A new species of Plagiopholis Boulenger, 1893 (Serpentes, Pseudoxenodontidae) from Guangdong, China

A new species of Plagiopholis Boulenger, 1893 (Serpentes, Pseudoxenodontidae) from Guangdong, China Shuo Qi1, Han-Ming Song1, Hao-Cong Yang1, Yu-Hao Xu2, Rui-Jian Fang3, Jun-Rong Su4, Zhi-Fa Liu5, Yue-Ning Gong5, Fang-Hua Li6, Chun-He Lyu7, Bing-Yang Wang8, Ying-Yong Wang1 1 School of Ecology / School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, Guangdong, China 2 State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, 810016, Qinghai, China 3 No. 42, Qiaole Road, Xiqiao Town, Nanhai District, Foshan 528211, Guangdong, China 4 Foshan Nature Fenxiangshe Nature Science Popularization Co., Foshan 528500, Guangdong, China 5 Administration of Guangdong Nanling National Nature Reserve, Shaoguan 512000, Guangdong, China 6 Administration of Guangdong Tianjingshan National Nature Park, Shaoguan 512726, Guangdong, China 7 Forest Resources Conservation Center of Guangdong Province, Guangzhou 510173, Guangdong, China 8 Guangdong Wildlife Rescue and Monitoring Center, Guangzhou 510520, Guangdong, China https://zoobank.org/E583E9A7-1EFB-4E0E-9F12-A8A688950607 Corresponding authors: Shuo Qi ([email protected]); Ying-Yong Wang ([email protected]) Academic editor: Justin Bernstein ♦ Received 21 September 2025 ♦ Accepted 20 October 2025 ♦ Published 17 November 2025 Abstract The genus Plagiopholis Boulenger, 1893 is a poorly studied genus from the Oriental realm, currently comprising six recognized species. We herein describe a new species of the genus, Plagiopholis maculosa sp. nov. from Guangdong Province, China. A morphological examination combined with two mitochondrial gene fragments (CO1 and cyt b), was used to test its distinctiveness within Plagiopholis. Morphologically, the new species differs from other congeners by the following diagnostic characteristics: no loreal; temporals 2+2; maxillary teeth 17; 104 ventrals, excluding two preventrals; 24 pairs of subcaudals, excluding the tail tip; presence of a large inverted “V”-shaped nuchal blotch; and a series of distinctive irregular blotches on the dorsum. The phylogenetic analyses shows that the new species exhibits pronounced genetic divergence from all recognized congeners (12.73%–15.88% in CO1, 16.17%–17.54% in cyt b). This discovery increases the number of valid species in the genus Plagiopholis to seven. Moreover, the extensive sampling gaps across its distribution suggest that additional cryptic species may remain to be discovered. Key Words Mountain Snakes, morphology, Nanling Mountains, Plagiopholis maculosa sp. nov., taxonomy Introduction Plagiopholis Boulenger, 1893, commonly known as the mountain snakes, is a poorly studied genus of small, semi-fossorial, non-venomous snakes, distributed in southern China, Myanmar, Laos, Vietnam and the central and northern parts of Thailand (Zhao 2006; Cai et al. 2025; Uetz et al. 2025). Although species of the genus Plagiopholis have a relatively wide distribution, specimens are rarely collected due to their cryptic habits. Consequently, for a long time, research on Plagiopholis relied exclusively on morphological data, until Zhong et al. (2015) provided molecular sequences for the genus by placing P. unipostocularis Zhao & Huang, 1979 in synonymy with P. blakewayi Boulenger, 1893. Nevertheless, comprehensive phylogenetic and biogeographic assessments of the genus remain hindered by substantial sampling gaps. Recently, two taxonomic studies provided molecular sequences of the topotypic material of P. styani (Boulenger, 1899), which enabled the recognition of additional cryptic linZoosyst. Evol. 101 (4) 2025, 2171–2180|DOI 10.3897/zse.101.172706 Copyright Qi, S. 