New Kunming Green Pit Viper Identified by DNA and Anatomy

A green pit viper found in forested hills near Kunming, China, has been formally described as a species new to science. Researchers named it Trimeresurus loong and proposed the English common name Kunming Green Pit Viper. The type series comprises six specimens collected during fieldwork in May and September 2025 at Qinglongxia, Anning City, Kunming City, Yunnan Province, at an elevation of approximately 1,822 metres above sea level.

Morphological examination and mitochondrial DNA analysis distinguished the population from every recognized species in the subgenus Viridovipera . The finding brings the number of recognized Trimeresurus species to 57 and the number recorded in Yunnan to nine. The study was an integrative taxonomic assessment of the Anning population, combining measurements and scale counts from preserved specimens, examination of coloration in life, internal reproductive anatomy, and phylogenetic analyses of mitochondrial DNA.

This approach was necessary because Asian green pit vipers can be exceptionally difficult to distinguish. Closely related species often have highly conserved scale counts, while differences in eye color, lateral stripes, tail patterning and reproductive structures may separate animals that otherwise look similar. The six Anning specimens were consistently distinguishable from known members of Viridovipera , and their genetic data supported recognition as a distinct evolutionary lineage rather than a local population of an existing species.

For the molecular work, the researchers extracted DNA from ethanol-preserved liver tissue and amplified three mitochondrial gene fragments: 16S ribosomal RNA, cytochrome b, conventionally abbreviated cyt b, and NADH dehydrogenase subunit 4, or ND4. The concatenated alignment was 2,314 base pairs long, comprising 508 base pairs of 16S, 1,034 of cyt b and 772 of ND4. Maximum-likelihood and Bayesian analyses produced congruent tree topologies.

All six specimens from Anning formed a strongly supported monophyletic clade, with SH-like support of 100, ultrafast bootstrap support of 100 and a Bayesian posterior probability of 1.0. The authors also calculated uncorrected pairwise genetic distances. The Anning population differed from all recognized congeners by 6.7–11.2% in cyt b and by 6.1–8.3% in ND4.

Phylogenetic analysis placed T. loong near specimens from Huili City, Sichuan Province, that had long been misidentified as T. yunnanensis . The Anning species was sister to these two Huili specimens, and the three together associated with three unidentified specimens from western Sichuan. The entire assemblage occupied the outer margin of the clade formed by the other recognized Viridovipera species.

Because suitable morphological data were unavailable for the Sichuan material, the authors could not determine its exact taxonomic status. They therefore referred to the Huili population provisionally as T. cf. loong and treated the western Sichuan specimens as an unnamed Trimeresurus lineage pending further examination. Trimeresurus loong is diagnosed by a combination of anatomical and color-pattern characters.

The first supralabial scale is completely separated from the nasal scale, while the hemipenis is short, robust and spinose, extending to the 10th or 11th subcaudal scale when fully everted. Its dorsal scales occur in 19, sometimes 21 or 23, anterior rows, 19 at midbody and 15 near the tail. Males have 150–151 ventral scales and 67–68 subcaudal scales; females have 157–158 ventral scales and 57–64 subcaudals.

The longest known male in the type series measured 748 millimetres in total length, including a 601-millimetre snout–vent length and 147-millimetre tail. The only known adult female measured 792 millimetres overall, with a 657-millimetre snout–vent length and 135-millimetre tail. Coloration supplies some of the most conspicuous distinctions from related vipers.

The head and body are uniformly bright grass-green in life. Adult males have amber irises with a faint reddish cast, whereas adult females have yellowish irises. Males possess a narrow white postocular streak, sometimes with scale margins tinged yellow or reddish-brown, while the streak is absent in both known adult females.

The ventrolateral stripe in males occurs in two forms: a narrow white band with a faint yellowish upper margin and a thin red lower border, sometimes above a diffuse brownish tinge, or a white band edged with faint yellow on both sides. In females, the stripe is either absent or a simple narrow white band. The dorsal tail begins green, changes gradually to nearly uniform orange or light orange-red, and ends in a blackish-brown tip.

The new species most closely resembles T. yunnanensis , but the two can be separated by several traits. Maximum female snout–vent length is smaller in T. loong , at 657 millimetres, than in T. yunnanensis , at 804 millimetres. Males of the new species also have fewer combined ventral and subcaudal scales, amber rather than bright or deep red irises, and a narrower ventrolateral stripe confined to the first dorsal scale row.

Its tail transitions smoothly from green to orange-red, whereas T. yunnanensis bears large, irregular dark-red blotches toward the front of the tail. Hemipenial measurements also differ. Relative to the hemipenial total length, T. loong has a shorter truncus than T. yunnanensis , with ratios of 0.62–0.66 versus 0.69.

The point at which the sulcus spermaticus divides is farther along the truncus, with a sulcus-bifurcation-distance-to-truncus-length ratio of 0.43–0.49 versus 0.30, and each side carries 14–19 conspicuously enlarged spines rather than 9–10. Field observations provide limited but useful information about the species’ natural history. All six specimens were encountered during the first half of the night, when temperatures ranged from 15 to 18 degrees Celsius.

They were coiled in shrubs on hillsides near streams within well-preserved broad-leaved forest at the type locality. One adult female defecated immediately when disturbed during capture. Its feces contained numerous bird feathers, suggesting that small birds may form part of the adult diet, although this single observation does not establish a complete dietary profile.

The study did not directly investigate activity patterns, prey selection, reproduction, population size or long-term habitat use, so those aspects remain unknown. The epithet loong is a Latinized form of the Chinese word “龙” (lóng), meaning “loong” or “dragon.” It refers both to the traditional description of snakes as “little dragons” and to Qinglongxia, the type locality, whose Chinese name means “Green Dragon Gorge.” The species’ vivid green coloration reinforces that association. The authors identify Yunnan and neighboring Himalayan regions as important areas of diversification within Viridovipera , while noting that the new lineage is presently known only from Qinglongxia.

Because the known distribution is restricted to the type locality and no population data are available, the authors recommended provisionally classifying T. loong as Data Deficient under International Union for Conservation of Nature criteria. Targeted field surveys are needed to determine its actual distribution, abundance and ecological requirements. The study also illustrates the broader taxonomic difficulty surrounding the T. yunnanensis complex: molecular trees, scale patterns, reproductive morphology and living coloration each reveal information that may be obscured when only one source of evidence is used.

The formal description of T. loong adds another narrowly distributed lineage to a genus in which many species remain difficult to identify and whose evolutionary diversity is still being resolved.

Subject of Research: Taxonomic description of the newly recognized green pit viper Trimeresurus loong from Kunming, Yunnan, China

Article Title: A ‘little dragon’ from Kunming City: a new green pit viper from Yunnan Province, China ( Squamata , Viperidae , Trimeresurus )

Article References: Xu, Y., Deng, J., Zhang, T., Nguyen, T. V., Weng, S., Poyarkov, N. A., Vogel, G., Sun, F., Liao, C., & Peng, L. (2025). A ‘little dragon’ from Kunming City: a new green pit viper from Yunnan Province, China (Squamata, Viperidae, Trimeresurus). Zoosystematics and Evolution, 101(4), 2267-2293. https://doi.org/10.3897/zse.101.175879

Image Credits: AI Generated

DOI: 10.3897/zse.101.175879

Keywords: Trimeresurus loong, green pit viper, new species, Kunming, Yunnan, snake taxonomy, mitochondrial DNA, hemipenial morphology, cryptic diversity, montane forest, little, dragon