Trimeresurus liqibini Liang, Ding, Wu, Yang & Chen sp. nov.

Figs 2, 3, 4

Type material.

Holotype • GXNU 251216, adult female, collected from Qinglong Gorge, Kunming City, Yunnan Province, China (25.05676540°N, 102.37080426°E; elevation 1831 m a. s. l.), collected by Li Ding on 20 June 2020.

Paratype • GXNU 251217, subadult female, collected in the same locality as the holotype by Li Ding on 28 May 2019. Morphological measurements are listed in Table 1.

Etymology.

The specific name is in honor of Prof. Qibin Li (Guangxi, China) for his significant contributions to snakebite prevention, treatment, and the clinical application of snake venom. As a common name, we suggest “ Li Qibin’s Green Pit Viper ” in English and “ Kūn Míng Zhú Yè Qīng (昆明竹叶青) ” in Chinese.

Diagnosis.

Trimeresurus liqibini sp. nov. can be distinguished from all other congeneric species by a combination of the following morphological characters: (1) Dorsal body grass-green, ventral body yellowish-green. (2) Lateral head grass-green above lower margin of eyes, and light green below, without postocular stripes in females. (3) Ventrolateral stripe white, present on outermost rows of dorsal scales in females. (4) Iris golden yellow in females. (5) First supralabial separated from nasal scale by a distinct suture. (6) Head scales feebly keeled; dorsal scale rows 19 (20) – 19–15 (N = 2), slightly keeled except the outermost rows; ventral scales 145–147 in females (N = 2); subcaudal scales 55–60 in females (N = 2). (7) Tail prehensile, predominantly reddish-brown; tail moderate in length, with TaL / TL ratios of 0.171–0.175 in females. (8) Internasals not in contact, usually separated by one scale. (9) Supraoculars large but elongate, separated by 10–11 cephalic scales.

Description of the holotype

(female) GXNU 251216 (Figs 2, 3, 4).

Morphology.

Body cylindrical and elongated (SVL 522 mm, TaL 111 mm, and TL 633 mm), tail moderate in length (TaL / TL 0.175) (Fig. 3). Head triangular in dorsal view (Fig. 4 A), elongate, clearly distinct from neck (HL 29.6 mm; HW 19.2 mm; HW / HL 0.649). Snout elongated, flattened, round anteriorly in dorsal view (Fig. 4 A), rather rectangular in lateral view (Fig. 4 C) (DEL 3.75 mm). Medium sized eyes (ED 3.54 mm, ED / HL 0.120); the pupil vertically elliptical.

Body scalation.

DSR 19–19 – 15, rhomboid, feebly keeled, gradually smoother towards ventral scales, the outermost rows smooth. VEN 147; SC 60, all paired, plus one terminal scale; anal shield entire; total number of VEN + SC 207.

Head scalation.

Rostral trapezoidal when viewed from the front, lower margin of rostral nearly twice as wide as upper margin, height six sevenths of width of base, and obliquely truncated when viewed from the lateral side; nasal large, sub-rectangular, undivided, completely separated from the 1 st supralabial by a suture behind the nostril; a pair of trapezoidal internasals significantly enlarged, separated from each other by a single triangular scale; nostril positioned centrally within the nasal scale; 3 / 3 preoculars elongated, present on each side of the head, two lower preoculars and the 2 nd supralabial encompass the loreal pit which is triangular; 2 / 2 upper preoculars above the loreal pit, the upper one largest and visible from above, both scales elongate and in contact with loreal; lower preocular forming the lower margin of loreal pit; the 2 nd supralabial completely contacts the anterior margin of the pit; 10 cephalic scales in a straight line between supraoculars, differing in size, all smooth, flat and juxtaposed; temporal and occipital scales feebly keeled; 9 / 10 supralabials; the 1 st supralabial triangular, small; the 2 nd supralabials tall, entirely bordering the anterior margin of the loreal pit, in contact with the nasal on both sides; the 3 rd supralabial is longest and highest, in contact with the subocular; the 4 th and 5 th supralabials are separated from the subocular by one large scale on each side; the 6 th supralabials are separated from subocular by 2 / 2 scales; 11 / 13 infralabials; the first pair of infralabials are longitudinally in contact with each other behind the mental; the first three pairs of infralabials are in contact with the anterior chin shields.

