First description of the female of Clamaria andersoni Yang & Zheng, 2018 (Squamata, Calamariidae), with an expanded diagnosis

Biodiversity Data Journal 13: e165597 doi: 10.3897/BDJ.13.e165597 Taxonomy & Inventories First description of the female of Clamaria andersoni Yang & Zheng, 2018 (Squamata, Calamariidae), with an expanded diagnosis Tierui Zhang , Yuhao Xu , Nguyen Van Tan , Nikolay Poyarkov , Lifang Peng , Jundong Deng , Xinge Wang , Song Huang ‡ Anhui Province Key Laboratory of the Conservation and Exploitation of Biological Resource, College of Life Sciences, Anhui Normal University, Wuhu, China § State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, China | The School of Medicine & Pharmacy, Duy Tan University, Da Nang, Vietnam ¶ Center for Entomology & Parasitology Research, Da Nang, Vietnam # Department of Vertebrate Zoology, Lomonosov Moscow State University, Moscow, Russia Corresponding author: Nguyen Van Tan ([email protected]), Song Huang ([email protected]) Academic editor: Johannes Penner Received: 18 Jul 2025 | Accepted: 19 Nov 2025 | Published: 15 Dec 2025 Citation: Zhang T, Xu Y, Tan N, Poyarkov N, Peng L, Deng J, Wang X, Huang S (2025) First description of the female of Clamaria andersoni Yang & Zheng, 2018 (Squamata, Calamariidae), with an expanded diagnosis. Biodiversity Data Journal 13: e165597. https://doi.org/10.3897/BDJ.13.e165597 Abstract Background Calamaria andersoni Yang & Zheng, 2018, was originally described from a single adult male collected in Dehong Prefecture, Yunnan Province, China. Until now, no female specimens had been reported, limiting understanding of sexual dimorphism and diagnostic variation. Based on newly collected material from Mangshi City and Lianghe County, we identified five males and one female as C. andersoni through morphological comparisons and mitochondrial cytochrome b gene analysis. ‡ § |,¶ # § § ‡ ‡ © Zhang T et al. 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. New information We provide the first morphological description of the female and revise the species diagnosis based on both sexes. The female is distinguishable by a higher number of ventrals and fewer subcaudals. Genetic data confirmed all specimens as belonging to a well-supported clade of C. andersoni, which is 9.8–10.1% divergent from C. yunnanensis . The known distribution of the species is extended to lower elevations (1,185–1,315 m a.s.l.) within tropical evergreen forests of Dehong. Given its relatively broad elevational range and occurrence in mature forests but no apparent population threats, we propose its conservation status as Least Concern (LC) under IUCN criteria. These findings provide new insight into sexual dimorphism, distribution, and species-level boundaries in Calamaria, emphasising the importance of continued surveys in underexplored montane regions of Yunnan and adjacent northern Myanmar. Keywords Reed Snake, morphology, phylogenetics, sexual dimorphism, China Introduction The Southeast Asian reed snake genus Calamaria H. Boie in Boie (1827), comprises small, burrowing, forest-dwelling, nonvenomous snakes. The genus currently includes 70 species distributed from eastern China and the Ryukyu Islands in the north, through Northeastern India, Vietnam, Laos, Cambodia, Thailand, and the Malay Peninsula to Myanmar in the west, and southward to Sulawesi, Seram, and the Philippines (Poyarkov et al. 2023, Uetz et al. 2025). In recent years, extensive field sampling combined with molecular phylogenetic analyses has led to the discovery and description of more than ten new species in this genus (e.g., Yang and Zheng 2018, Poyarkov et al. 2019, Lee 2021, Yeung et al. 2022, Cai et al. 2023). To date, seven species of Calamaria have been recorded from China: C. arcana Yeung, Lau & Yang; C. andersoni Yang & Zheng; C. berezowskii Günther; C. jinggangensis Cai, Jiang, Wu, Huang, Fei & Ding; C. pavimentata Duméril, Bibron & Duméril; C. septentrionalis Boulenger; and C. yunnanensis Chernov (Cai et al. 2023, Liang et al. 2024, Uetz et al. 2025). The