprise, Bao Lam District, Lam Dong Province, southern Vietnam. Because of its fossorial lifestyle, this species is quite elusive and difficult to detect in the field. Until today, C. nguyenvansangi has only been reported from six localities in southern Vietnam, namely, Loc Bac and Di Linh districts in Lam Dong Province, Bu Gia Map National Park and Bu Dang District in Binh Phuoc Province, Tuy Duc District in Dak Nong Province, Buon Ma Thuot City and Krong Buk District in Dak Lak Province, and Cat Tien National Park in Dong Nai Province (see
Distribution of the genus Colubroelaps in Vietnam. Localities: Colubroelaps adleri sp. nov. (red): (1) Hon Tre Island within Nha Trang Bay, Khanh Hoa Province (type locality); C. nguyenvansangi (green): (2) Loc Bac, Lam Dong Province (type locality); (3) Di Linh, Lam Dong Province; (4) Bu Gia Map NP, Binh Phuoc Province; (5) Bu Dang, Binh Phuoc Province; (6) Tuy Duc, Dak Nong Province; (7) Cat Tien NP, Dong Nai Province; (8) Buon Ma Thuot, Dak Lak Province; (9) Krong Buk, Dak Lak Province.
Khanh Hoa Province is located in the southern part of the coastal region of Vietnam and currently harbors 176,382 ha of evergreen forest (Anonymous, 2023). However, the biodiversity of this province is still poorly studied, in particular the herpetofauna. Ten new species were recently described with their type localities from Khanh Hoa Province within the last fifteen years, namely: Kalophrynus honbaensis Vassilieva, Galoyan, Gogoleva & Poyarkov, 2014; Kurixalus viridescens Nguyen, Matsui & Hoang, 2014; Acanthosaura murphyi Nguyen, Do, Hoang, Nguyen, McCormack, Nguyen, Orlov, Nguyen & Nguyen, 2018; Cyrtodactylus cucdongensis Schneider, Phung, Le, Nguyen & Ziegler, 2014; C. raglai Nguyen, Duong, Grismer & Poyarkov, 2021; C. yangbayensis Ngo & Chan, 2010; Gekko truongi Phung & Ziegler, 2011; Sphenomorphus yersini Nguyen, Nguyen, Nguyen, Orlov & Murphy, 2018; Lycodon anakradaya Nguyen, Duong, Wood & Grismer, 2022; and L. truongi Nguyen, Duong, Wood & Grismer, 2022 (see
During our recent field surveys on Hon Tre Island in Nha Trang Bay, Khanh Hoa Province, we encountered a specimen of Colubroelaps sp. that was superficially similar to C. nguyenvansangi in its overall morphological habitus and body coloration. Closer morphological examination of scalation, pattern, color, and morphometric characteristics of the Hon Tre specimen demonstrated clear morphological differences from C. nguyenvansangi in a number of taxonomically important traits. Therefore, in the present paper, we describe the Colubroelaps population from Hon Tre Island as a new species.
Fieldwork was carried out in Hon Tre Island within Nha Trang Bay, Khanh Hoa Province, Vietnam, by N. A. Poyarkov and A. M. Bragin from 15 to 20 of June 2023 (Fig.
Measurements and meristic counts followed
We conducted a detailed comparison of the morphological and coloration characters of the examined specimen with three available specimens of C. nguyenvansangi, including the holotype ZISP 25682, reported by
Morphological data on the type series of Colubroelaps adleri sp. nov. and C. nguyenvansangi; diagnostic differences from the new species are marked in bold. Notes: for abbreviations, see the Materials and methods section; “*”: data on the holotype of C. nguyenvansangi as reported by
Species | Colubroelaps adleri sp. nov | C. nguyenvansangi | ||
---|---|---|---|---|
Collection number | ZMMU Re-18000 | ZISP 25682 | ZMMU Re-15484 | ZMMU Re-15485 |
Type status | Holotype | Holotype | — | — |
Locality | Dam Bay, Hon Tre Isl., Khanh Hoa Prov., Vietnam | Loc Bac, Bao Lam Dist., Lam Dong Prov., Vietnam | Bu Gia Map NP., Binh Phuoc Prov., Vietnam | Cat Tien NP., Tan Phu Dist., Dong Nai Prov., Vietnam |
Sex | Female | Female | Male | Male |
SVL (mm) | 362 | 393 | 399 | 368 |
TaL (mm) | 40.2 | 107 | 121 | 98 |
TL (mm) | 402 | 500 | 520 | 466 |
TaL/TL | 0.10 | 0.21 | 0.23 | 0.21 |
HL (mm) | 8.0 | 5.9 | 5.9 | 5.5 |
HW (mm) | 5.2 | 4.3 | 4.3 | 4.0 |
SnL (mm) | 2.8 | 2.0 | 2.4 | 2.1 |
ED (mm) | 0.5 | 0.8 | 1.0 | 0.8 |
