Trimeresurus nujiang, Liang & Ding & Vogel & Chen & Wu, 2025

Liang, Ya-Ting, Ding, Li, Vogel, Gernot, Chen, Ze-Ning & Wu, Zheng-Jun, 2025, A new species of the genus Trimeresurus Lacépède, 1804 (Reptilia, Squamata, Viperidae) from Southwestern China, Zoosystematics and Evolution 101 (4), pp. 1653-1668 : 1653-1668

Trimeresurus nujiang sp. nov.

Type material.

Holotype • CIB DL R 353 , an adult male from Cikai Town , Gongshan County, Nujiang Lisu Autonomous Prefecture, Yunnan Province, China ( 27°46'1.32"N, 98°40'50.78"E; altitude ca. 1537 m a. s. l); collected by Li Ding on 3 September 2020 (Figs 3 , 4 ).

Paratypes ( N = 10) • CIB DL 10 ( male), CIB DL 19 ( male), CIB DL R 364 ( male), CIB DL R 375 ( male), CIB DL R 380 ( male), CIB DL- 03-622 ( female) and GXNU 2024061101 ( female) are around the site where the holotype was found . CIB DL R 362 ( female), CIB DL R 363 ( female) and CIB DL R 365 ( female) collected in Bingzhongluo Town , Gongshan County, Yunnan on 2 September 2020. Ten specimens collected at elevations between 1495–1699 m a. s. l. by Li Ding. Detailed information is presented in Table 2 .

Etymology.

The specific name “ nujiang ” refers to the location of type specimens, the area around the Nujiang River. As common name we suggest “ Nujiang green pit-viper ” in English and “ Nù Jiāng Zhú Yè Qīng (怒江竹叶青) ” in Chinese.

Diagnosis.

A species of the genus Trimeresurus has a combination of the following characters: (1) Dorsal body olive drab or grass green, without bands or markings; interstitial skin greyish-black; ventral body yellow green. (2) Tail mostly reddish brown with dark brown tail end. (3) Dorsum of the head has the same color as the body, the upper labials are light green. (4) Moderate body size, with the maximum total length exceeding 804 mm. (5) White (above) and dark red (below) ventrolateral stripe present on the first row of dorsal scales, and the ventrolateral stripe continuous on the tail in males; faint white ventrolateral stripe in females. (6) Postocular streak absent in both sexes. (7) Iris golden-yellow in both sexes in life. (8) First supralabial completely separated from nasal scale. (9) Head scales not keeled; dorsal scale row 19 (rarely 21 or 22) – 19–15 (rarely 13) ( N = 11), feebly keeled except the outermost rows. (10) Internasals not in contact, most usually separated by 1–2 scales. (11) Supraoculars large but elongate, separated by 10–11 smooth cephalic scales. (12) Ventral scales 164–173 in males ( N = 6), 165–168 in females ( N = 5). (13) Subcaudal scales 59–68 in males ( N = 4), 57–60 in females ( N = 5). (14) Total number of VEN + SC 226–241 in males ( N = 4), 222–226 in females ( N = 5). (15) Tail relatively short, and tail to total length ratio ( TaL / TL) 0.147 –0.163 in males ( N = 4), 0.144 –0.152 in females ( N = 5). (16) Hemipenes short and spinose, bilobed at 6 th / 7 th plate when unextruded, tips reaching SC 10, sulcus spermaticus shallow, visible, divides at the base of the organ.

Description of holotype male DL R 353.

(Figs 3 , 4 ).

Morphology. Body cylindrical, long and thin, SVL 694 mm; TaL 110 + mm, the tail a bit missing; TL 804 + mm, ratio of tail length to total length ( TaL / TL) over 13.7 %. Head triangular, elongate, clearly distinct from the neck, head length 35.2 mm ( HL / SVL 0.051); head width 22.6 mm ( HW / HL 0.642). Distance between tip of snout and anterior border of eye 11.1 mm on both sides. Eyes large, eye diameter 4.4 mm (ED / HL 0.125); pupil vertically elliptic.

Body scalation. Dorsal scales in 21–19 – 13 rows; dorsal scales rhomboid, feebly keeled except the first row of scales, which are smooth; 169 ventral scales (plus 1 preventrals); 41 + / 42 + subcaudals, paired; anal shield single and entire.