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. zse.pensoft.net Qi, S. et al.: A new species of Plagiopholis2172 eages within Plagiopholis. In the same context, two new species from China were described and the distribution range of P. styani was revised (Cai et al. 2025; Liu et al. 2025). This brings the total number of valid species in the genus to six: P. acuta Xu, Ma & Cai, 2025, P. blakewayi, P. delacouri Angel, 1929, P. nuchalis (Boulenger, 1893), P. pluvialis Cai, Xu & Ma, 2025, and P. styani. Among these, all species except P. delacouri occur in China. Historically, records of Plagiopholis from Guangdong Province, China have been sparse. Mell (1929) hypothesized that Trirhinopholis styani might occur in northern Guangdong near the border with Jiangxi. The first formal record was reported by Liang (2003), who identified a specimen from the Nanling National Nature Reserve as Plagiopholis styani. In the more than two decades since, only a few sighting records have been documented, but no additional specimens have been obtained. During recent herpetological surveys in Tianjingshan National Forest Park, Nanling National Nature Reserve, one snake specimen was collected. Detailed morphological examinations and further molecular analyses revealed that this specimen represented a separately evolving lineage within the genus Plagiopholis which can be distinguished from all recognized congeners. In light of these findings, we provide a detailed description of the new species herein. Materials and methods Morphometrics Morphological examinations were performed on a single specimen collected from Tianjingshan National Forest Park, Ruyuan County, Shaoguan City, Guangdong Province, China (Fig. 1). The specimen was fixed in 10% buffered formalin after taking the tissue samples (liver and muscle), and then transferred to 70% ethanol for permanent preservation. The specimens are deposited in the Museum of Biology, Sun Yat-sen University (SYS r002979). Morphological descriptions follow Dowling (1951) and Zhao (2006). The following measurements were taken with digital calipers (Neiko 01407A Stainless Steel 6-Inch Digital Caliper, USA) to the nearest 0.1 mm: TL total length (from tip of snout to tip of tail); SVL snout-vent length (from tip of snout to posterior margin of cloacal plate); TaL tail length (from posterior margin of cloacal plate to tip of tail); HL head length (from tip of snout to posterior margin of the mandible); HW maximum head width; ED eye horizontal diameter. Scalation features and their abbreviations are as follows: DSR dorsal scale rows, counted at one head length behind head, at midbody, and at one head length before Figure 1. The type locality of Plagiopholis maculosa sp. nov. and previously recorded locality of Plagiopholis cf. styani in Guangdong Province, China. Zoosyst. Evol. 101 (4) 2025, 2171–2180 zse.pensoft.net 2173 Table 1. Sample list of the genus Plagiopholis and outgroup for phylogenetic analysis in this study. Species Voucher Locality CO1 Cyt b Reference 1Plagiopholis maculosa sp. nov. SYS r002979 China: Guangdong: Ruyuan: Mt. Tianjing C_AA125965 C_AA126388 This study 2Plagiopholis acuta QHU 2024009 China: Hunan: Xinshao PV335150 PV340623 Cai et al. 2025 3Plagiopholis acuta QHU 2024011 China: Hunan: Xinshao PV335152 PV340625 Cai et al. 2025 4Plagiopholis acuta QHU 2024012 China: Hunan: Xinshao PV335153 PV340626 Cai et al. 2025 5Plagiopholis acuta QHU 2024044 China: Hunan: Xinshao PV335154 PV340627 Cai et al. 2025 6Plagiopholis blakewayi HS 11148 China: Yunnan: Mengzi MK064686 MK201341 Li et al. 2020 7Plagiopholis blakewayi 10-Jun China: Yunnan MK201340 MK064685 Li et al. 2020 8Plagiopholis blakewayi SYS r002136 China: Yunnan: Wenshan / PV340636 Cai et al. 2025 9Plagiopholis blakewayi SYS r002207 China: Sichuan: Yanbian PV335163 PV340637 Cai et al. 2025 10 Plagiopholis nuchalis QHU 2024045 China: Yunnan: Xishuangbanna PV335164 PV340638 Cai et al. 2025 11 Plagiopholis nuchalis MS 853 China: Yunnan: Simao