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| Trimeresurus lii Cai, Liu, Liang, Wang & Ding, in Cai, Gou, Wang, Liu, Liang, X. Gu, H. Gu, Fang, Liu, Li et Ding, 2026. |
Abstract
The genus Trimeresurus Lacépède comprises over 57 species, with recent taxonomic revisions recognizing six subgenera. Despite extensive research, many regions in China remain understudied, particularly the biodiversity-rich West China Rain Zone. This study reports a new pitviper species from western Sichuan Province, China, based on comprehensive morphological and molecular analyses. Specimens collected from the West China Rain Zone were examined using detailed morphological comparisons and phylogenetic analyses of three mitochondrial genes (16S, cytb, and ND4). The results show that this population, together with T. loong, forms a distinct monophyletic clade within the subgenus Viridovipera Malhotra & Thorpe, with uncorrected genetic distances to its closest relatives exceeding 6.50% (cytb) and 5.77% (ND4). Diagnostic morphological differences, including smooth cephalic scales, a postocular streak extending beyond the 2nd supralabial in males, dorsal scale rows of 21–21–15, and a grass-green body color lacking bands or markings, further support its taxonomic distinctness. We propose the new species Trimeresurus lii sp. nov., which represents the second species of Viridovipera in Sichuan Province and the 58th species of Trimeresurus worldwide, and contributes to understanding biodiversity in the Giant Panda National Park region. This discovery highlights the importance of continued field surveys in biodiversity hotspots for documenting and conserving unique faunal assemblages.
Key Words: Bamboo pitviper, biodiversity hotspots, Giant Panda National Park, morphology, snakebite envenoming, Viridovipera, West China Rain Zone
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| Trimeresurus lii sp. nov. in life: paratype CIB CB2120, male (A, B); allotype CIB 122872, female (C, D); and paratype CIB CB249CD03, juvenile male (E, F). Photographs by Bo CAI. |
Trimeresurus lii Cai, Liu, Liang, Wang & Ding, sp. nov.
Diagnosis: (Table 2). This new species can be distinguished from all of its congeners by the following combination of morphological characters: (1) dorsal scale rows 21-21-15; (2) ventrals 152–167 in males and 160–168 in females; (3) subcaudals 64–75 in males and 63–70 in females; (4) skin coloration is black to dark gray, and body coloration is grass green without bands or markings in both sexes; (5) eye color is amber in males and orange-yellow in females; (6) postocular stripe is red and white, extending to the 2nd supralabial in males, but yellow or faintly developed yellow in females; (7) ventrolateral stripe is white (above) and red (below) in males, but yellow in females; (8) temporal scales and occipital scales smooth, dorsal scales rhomboid, feebly keeled except the first row of scales, which are smooth in both sexes.
Etymology. The specific epithet lii is a Latinized genitive form honoring LI Er (c. 6th–5th century BCE), traditionally revered as Laozi, the ancient Chinese philosopher whose teachings emphasize harmonious coexistence between humans and nature—a principle that aligns closely with the conservation ethos of the Giant Panda National Park, where this species was discovered. The known distribution of Trimeresurus lii sp. nov. in western Sichuan Province falls within the West China Rain Zone, a region historically associated with the early development of Daoist thought. In light of its geographic range and ecological context, we propose ‘Huaxi Green Pitviper’ as the English common name and ‘华西竹叶青蛇’ (Huáxī Zhúyèqīng Shé) as the Chinese name.
Bo Cai, Yubo Gou, Gang Wang, Fengjing Liu, Dong Liang, Xiaodong Gu, Haijun Gu, Haolong Fang, Yuzhou Liu, Qiujie Li and Li Ding. 2026. A New Species of the Genus Trimeresurus Lacépède, 1804 (Squamata, Viperidae) from western Sichuan Province, China. Zoosystematics and Evolution. 102(1): 285-302. DOI: doi.org/10.3897/zse.102.178601 [30 Jan 2026]