EN (mm) | 1.5 | 1.2 | 1.2 | 1.1 |
IO (mm) | 3.0 | 2.7 | 2.8 | 2.5 |
SL | 6/6 | 6/6 | 6/6 | 6/6 |
IL | 7/7 | 7/7 (6/6)* | 7/7 | 7/7 |
PrO | 1/1 | 1/1 | 1/1 | 1/1 |
PO | 1/1 | 1/1 | 1/1 | 1/1 |
Lor | 1/1 | 1/1 (0/0)* | 1/1 | 1/1 |
AT | 1/1 | 1/1 | 1/1 | 1/1 |
PT | 2/2 | 2/2 | 2/2 | 2/2 |
ASR | 14 | 16 | 16 | 16 |
MSR | 14 | 16 | 16 | 16 |
PSR | 14 | 16 | 16 | 16 |
VEN | 234 | 267 | 282 | 292 |
SC | 30 | 81 | 87 | 86 |
Cloacal plate | divided | divided | divided | divided |
Dorsal color and pattern | light brown with interrupted dark stripe along spine | reddish-brown with continuous stripe along spine | reddish-brown with continuous stripe along spine | reddish-brown with continuous dark stripe along spine |
Pattern in the anterior part of head | dirty yellow-brown, narrow | uniform light yellow or white, wide | uniform light yellow or white, wide | uniform light yellow or white, wide |
Our morphological analysis, which recovered a number of important diagnostic characters summarized below, allows unambiguously distinguishing the population of Colubroelaps sp. from Khanh Hoa Province from C. nguyenvansangi. These results support our hypothesis that this recently discovered lineage of Colubroelaps sp. from Khanh Hoa Province represents a previously unknown species, which we formally describe below.
• ZMMU Re-18000 (field tag NAP-15227), adult female, collected by Nikolay A. Poyarkov and Andrey M. Bragin on June 17, 2023, from Dam Bay Research Station, Hon Tre Island, within Nha Trang Bay in Vinh Nguyen Ward, Nha Trang City, Khanh Hoa Province, Vietnam (12.198°N, 109.289°E; at the elevation of 30 m asl.).
Colubroelaps adleri sp. nov. can be distinguished from C. nguyenvansangi by the following combination of morphological characters: body size small (TL 402 mm); tail relatively short (ratio TaL/TL 0.10); dorsal scales in 14–14–14 rows; supralabials six, third and fourth entering orbit; infralabials seven; loreal present; ventral scales 234; subcaudals 30, all divided; cloacal plate divided; dorsal coloration pale brown with narrow and interrupted dark stripe along spine; body flanks dark gray lacking bluish iridescence; ventrally uniform off-white; head black with rostral, nasals, prefrontals, preoculars, loreal, and the two anterior supralabials, as well as the anterior parts of supraoculars and frontal shields dirty yellowish-brown with dark brown spots.
Adult female specimen in a good state of preservation (Fig.
The holotype of Colubroelaps adleri sp. nov. in life (ZMMU Re-18000, adult female) from Hon Tre Island, Khanh Hoa Province, Vietnam. A. Dorsal view of the head; B. Ventral view of the head; C. Lateral view of the right side of the head; D. Lateral view of the left side of the head; E. Ventral view of the tail; F. Ventral view of the body; G. Dorsal view of the body. Scale bars: 5 mm (A–D); 10 mm (E–G). Photographs by A. M. Bragin.
Line drawings of head scalation of the Colubroelaps adleri sp. nov. holotype (ZMMU Re-18000, adult female; A–C) and of the C. nguyenvansangi holotype (ZISP 25682, adult female; D–F). Line drawings show the head scales in lateral (A, D), dorsal (B, E), and ventral (C, F) aspects. Abbreviations: ACS = anterior chin shield; AT = anterior temporal; F = frontal; G = gular scale; IL = infralabial; IN = internasal; L = loreal; LPT = lower posterior temporal; M = mental; N = nasal; P = parietal; PCS = posterior chin shield; PF = prefrontal; PO = postocular; PrO = preocular; R = rostral; SL = supralabial; SO = supraocular; UPT = upper posterior temporal. Scale bar equals 5 mm. Line drawings by A. M. Bragin.
Body glossy but lacking the metal/bluish iridescence (Figs
Two species of the genus Colubroelaps in life. A. Colubroelaps adleri sp. nov., holotype ZMMU Re-18000, adult female from Dam Bay Research Station, Hon Tre Island, Khanh Hoa Province, Vietnam; B. Colubroelaps nguyenvansangi, ZMMU Re-15485, adult male from Cat Tien NP., Tan Phu District, Dong Nai Province, Vietnam. Photographs by: A. M. Bragin (A); E. A. Galoyan (B).
