IUCN threat status:

Least Concern (LC)

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The dangerously venomous Trimeresurus yunnanensis is one of a group of morphologically similar green and arboreal Asian pitviper species known as "green pitvipers" (these species are sometimes segregated into a genus Viridovipera, e.g., V. yunnanensis; Malhotra and Thorpe 2004a,b,2005, Guo et al. 2009).  Most green pitviper species share a common color pattern consisting of a uniform green coloration with a white lateral line on the first dorsal scale row, often also with red lateral lines and postocular stripes (Guo et al. 2009). Green pitvipers are among the most common venomous snakes in Asia and in many Asian countries account for a large fraction of snakebites, but working out the systematics and taxonomy of this group has been challenging. Guo et al. (2009) discuss these challenges in their review of Viridovipera and analysis of the status of V. yunnanansis, as do Malhotra and Thorpe (2004b) in their analysis of the V. stejnegeri complex.

Trimeresurus yunnanensis is known from Myanmar (Chin State [Haka], Kachin State), China (Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Sichuan, Yunnan, Zhejiang), Taiwan, Vietnam (Lao Cai, Vinh Phú, and possibly Bac Thai, Da Nang, Gia Lai, and Hoa Binh), and Laos. It has been recorded at 1206 m in the mountainous regions of Yunnan in Nuijiang Langcang Gorge alpine conifer and mixed forest. It has been reported (as T. stejnegeri) from elevations up to 2845 m. Historical records for Myanmar place this species in subtropical forests (northern triangle) and Chin Hills-Rakhine montane forest. Individuals have been recorded in bushes and trees and on the ground in grass, as well as from grassy slopes with shrubs and from mixed forest. (Leviton et al. 2003 and references therein)

This species has sometimes been treated as a subspecies of T. stejnegeri. It is clear that the nominal T. stejnegeri, T. yunnanensis, and T. medoensis are all closely related. Leviton et al. (2003), Malhotra and Thorpe 2004a,b,2005, and Guo et al. (2009) recognized the validity of T. yunnanensis based on a range of data, but called for further study to clarify species boundaries within this clade. (Leviton et al. 2003 and references therein)

Guo and Zhao (2006) undertook an analysis of skull morphology of nine Asian pit vipers, including Viridovipera yunnanensis..

Leviton et al. (2003)  provide a technical description of Trimeresurus yunnanensis: Scales in 19 (rarely 21) longitudinal rows at midbody and 19 (-21) on neck; 9-10 (rarely 11) upper labials, first upper labials separated from nasals by a distinct suture; a single narrow supraocular, sometimes divided by transverse suture; 11-16 scales in a line between supraoculars; above bright to dark green, below pale green to whitish, the two separated by a bicolored orange or brown (below) and white (above) (males) or white only or absent (females) ventrolateral stripe, which occupies the whole of the outermost scale row and a portion of the second row; ventrals 155-165 (-170); subcaudals (58-) 61-68, all paired; hemipenes short, spinose beyond bifurcation. Total length: 750 mm; tail length: 145 mm.


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