Amolops cuongi (Amphibia, Anura, Ranidae), a new species from the Hoang Lien Range, Vietnam

235 Amolops cuongi (Amphibia, Anura, Ranidae), a new species from the Hoang Lien Range, Vietnam Anh Van Pham1, Chung Van Hoang2,3 , Benjamin Tapley4, Luan Thanh Nguyen5, Hanh Huu Nguyen6, Toi Van La6, Thomas Ziegler7,8 , Jodi J. L. Rowley9,10 , Truong Quang Nguyen2,11 , Minh Duc Le1,12,13 1 Faculty of Environmental Sciences, University of Science, Vietnam National University, Hanoi, 334 Nguyen Trai Road, Hanoi, Vietnam 2 Institute of Biology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Hanoi 10072, Vietnam 3 Green Environment Centre, 119, Lane 3, Tho Lao Street, Hanoi, Vietnam 4 Zoological Society of London, Regent’s Park, London, NW1 4RY, UK 5 Asian Turtle Program of Indo-Myanmar Conservation, R.1301, CT1 Bac Ha C14 Building, To Huu Str., Hanoi, Vietnam 6 Hoang Lien National Park, 89 Nguyen Chi Thanh Street, Sa Pa, Lao Cai Province, Vietnam 7 AG Zoologischer Garten Köln, Riehler Strasse 173, D–50735 Cologne, Germany 8 Institute of Zoology, University of Cologne, Zülpicher Strasse 47b, D–50674 Cologne, Germany 9 Australian Museum Research Institute, Australian Museum, 1 William St, Sydney, NSW, 2010, Australia 10 Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney NSW 2052, Australia 11 Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Hanoi 10072, Vietnam 12 Central Institute for Natural Resources and Environmental Studies, Vietnam National University, Hanoi, 19 Le Thanh Tong, Hanoi, Vietnam 13 Department of Herpetology, American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024, USA Corresponding authors: Benjamin Tapley ([email protected]); Truong Quang Nguyen ([email protected]); Minh Duc Le ([email protected]) Copyright: © Anh Van Pham et al. This is an open access article distributed under terms of the Creative Commons Attribution License (Attribution 4.0 International – CC BY 4.0). Research Article Abstract A new species of the genus Amolops is described from the Hoang Lien Range, northwestern Vietnam as Amolops cuongi sp. nov. While morphological and molecular data assign these individuals to the Amolops mantzorum group, the new species is distinguishable from its congeners on the basis of a combination of the following diagnostic characters: size small (SVL 33.9–36.9 mm in males; 37.9–44.4 mm in females); head longer than wide; vomerine teeth absent or weakly developed; snout short (SE/ SVL 0.15–0.17 in males; 0.14–0.16 in females); tympanum small (TD/ED 0.26–0.37 in males; 0.25–0.35 in females); the absence of circummarginal groove on the first finger; disc of finger III larger than tympanum; supratympanic fold present; dorsolateral fold absent; webbing formula I0–1II0–1III0–1IV1–0V; the presence of a band of small spinules and/or tubercles running from below nares, along upper lip, around lower half of eye, between tympanum and eye and rear axis of mandibles; granular skin on flanks and ventral surfaces of body; in life, dorsal body colouration of dark brown with diffuse-edged blotches of bluish grey, copper and yellowish green or pale green and copper; ventral surface of throat, chest and belly pale cream with white dots; males without vocal sacs; and nuptial pad velvety without spines. In the phylogenetic analysis using a combination of mitochondrial 16S ribosomal RNA, ND2, and cytochrome b (cyt b) genes, the new species is strongly supported as the most genetically distinct member of the Amolops mantzorum group with genetic distance ≥ 1.53% in the 16S rRNA, ≥ 8.70% in ND2, and ≥ 8.56% in cyt b compared to other members within the genus Amolops. Key words: Amolops mantzorum group, genetically distinct, molecular phylogenetics, morphology, taxonomy Academic editor: Anthony Herrel Received: 13 May 2025 Accepted: 8 August 2025 Published: 22 October 2025 ZooBank: https://zoobank.org/ D53E78E9-481F-4866-B7756CA91B63EF8C Citation: Pham AV, Hoang CV, Tapley B, Nguyen LT, Nguyen HH, La TV, Ziegler T, Rowley JJL, Nguyen TQ, Le MD (2025) Amolops cuongi (Amphibia, Anura, Ranidae), a new