In this study, 34 specimens of Scutiger (25 adults, 1 subadult, 2 juveniles, and 6 tadpoles) were collected from Luozha County, Shannan Prefecture, Tibet Autonomous Region, China. The specimens were euthanized and then fixed in 75% ethanol before being deposited in the Herpetology Museum of Chengdu Institute of Biology (CIB), Chinese Academy of Sciences. The sex of specimens was determined by the presence of nuptial spines, chest spines, eggs, or examination of gonads when necessary. Tissue samples were taken from legs and preserved separately in 95% ethanol before fixation.

Total genomic DNA was extracted using QIAamp DNA Mini Kit (QIAGEN, Hilden, Germany) following protocol. Fragments of two mitochondrial genes (16S rRNA and COI) and one nuclear gene (RAG1) were amplified and sequenced. The primer sequences for these genes were retrieved from the literature for 16S rRNA (Simon et al. 1994), COI (Che et al. 2012), and RAG1 (Mauro et al. 2004). PCR amplifications for the gene were performed in a 25 μl volume reaction with the following conditions: an initial denaturing step at 95 °C for 4 min; 36 cycles of denaturing at 95 °C for 40 s, annealing at 52 °C (for COI and RAG1) or 54 °C (for 16S rRNA) for 40 s and extending at 72 °C for 40 s, and a final extending step of 72 °C for 10 min. PCR products were sequenced by Beijing Qingke New Industry Biotechnology Co., Ltd., Beijing, China. Sequences were assembled and aligned using BioEdit v. 7.2.5 (Hall 1999) with default settings and were further revised manually when necessary. The COI and RAG1 sequences were translated to amino acid sequences in MEGA X (Kumar et al. 2018), adjusted for open reading frames, and checked to ensure the absence of premature stop codons. All new sequences were deposited in GenBank.

For phylogenetic analysis, corresponding available sequences of Scutiger and three outgroups including Oreolalax omeimontis, Leptobrachium boringii, and Leptobrachella liui were obtained from GenBank in accordance with previous studies (Hofmann et al. 2017; Che et al. 2020). A mitochondrial DNA sequence (16S + COI) matrix was generated for the phylogenetic analyses. Phylogenetic analyses were conducted using maximum likelihood (ML) and Bayesian Inference (BI) methods implemented in Phylosuite (Zhang et al. 2020). Each gene was considered as a partition, and the best evolutionary model was chosen for each partition using PartitionFinder2 (Lanfear et al. 2017) based on Bayesian Inference Criteria (BIC). GTR+G and HKY+G were chosen as the best model for the combined mitochondrial DNA sequences and RAG1 respectively. ML phylogenies were inferred using IQ-TREE (Nguyen et al. 2015) under Edge-linked partition model for 10000 ultrafast bootstraps (Minh et al. 2013), as well as the Shimodaira-Hasegawa-like approximate likelihood-ratio test (Guindon et al. 2010). BI phylogenies were inferred using MrBayes 3.2.6 (Ronquist et al. 2012) under partition model (2 parallel runs, 10 million generations), in which the initial 25% of sampled data were discarded as burn-in. Genetic distances between species for each gene were estimated using MEGA X. All sequences used in this study are listed in Table 1.