PV335165 PV340639 Cai et al. 2025 12 Plagiopholis pluvialis HS 09028 China: Sichuan: Mianyang MK064681 MK201336 Li et al. 2020 13 Plagiopholis pluvialis YBU 13224 China: Guizhou: Tongren / KT199002 Zhong et al. 2015 14 Plagiopholis pluvialis EM 1906004 China: Sichuan: Leshan MW697084 MW697084 Li et al. 2020 15 Plagiopholis pluvialis GP 833 China: Sichuan: Anzhou / KT199000 Zhong et al. 2015 16 Plagiopholis pluvialis QHU 2024006 China: Sichuan: Dujiangyan PV335155 PV340628 Cai et al. 2025 17 Plagiopholis pluvialis QHU 2024007 China: Sichuan: Wenchuan PV335156 PV340629 Cai et al. 2025 18 Plagiopholis pluvialis CIB XMG 2023001 China: Sichuan: Dujiangyan PV335157 PV340630 Cai et al. 2025 19 Plagiopholis pluvialis CIB CB2024EMS001 China: Sichuan: Emeishan PV335158 / Cai et al. 2025 20 Plagiopholis pluvialis CIB 119370 China: Sichuan: Emeishan PV335159 PV340632 Cai et al. 2025 21 Plagiopholis pluvialis SYS r002035 China: Guizhou: Bijie PV335162 PV340635 Cai et al. 2025 22 Plagiopholis styani KIZ 20180002 China: Fujian: Wuyishan: Guadun PV833807 PV847831 Liu et al. 2025 23 Plagiopholis styani CIB WYS2024001 China: Jiangxi: Yanshan PV335147 PV340620 Cai et al. 2025 24 Plagiopholis styani ZJFRR 202407001 China: Zhejiang: Huzhou PV335148 PV340621 Cai et al. 2025 25 Plagiopholis styani ZJFRR 202207001 China: Zhejiang: Hangzhou PV335149 PV340622 Cai et al. 2025 26 Pseudoxenodon bambusicola SYS r000922 China: Guangdong: Shaoguan: Xiaokeng Town MK064772 / Li et al. 2020 vent; SPL supralabials; IFL infralabials; CS chin shields; PrO preoculars; PtO postoculars; LoR loreal; TMP temporals; V ventral scales; PrC precloacal plate; SC subcaudals. Gender was determined by dissection or by the presence/absence of everted hemipenes. The numbers of maxillary teeth (MT) were counted by carefully dissecting the gums of the right maxilla under the stereo microscope. Laboratory methods Total genomic DNA was extracted from the liver tissue sample using the TIANamp Genomic DNA Kit (Tiangen Biotech Co., Ltd, Beijing). Two mitochondrial gene fragments, the partial cytochrome c oxidase subunit 1 gene (CO1) and the partial cytochrome b gene (cyt b), were amplified using the polymerase chain reaction (PCR). For PCR experiments, the primers and conditions followed Cai et al. (2025). After spin column purification, PCR products were sequenced by Tianyi Huiyuan Biotech Co., Ltd, Wuhan using forward primers on an ABI 3730 automated genetic analyzer. Molecular phylogenetic analysis A total of 26 samples, comprising six Plagiopholis species and an outgroup Pseudoxenodon bambusicola Vogt, 1922, were included in the phylogenetic analyses (Table 1). Among them, newly sequenced data have been deposited in GenBase (https://ngdc.cncb.ac.cn/genbase), and all other sequences were downloaded from GenBank (https://www.ncbi.nlm.nih.gov/genbank). All sequences were aligned using the MAFFT (Multiple Alignment using Fast Fourier Transform) algorithm with default parameters in MAFFT v7.037b (Katoh and Standley 2013), edited in order and concatenated seriatim as a final dataset of 1632 bp (605 bp for CO1 and 1027 bp for cyt b) in MEGA 11 (Tamura et al. 2021). Then the dataset was analyzed using the methods of Bayesian Inference (BI) and Maximum Likelihood (ML) in MrBayes 3.2.4 (Ronquist et al. 2012) and IQ-TREE 2.2.2.6 (Minh et al. 2020), respectively. For the BI analysis, two independent runs of 200,000,000 generations of Markov chain Monte Carlo each were performed with default parameters using the following settings: sampling every 1000 generations with the final 25% samples from the beginning discarded as burn-in, resulting in a potential scale reduction factor less than 0.005. For the ML analysis, the best substitution model for the whole dataset was chosen using ModelFinder based on Bayesian information criteria (Kalyaanamoorthy et al. 2017), and a