Head scalation. Rostral slightly visible when viewed from above, subtriangular; a large pair of enlarged and subrectangular internasals bordered by one scale; nostril completely enclosed in nasal scale; nasal scale complete, completely separated from 1 st supralabial, with only a trace of a suture, sub-pentagonal; three elongated preoculars on each side of the head, two lower preoculars and 2 nd supralabial encompass the loreal pit; one elongate and narrow supraocular; one long, thin, crescent-like subocular scale; 2 nd supralabials completely contact the anterior margin of the pit; two small scales on the left side and one small scale on the right side between the nasal and the foveal; 10 small and irregular cephalic scales between the supraoculars; temporal and occipital scales feebly keeled. 9 / 9 supralabials; 1 st supralabial triangular, small; 2 nd as high as the 1 st supralabial, nearly of the same width throughout; 3 rd supralabial largest, wider than high, and in contact with the subocular; 4 th and 5 th supralabials separated from the subocular by a single row of smooth scales; 6 th supralabials separated from subocular by 2 / 2 scales. 12 / 12 infralabials; the first pair of infralabials are in contact with each other behind the mental; the first three pairs of infralabials are in contact with the anterior chin shields.

Coloration in preservation (Figs 3 , 4 ). Description based on holotype DL R 353 fixed in formalin and later stored in 75 % ethanol for approximately three years. Dorsal head and body olive drab, ventral color faded to whitish green. Lateral head olive above lower margin of eye, upper labials light green with bluish tint. The ventral surfaces of the head are creamy white with a bluish tint. Ventral surface of tail whitish green anteriorly, becoming paler bluish-green at the middle and end of tail. Ventrolateral stripe present, with white (above) and dark brown (below) on first dorsal scale rows.

Coloration in life (Fig. 5 ). Dorsal body generally olive drab in males and grass green in females, with greyish-black interstitial skin. Lateral head jungle-green above lower margin of eyes, and light green below, without postocular stripes in both genders. Lateral body deep green above and gradually become light green below. A white (above) and dark red (below) ventrolateral stripe present in males, a thin and light white ventrolateral stripe present in females, which ventrolateral stripe present on each scale of the first dorsal scale. Venter uniform yellowish-green. Tail mostly reddish-brown, dark brown at the end of the tail. Iris golden-yellow in both males and females, pupils edged with lighter color.

Hemipenis. Description based on two specimens, namely the holotype DL R 353 and paratype DL 19. The hemipenis is relatively short, papilloma, reaching only 10 th subcaudal, and bifurcates at 6 th – 7 th subcaudal when unextruded. Sulcus spermaticus shallow, visible, divides at the base of the organ.

Intraspecific morphological variation. The ten paratypes agree with the description of the holotype in most aspects except for the following difference: (1) ventrolateral stripe always present, males have obvious white or bicolored stripes, while females have thin and light white stripes; (2) dorsal scales in 19 (rarely 21 or 22) – 19–15 (rarely 13) rows; (3) ventral scales 164–173 in males ( N = 6), while 165–168 in females ( N = 5); (4) subcaudal scales 59–68 in males ( N = 4), while 57–60 in females ( N = 5); (5) total number of VEN + SC 226–241 in males ( N = 4), while 222–226 in females ( N = 5). (6) TaL / TL 0.147 –0.163 in males ( N = 4), 0.144 –0.152 in females ( N = 5); supralabial scales vary between 9 or 10 ( N = 11); (7) infralabial scales vary from 11 to 13 ( N = 11); (8) cephalic scales vary from 10 to 11 ( N = 11) (See details in Table 2 ).

Comparison.

The new species is morphologically and phylogenetically classified in the subgenus Viridovipera ( Malhotra and Thorpe 2004 a; Guo et al. 2009). We here compare the new species with the six other species of the subgenus Viridovipera ( T. stejnegeri , T. yunnanensis , T. medoensis , T. vogeli , T. truongsonensis , T. mayaae ) and other species of Trimeresurus occurring in Yunnan Province of China ( T. albolabris , T. caudornatus , T. guoi , T. popeiorum , T. lanna ). The main features that distinguish the new species from those known members of the subgenus Viridovipera are summarised in Suppl. material 3.

Trimeresurus nujiang sp. nov. is distinguishable from T. stejnegeri by having: (1) Higher max SVL in both sexes ( 649 mm vs. 610 mm in males, 682 mm vs. 627 mm in females). (2) Lower ratio TaL / TL in both sexes ( 0.147 –0.163 vs. 0.175 –0.230 in males, 0.144 –0.152 vs. 0.157 –0.179 in females). (3) Slightly higher number of ventral scales in males (164–173 vs. 155–169). (4) Slightly lower number of subcaudal scales (59–68 vs. 61–77 in males, 57–60 vs. 57–68 in females). (5) MSR 19 vs. 21 in T. stejnegeri . (6) Postocular streak absent in both sexes vs. white (below) and red (above) or white in males and faint white or absent in females in T. stejnegeri . (7) Ventrolateral stripe present in males, dark red (below) and white (above) vs. red (below) and white (above) or white in T. stejnegeri . (8) Different eye color in both sexes (golden-yellow vs. bright red or amber (rarely yellow) in males, golden-yellow vs. yellow or amber in females).