For adults, measurements were taken with a dial caliper to the nearest 0.1 mm. In total, 24 measurements of 21 adults were measured: SVL (snout-vent length: distance from the tip of the snout to the posterior edge of the vent), AG (trunk length between axilla and groin: distance between middle point of the two axillae and middle point of groins); HL (head length: distance from the rear of the mandible to the tip of the snout); HW (head width: distance between the posterior angles of jaw); HH (head height: head height at the corner of jaws); SL (snout length: distance from tip of snout to anterior border of the orbit); IND (internasal distance: distance between inner edge of two nostrils); IOS (interorbital space: shortest distance between inner edge of upper eyelids); UEW (maximum upper eyelid width); ACED (distance between anterior corner of eyes); PCED (distance between posterior corner of eyes); ED (horizontal eye diameter); SND (nostril-snout distance: distance from center of the nostril to tip of the snout); END (eye-nostril distance: distance from front of eye to the center of nostril); LAL (lower arm length: distance from elbow to wrist); LAD (lower arm width: largest diameter of forearm); HAL (hand length: distance from wrist to tip of third digit); HLL (hindlimb length: distance between vent and tip of fourth toe when leg straightened at right angle to the body); THL (thigh length: distance from cloaca to knee); TL (tibia length: distance from knee to ankle); TFL (tarsal-foot length: length from heel to the tip of the fourth digit); FL (foot length: distance from the proximal end of the inner metatarsal tubercle to the tip of the fourth digit); TW (tibia width: largest tibia width); IMTL (inner metatarsal tubercle length). Morphological terminologies were mostly based on Fei et al. (2009) and webbing formulae are described based on Savage and Heyer (1997). Morphological comparison between the unknown species from Luozha and valid species of genus Scutiger were conducted based on data obtained from references (Table 2) and 31 examined specimens of 8 species. For phylogenetical close species, further morphometrics comparison using one-way ANOVA was conducted based on SVL and ratios of another 18 characters to SVL of examined male specimens.

For tadpoles, the stages were identified following Gosner (1960). Thirteen morphometric characters of two tadpoles were measured: LTRF (labia tooth row formulae); TOL (total length: distance from tip of snout to tip of tail); BL (body length: distance from tip of snout to trunk-tail junction); BH (maximum body height); BW (maximum body width); SNL (snout length: distance from tip of snout to anterior border of the orbit); SSD (distance from snout to spiraculum: distance from tip of snout to opening of spiraculum); ODW (oral disc width: largest width of oral disc); IOS (interocular space: minimum distance of eyes); TMW (maximum tail muscle width); TAL (tail length: distance between posterior side of opening of cloaca to tip of tail); TMH (maximum tail muscle height); HLL (hindlimb length). Morphological terminologies were based on Fei et al. (2009).

The aligned sequence matrices of 16S rRNA, COI, and RAG1 genes contain 532 bps, 622 bps, and 1017 bps, respectively. Mitochondrial phylogenetic analysis indicates that Scutiger species can be included in five clades, the topology of phylogenetic tree (Fig. 1) is generally similar to those of previous research (Hofmann et al. 2017; Che et al. 2020). Clade A contains only one species, S. wuguanfui. Positions for the four species from central and western Himalaya (S. ghunsa, S. occidentalis, S. nepalensis, S. sikimmensis) are uncertain. The clade B are the largest, containing S. boulengeri species complex, S. jiulongensis, S. wanglangensis, S. liupanensis, S. mammatus, S. glandulatus, S. muliensis, S. tuberculatus, and a lineage including S. cf. mammatus and S. sp. from Yunnan. The S. boulengeri species complex contained three lineages as Lin et al (2023) reported. Clade C contains three species, S. feiliangi, S. ningshanensis and S. chintingensis. The samples collected from Luozha County formed an independent lineage (Luozha lineage) with high bootstrap supports (BS = 99) and Bayesian posterior probabilities (BPP = 1.00). The Luozha lineage further clustered with S. gongshanensis, and S. nyingchiensis with strong supports (BS = 99, BPP = 1.00). These three species further form clade D with S. tengchongensis and S. spinosus. Phylogenetic analysis based on RAG1 resulted in a similar topology (Fig. 2). The Luozha lineage is sister to S. nyingchiensis.

Figure 1. 

Phylogenetic relationships of Scutiger using maximum likelihood (ML) based on the mitochondrial 16S and COI gene sequences. ML bootstrap support/Bayesian posterior probability is denoted beside each node. The symbol “-” represents a value below 70/0.70. For sample numbers refer to Table 1.

Figure 2. 

Phylogenetic relationships of Scutiger using maximum likelihood (ML) based on RAG1 gene sequences. ML bootstrap support/Bayesian posterior probability is denoted beside each node. The symbol “-” represents a value below 70/0.70. Sample number refer to Table 1.