consensus tree was inferred from 1000 replicates each of the ultrafast bootstrap and SH-aLRT (approximate likelihood ratio test) (Anisimova et al. 2011; Minh et al. 2013). Node support was evaluated using Bayesian posterior probabilities (BPP), ultrafast bootstrap (UFB) values, and SH-aLRT values. Nodes with BPP ≥ 0.95, UFB ≥ 95, and SH-aLRT ≥ 80 were considered strongly supported. Pairwise genetic distances were calculated in MEGA 11 (Tamura et al. 2021) for CO1 and cyt b respectively using the Kimura 2-parameter model with default options. The final alignment matrix consisted of 605 bp from 22 sequences for CO1 and 1027 bp from 24 sequences for cyt b. zse.pensoft.net Qi, S. et al.: A new species of Plagiopholis2174 Results The BI and ML analyses produced identical topologies, which were integrated in Fig. 2. The pairwise distances based on CO1 and cyt b genes among all species are given in the Suppl. materials S1, S2, respectively. Phylogenetic analyses recovered a strongly supported monophyletic clade comprising all samples of the genus Plagiopholis (BPP 1.00). Within Plagiopholis, six well-supported clades were resolved, corresponding to the five currently recognized species plus a newly proposed species from Guangdong. The single Guangdong specimen constitutes a separate, strongly supported lineage (BPP = 0.95; UFB = 82; SH-aLRT = 96.2) that is sister to a clade containing P. pluvialis and (P. acuta + P. styani). The Guangdong specimen exhibits pronounced genetic divergence from all recognized congeners (12.73%–15.88% in CO1, 16.17%–17.54% in cyt b), exceeding the interspecific distances observed among the known species (4.87%–19.02% in CO1, 6.50%–20.57% in cyt b). Based on their phylogenetic relationships, genetic differentiation, and morphological distinctiveness (see Taxonomic accounts below), we hypothesize that the single specimen from Guangdong represents a separately evolving lineage and should be described as a new species. Taxonomic accounts Plagiopholis maculosa Qi, Song, Yang, Xu, Fang, Su & Wang, sp. nov. https://zoobank.org/7B70CA92-FA40-4E84-B38C-6D6A09548493 Type material. Holotype. SYS r002979, adult female (Figs 3–5A), collected by Rui-Jian Fang and Jun-Rong Su on 23 June 2025 from Tianjingshan National Forest Park (24.687856°N, 113.033517°E; ca 680 m a.s.l.), Nanling National Nature Reserve, Ruyuan County, Shaoguan City, Guangdong Province, China. Etymology. The specific epithet maculosa is the feminine nominative singular of the Latin adjective maculosus (“spotted, blotched”), chosen to agree in gender with the feminine generic name Plagiopholis. It refers to the distinctive series of irregular blotches along the dorsum of the new species. Suggested common name. Based on the type locality, we propose the English common name as “Nanling mountain snake”, and Chinese formal name as “南岭颈 斑蛇” (nánlǐng jǐngbānshé). Diagnosis. Plagiopholis maculosa sp. nov. can be differentiated from its congeners by the combination of the following morphological characters: (1) no loreal; (2) temporals 2+2; (3) maxillary teeth 17 in a single Figure 2. Maximum Likelihood consensus tree inferred from CO1 and cyt b genes. Node labels indicate BPP/UFB/SH-aLRT. SYS r000922 QHU 2024045 MS 853 HS 11148 SYS r002207 SYS r002136 10-Jun SYS r002979 YBU 13224 SYS r002035 HS 09028 QHU 2024006 CIB CB2024EMS001 QHU 2024007 CIB XMG 2023001 EM 1906004 GP 833 CIB 119370 QHU 2024044 QHU 2024012 QHU 2024011 QHU 2024009 CIB WYS2024001 ZJFRR 202407001 ZJFRR 202207001 KIZ 2018002 1.00/92/93.8 1.00/100/99.7 1.00/100/100.0 1.00/99/99.9 1.00/100/100.0 0.95/82/96.2 - /38/15.5 1.00/100/98.2 1.00/100/99.5 0.05 Plagiopholis Pseudoxenodon bambusicola nuchalis blakewayi maculosa sp. nov. pluvialis acuta styani 1.00/ - / - Zoosyst. Evol. 101 (4) 2025, 2171–2180 zse.pensoft.net 2175 female; (4) 104 ventrals, excluding two preventrals