The main differences between the new species and C. nguyenvansangi are summarized in Table
The species epithet ‘adleri’ is a patronymic adjective in genitive singular. We name the new species in honor of Dr. Kraig Adler, Professor Emeritus at Cornell University (New York, USA), in recognition of his outstanding support to the international herpetological community as well as his remarkable scientific contribution to Asian herpetology. We suggest the following common names for the new species: “Adler’s lace snake” (in English), “Shnurkovaya zmeya Adlera” (Шнурковая змея Адлера, in Russian), and “Rắn hổ nước Át-Lơ” (in Vietnamese).
Currently, Colubroelaps adleri sp. nov. is known only from a single locality in secondary dry maritime evergreen forest on Hon Tre Island, Khanh Hoa Province, South Central Coastal Region of Vietnam (Figs
A parasitic invasion of the Acanthocephala (Kölr.) worm was found in the subcutaneous cavity between the skin and the body muscles in the posterior third of the specimen length on its dorsal side (Figs
During the re-examination of the C. nguyenvansangi holotype (ZISP 25682), we found several inconsistencies contradicting its original description by
Therefore, based on re-examination of the holotype and examination of two additional specimens of C. nguyenvansangi, both males, we provide below a revised diagnosis for this species as follows: body size comparatively large (TL 466–520 mm in males, 500 mm in a single female), tail relatively long (TaL/TL ratio 0.21–0.23 in males, 0.21 in a single female); dorsal scales in 16–16–16 rows; supralabials six, third and fourth entering orbit; infralabials seven; loreal present; 1/1 nasal, nostril completely enclosed in nasal scale; ventral scales 282–292 in males, 267 in a single female; subcaudals 86–87 in males, 81 in a single female, all divided; cloacal plate divided; dorsally reddish-brown with narrow and continuous dark stripe along spine; flanks dark gray, nearly black with bluish iridescence; ventral surfaces bluish-white; head black with rostral, nasals, prefrontals, preoculars, loreal, and the two anterior supralabials and the anterior parts of supraocular and frontal shields uniform light yellow or white lacking dark markings.
Based solely on morphological characters, we have identified the Hon Tre specimen of Colubroelaps as a new species. Further molecular analyses are required to clarify the degree of genetic divergence between the two species of Colubroelaps, as well as to shed light on the phylogenetic position of this enigmatic genus within Colubroidea. Colubroelaps adleri sp. nov. occurs at low elevations of ca. 30 m asl. and appears to be restricted to the unique maritime dry evergreen forests of southern Vietnamese coasts, in contrast to its sister species C. nguyenvansangi, which occurs at elevations of 100–930 m asl. in lowland and mid-elevation seasonally dry monsoon semideciduous forests of southern Vietnam as defined by
Our discovery of Colubroelaps adleri sp. nov. significantly expands the knowledge on the geographic distribution of the genus Colubroelaps, which is now for the first time recorded from the coastal areas of southern and central Vietnam (Fig.
The fieldwork in Vietnam was completed within the frameworks and with partial financial support from the research project E-1.2 of the Joint Vietnam-Russia Tropical Science and Technology Research Center for 2024 (Task No. 3). Permission to conduct fieldwork in Khanh Hoa Province was granted by the Bureau of Forestry, Ministry of Agriculture and Rural Development of Vietnam, as well as by the local administration, the Forest Protection Department of the Peoples’ Committee of Khanh Hoa Province (permit number #5565/UBND-KT of 08.06.2023). We are deeply grateful to Eduard A. Galoyan (ZMMU, Russia), Alina V. Alexandrova (MSU, Russia), and Thuc Van Phan (SIFASV, Vietnam) for providing photos and information. We also warmly thank Duc Trong Nguyen (SIFASV, Vietnam) for help in the preparation of the map. We thank Valentina F. Orlova (ZMMU) and Natalia B. Ananjeva (ZISP) for permission to examine specimens under their care. We thank Sabira S. Idiiatullina (MSU) for assistance in the laboratory. NAP and AMB are grateful to Andrei N. Kuznetsov, Hoi Dang Nguyen, Svetlana P. Kuznetsova, and Leonid P. Korzoun for their support and organization of fieldwork. We are thankful to Andrei N. Kuznetsov for help with plant identification. We are grateful to two anonymous reviewers for their comments on the earlier version of the manuscript. This work was supported by the Russian Science Foundation to N. A. Poyarkov (Grant No. 22-14-00037, specimen collection and preservation and morphological analyses, data analysis) and in part by the Rufford Foundation to T. V. Nguyen (Grant No. 45888-2; data analysis).