Genetic distances between species of Scutiger are shown in Suppl. materials 1–3 based on 16S rRNA, COI, and RAG1 genes, respectively. The smallest genetic distances between the Luozha lineage and other taxa of Scutiger based on 16S rRNA and COI are 0.026–0.030 and 0064–0.068 respectively (vs S. nyingchiensis). These are comparable or larger than multiple known species pair (e.g., S. glandulatus vs S. jiulongensis 0.066–0.068 for COI; S. liupanensis vs S. mammatus 0.024 for 16S rRNA, 0.064–0.068 for COI; S. tengchongensis vs S. chintingensis 0.029 for 16S rRNA, S. muliensis vs S. tuberculatus 0.008 for 16S rRNA, 0.055 for COI). The genetic distances for nuclear gene RAG1 between the Luozha lineage and other species are much smaller (0.001–0.020); however, three species (S. occidentalis, S. nepalensis, S. sikimmensis) even share the same RAG1 haplotype.

Comparisons based on ten selected morphological characters for all Scutiger species are summarized in Table 2. Images of two phylogenetically close related species to the Luozha lineage (S. nyingchiensis and S. gongshanensis) were demonstrated in Fig. 3. The Luozha lineage is morphologically distinguished from other known species of Scutiger based on a combination of morphological features as follows:

Figure 3. 

Adult male Scutiger nyingchiensis (CIB QX207) from Nyingchi, Tibet, China (A–D) and adult male S. gongshanensis (KIZ 036221) from Gongshan, Yunnan, China (E–H) A dorsolateral body B ventral body C dorsal right hand and D ventral foot E dorsolateral body F ventral body G dorsal right hand and H ventral foot. Photographed by SCS.

For S. adungensi, the Luozha lineage differs by absence of vocal sac for adult males(vs presence); absence of maxillary teeth and budding (vs presence of budding); smaller male body size (SVL 47.0–67.2 mm vs 71–73 mm); presence numerous dense tiny black nuptial spines present on dorsal surface of fingers I, II and inner surface of finger III of males in breeding condition (vs large spines on inner two fingers); two pair of spine patches on chest of breeding male (vs one pair).

For S. bangdaensis, the Luozha lineage differs by presence of one to six separated spines on top of each dorsal tubercle of males in breeding condition (vs absence of spines on tubercles); rudimentary webbing between toes (vs developed).

For S. bhutanensis, the Luozha lineage differs by numerous dense tiny black nuptial spines present on dorsal surface of fingers I, II and inner surface of finger III of males in breeding condition (vs 16–18 large nuptial spines on each of inner two fingers of males); space between upper eyelids being wider than upper eyelids (vs narrower); forearm being longer than hand (vs equal); relatively larger feet in males (FL/SVL 40.9–50.4% vs 38.5%).

For S. biluoensis, the Luozha lineage differs by absence of maxillary teeth (vs presence); presence of nuptial spines on dorsal surface of fingers I, II and inner surface of finger III of males in breeding condition (vs on inner two fingers); smaller male body size (SVL 47.0–67.2 mm vs 73 mm).

For S. boulengeri, the Luozha lineage differs by absence of spine patches on belly of males in breeding condition (vs presence); rudimentary webbing between toes (vs well-developed webbing); coloration of dorsal body olive brown to bronze (vs greyish olive).

For S. chintingensis, the Luozha lineage differs by absence of spines on inner surface of upper arm and forearm of males in breeding condition (vs presence); rudimentary webbing between toes (vs 1/3 webbing between toes); absence of maxillary teeth (vs developed maxillary teeth); absence of a pair of long glandular skin ridges on shoulder or middle dorsum (vs presence); absence of femoral glands (vs presence).

For S. feiliangi, the Luozha lineage differs by presence of one to six separated spines on top of each dorsal tubercle of males in breeding condition (vs a layer of keratinized dense tiny spines on tubercles on dorsum of both gender in breeding); absence of spines on inner surface of forearm of males in breeding condition (vs presence); upper and lower half of iris uniformly bicolored (vs upper half golden, lower half brown).