species from the Hoang Lien Range, Vietnam. ZooKeys 1256: 235–257. https://doi. org/10.3897/zookeys.1256.158846 ZooKeys 1256: 235–257 (2025) DOI: 10.3897/zookeys.1256.158846 236 ZooKeys 1256: 235–257 (2025), DOI: 10.3897/zookeys.1256.158846 Anh Van Pham et al.: New Amolops from Vietnam Introduction The genus Amolops Cope, 1865 currently contains 87 recognized species distributed in Asia from Nepal and northern India eastwards to China and southwards to Malaysia (Frost 2025). Recent studies assigned the members of this genus into ten species groups, namely the Amolops chayuensis group, A. daiyunensis group, A. hainanensis group, A. laurentis group, A. mantzorum group, A. marmoratus group, A. monticola group, A. ricketti group, A. spinapectoralis group, and A. viridimaculatus group (Jiang et al. 2021; Liu et al. 2024). Morphologically, the members of the Amolops mantzorum group are characterised by the absence of dorsolateral folds (glandular dorsolateral folds may be present), circummarginal groove on the disc of the first finger, and tarsal fold and tarsal glands (Fei et al. 2005, 2009; Tang et al. 2023; Qian et al. 2023). Fei et al. (2009) listed five species in the Amolops mantzorum group, namely A. granulosus (Liu & Hu), A. lifanensis (Liu), A. loloensis (Liu), A. mantzorum (David), and A. viridimaculatus (Jiang). Lu et al. (2014) suggested that the Amolops mantzorum species group consists of four well-recognised species, i.e., A. granulosus, A. lifanensis, A. loloensis, and A. viridimaculatus, along with five putative species, comprising three disputable species, Amolops kangtingensis Inger, A. jinjiangensis (Su, Yang & Li) and A. tuberodepressus Liu & Yang, and the nominal species A. mantzorum, which may in fact consist of two cryptic species (Lu et al. 2014). Fei et al. (2017) described a new species of this group, A. xinduqiao Fei, Ye, Wang & Jiang, and considered A. kangtingensis a synonym of A. mantzorum. However, Dufresnes and Litvinchuk (2022) subsequently regarded A. xinduqiao as a subspecies of A. mantzorum. In addition, Zeng et al. (2020) and Wu et al. (2020) removed Amolops viridimaculatus from the A. mantzorum group and placed it in a separate group. Recently, Liu et al. (2024) synonymised A. ottorum with A. minutus based on morphological and molecular evidence. Currently, the A. mantzorum group contains eleven species, comprising A. ailao Tang, Sun, Liu, Luo, Yu & Du; Amolops dafangensis Li, Liu, Ke, Cheng & Wang; A. granulosus (Liu & Hu); A. jinjiangensis Su, Yang & Li; A. lifanensis (Liu); A. loloensis (Liu); A. mantzorum (David); A. minutus Orlov & Ho; A. sangzhiensis Qian, Xiang, Jiang, Yang & Gui; A. shuichengicus Lyu & Wang; and A. tuberodepressus Liu & Yang (Zeng et al. 2020; Dufresnes and Litvinchuk 2022; Tang et al. 2023; Liu et al. 2024). During our recent field work in northern Vietnam, specimens of Amolops were collected from the Hoang Lien Range in Lai Chau and Lao Cai provinces. These specimens were identified as an unnamed taxon of the A. mantzorum species group based on molecular and morphological data. Therefore, we herein describe it as a new species to science, Amolops cuongi sp. nov. Materials and methods Sampling Specimens were collected at night in forest habitats in the Hoang Lien Range, northern Vietnam between September 2017 and September 2020 (Fig. 1). The geographical coordinates were recorded using GPS Garmin 62s and Garmin GPSMAP 64CSx GPS receiver. Coordinates were recorded as latitude and longitude in decimal degrees and referenced to the World Geodetic System of 1984 237 ZooKeys 1256: 235–257 (2025), DOI: 10.3897/zookeys.1256.158846 Anh Van Pham et al.: New Amolops from Vietnam Figure 1. A. Map of the type localities of species in the Amolops mantzorum group; B. Zoomed in area showing the known localities and predicted distribution of Amolops cuongi sp. nov. Star indicates type locality of Amolops cuongi sp. nov. The precise type locality of A. lifanensis is not known (Lishan and Maoxian counties in central Sichuan Province). (WGS84). Specimens were collected