in a single female; (5) 24 pairs of subcaudals, excluding tail tip in a single female; (6) presence of a large inverted “V”-shaped nuchal blotch; (7) dorsal surface of the body reddish-brown, with large black-brown spots scattered along the sides; the scales between these lateral spots have white margins, while the anterior and posterior adjacent scales are darker with black-brown edges, together forming irregular blotches along the dorsum. Description of holotype. Adult female (Figs 3–5A, 6A). Body size small and stubby, TL 295.9 mm (SVL 261.4 mm, TaL 34.5 mm), tail short (TaL/TL: 0.12). Head small, indistinct from neck, longer than width and narrow anteriorly, HL 13.3 mm, HW 8.4 mm (HW/ HL: 0.63); eye relative moderate, ED 2.4 mm (ED/HL: 0.18), pupil round. Rostral triangular, much wider than high, visible from dorsum; nostril laterally pointed, located in the middle of nasal; nasal divided into two scales by nostril; no loreal; postnasal in contact with one enlarged preocular; two postoculars, upper one larger than the lower; two anterior temporals and two posterior temporals on each side; six supralabials on each side, first and second in contact with nasal, fourth and fifth entering the orbit, the sixth largest; two pairs of chin shields, elongate, the anterior pair in contact with the mental and slightly longer than posterior one; six infralabials on each side, first to third in contact with anterior pair of chin shields, third and forth in contact with posterior chin shields; internasals and prefrontals paired; frontal single and enlarged, narrowed posteriorly; parietals paired, longer than width, in contact with each other medially, with upper anterior and posterior temporals laterally. Dorsal scales in 15–15–15 rows, smooth throughout, without apical pits, the outermost dorsal scale rows are enlarged and significantly differ in size from adjacent scales; 104 ventrals, excluding two preventrals; 24 pairs of subcaudals, excluding tail tip; precloacal plate entire. Coloration in life. Dorsal surface of head reddish-brown, with scattered small black spots and brown blotches; the supralabials and infralabials are creamywhite with black and brown edges on both sides. Ventral surface of head cream-white, with scattered large irregular black-brown blotches on the throat. A large, blackbrown, inverted “V”-shaped nuchal blotch is present on the neck, across eight scales at its widest point, across two or three scales on each side, with its posterior margin faintly tinged with yellow. Dorsal surface of the body reddish-brown, with large black-brown spots scattered along the sides; the scales between these lateral spots have white margins, while the anterior and posterior adjacent scales are darker with black-brown edges, together formFigure 3. The holotype of Plagiopholis maculosa sp. nov. in life. A. Dorsolateral view of body; B. Ventral view of body; C. Dorsal head; D. Lateral head; E. Ventral head. Photos by Shuo Qi and Hao-Cong Yang. zse.pensoft.net Qi, S. et al.: A new species of Plagiopholis2176 Figure 4. The holotype of Plagiopholis maculosa sp. nov. in preservation. A. Dorsol view of body; B. Ventral view of body. Photos by Shuo Qi. ing irregular blotches along the dorsum. The ventral surface of the neck is cream-white in ground color, bearing brown blotches edged with black. The ventral coloration of the body is slightly darker, composed of numerous orange-red pigment spots, with some ventral scales bearing larger dark brown blotches on both sides. The ventral surface of the tail is slightly yellowish. Coloration in preservation. The coloration of the dorsum faded to grayish brown. The irregular blotches on the dorsum became more distinct. The ventral surface faded to yellowish white. Comparisons. Plagiopholis maculosa sp. nov. is distinguishable from its congeners by a combination of the