For S. ghunsa, the Luozha lineage differs by pectoral spine patches being slightly larger than the axillary spine patches (vs twice or even larger); larger male body size (SVL 47.0–67.2 mm vs 42.0–47.8 mm); the yellow tubercles scattered around cloaca of males in breeding condition (vs creamy white granules surrounding vent); coloration of dorsal body olive brown to bronze (vs pale brown); absence of dark brown bands on upper lip (vs present); absence of irregular black spots on limbs (vs present).

For S. glandulatus, the Luozha lineage differs by smaller and moderate male body size (SVL 47.0–67.2 mm vs 68.0–90.0 mm, body stout); presence of nuptial spines on dorsal surface of fingers I, II and inner surface of finger III of males in breeding condition (vs on inner two fingers); pectoral spine patches being slightly larger than the axillary spine patches (vs twice or even larger); rudimentary webbing between toes (vs well-developed webbing); presence of spine on warts and tubercles on dorsum (vs absence).

For S. gongshanensis, the Luozha lineage differs by absence of vocal sac for adult males (vs presence); absence of maxillary teeth and budding (vs presence of budding); presence of numerous tiny dense nuptial spines on dorsal surface of fingers I, II, and inner surface of finger III of males in breeding condition (vs large spines on inner two fingers); two pair of spine patches on chest of breeding male (vs one pair); presence of spine on warts and tubercles on dorsum (vs absence); absence of a wide dark strip on dorsum from behind eyes to vent (presence) (Fig. 3).

For S. jiulongensis, the Luozha lineage differs by smaller and moderate male body size (SVL 47.0–67.2 mm vs 67.4–81.5 mm, body stout); presence of nuptial spines on dorsal surface of fingers I, II and inner surface of finger III of males in breeding condition (vs on inner two fingers); pectoral spine patches being slightly larger than the axillary spine patches (vs twice or even larger); presence of one to six separated spines on top of each dorsal tubercle of males in breeding condition (vs absence of spines on tubercles).

For S. liupanensis, the Luozha lineage differs by absence of maxillary teeth and budding (vs presence of budding); absence of spine patches on belly of males in breeding condition (vs presence); absence of a pair of large tubercles around cloaca (vs presence).

For S. maculatus the Luozha lineage differs by absence of maxillary teeth and budding (vs presence of budding); rudimentary webbing between toes (vs well-developed webbing).

For S. mammatus, the Luozha lineage differs by moderate body (vs stout body); presence of nuptial spines on dorsal surface of fingers I, II and inner surface of finger III of males in breeding condition (vs on inner two fingers); two pair of spine patches on chest of breeding male (vs one pair); rudimentary webbing between toes (vs well-developed webbing); presence of one to six separated spines on top of each dorsal tubercle of males in breeding condition (vs absence of spines on tubercles).

For S. meiliensis, the Luozha lineage differs by absence of maxillary teeth and budding (vs presence of teeth); presence of nuptial spines on dorsal surface of fingers I, II and inner surface of finger III of males in breeding condition (vs on inner two fingers); smaller male body size (SVL 47.0–67.2 mm vs 70 mm).

For S. muliensis, the Luozha lineage differs by moderate body and smaller male body size (SVL 47.0–67.2 mm vs stout body, 68.2–80.0 mm); presence of nuptial spines on dorsal surface of fingers I, II and inner surface of finger III of males in breeding condition (vs on inner two fingers); two pair of spine patches on chest of breeding male (vs one pair); presence of spine on warts and tubercles on dorsum (vs absence).

For S. nepalensis, the Luozha lineage differs by smaller male body size (SVL 47.0–67.2 mm vs 68.0–76.0 mm); head width being smaller than (males) or subequal to (females) tibia length (vs head width equal or greater than tibia length for males and females of S. nepalensis respectively).