by hand from 19:00 to 22:00 and from 04:30 to 05:30. Specimens were photographed in life before being euthanised using a 20% solution of benzocaine applied to the ventral surface of the frog. Tissue samples (liver) for molecular analyses were extracted from freshly euthanised specimens and stored in absolute ethanol prior to the fixation of specimens with 10% formalin or fixed in 85% ethanol and subsequent storage in 70% ethanol. Voucher specimens were subsequently deposited in the collection of the Institute of Biology (IB, formerly known as Institute of Ecology and Biological Resources – IEBR), Hanoi, Vietnam, the Institute of Institute of Life Science– Herpetology (ILS H), Ho Chi Minh City, Vietnam. A referred specimen was deposited at the Hoang Lien National Park headquarters (HLNP) as a reference for national park scientists. Molecular analysis Tissue samples were extracted using PureLink RNA Micro Scale Kit (Thermo Fisher Scientific company), following the manufacturer’s instructions. Genomic DNA was amplified using an Applied Biosystems PCR machine. The PCR total volume was 25 μl, consisting of 12 μl of mastermix, 6 μl of water, 1 μl of each primer at a concentration of 10 pmol/μl, and 5 μl of DNA. Primers used in the PCR 238 ZooKeys 1256: 235–257 (2025), DOI: 10.3897/zookeys.1256.158846 Anh Van Pham et al.: New Amolops from Vietnam and sequencing were as follows: the primer pair, LR N 13398 (5’-CGCCTGTTTACCAAAAACAT3’; forward), LR J 12887 (5’-CCGGTCTGAACTCAGATCACGT-3’; reverse) (Simon et al. 1994) was used to amplify a fragment of the mitochondrial 16S rRNA gene; the primer pair Met-LND2 (5’-CAATGTTGGTTAAAATCCTTCC-3’), and Trpe-HND2 (5’-AGGCTTTGAAGGCCTTTGGTC-3’) (Stuart et al. 2006), was used to amplify a fragment of the NADH dehydrogenase subunit 2 (ND2) gene; and the primer pair AmF1 (5’-TCTCATCCTGATGAAACTTTGGCTC-3’) and AmR3 (5’-CTACTGGTTGTCCTCCGATTCATGT-3’) (Lu et al. 2014) was used to amplify a fragment of the cytochrome b (cytb) gene. PCR products were sent to Apical Scientific (Malaysia) (https://apicalscientific.com) for sequencing. The obtained sequences were deposited in GenBank (Suppl. material 1: table S1). In addition to sequences generated for six samples of the new population from Lai Chau and Lao Cai provinces, we used 16S rRNA, ND2, and cytb data of 35 samples belonging to species within the Amolops mantzorum group available from GenBank for phylogenetic analyses. Sequences of Amolops species outside the A. mantzorum group and Odorrana jingdongensis Fei, Ye & Li were included in the analysis as the outgroups (Wu et al. 2020). Localities and accession numbers of all sequences used in the study can be found in Suppl. material 1: table S1. Chromas Pro software (Technelysium Pty Ltd., Tewantin, Australia) was used to edit the sequences, which were then aligned using ClustalX (Thompson et al. 1997) as embedded in MEGA11 (Tamura et al. 2021) with default parameters and subsequently optimised manually in BioEdit 7.0.5.2 (Hall 1999). Pairwise comparisons of uncorrected sequence divergence (p distance) were calculated using MEGA11 (Tamura et al. 2021). Variance was estimated using bootstrap method with 1000 replicates using nucleotide substitution while gap/missing data were treated via pairwise deletion. Prior to Bayesian analyses, the optimum nucleotide substitution models for 16S rRNA, ND2 and cytb partitions were selected using Kakusan 4 (Tanabe 2011), based on the Akaike information criterion (AIC). Bayesian inference (BI) was estimated using MrBayes v. 3.2 (Ronquist et al. 2012) and GTR + G model. Two independent runs of four Markov Chains, three heated and one cold, were performed for 10,000,000 generations. Tree was sampled every 100 generations, and a consensus topology was calculated using 70,000 trees after discarding the first 30000 trees (burnin = 3,000,000). We checked parameter estimates and convergence using Tracer v. 1.7.1 (Rambaut et al. 2018). For maximum likelihood (ML) analysis, IQ-TREE v. 1.6.12 (Nguyen et al. 2015) along with GTR+F+I+G4 model was used with 10,000 