Anderson’s Reed Snake, Calamaria andersoni, was described based on a single adult male specimen collected from Tongbiguan Township, Yingjiang County, Dehong Dai and Jingpo Autonomous Prefecture, Yunnan Province, China (Yang and Zheng 2018 ). According to Yang and Zheng (2018), a mitochondrial Cyt b gene analysis revealed that C. andersoni is most closely related to C. yunnanensis, yet it can be distinguished from the latter by several morphological characters: presence of a preocular scale (vs. absent in C. yunnanensis), fewer ventral scales in males (171 vs. 179–201), a higher number of subcaudals in males (23 vs. 15–22), all dorsal scale rows pigmented (vs. outermost one or two dorsal scale rows unpigmented), and ventral scales with dark lateral corners (vs. 2Zhang T et al immaculate ventrals in C. yunnanensis). However, no comparisons have yet been made between females of these two species. Despite its initial discovery, C. andersoni has remained poorly known due to the lack of additional specimens, particularly females. This gap has limited our understanding of the species' diagnostic traits and distribution. During a herpetofaunal survey in Yunnan Province, China, six specimens of Calamaria (one female and five males) were collected from Mangshi City and Lianghe County in Dehong Dai and Jingpo Autonomous Prefecture (Fig. 1, Table 1). Morphological comparisons and molecular phylogenetic analyses confirmed their identity as Calamaria andersoni. In this study, we provide the first morphological description of the female C. andersoni, update the known distribution of the species, and revise its diagnostic characters. Number on the map Verified by morphology data Verified by molecular data Location Sources Calamaria andersoni 1 yes yes Tongbiguan, Yingjiang, Dehong, Yunnan, China (type locality) Yang and Zheng (2018) 2 yes yes Mangdong, Lianghe, Dehong, Yunnan, China this study 3 no yes Tengchong, Baoshan, Yunnan, China Cai et al. (2023) 4 yes yes Mangshi, Dehong, Yunnan, China Cai et al. (2023); this study Calamaria yunnanensis 1 yes no Jingdong, Pu’er, Yunnan, China (type locality) Lee (2021) 2 yes yes Mt. Wanzhangshan, Simao, Yunnan, China Lee (2021); this study 3 yes no Mengsong, Mengla, Xishuangbanna, Yunnan, China this study Materials and methods Sampling Five adult male specimens and one adult female specimen of Calamaria were collected from Dehong Dai and Jingpo Autonomous Prefecture, Yunnan Province, China (Fig. 1). The specimens were humanely euthanised using a 0.7% solution of tricaine Table 1. List of localities of the Calamaria andersoni and C. yunnanensis appearing on Fig. 1. Symbols: (1) = Number on the map; (2) = Verified by morphology data (yes/no); (3) = Verified by molecular data (yes/no). Data is derived from own work (this study) and the literature (column 5), Cai et al. (2023) provides only molecular data. First description of the female of Clamaria andersoni Yang & Zheng, ... 3 methanesulfonate (MS-222) through intraperitoneal injection. Fresh liver tissue was extracted and immediately preserved in 95% ethanol for molecular analyses. The specimens were fixed and stored in 75% ethanol for long-term preservation and are deposited in the museum collections of Anhui Normal University (ANU), Anhui, China, and Qinghai University (QHU), Qinghai, China. All procedures complied with the Wildlife Protection Law of China and were approved by the Institutional Ethics Committee of Qinghai University (protocol number PJ202501-89) and the Animal Ethics Committee of Anhui Normal University (protocol number AHNU-ET2024169). Molecular phylogeny Total genomic DNA was extracted from preserved liver tissue with OMEGA Tissue DNA Kit D3396 (Omega Bio-Tek, Norcross, GA, USA). A fragment of the mitochondrial cytochrome b (Cyt b) gene was amplified using the primer pair L14910 (5’- GACCTGTGATMTGAAACCAYCGTTGT-3’) and H16064 (5’-CTTTGGTTTACAAGA ACAATGCTTTA-3’) (Burbrink et al. 2000). The double-stranded products were sequenced by General Biosystems (Anhui) Corp. Ltd (Chuzhou, China), and raw sequences were assembled using SeqMan in the DNASTAR software package (Burland 2000). Figure 1. Distribution ranges of Calamaria andersoni and C. yunnanensis in Yunnan, China. Numbers correspond to locality records (see Table 1 for locality details). Map was created in QGIS using open-source DEM data (NASA JPL 2013).  