For S. ningshanensis, by absence of maxillary teeth and budding (vs presence of teeth); absence of spine patches on belly of males in breeding condition (vs presence); dozens of yellow tubercles scattered around cloaca of males in breeding condition (vs a pair of white glands around vent); absence of a blue spot on tip of snout (vs present).

For S. nyingchiensis, the Luozha lineage differs by rudimentary webbing between toes (webbing formula I½–1II½–2III1½–2½IV2½–2V vs 1/5 webbing on toe IV, webbing formula I0–½II0–1½III1–2IV2–1½V); absence of maxillary teeth and budding (vs presence of budding); coloration of dorsal body olive brown to bronze (vs greyish olive) (Fig. 3).

For S. occidentalis, the Luozha lineage differs by coloration of dorsal body olive brown to bronze (vs greyish olive, e.g., fig. S3.2. of Hofmann et al. 2017); rudimentary webbing between toes (vs clear webbing between toes).

For S. pingwuensis the Luozha lineage differs by smaller female body size (SVL 49.8–66.2 mm vs 77.5 mm); pectoral spine patches being slightly larger than the axillary spine patches (vs twice or even larger); absence of spine patches on belly of males in breeding condition (vs presence); absence of spines on inner surface of upper arm and forearm of males in breeding condition (vs presence).

For S. sikimmensis, the Luozha lineage differs by absence of maxillary teeth and budding (vs presence of budding); presence of numerous tiny dense nuptial spines on dorsal surface of fingers I, II and inner surface of finger III of males in breeding condition (vs large spines on inner two fingers, small spines on inner surface of third finger); absence of distinct irregular cross bands on limbs (vs presence); space between upper eyelids being wider than upper eyelids (vs narrower).

For S. spinosus, the Luozha lineage differs by some large warts and tubercles on dorsum gathered into short skin ridges with several spines present on top (vs prominent, conical-shaped tubercles on dorsal and lateral surfaces independent, each tubercle bearing only one black spine); absence of small patches of black spines present near armpit of males in breeding condition (vs presence); pectoral spine patches being slightly larger than the axillary spine patches (vs pectoral twice longer than axillary); absence of cross bands on limbs (vs present).

For S. tengchongensis, the Luozha lineage differs by larger male body size (SVL 47.0–67.2 vs 36.0–40.1 mm); absence of small patches of black spines present near armpit of males in breeding condition (vs presence); numerous tiny dense nuptial spines on dorsal surface of fingers I, II and inner surface of finger III of males in breeding condition with similar size (vs black nuptial spines on the first and second fingers being larger than those on the third finger); coloration of dorsal body olive brown to bronze (vs reddish brown).

For S. tuberculatus, the Luozha lineage differs by moderate and smaller male body (SVL 47.0–67.2 mm vs stout body 68.0–76.0 mm); numerous tiny dense nuptial spines on dorsal surface of fingers I, II and inner surface of finger III of males in breeding condition (vs large spines on dorsal surface of fingers I, II); pectoral spine patches being slightly larger than the axillary spine patches (vs twice or even larger); presence of spines on tubercles on dorsum (vs absence of spines on large warts on dorsum).

For S. wanglangensis, the Luozha lineage differs by absence of maxillary teeth and budding (vs presence of budding); pectoral spine patches being slightly larger than the axillary spine patches (vs twice or even larger); absence of spine patches on belly of males in breeding condition (vs presence); absence of small patches of black spines present near armpit of males in breeding condition (vs presence); rudimentary webbing between toes (vs 1/5 to 1/3 webbing); coloration of dorsal body olive brown to bronze (vs greyish olive); absence of a longitudinal strip on middle dorsum connecting with brown triangle between eyes (vs presence).

For S. wuguanfui, the Luozha lineage differs by moderate and smaller body (SVL 47.0–67.2 mm for male, 49.8–66.2 mm for female vs stout body, 77.5–83.8 mm for male, 107.4–116.7 for female); absence of vocal sac for adult males (vs presence of an internal single subgular vocal sac for males); absence of numerous small black spines on upper chest (vs presence); space between upper eyelids being wider than upper eyelids (vs narrower).