ultrafast bootstrap replications (UFB) (Hoang et al. 2018). We considered Bayesian posterior probability (BPP) and ultrafast bootstrap (UFB) support values of greater than or equal to 0.95 for BPP and 95% for UFB as strong support for a clade (Ronquist et al. 2012; Hoang et al. 2018). Morphological analysis Measurements were taken from 19 preserved specimens using a digital caliper to the nearest 0.1 mm; morphometrics followed Orlov and Ho (2007), Stuart et al. (2010), and Pham et al. (2019): SVL snout-vent length (from tip of snout to cloaca); HL head length (from the back of mandible to tip of snout); 239 ZooKeys 1256: 235–257 (2025), DOI: 10.3897/zookeys.1256.158846 Anh Van Pham et al.: New Amolops from Vietnam HW maximum head width (across angles of jaws); SE distance from tip of snout to anterior corner of eye; SND distance from nostril to the tip of snout; END eye to nostril distance (from anterior corner of eye to the nostril); IND internarial distance (distance between nostrils); IOD interorbital distance (minimum distance between upper eyelids); ED horizontal eye diameter (from the anterior corner to the posterior corner of the eye); TD maximum tympanum diameter; TED tympanum-eye distance (from anterior margin of tympanum to posterior corner of the eye); HND Hand length (from base of palm to tip of third finger); FTD maximum width of disc of finger III; FL femur length (from vent to knee); TL tibia length (from knee to tarsus); FOT foot length (from proximal edge of inner metatarsal tubercle to tip of fourth toe); and HTD maximum width of disc of fourth toe. All measurements were taken from the right side of the specimen and by the first, second, and fourth author for consistency. Interdigital toe webbing formula follows Savage and Heyer (1997). Sex and maturity were determined by gonadal inspection and the presence of nuptial pads. Species distribution mapping An estimated species distribution map (Fig. 1) was created in ArcGIS Pro3.5 (Esri, California, USA). The species’ distribution was generated using the International Union for Conservation of Nature (IUCN) elevation raster (IUCN SSC 2017). The range for the newly described species was estimated by clipping the elevation to above 1900 m a.s.l. Areas of habitat were deemed suitable and included in maps if they are within species’ estimated elevation range, and are not separated from known localities by any continuous stretch of unsuitable habitat with a distance equal to or greater than 1 km. Extent of occurrence (EOO), defined as the area of a minimum convex polygon that passes all known and inferred sites occupied by the species, was measured using the EOO Calculator for ArcGIS Pro (Toolbox v. 2.0). Results Phylogenetic analyses The combined matrix of 16S rRNA, ND2, and cytb contained 2296 aligned characters. In terms of pairwise genetic distance based on 16S rRNA data, interspecific uncorrected p-distance of the Amolops mantzorum group ranged from 0.19% (between A. jinjiangensis and A. sangzhiensis) to 6.75% (between A. lifanensis and A. ailao) (Suppl. material 1: tables S2–S4). The genetic divergence between the new form from Vietnam and its congeners ranged from 1.35% (A. shuichengicus) to 5.14% (A. lifanensis) (Suppl. material 1: table S2). In the ND2 gene, interspecific uncorrected p-distance of the Amolops mantzorum group ranged from 240 ZooKeys 1256: 235–257 (2025), DOI: 10.3897/zookeys.1256.158846 Anh Van Pham et al.: New Amolops from Vietnam 3.99% (between A. loloensis and A. jinjiangensis) to 19.36% (between A. loloensis and A. lifanensis). The genetic divergence of the new form from Vietnam and its congeners varied from 8.70% (A. minutus) to 19.14% (A. lifanensis) (Suppl. material 1: table S3). In the cytb gene, interspecific uncorrected p-distance of the Amolops mantzorum group ranged from 5.04% (between A. loloensis and A. jinjiangensis) to 11.53% (between A. mantzorum ssp. and the new form). The genetic divergence of the new form from Vietnam and its congeners ranged from 7.80% (A. loloensis) to 11.53% (A. mantzorum