following morphological characters (Table 2; Figs 5; 6). Zoosyst. Evol. 101 (4) 2025, 2171–2180 zse.pensoft.net 2177 Figure 5. Comparisons of general morphological aspect among all Plagiopholis species in China. A. Plagiopholis maculosa sp. nov., from Ruyuan County, Guangdong Province, photo by Hao-Cong Yang; B. Plagiopholis acuta, from Xinshao County, Hunan Province, photo by Yu-Hao Xu; C. Plagiopholis blakewayi, from Yanbian County, Sichuan Province, photo by Jian Wang; D. Plagiopholis nuchalis, from Dai Autonomous Prefecture of Xishuangbanna, Yunnan Province, photo by Tie-Rui Zhang; E. Plagiopholis pluvialis, from Wenchuan County, Sichuan Province, photo by Yu-Hao Xu; F. Plagiopholis styani, from Lin’an District, Zhejiang Province, photo by Yu-Hao Xu. Table 2. Diagnostic characters among all seven species of the genus Plagiopholis. Species SPL IFL LoR PrO PtO TMP V SC MT NB Reference Plagiopholis maculosa sp. nov. 6 6 0 1 2 2+2 104 in a single female 24 in a single female 17 in a single female inverted “V”- shaped This study Plagiopholis acuta 6, rarely 7 6 0 1 2 2+2, 114–115 in males; 115–121 in females 29–30 in males; 24–25 in females 17–18 in males; 15–17 in females pentagonal or sub-annular shaped Cai et al. (2025) Plagiopholis blakewayi 5 or 6 6, rarely 4 or 5 0, rarely 1 1 2, rarely 1 0+1 or 1+1 107–125 in males; 115–132 in females 20–31 in males; 17–28 in females n/a arrow-shaped, irregular, or absent Zhao (2006); Huang (2021) Plagiopholis delacouri 6 n/a n/a 1 2 1+2 113–129 22–28 n/a inverted “V”- shaped Angel (1929) Plagiopholis nuchalis 6 6 1 1 2 1+2 122–142 23–30 20–22 inverted “V”- shaped Zhao (2006) Plagiopholis pluvialis 6 6 0, rarely 1 1 2 2+2, rarely 2+1 102–110 in males;114–122 in females 26–31 in males; 16–26 in females 18 in males inverted “V”- shaped Cai et al. (2025) Plagiopholis styani 6, rarely 7 6, rarely 5 0, rarely 1 1 2 2+2, rarely 2+1 114–121 in males; 116–122 in females 26–30 in males; 23–28 in females 20–21 in males; around 18 in female pentagonal, sub-annular or sagittate shaped Liu et al. (2025); Cai et al. (2025) By absence of the loreal, Plagiopholis maculosa sp. nov. can be distinguished from P. nuchalis (single loreal). By having temporal scales 2+2, Plagiopholis maculosa sp. nov. can be distinguished from P. blakewayi (0/1+1), P. nuchalis (1+2), and P. delacouri (1+2). By having fewer ventral scales (104 in the single female), Plagiopholis maculosa sp. nov. can be distinguished from P. acuta (114–115 in males; 115–121 in females), P. blakewayi (107–125 in males; 115–132 in females), P. delacouri (113–129), P. nuchalis (122–142), P. pluvialis (102–110 in males; 114–122 in females), P. styani (114–121 in males; 116–122 in females). By having a large inverted “V”-shaped nuchal blotch, Plagiopholis maculosa sp. nov. can be distinguished from P. acuta (pentagonal or sub-annular shaped) and P. styani (pentagonal, sub-annular or sagittate shaped). By having a series of irregular blotches on the dorsum, Plagiopholis maculosa sp. nov. can be distinguished from all congeners (reticulated pattern on the dorsum). Distribution and ecology. Plagiopholis maculosa sp. nov. is currently known only from Tianjingshan National Forest Park, Nanling National Nature Reserve, Ruyuan County, Shaoguan City, Guangdong Province, China. The holotype was discovered at approximately 9:00 a.m. in a roadside ditch within evergreen broad-leaved forest at an elevation of ca. 680 m. The forest is characterized by dense canopy cover, abundant leaf litter, and a moist microenvironment typical of the Nanling Mountains region. zse.pensoft.net Qi, S. et al.: A new species of Plagiopholis2178 Figure 6. Dorsal (left), lateral (middle), and ventral (right) head comparisons among Plagiopholis species in China. A. Plagiopholis maculosa sp. nov., SYS r002929, from Mt. Tianjing, Guangdong Province, Photos by