Morphometric comparisons based on 19 characters between the Luozha lineage and two phylogenetically close species S. gongshanensis and S. nyingchiensis are shown in Table 3 (detailed data provided in Suppl. material 4). The Luozha lineage further differs from S. gongshanensis in HL/SVL, LAL/SVL, LAW/SVL, HLL/SVL, THL/SVL, TFL/SVL, FL/SVL, and S. nyingchiensis in IND/SVL, LAL/SVL, LAW/SVL.

In conclusion, the unknown Scutiger from Luozha presents an independent lineage with interspecific genetic divergence, and it is morphologically distinct from all known species. It is diagnosed as a new species and hence described herein.

Scutiger boulengeri (three adult males): CIB GGS-MGC4-1, CIB GGS-MGC4-9, CIB GGS-MGC4-12 from Kangding, Sichuan, China.

S. ghunsa (two adults): male Holotype NHM-TU-17A-0116 and female paratype NHM-TU-17A-0117 from Ghunsa, Taplejung, Nepal.

S. glandulatus (three adult males): CIB GGS-PBX2-14, CIB GGS-PBX3-1, CIB GGS-GGSX2-1 from Kangding, Sichuan, China.

S. gongshanensis (two adult males): KIZ036221 from Lushui, Nujiuang, Yunnan, China; topotype KIZ036222 from Gongshan, Yunnan, China.

S. mammatus, (four adult males from near type locality): CIB GGS-SDX1-1, CIB GGS-PBX4-3, CIB GGS-PBX4-4, GGS-PBX4-5 from Kangding, Sichuan, China.

S. muliensis (one adult male): topotypic adult male CIB ML20200727-42 from Muli, Sichuan, China.

S. nyingchiensis (ten adults): eight males CIB QZ207, CIB QZ398, CIB QZ401, CIB QZ402, CIB QZ403, CIB QZ408, CIB QZ409, CIB QZ410; two females CIB QZ411, CIB QZ407 from Lulang Town, Bayi District, Tibet, China.

S. wuguanfui (six adults of type series): five adult males KIZ030101 (holotype), KIZ030103, KIZ030105, KIZ030106, KIZ030104, adult female KIZ030102 from Medog, Tibet, China.

Scutiger species are distributed in high-altitude regions, such as the Tibetan Plateau, the Himalayas, the Tsingling Mountains, and the Hengduan Mountains. The discovery of Scutiger luozhaensis sp. nov. provides additional evidence to support the Paleo-Tibetan origin hypothesis by Hofmann et al. (2017). The unique geomorphic features of the Qinghai-Tibetan Plateau, including rapid uplift and mountainous barrier (Ding et al. 2020; Li et al. 2021; Xu et al. 2021; Miao et al. 2022), may have led to high cryptic species diversity of Scutiger in the region, multiple species were not discovered until about recent ten years (Jiang et al. 2012; Jiang et al. 2016; Yang and Huang 2019; Rao "2020", 2022). These specific historical processes and genetic patterns have likely contributed to the diverse and intriguing species patterns observed in Scutiger (Chen et al. 2009; Che et al. 2020; Lin et al. 2023), necessitating further research. Due to the limited sampling and genetic data, more research is recommended to fully understand the evolutionary history of Scutiger. Such as, there are still puzzles about the S. boulengeri species complex, which contained three lineages in this research and as Lin et al. (2023) reported. This also raises the problem of the relationship between S. bangdaensis and S. boulengeri. The former was described based on morphological data of few specimens only, the diagnostic characters were sorely based on morphological comparisons with S. boulengeri and S. maculatus without mention of the localities of specimens of S. boulengeri compared (Rao "2020", 2022). However, the samples of S. boulengeri from Basu (type locality of S. bangdaensis) form part of the W.a clade of Lin et al. (2023) with samples from Zaduo (Upper Yangtze Kiang River, near or at the type locality of S. boulengeri, and near Chindu, the locality of neotype S. boulengeri) and all other samples from Tibet Autonomous Region (Bedriaga 1898; Fei et al. 2009; Lin et al. 2023). One of the morphological diagnoses “absence of spines on ventral belly” was based on specimens collected in October 2016, those spines might have faded in October after breeding season. Other diagnoses “body length 45–50 mm; head width almost equal head length; large tubercles present on dorsolateral body, light colored, and rounded” could not distinctly differ from those specimens of S. boulengeri from Tibet Autonomous Region (Fei et al. 2009; Che et al. 2020; Rao 2022 “2020”). These imply that S. bangdaensis is possibly a junior synonym of S. boulengeri. Further research based on more specimens and genetical data is recommended to solve the puzzles of S. boulengeri species complex.