sp.) (Suppl. material 1: table S4). Phylogenetic analyses employing ML and BI methods were nearly identical, with most well-supported nodes on the ML tree also well-supported on the BI tree, and only the BI tree is presented in Fig. 2. The new form is strongly supported as a member of the A. mantzorum group and as a sister clade to all remaining species of the A. mantzorum group (BPP = 1, UFB = 97), except for A. lifanensis, while the latter was weakly recovered as a taxon within the species group (BPP = 0.66, UFB = 86) (Fig. 2). In the following, based on distinct genetic divergence in concert with diagnostic morphological differences compared to their congeners, we describe the newly discovered population of Amolops from Lai Chau and Lao Cai province as a species new to science. Species description Amolops cuongi sp. nov. https://zoobank.org/E3F15F15-12DE-44F1-BC6A-37579E18E48A Figs 3–6 Type material. Holotype. IEBR A.5139 (Field No. LC2020.82), • adult male, collected by C. T. Pham, C. V. Hoang, T. V. Phan, N. B. Sung, and A. V. Pham on 16 May 2020, found in evergreen forest near Ho Thau Village, Ho Thau Commune, Figure 2. Bayesian phylogeny based on 16S, ND2, and cytb genes. Numbers on branches are BPP and UFB, respectively. 241 ZooKeys 1256: 235–257 (2025), DOI: 10.3897/zookeys.1256.158846 Anh Van Pham et al.: New Amolops from Vietnam Figure 3. A. Dorsolateral view and; B. Ventral view of the male holotype (IEBR A. 5139) of Amolops cuongi sp. nov. in life. Lai Chau Province, Vietnam (22.408313°N, 103.608094°E, at an elevation of 2442 m). Paratypes. In Lai Chau Province, Vietnam: • two adult females, IEBR A.5140 (Field No. LC2020.179), IEBR A.5141 (Field No. LC2020.181), the same data as the holotype. • one adult male ILS H.3665 (Figs 5, 6A) and one adult female ILS H.3666nd, collected in disturbed evergreen forest of Hoang Lien Range in (22.3473°N, 103.77226°E; 1928 m a.s.l.), on 10 September 2018 by L. T. Nguyen, C. T. Nguyen, and H. V. Luong. In Lao Cai Province, Vietnam: • specimens collected in the forest of Hoang Lien Range, near Sa Pa by L. T. Nguyen, C. T. Nguyen, B. Tapley and L. Harding: • one adult female ILS H.3662 (Fig. 6E) and one subadult ILS H.3663 (Fig. 6G) (22.31517°N, 103.76897°E; 2629 m a.s.l.) on 14 September 2017; • one adult female ILS H.3664 (22.31488°N, 103.76845°E; 242 ZooKeys 1256: 235–257 (2025), DOI: 10.3897/zookeys.1256.158846 Anh Van Pham et al.: New Amolops from Vietnam Figure 4. A. Palmar aspect of right hand; B. Plantar aspect of right foot of the male holotype (IEBR A. 5139) of Amolops cuongi sp. nov. 2690 m a.s.l.) on 14 September 2017; collected by L. T. Nguyen, C. T. Nguyen and L. V. Hoang on 13 June 2018: • one adult male ILS H.3667 (22.3149°N, 103.7686°E; 2635 m a.s.l.) and one adult female ILS H.3668 (22.3145°N, 103.7675°E; 2685 m a.s.l.); • one adult female ILS H.3671 (22.31394°N, 103.76561°E; 2784 m a.s.l.), collected on 19 June 2019 by L. T. Nguyen and C. T. Nguyen; One adult male ILS H.3674 and one subadult ILS H.3675 (22.31394°N, 103.76561°E; 2784 m a.s.l.), collected on 8 September 2019 by C. T. Nguyen; • one adult female ILS H.3666 (Fig. 6B) (22.3473°N, 103.77226°E; 1928 m a.s.l.) collected on 10 September 2018 by L. T. Nguyen, C. T. Nguyen, and L. V. Hoang; • one subadult ILS H.3669 (22.9474°N, 103.8030°E; 2578 ma.s.l.), collected on 14 September 2018 by L. T. Nguyen, C. T. Nguyen, and H V. Luong; • three adult males ILS H.3683 (Fig. 6C), ILS H.3685 and ILS H.3686 and two adult females ILS H.3673 and ILS H.3684 (Fig. 6D) (22.14565°N, 103.96281°E; 2321 m a.s.l.), one adult female ILS H.3672 (22.14087°N, 103.95631°E; 2311 m a.s.l.), collected in undisturbed evergreen forest on Mount Nam Kang Ho Tao, Sa Pa on 13 September 2020 by C. T. Nguyen, G. T. Hoang and Q. L. Tan; • one adult male ILS H.3670 collected in disturbed evergreen forest on Mount Pu Ta Leng, Bat Xat (22.4263°N, 103.61322°E, 2362 m a.s.l.) on 22 March 2018 by C. T. Nguyen, L. T. Nguyen, B. Tapley and C. Portway. Referred specimen. One subadult HLNP2017 1409 00030 (Fig. 6F) found in bamboo forest