Trimeresurus nujiang sp. nov. differs from T. yunnanensis by having: (1) More or less the same size vs. exhibiting sexual dimorphism in T. yunnanensis . (2) Lower ratio TaL / TL in both genders ( 0.147 –0.163 vs. 0.162 –0.207 in males, 0.144 –0.152 vs. 0.151 –0.177 in females). (3) Internasals are usually separated by 1–2 scales vs. internasals are always in contact or separated by one or two scales in T. yunnanensis . (4) MSR 19 vs. 19 (45.16 %) / 21 (54.84 %) in T. yunnanensis . (5) Postocular stripe always absent in both genders vs. absent or only thin and white present in females in T. yunnanensis . (6) Different color of ventrolateral stripe, dark red (below) and white (above) ventrolateral stripe in males vs. bright or deep red (below) and white (above) in T. yunnanensis ; a faint white ventrolateral stripe present in females vs. white or absent in T. yunnanensis . (7) Different eye color in males, golden-yellow vs. deep red or sepia in T. yunnanensis .

Trimeresurus nujiang sp. nov. is distinguished from T. medoensis by having: (1) Higher max SVL in both genders ( 649 mm vs. 573 mm in males, 682 mm vs. 555 mm in females). (2) Lower ratio TaL / TL in both genders ( 0.147 –0.163 vs. 0.165 –0.208 in males, 0.144 –0.152 vs. 0.163 –0.185 in females). (3) Higher number of ventral scales in both genders (164–173 vs. 138–149 in males, 165–168 vs. 138–149 in females). (4) Higher number of subcaudal scales in males (59–68 vs. 53–63). (5) Higher total number of ventral scales and subcaudal scales in both genders (226–241 vs. 192–208 in males, 222–226 vs. 195–206 in females). (6) Cephalic scales 10–11 vs. 6–9 (rarely 10) in T. medoensis . (7) 19 dorsal rows at mid-body vs. 17 in T. medoensis . (8) Different color of ventrolateral stripe, dark red (below) and white (above) in males vs. red (below) and white (above) or white in T. medoensis ; a white ventrolateral stripe present in females vs. a bright bicolored red (below) and white (above) in T. medoensis .

Trimeresurus nujiang sp. nov. differs from T. vogeli by having: (1) Lower ratio TaL / TL in both sexes ( 0.147 –0.163 vs. 0.175 –0.208 in males, 0.144 –0.152 vs. 0.149 –0.170 in females). (2) Slightly higher number of VEN in males (164–173 vs. 154–169), but slightly lower number of VEN in females (165–168 vs. 157–173). (3) Slightly lower number of SC in both sexes (59–68 vs. 62–74 in males, 57–60 vs. 59–65 in females). (4) Slightly higher total number of VEN + SC in males (226–241 vs. 221–239), while lower total number of VEN + SC in females (222–226 vs. 218–233). (5) Fewer cephalic scales, 10–11 vs. 11–14 in T. vogeli . (6) 19 dorsal scales at mid-body, slightly keeled vs. 21 (rarely 20) rows at mid-body, strongly keeled in T. vogeli . (7) Postocular streak absent in males vs. whitish yellow and rather faint or absent in T. vogeli . (8) Ventrolateral stripe present, dark red (below) and white (above) vs. red (below) and white (above) or white in T. vogeli . (9) Eye golden-yellow in both sexes vs. yellow or yellowish green in T. vogeli . (10) Tail mostly reddish brown in life vs. mostly green with only the tip or the last 20 % of its length mottled with rusty brown in T. vogeli . (11) White vertebral spots absent in males vs. constantly present in T. vogeli .

Trimeresurus nujiang sp. nov. differs from T. truongsonensis by having: (1) Higher max SVL in both sexes ( 649 mm vs. 521 mm in males, 682 mm vs. 462 mm in females). (2) Lower ratio TaL / TL in both sexes ( 0.147 –0.163 vs. 0.181 –0.207 in males, 0.144 –0.152 vs. 0.199 in females). (3) Lower total number of VEN + SC in both sexes (226–241 vs. 235–243 in males, 222–226 vs. 235 in females). (4) 19 dorsal scale rows at mid-body vs. 21 in T. truongsonensis . (5) Immaculate green dorsal colouration vs. dorsal colouration with blotches, spots, bands or crossbars in T. truongsonensis . (6) Dark red (below) and white (above) ventrolateral stripe in males vs. red-brown (below) and light greenish-blue (above) or white in T. truongsonensis . (7) Eye golden-yellow in males vs. greenish-yellow in T. truongsonensis .