This species was described based on specimens from Taining Town, Daofu County, Sichuan Province, China (Liu 1950). It was synonymized with S. glandulatus (Liu, 1950) by Liu and Hu (1961) for the reason that adults of the former in preservative are difficult to differentiate from those of the latter. However, the name S. glandulatus was adopted by some researchers probably because the pages describing S. brevipes are anterior to those pages describing S. glandulatus (Liu 1950; Ye et al. 1992; Fu et al. 1997; Jiang et al. 2012, 2016; Khatiwada et al. 2019; Yang and Huang 2019; Frost 2023). Fei et al. (2009) discussed that S. brevipes should remain as a junior synonym of S. glandulatus, because "When the precedence between names or nomenclatural acts cannot be objectively determined, the precedence is fixed by the action of the first author citing in a published work those names or acts and selecting from them..." according to article 24.2.1. of the International Code of Zoological Nomenclature (ICZN 1999). Frost (2023) regards S. brevipes as a valid species because Fei et al. (2009) did not address the evidence of Fu et al. (1997). However, Fu et al. (1997) re-analyzed the morphological character data of Ye et al. (1992) but never mentioned the name S. glandulatus. Other research treated both S. glandulatus and S. brevipes as valid species but did not provide evidence supporting both names (Jiang et al. 2012, 2016; Khatiwada et al. 2019; Yang and Huang 2019). Thus, there is no evidence supporting the validity of S. brevipes, and S. brevipes should be retained as a junior synonym of S. glandulatus.

Although Scutiger luozhaensis is a common species in its habitat, its distribution range may be limited to a small area, including the canyon of Luozha County and possibly adjacent Bhutan. The population size and distribution area for the species are still not clear. The conservation status for this species is suggested to be Data Deficient (DD) and further investigations on this species are recommended.

The authors have declared that no competing interests exist.

No ethical statement was reported.

This work is funded by the Survey of Wildlife Resources in Key Areas of Tibet (ZL202203601), the Second Tibetan Plateau Scientific Expedition and Research Program (STEP, 2019QZKK05010503), and China Biodiversity Observation Networks (Sino BON-Amphibian & Reptile).

Sheng-Chao Shi: methodology, investigation and resources, data analysis, validation, writing: orgination and draft, writing: review and editing; Lu-Lu Sui: laboratory work, methodology, investigation and resources, data analysis, validation, writing: orginationand draft, writing: review and editing; Shun Ma: investigation and resources, writing: review and editing; Fei-Rong Ji: investigation and resources, writing: review and editing; A-Yi Bu-Dian: investigation and resources, writing: review and editing; Jian-Ping Jiang: conceptualization, data curation, project administrition, resources, supervision, writing: review and editing.

Sheng-Chao Shi https://orcid.org/0000-0003-2337-6572

Lu-Lu Sui https://orcid.org/0009-0007-5229-5401

Shun Ma https://orcid.org/0009-0003-8611-4550

Fei-Rong Ji https://orcid.org/0009-0005-6900-0556

A-Yi Bu-Dian https://orcid.org/0009-0004-9375-5724

Jian-Ping Jiang https://orcid.org/0000-0002-1051-7797

All of the data that support the findings of this study are available in the main text or Supplementary Information.