on Mount Fansipan, Sa Pa, Lao Cai Province, Vietnam 243 ZooKeys 1256: 235–257 (2025), DOI: 10.3897/zookeys.1256.158846 Anh Van Pham et al.: New Amolops from Vietnam Figure 5. Amolops cuongi sp. nov. in preservative, adult male paratype ILS H.3665. A. Dorsal view; B. Ventral view; C. Lateral view; D. Palmar aspect of right hand; E. Plantar aspect of right foot. Scale bars 10 mm. (N22.31483, E103.76883; 2625 m a.s.l.) on 14 September 2017 by L. T. Nguyen, C. T. Nguyen, B. Tapley, and L. Harding. This specimen is not included in the type series due to it being deposited in a local collection. The taxonomic identity of the specimen is not in question. Diagnosis. Amolops cuongi sp. nov. from the Hoang Lien Range is assigned to the A. mantzorum species group based on the absence of a dorsolateral fold and the absence of a circummarginal groove on the first finger (Fei et al. 2009, 250 ZooKeys 1256: 235–257 (2025), DOI: 10.3897/zookeys.1256.158846 Anh Van Pham et al.: New Amolops from Vietnam in A. lifanensis) (Su et al. 1986; Fei et al. 2009); from A. loloensis by having a smaller size (SVL 33.9–36.9 mm vs 54.5–62.0 mm in males; 37.9–44.4 mm vs 69.5–77.5 mm in females in A. loloensis), tympanum distinct (vs invisible in A. loloensis), dorsal colour pattern (dark brown with diffuse-edged blotches of bluish grey, copper, and yellowish green or pale green and copper vs dark green with many large brown spots in A. loloensis), tibiotarsal articulation reaching to the nostril (vs tibiotarsal articulation reaching to the eye in A. loloensis), head longer than wide (vs wider than long or long as wide in A. loloensis), and relative finger lengths: I<II<IV<III (vs I = II<IV<III in A. loloensis) (Liu 1950; Fei et al. 2009); from A. mantzorum by having a smaller size (SVL 33.9–36.9 mm vs 48.8–57.0 mm in males, 37.9–44.4 mm vs 57.5–72.0 mm in females in A. mantzorum), tympanum distinct (vs invisible in A. mantzorum), and hind limbs with dark crossbars (vs without dark crossbars in A. mantzorum) (Liu 1950; Fei et al. 2009, 2017); from A. minutus by having a smaller tympanum (TD/ED 0.24–0.37 vs 0.38–0.41 in males; 0.26–0.35 vs 0.38–0.40 in females in A. minutus), a larger disc of finger III (FTD/ED 0.43–0.52 vs 0.29–0.33 in males, 0.46–0.67 vs 0.36–0.39 in females in A. minutus; FTD/SVL 0.07–0.08 vs 0.04–0.05 in A. minutus), a granular ventral surfaces and flanks (vs smooth in A. minutus), the presence of a band of small spinules running from below nares, along upper lip, around lower half of eye, between tympanum and eye and rear axis of mandibles (vs spinules typically only present posterior of tympanum in A. minutus), and the absence of dorsolateral glandular folds (vs present in A. minutus) (Orlov et al. 2007; Pham et al. 2019; Suppl. material 2: fig. S2); from A. sangzhiensis by having a smaller size (SVL 33.9–36.9 mm vs 40.3–40.9 mm in males, 37.9–44.4 mm vs 52.6–57.7 mm in females in A. sangzhiensis), and tympanum smooth (vs covered in fine granules in A. sangzhiensis) (Qian et al. 2023); from A. shuichengicus by having a smaller size in females (SVL 37.9–44.4 mm vs 48.5–55.5 mm in A. shuichengicus), the absence of dorsolateral glandular folds (vs present in A. shuichengnicus), and the absence of a cream maxillary gland (vs present in A. shuichengnicus) (Lyu et al. 2019); and from A. tuberodepressus by having a smaller size (SVL 33.9–36.9 mm vs 44.0–57.0 mm in males; SVL 37.9–44.4 mm vs 61.0–70 mm in A. tuberodepressus in females), tibiotarsal articulation reached to the nostril (vs tibiotarsal articulation reaching beyond tip of snout in A. tuberodepressus), tympanum distinct (vs invisible in A. tuberodepressus), and different dorsal colour pattern (green with some dark or pale green spots and irregular small black dots in A. tuberodepressus) (Liu et al. 2000; Fei et al. 2009). Discussion Our new finding brings the total number of Amolops species from Hoang Lien Mountain Range to eight, namely A. cuongi, A. cucae (Bain, Stuart & Orlov), A. daorum (Bain, Lathrop, Murphy, Orlov & Ho), A. mengyangensis Wu & Tian, A. minutus