Trimeresurus nujiang sp. nov. differs from T. mayaae by having: (1) Higher max SVL in both genders ( 649 mm vs. 610 mm in males, 682 mm vs. 590 mm in females). (2) Tail relatively smaller, ratio TaL / TL 0.147 –0.163 vs. 0.165 –0.234 in males, 0.144 –0.152 vs. 0.165 –0.169 in females. (3) More ventral scales in both genders (164–173 vs. 153–163 in males, 165–168 vs. 153 in females). (4) More subcaudal scales in females (57–60 vs. 54–55). (5) Higher total number of VEN + SC in both genders (226–241 vs. 211–231 in males, 222–226 vs. 207–208 in females). (6) 19 dorsal scales at mid-body, weakly keeled vs. 19 (15.80 %) or 20 (7.69 %) or 21 (69.23 %), moderately keeled in T. mayaae . (7) Postocular stripe absent in males vs. conspicuous bicolored postocular stripe in T. mayaae . (8) Dark red (below) and white (above) ventrolateral stripe in males vs. vivid, wide bicolored ventrolateral stripe, deep red (below) and white (above) in T. mayaae . (9) Differences in eye color, eyes golden-yellow in both genders vs. rust in males and green in females in T. mayaae .

Trimeresurus nujiang sp. nov. is different from T. albolabris , T. caudornatus , T. guoi by having the first supralabial completely separate from nasal scale (vs. partially or completely fused to the nasal scale), scales in 19 longitudinal rows at mid-body (vs. 21 or rarely 19), and different structure of the hemipenes.

Trimeresurus nujiang sp. nov. is different from T. popeiorum by: (1) Different color of dorsal surfaces, olive drab or grass green vs. various shades of green, bluish-green or even turquoise blue in T. popeiorum . (2) Different color of ventrolateral stripe in both genders, dark red (below) and white (above) vs. bright and deep red (below) and white (above) in males; thin white vs. thin white or yellow in females. (3) No postocular streak in males vs. bicolored postocular streak present in T. popeiorum . (4) Eyes golden-yellow in both males and females vs. red or deep red in T. popeiorum . (5) MSR 19 vs. 21 in T. popeiorum . (6) Shorter hemipenes, short and spinose vs. long and no spines in T. popeiorum . (7) 10–11 cephalic scales between the supraoculars vs. 10–13 in T. popeiorum . (8) Tail relatively shorter, 0.147 –0.162 vs. 0.18–0.21 in males, 0.140 –0.152 vs. 0.14–0.19 in females.

Trimeresurus nujiang sp. nov. is different from T. lanna by: (1) Dorsal surfaces generally olive drab or grass green vs. deep green in T. lanna . (2) Postocular streak absent in both genders vs. white and thin ventrally, broad and bright red dorsally, covering two or three temporal scales in males and streak absent or only white in females. (3) Bicolored ventrolateral stripe in males, dark red below and white above vs. a wide, bright and deep red below, white above; a thin white ventrolateral stripe present in females vs. thin and pale yellow anteriorly, whitish posteriorly. (4) 19 dorsal scales rows at mid-body vs. 21 (93.3 %) or rarely 20 (6.7 %) in T. lanna . (5) Hemipenes short and spinose, reaching only 10 th SC vs. long and forked without spines, reaching at least 25 th SC.

Distribution and habitat.

Currently, Trimeresurus nujiang sp. nov. is known only from the type locality in Gongshan County, Nujiang Lisu Autonomous Prefecture, Yunnan Province, China (Fig. 6 ). The collected individuals were encountered at night, perched on tree branches near the Grand Canyon of the Nujiang. It is currently known to be found in subtropical broad-leaved evergreen forests at elevations reaching approximately 1500–1700 m in Gongshan, Yunnan, China (Fig. 7 ). Gongshan County is located in the Nujiang Lisu Autonomous Prefecture in the northwestern part of Yunnan Province, bordering Myanmar to the west. Nujiang River originates on the Tibetan Plateau and flows through the Nujiang Lisu Autonomous Prefecture in Yunnan Province, where it exits and flows into Myanmar. It is assumed that the new species may also be distributed in Myanmar.

Figures

Figure 3. Holotype of Trimeresurus nujiang sp. nov. (male, CIB DL R 353): A. Dorsal view; B. Ventral view.

Figure 4. Holotype of Trimeresurus nujiang sp. nov. (male, CIB DLR 353): A. Dorsal head; B. Ventral head; C. Left head; D. Dorsal views of the tail; E. Ventral views of the tail; F. Dorsolateral view of body.

Figure 5. Trimeresurus nujiang sp. nov. in life: A. Holotype, male (DL R 353); B. Paratype, female (CIB DL- 03-622). Photographed by Li Ding.

Figure 6. Distribution points of T. nujiang sp. nov. (Purple), T. yunnanensis (Pink) and T. gumprechti syn. nov. (Green) in Yunnan Province, China. The star patterns inside represent the type locality.

Figure 7. Habitat of Trimeresurus nujiang sp. nov. in the type locality of Gongshan County, Nujiang Lisu Autonomous Prefecture, Yunnan Province.