Species diversity within the green pit vipers of the genus Trimeresurus is likely underestimated. In this study, we describe a new species of Trimeresurus from the Xizang Autonomous Region, China, based on both morphological and molecular evidence. The new species, Trimeresurus pretiosus sp. nov., is assigned to the subgenus Viridovipera Malhotra Thorpe. It is distinguished from its congeners by the following combination of morphological characters: (1) first supralabial completely separated from nasal scale; (2) hemipenis short and spinose, reaching the 12th subcaudal when fully everted; (3) small adult size, with a maximum known snout-vent length of 516 mm in males and 512 mm in females; (4) dorsal scales in 19–19–15 rows, weakly keeled except for the outermost rows; (5) 140–143 ventral scales; (6) 56–58 subcaudal scales in males and 54 in females, partially arranged in a single row; (7) iris reddish-brown in males, orange-yellow in females; (8) body uniformly bright grass-green; postocular streak absent or faint white in males, absent in females; (9) ventrolateral stripe consisting of red above and white below and wide in males, only white and narrow in females; (10) ventral surfaces greenish-yellow; (11) tail distinctly reddish-brown dorsally, with the colouration extending from tail base to tip. Molecular analyses based on the mitochondrial 16S, cyt b, and ND4 gene fragments indicate that the new species is genetically divergent from all congeners, with uncorrected p-distances ranging from 5.8% to 12.5% in the cyt b gene and from 6.7% to 11.0% in the ND4 gene. The new species is currently known only from the southern slopes of the central Himalayas in Yadong County, and it represents the second known Viridovipera species from the southern Himalayas. With this discovery, the total number of snake species known from the Xizang Autonomous Region increases to 67, underscoring the importance of continued herpetofaunal surveys in this biogeographically complex region.

Keywords: Viridovipera; morphology; taxonomy; molecular phylogeny; systematics; Himalaya

Trimeresurus pretiosus Xu, Nguyen, Wang, Zhang, Poyarkov, Wei, Vogel, Peng, and Weng sp. nov.

Holotype. QHU R2025019, adult male, collected from Xiayadong Township, Yadong County, Xigaze City, Xizang Autonomous Region, China (27.262° N, 89.016° E; elevation 1824 m a.s.l.), collected by Zhenqi Wang, Yuhao Xu, Fanyue Sun, and Lifang Peng on 22 June 2025.

 

Diagnosis. Trimeresurus pretiosus sp. nov. is distinguished from all of its congeners by a combination of the following morphological characters: (1) first supralabial completely separated from nasal scale; (2) hemipenis short and spinose, reaching 12th subcaudal when fully everted; (3) adult body size relatively small, with a maximum known snout-vent length of 516 mm in males and 512 mm in females; (4) dorsal scales in 19–19–15 rows, weakly keeled except for the outermost rows; (5) 140–143 ventral scales; (6) 56–58 subcaudal scales in males and 54 in females, partially arranged in a single row; (7) iris reddish-brown in males, orange-yellow in females; (8) body uniformly bright grass-green; postocular streak absent or faint white in males, absent in females; (9) ventrolateral stripe consisting of red above and white below and wide in males; white only and narrow in females; (10) ventral surfaces greenish-yellow; (11) tail distinctly reddish-brown dorsally, with the colouration extending from tail base to tail tip.

Etymology. The specific epithet “pretiosus” is a Latin adjective in the nominative case (masculine gender, singular), meaning “precious” or “valuable”. The name refers to the species’ striking and vivid colouration, which makes it resemble a hidden green gem within the pristine forest. Furthermore, although herpetologists have conducted numerous field surveys in Yadong County, Xizang AR, China, for several decades, no green pit viper has ever been recorded from the area until now. The new species represents the currently known westernmost distribution of the subgenus Viridovipera and is extremely rare in the wild. Therefore, through the specific epithet, we hope to raise awareness not only of the new species but also of the rich biodiversity of Yadong County, thereby promoting greater attention to and protection of its unique ecological environment. Based on its type locality, Yadong County, we recommend “Yadong Green Pit Viper” as the common English name, “亚东竹叶青蛇” (Yă Dōng Zhú Yè Qīng Shé) as the Chinese name, “Rắn lục xanh báu vật” as the Vietnamese name, “Драгoценная бамбукoвая куфия” (Dragotsennaya bambukovaya kufiya) as the common name in Russian, and “Yadong-Grubenotter” as the common name in German.

Etymology. Spelaeus, adjective in the masculine gender. The epithet as a reference to the Latin word spelaeus, meaning “cave”.

Distribution. Only known from in Rolo Vergara Cave, municipality of Chos Malal, Neuquén Province, Argentina (Figure 5).

Two new endemic species of Anaulacodesmus Attems, 1898, a genus of millipede native to Chile, are described. Anaulacodesmus panterae sp. nov. and Anaulacodesmus picassovallebuonai sp. nov. were discovered in fragments of Valdivian temperate forest in southern Chile. These species can be separated from the rest of the congeners based on their larger size and gonopodal characters. A. panterae from Valdivia (Los Ríos Region), has distally swollen gonopods, a trait it shares with A. dahli Chamberlin, 1957 and a A. enkrates (Attems, 1898). Anaulacodesmus picassovallebuonai sp. nov., from Temuco and Lake Villarrica (La Araucanía Region), is morphologically similar to A. bifidus Golovatch, 2014 with which it shares the bifid structure of the telopodite. Detailed descriptions and character illustrations are provided for both species.