Orlov & Ho, A. spicalinea, A. shihaitaoi Wang, Li, Du, Hou & Yu, and A. viridimaculatus Jiang (Frost 2025). Of which, A. cucae, A. daorum, A. mengyangensis, and A. spicalinea are placed in the A. monticola group, A. shihaitaoi within the A. ricketti group, A. viridimaculatus within the A. viridimaculatus group (Wu et al. 2020; Patel et al. 2021), and A. cuongi and A. minutus within the A. mantzorum group. Amolops minutus is currently known from Bat Xat, Sa 251 ZooKeys 1256: 235–257 (2025), DOI: 10.3897/zookeys.1256.158846 Anh Van Pham et al.: New Amolops from Vietnam Pa, and Tam Duong districts, Lai Chau Province, and Muong La District, Son La Province (Orlov and Ho 2007; Pham et al. 2019; Liu et al. 2024; this study). In terms of genetic distance, Amolops cuongi is closely related to A. shuichengicus based on the 16S rRNA gene, A. minutus according to the ND2 gene, and A. loloensis in terms of the cytb gene, but the new species differs from a minimum of 1.35% (A. shuichengicus according to the 16S rRNA gene) to a maximum of 19.14% (A. lifanensis in the ND2 gene). Phylogenetically, the new species is the most distinct taxon within the A. mantzorum group, as it is placed in a clade sister to all remaining group members, except for A. lifanensis. The latter is weakly recovered as a member of the A. mantzorum group with insignificant support values (BPP = 0.66, UFB = 86). Similarly, previous molecular studies demonstrate that A. lifanensis is either paraphyletic to the A. mantzorum group (Wiens et al. 2009; Wu et al. 2020) or clusters with the group with a low support value (Qian et al. 2023). The phylogenetic placement of A. lifanensis should be investigated in future studies using multilocus data, including both nuclear and mitochondrial markers. Amolops cuongi and A. minutus were found in sympatry in the evergreen forest of Lai Chau Province. Amolops cuongi could occur more widely and potentially at lower elevations. Establishing the true lower elevation range of this species should also be considered as it may inform future survey effort and extinction risk assessments. Future research should aim to elucidate more life history information including the identification of breeding habitat and formal scientific description of the call and larvae. The description of Amolops cuongi further highlights the significance of the Hoang Lien Range as an area of exceptional amphibian species diversity. Ten amphibians have been described from the Hoang Lien Range as new species to science within the last decade (Matsui et al. 2017; Tapley et al. 2017, 2018, 2020; Kropachev et al. 2019; Nguyen et al. 2021, 2024a, b, 2025). With the exception of Rhacophorus duboisi Ohler, Marquis, Swan & Grosjean, 2000, the entire amphibian assemblage above 2600 m a.s.l. on Mount Fansipan consists of species that were described as new species to science since 2013 (Nguyen et al. 2013; Rowley et al. 2013; Tapley et al. 2018; this study) and all of these newly described species are highly threatened (IUCN SSC Amphibian Specialist Group 2021a, b, c) or likely qualify for being assessed as Vulnerable on the basis of available information (this study). The recent scientific discovery of Oreolalax adelphos Nguyen Tapley, Kane, Tran, Cui & Rowley on the summit of Mount Po Ma Lung indicates that further species, or even assemblages, on other mountain summits in the Hoang Lien Range may await formal scientific description. Further surveys and integrative taxonomic work should be undertaken soon as these areas are increasingly degraded by infrastructural developments and habitat degradation associated with tourism. Furthermore, climate change is highly likely to be particularly problematic for these high elevation, range restricted species. Several studies have shown that some amphibian species will migrate to higher elevations as the climate warms (Duan et al. 2016; Sillero 2021); for species already occurring at high elevation, this is simply not possible and the ranges of these already range-restricted species can only contract further. This underscores the significance of protecting the last remaining tracts of high elevation natural forest in Vietnam as climatic refuges for amphibians. 