4Zhang T et al A total 44 sequences from 14 known Calamaria species and three out-group species, Elaphe quatuorlineata (Lacépède), Orientocoluber spinalis (Peters), and Lycodon rufozonatus Cantor, were obtained from GenBank or newly sequenced and incorporated into our dataset (Suppl. material 1 Table S1). DNA sequences were aligned by the Clustal W algorithm with default parameters (Thompson 1997) and trimmed with gaps partially deleted in MEGA X (Kumar et al. 2018). Bayesian inferences (BI) were conducted in MRBAYES v. 3.2.7a (Ronquist et al. 2012) under the GTR + I + G model on Phylosuite v1.2.3 (Zhang et al. 2020, Xiang et al. 2023). In the BI analysis, three independent runs were conducted with 1 × 10 generations and sampled every 1,000 generations, with the first 25% of samples were discarded as burn-in. In the ML analysis, the bootstrap consensus tree was inferred from 1000 replicates. Maximum likelihood (ML) was conducted under the best-fit substitution model (GTR + I + G) in RaxmlGUI 1.3 ( Silvestro and Michalak 2011). Bootstrap proportions (BSP) were investigated with 1,000 bootstrap replicates using the fast-bootstrapping algorithm. Uncorrected pairwise genetic distances (p-distance) of Cyt b gene among congeners were calculated with MEGA X ( Kumar et al. 2018). Morphological comparison Terminology and measurements follow Inger and Marx (1965). Measurements were taken with a digital slide caliper to the nearest 0.1 mm, except for body and tail lengths, which were measured to the nearest millimetre with a measuring tape. The number of ventral scales was counted according to Dowling (1951). The numbers of dorsal scale rows are given at one head length behind the head, at midbody, and at one head length before the vent. The sex was determined by dissection (inspection of gonads). Maxillary teeth of the specimens were counted by examining both maxillae using a dissecting pin under a binocular microscope prior to preservation. The following measurements (all in mm) and counts were taken: head length (HL, from snout tip to jaw angles); head width (HW, measured at the widest point of the head); eye diameter (ED, horizontal); eye-mouth distance (Eye-MouthD, measured from the anterior point of the eye to the mouth gap); naris–eye distance, measured from the anterior point of the eye to the medial point of the nostril (NarEye); interorbital distance, the straight-line distance between the eyes at the border of the supraoculars (IOD); snout-vent length (SVL); tail length (TaL); total length (TL); ratio of tail length/total length (TaL/TL); number of maxillary teeth (MT); dorsal scale rows number (DSR); supralabial scales (SL); number of supralabials touching the eye (SL-E); infralabial scales (IL); preocular scales (PrO); postocular scales (PoO); subcaudal scales (SC); ventral scales (VEN); contact of posterior chin shields (CPCS). Asymmetric characters are given in left/right order. Other abbreviations. Mt. = Mountain; NP = National Park; a.s.l. = above sea level. Museums, private collections and biorepository abbreviations are shown in Suppl. material 1 Table S2. 7 First description of the female of Clamaria andersoni Yang & Zheng, ... 