Shuo Qi; B. P. acuta, QHU 2024009, from Xinshao County, Hunan Province, Photos by Yu-Hao Xu; C. P. blakewayi, QHU R2024056, from Liupanshui City, Guizhou Province, Photos by Yu-Hao Xu; D. P. nuchalis, ANU ZR24067, from Xishuangbanna, Yunnan Province, Photos by Tie-Rui Zhang; E. P. pluvialis, QHU 2024007, from Dujiangyan, Sichuan Province, Photos by Yu-Hao Xu; F. P. styani, ZJFRR 2022001, from Lin’an District, Zhejiang Province, Photos by Yu-Hao Xu. Images are not to scale. Discussion The Nanling Mountains, situated at the junction of several major biogeographic regions of southern China, function as both a refugium and a dispersal corridor. Recognized as a biodiversity hotspot harboring unique amphibian and reptile lineages, the discovery of Plagiopholis maculosa provides additional evidence of the region’s remarkable faunal diversity and biogeographic significance. Although P. maculosa is described based on a single specimen, both morphological distinctiveness and significant genetic divergence from all congeners provide sufficient evidence to justify its recognition as a valid species. The rarity of Plagiopholis in field collections may be attributed to its secretive habits, narrow habitat preference, and low population density, which together explain the scarcity of available specimens. Liang (2003) reported a new record of Plagiopholis styani from Guangdong Province, describing its nuchal Zoosyst. Evol. 101 (4) 2025, 2171–2180 zse.pensoft.net 2179 marking as a black transverse band. This feature differs from that of P. maculosa described herein, but corresponds to the diagnostic characters of P. acuta and P. styani. Therefore, pending the acquisition of additional specimens, the distribution record of P. styani in Guangdong is retained. Despite recent advances in the systematics of Plagiopholis (Zhong et al. 2015; Cai et al. 2025; Liu et al. 2025; this study), the genus still suffers from significant sampling gaps. Nearly all molecular data available so far have been derived from Chinese populations, while no genetic data are available from Myanmar, Laos, Vietnam, or Thailand. Consequently, the taxonomic status of P. delacouri from Vietnam and Laos remains uncertain, and the possibility of cryptic lineages within populations from Myanmar and Thailand cannot be ruled out. Comprehensive sampling across the full distribution of the genus is therefore essential. Such efforts will provide a more complete understanding of its species diversity and evolutionary history. Acknowledgements We are grateful to Shun Ma for his help in the preparation of the manuscript. We also grateful to Tie-Rui Zhang for providing the photo of Plagiopholis nuchalis. We express our sincere gratitude to Dr. Bo Cai, Dr. Gernot Vogel, and the scientific editor, for their valuable comments and suggestions that greatly improved the manuscript. This work was supported by DFGP Project of Fauna of Guangdong-202115, Science and Technology Planning Projects of Guangdong Province (Grant/Award Number: 2021B1212110002), and the project “Population Survey and Monitoring of the Shinisaurus crocodilurus and Syntopic Amphibian and Reptile Inventory” supported by the Guangdong Wildlife Rescue and Monitoring Center. References Angel F (1929) Liste des reptiles et batraciens du Haut-Laos recueillis par M. Delacour. Description d’un genre, de deux espèces et une variété d’ophidiens. Bulletin du Muséum National d’Histoire Naturelle 1(2): 75–81. Anisimova M, Gil M, Dufayard JF, Dessimoz C, Gascuel O (2011) Survey of branch support methods demonstrates accuracy, power, and robustness of fast likelihood-based approximation schemes. Systematic Biology 60(5): 685–699. https://doi.org/10.1093/sysbio/syr041 Boulenger GA (1893) Catalogue of the Snakes in the British Museum (Natural History) (Vol. I). 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