252 ZooKeys 1256: 235–257 (2025), DOI: 10.3897/zookeys.1256.158846 Anh Van Pham et al.: New Amolops from Vietnam Acknowledgements For the fruitful cooperation within joint research projects, we cordially thank A.H. Le (IB, Hanoi), as well as T. Pagel and C. Landsberg (Cologne Zoo). We sincerely thank S. N. Nguyen (Institute of Life Science, Ho Chi Minh City, Vietnam) for his generous support in accepting and curating the specimens at the institute, ensuring their availability for future research. We thank Roshmi Sarma and Timothy Cutajar for sequencing specimens at the Australian Museum. We thank the Asian Turtle Program of Indo-Myanmar Conservation (ATP /IMC) for institution support for L.T. Nguyen. We thank A.T.N. Ho (VNU-HUS), N.S. Ba (TBU), and T.Q. Phan (IB) for supporting the laboratory and field work and D. Kane, T.D.T. Tran, C.T. Nguyen, L. Harding, L.V. Hoang, G.T. Hoang, C. Portway and Q. L. Tan for assistance with field work. Ethical approval was granted by the Zoological Society of London’s ethics committee (project ZFP1). Comments from two reviewers greatly improved the paper. Additional information Conflict of interest The authors have declared that no competing interests exist. Ethical statement No ethical statement was reported. Use of AI No use of AI was reported. Funding This research was support by the Rufford Foundation (grant No. 43835-1) to C.V. Hoang, the Ocean Park Conservation Foundation Hong Kong to B. Tap ley, L. Nguyen, and J. Rowley, a ZSL EDGE Fellowship to L. Nguyen and the Small Grants Programme by the ASEAN Centre for Biodiversity II. Author contributions Conceptualization: A.V.P, M.D.L., T.Q.N. and B.T..; methodology: A.V.P, M.D.L, C.V.H.; validation: all authors.; formal analysis: A.V.P, C.V.H., L.T.N., B.T.; investigation: A.V.P., C.V.H., L.T.N; resources: A.V.P., C.V.H., L.T.N., J.R., B.T., M.D.L..; data curation: A.V.P., C.V.H., T.Q.N., L.T.N., B.T.; writing—review and editing: all authors. Author ORCIDs Anh Van Pham https://orcid.org/0000-0002-6023-3418 Chung Van Hoang https://orcid.org/0000-0002-0709-974X Benjamin Tapley https://orcid.org/0000-0002-9787-3793 Luan Thanh Nguyen https://orcid.org/0000-0002-4663-125X Thomas Ziegler https://orcid.org/0000-0002-4797-609X Jodi J. L. 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Molecular Phylogenetics and Evolution 146(106753): 1–9. https://doi.org/10.1016/j.ympev.2020.106753 257 ZooKeys 1256: 235–257 (2025), DOI: 10.3897/zookeys.1256.158846 Anh Van Pham et al.: New Amolops from Vietnam Supplementary material 1 Supplementary tables Authors: Anh Van Pham, Chung Van Hoang, Benjamin Tapley, Luan Thanh Nguyen, Hanh Huu Nguyen, Toi Van La, Thomas Ziegler, Jodi J. L. Rowley, Truong Quang Nguyen, Minh Duc Le Data type: docx Explanation note: table S1. Samples used for the phylogenetic analyses in this study. table S2. Uncorrected pairwise genetic distance (%) between members of the genus Amolops estimated from 16S sequences. table S3. Uncorrected pairwise genetic distance (%) between members of the genus Amolops estimated from ND2 sequences. table S4. Uncorrected pairwise genetic distance (%) between members of the genus Amolops estimated from cytb sequences Copyright notice: This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited. Link: https://doi.org/10.3897/zookeys.1256.158846.suppl1 Supplementary material 2 Supplementary figures Authors: Anh Van Pham, Chung Van Hoang, Benjamin Tapley, Luan Thanh Nguyen, Hanh Huu Nguyen, Toi Van La, Thomas Ziegler, Jodi J. L. Rowley, Truong Quang Nguyen, Minh Duc Le Data type: docx Explanation note: fig. S1. Habitat of Amolops cuongi sp. nov. in the Hoang Lien Range. fig. S2. (A–C) Amolops cuongi sp. nov. adult male paratype ILS H.3665 dorsal, ventral and lateral views in preservative. Copyright notice: This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited. Link: https://doi.org/10.3897/zookeys.1256.158846.suppl2