5 Taxon treatment Calamaria andersoni Yang & Zheng, 2018 Materials a. scientificName: Calamaria andersoni; taxonID: urn:lsid:biosci.ohio-state.edu:osuc_names: 275502; scientificNameID: Calamaria andersoni; class: Reptilia; order: Squamata; family: Calamariidae; genus: Calamaria; specificEpithet: andersoni; scientificNameAuthorship: Yang & Zheng, 2018; country: China; countryCode: CN; stateProvince: Yunnan; locality: Mangshi City, Dehong Dai and Jingpo Autonomous Prefecture; verbatimElevation: 1315 m; verbatimLatitude: 24.520531°N; verbatimLongitude: 98.589152°E; verbatimCoordinateSystem: WGS84; eventDate: 5/3/2025; eventRemarks: collected by J.D. Deng; individualCount: 1; sex: male; lifeStage: adult; catalogNumber: ANU ZR25022; language: en; collectionCode: Reptilia; basisOfRecord: PreservedSpecimen; occurrenceID: E82D8737-6380-5668-BC4A-0939E497D4F9 b. scientificName: Calamaria andersoni; taxonID: urn:lsid:biosci.ohio-state.edu:osuc_names: 275502; scientificNameID: Calamaria andersoni; class: Reptilia; order: Squamata; family: Calamariidae; genus: Calamaria; specificEpithet: andersoni; scientificNameAuthorship: Yang & Zheng, 2018; country: China; countryCode: CN; stateProvince: Yunnan; locality: Lianghe County, Mangdong Town, Dehong Dai and Jingpo Autonomous Prefecture; verbatimElevation: 1185 m; verbatimLatitude: 24.674581°N; verbatimLongitude: 98.221510°E; verbatimCoordinateSystem: WGS84; eventDate: 6/15/2021; eventRemarks: collected by J.D. Deng; individualCount: 1; sex: female; lifeStage: adult; catalogNumber: HS R21036; language: en; collectionCode: Reptilia; basisOfRecord: PreservedSpecimen; occurrenceID: C3122350-A780-5D0A-A867-21B1B0CFB089 c. scientificName: Calamaria andersoni; taxonID: urn:lsid:biosci.ohio-state.edu:osuc_names: 275502; scientificNameID: Calamaria andersoni; class: Reptilia; order: Squamata; family: Calamariidae; genus: Calamaria; specificEpithet: andersoni; scientificNameAuthorship: Yang & Zheng, 2018; country: China; countryCode: CN; stateProvince: Yunnan; locality: Lianghe County, Mangdong Town, Dehong Dai and Jingpo Autonomous Prefecture; verbatimElevation: 1185 m; verbatimLatitude: 24.674581°N; verbatimLongitude: 98.221510°E; verbatimCoordinateSystem: WGS84; eventDate: 7/8/2024; eventRemarks: collected by J.D. Deng; individualCount: 1; sex: male; lifeStage: adult; catalogNumber: ANU ZR24017; language: en; collectionCode: Reptilia; basisOfRecord: PreservedSpecimen; occurrenceID: AF0FF5F1-E3D6-5819-9139-1B313EE7FD69 d. scientificName: Calamaria andersoni; taxonID: urn:lsid:biosci.ohio-state.edu:osuc_names: 275502; scientificNameID: Calamaria andersoni; class: Reptilia; order: Squamata; family: Calamariidae; genus: Calamaria; specificEpithet: andersoni; scientificNameAuthorship: Yang & Zheng, 2018; country: China; countryCode: CN; stateProvince: Yunnan; locality: Lianghe County, Mangdong Town, Dehong Dai and Jingpo Autonomous Prefecture; verbatimElevation: 1185 m; verbatimLatitude: 24.674581°N; verbatimLongitude: 98.221510°E; verbatimCoordinateSystem: WGS84; eventDate: 5/5/2025; eventRemarks: collected by J.D. Deng; individualCount: 1; sex: male; lifeStage: adult; catalogNumber: QHU R2025016; language: en; collectionCode: Reptilia; basisOfRecord: PreservedSpecimen; occurrenceID: 4971066E-766B-546C-81B9-ED2A161A67BD e. scientificName: Calamaria andersoni; scientificNameID: Calamaria andersoni; class: Reptilia; order: Squamata; family: Calamariidae; genus: Calamaria; specificEpithet: andersoni; scientificNameAuthorship: Yang & Zheng, 2018; country: China; countryCode: CN; stateProvince: Yunnan; locality: Lianghe County, Mangdong Town, Dehong Dai and 6Zhang T et al Jingpo Autonomous Prefecture; verbatimElevation: 1185 m; verbatimLatitude: 24.674581°N; verbatimLongitude: 98.221510°E; verbatimCoordinateSystem: WGS84; eventDate: 5/5/2025; eventRemarks: collected by J.D. Deng; individualCount: 1; sex: male; lifeStage: adult; catalogNumber: QHU R2025017; language: en; collectionCode: Reptilia; basisOfRecord: PreservedSpecimen; occurrenceID: 253E96DA-1AC2-5A2E-914F-D2CCFB7A5814 f. scientificName: Calamaria andersoni; scientificNameID: Calamaria andersoni; class: Reptilia; order: Squamata; family: Calamariidae; genus: Calamaria; specificEpithet: andersoni; scientificNameAuthorship: Yang & Zheng, 2018; country: China; countryCode: CN; stateProvince: Yunnan; locality: Lianghe County, Mangdong Town, Dehong Dai and Jingpo Autonomous Prefecture; verbatimElevation: 1185 m; verbatimLatitude: 24.674581°N; verbatimLongitude: 98.221510°E; verbatimCoordinateSystem: WGS84; eventDate: 5/5/2025; eventRemarks: collected by J.D. Deng; individualCount: 1; sex: male; lifeStage: adult; catalogNumber: QHU R2025018; language: en; collectionCode: Reptilia; basisOfRecord: PreservedSpecimen; occurrenceID: 8E047098C3BE-5A2B-8F70-C58A4F2436B6 Description of the female specimen (HS R21036) Measurements and scalation (Fig. 2). Specimen HS R21036 is in excellent condition. Body slender and cylindrical (SVL 294 mm, TL 312 mm). Tail short, not as thick as body (TaL 18 mm, TaL/TL 5.8%); tail uniformly cylindrical in the anterior part, tail slowly tapering anteriorly, then abruptly tapering at tip; head small, elliptical in dorsal view (HL 7.8 mm, HW 4.2 mm, HH 3.5 mm); eye small and round (ED 0.9 mm), larger than eye-mouth distance (Eye-MouthD 0.9 mm), ED/HL 11.5%. Figure 2. Calamaria andersoni in preservative. Specimen HS R21036, adult female: A general dorsal view; B general ventral view; C dorsal view of head; D ventral view of head; E right lateral view of head; F left lateral view of head. Photographs by T.R. Zhang  First description of the female of Clamaria andersoni Yang & Zheng, ... 7 Rostral wider than high, portion visible from above almost equal to the length of the prefrontal suture; prefrontal slightly shorter than frontal, not entering orbit, in contact with 1 and 2 supralabial; frontal hexagonal, longer than wide, about 3.0 times the maximum width of the supraocular; paraparietal surrounded by six scales; preocular 1/1, higher than wide, slightly higher than postocular, not as high as eye diameter; postocular 1/1, higher than wide; nasals small, barely surrounding nostrils, surrounded by the 1 supralabial, rostral, and prefrontal; supralabials 4/4, 2 and 3 entering orbit, 4 largest, relative supralabial width 4>2>1>3; mental triangular, not in contact with the anterior chin shields; infralabials 5/5, first three pairs touching anterior chin shields, first pair meeting in midline, 4 largest; anterior chin shields longer than wide, pentagonal, meeting in midline; posterior chin shields shorter than the anterior ones, touching at their foremost ends and separated posteriorly by first gular scales. Dorsal scales in 13 rows throughout the body, reducing to six rows above the fifth subcaudal and to four rows above the second to last subcaudals. Dorsal scales homogeneous in size, entirely smooth; vertebral row not enlarged. Ventrals 186. Anal plate undivided. Subcaudals 14, paired and smooth; terminal scale single and rigid. Dentition. Maxillary teeth enlarged, uniformly arranged, nine on each side (9/9). Colouration in preservative (Fig. 2). Dorsal surface of the head, body, and tail light to dark brown, with a slightly faded pattern compared to the colouration in life. Lateral stripes are obscure or absent. The dorsal head scales are uniformly brown, with faint lighter mottling along the edges of the supralabials. The eye appears cloudy white due to fixation. The ventral surface is pale cream to yellowish white, with irregular brown to dark brown mottling along the outer margins of the ventral scales, especially pronounced on the anterior half of the body. The posterior venter and subcaudals are more uniformly cream-coloured with sparse dark markings. The chin and throat are pale, with scattered brown speckling on the infralabials and gular region. The tail tip is slightly darker dorsally and lighter ventrally, and has the same color as the adjacent trunk areas. Description of additional specimens Morphology. Body slender and cylindrical [the longest known specimen is 312 mm long (HS R21036); the longest known male is 295 mm long (SVL 269 mm, TaL 26 mm; ANU ZR24017); tail uniformly cylindrical in the anterior part, tail slowly tapering anteriorly, then abruptly tapering at tip (TaL/TL 8.8–9.2% in males (n=6) and 5.8% in females (n=1)). Body scalation. Dorsal scales in 13 rows throughout the body, reducing to 6 rows above the 4 –9 subcaudals and to 4 rows above the second and 5 to last subcaudals. Dorsal scales homogeneous in size, entirely smooth; vertebral row not enlarged. Ventrals 164–172 in males (n = 6), 186 in the female (n = 1). Anal plate st nd st nd rd th th th th th 8Zhang T et al undivided. Subcaudals 20–23 in males (n = 6), 14 in the female (n = 1), paired and smooth; terminal scale single and rigid. Head scalation. Rostral wider than high; portion visible from above almost equal to the length of the prefrontal suture; prefrontal slightly shorter than frontal, not entering orbit, in contact with 1 and 2 supralabial; frontal hexagonal, longer than wide; paraparietal surrounded by six scales; preocular 1/1, higher than wide, slightly higher than postocular, not as high as eye diameter; postocular 1/1, higher than wide; nasals small, barely surrounding nostrils, surrounded by 1 supralabial, rostral and prefrontal; supralabials 4/4, 2 and 3 entering orbit, 4 largest, relative supralabial width 4>2>1>3; mental triangular, not in contact with the anterior chin shields; infralabials 5/5, first three pairs touching anterior chin shields, first pair meeting in midline, 4 largest; anterior chin shields longer than wide, pentagonal, meeting in midline; posterior chin shields shorter than the anterior ones, touching anteriorly and separated posteriorly by first gular scales. Dentition. Maxillary teeth enlarged, uniformly arranged, nine on each side (9/9). Hemipenis (based on fully everted organ of adult male specimen QHU 2025018; Fig. 3 G-I). The hemipenis is bilobed, relatively short and thick, with two hemispherical lobes approximately equal in size. Lobes moderately expanded and rounded distally. The organ is deeply bifurcated, with the bifurcation starting at approximately the level of the 4 subcaudal scale and extending terminally to the tip of each lobe. The entire organ extends posteriorly to the level of the 7 subcaudal scale. Sulcus spermaticus is single, centrally positioned, bifurcating shortly before the base of the lobes, and terminating apically on each lobe. The truncus (stem) is cylindrical, unornamented, and smooth, lacking spines, folds, or calyces. The surface of both lobes and the proximal part of the truncus is smooth throughout, without papillate or spinulate structures. In preservative, the organ is uniformly pinkish to pale reddish, with the lobes slightly more pigmented than the basal stem. Colouration in life (Fig. 4 A-F). Dorsal surface of head, body, and tail uniformly dark brown to blackish, with subtle iridescence visible under direct light. A series of indistinct narrow dark stripes is present on the lateral sides of the body, often only faintly visible. Dorsal scales lack any conspicuous markings or collars. Supralabials and lower jaw are dark brown, with diffuse yellow to orange suffusion on the infralabials and throat region. Ventral surface bright orange to orange-yellow, bordered laterally by a narrow line of dark pigmentation at the outermost edges of the ventral scales. No light-coloured rings or collar markings are present on the nape or tail. The colouration of the tail tip is similar with that of the dorsum or slightly paler ventrally. Variation. 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Molecular Ecology Resources 20 (1): 348‑355. https://doi.org/10.1111/1755-0998.13096 Supplementary material Suppl. material 1: Tables S1–S4 Authors: Tierui Zhang, Yuhao Xu, Tan Van Nguyen, Nikolay A. Poyarkov, Lifang Peng, Jundong Deng, Xinge Wang, Song Huang Data type: occurences and morphological Brief description: Table S1. DNA sequences, voucher specimens, and GenBank accession numbers of the genus Calamaria and outgroup taxa used in this study. Table S2. Museums, private collections and biorepository abbreviations mentioned in this study. Table S3. Uncorrected p-distances (%) among Calamaria species based on 1,105 base pairs from the mitochondrial genes Cyt b. The serial numbers in Table S3 are consistent with those in Table S1. Table S4. Overview measurements of the examined specimens of Calamaria andersoni and C. yunnanensis from Yunnan, China. Download file (249.00 kb) First description of the female of Clamaria andersoni Yang & Zheng, ... 17