Coloration in life

(Fig. 2). Description based on holotype GXNU 251216. The dorsal surface of the head and body is uniformly grass-green, the lateral body mostly grass-green above and gradually lighter from spine to ventral, with a white ventrolateral stripe present on the first of DSR. Lateral head green above lower margin of eyes, and gradually yellowish-green below, without postocular stripes. Supralabials and infralabials yellowish-green edged with blue and molted with light cyan. Interstitial skin is predominantly black. The ventral surface is yellowish-green. Tail mostly reddish-brown, green laterally with a visible border between the colors. Eyes golden-yellow, with a blue edge from the snout to around the pupil.

Coloration in preservation

(Figs 3, 4). Description is based on holotype GXNU 251216, which is stored in 75 % ethanol for about two years. The dorsal body is uniformly olive drab above and on the upper part of the sides and gradually turns yellowish-green on the lower sides, with a white ventrolateral stripe. Lateral head olive drab above lower margin of eye, and greyish-green below, without a postocular stripe. The color of the iris fades to gray white. Tail olive drab as the body anteriorly, the posterior 30 % gradually rusty brown.

Comparison.

The new species is assigned to the subgenus Viridovipera based on phylogenetic evidence and morphological characteristics (such as the first supralabials being completely separated from the nasal scale) (Malhotra and Thorpe 2004). The eight recognized species within the subgenus Viridovipera (T. stejnegeri, T. yunnanensis, T. medoensis, T. vogeli, T. truongsonensis, T. mayaae, T. nujiang, T. pretiosus) are regarded as the most relevant taxa for differential diagnosis. The main diagnostic characters distinguishing Trimeresurus liqibini sp. nov. from the other known members of the subgenus Viridovipera are (Suppl. material 1: table S 3):

Trimeresurus liqibini sp. nov. closely resembles T. nujiang in morphology but differs from the latter by the following characters: (1) Smaller maximum SVL in females (522 mm vs. 682 mm); lower number of VEN in females (145–147 [146.0 ± 1.0] vs. 165–168 [166.6 ± 1.2]); lower total number of VEN + SC in females (200–207 [203.5 ± 3.5] vs. 222–226 [224.8 ± 1.6]). (2) Different color pattern in the outermost dorsal scale row in females. The upper and the lower parts of the first scale row are green, with a white ventrolateral stripe that occupies one-half of the outermost scale row in the middle vs. the lower third, and the upper portion of the first dorsal scale row yellowish-green and the middle third white in T. nujiang. (3) Different color pattern of the head, a blue edge present from the snout to around the pupil vs. a blue edge absent in T. nujiang.

Trimeresurus liqibini sp. nov. is similar to T. yunnanensis but can be distinguished from the latter by having: (1) Smaller body size, with the maximum SVL 522 mm in females vs. 1047 mm in T. yunnanensis; lower number of VEN in females (145–147 [146.0 ± 1.0] vs. 155–170 [160.6 ± 5.0]); lower total number of VEN + SC in females (200–207 [203.5 ± 3.5] vs. 209–232 [217.8 ± 6.1]). (2) Cephalic scales 10–11 vs. 9–12 (rarely 7 or 8) in T. yunnanensis.

Trimeresurus liqibini sp. nov. is distinct from T. stejnegeri by the following characters: (1) Smaller maximum SVL in females (522 mm vs. 627 mm); lower number of VEN in females (145–147 [146.0 ± 1.0] vs. 155–168 [162.6 ± 4.3]); lower number of SC in females (55–60 [57.5 ± 2.5] vs. 57–68 [61.1 ± 3.6]; lower total number of VEN + SC in females (200–207 [203.5 ± 3.5] vs. 212–231 [222.6 ± 6.9]). (2) Fewer dorsal scale rows at mid-body (MSR 19 vs. 21). (3) Eyes golden-yellow in females vs. yellow or amber in T. stejnegeri.

Trimeresurus liqibini sp. nov. is different from T. medoensis by the following characters: (1) Lower max SVL in females (522 mm vs. 555 mm). (2) MSR 19 vs. 17 in T. medoensis. (3) Higher number of cephalic scales, 10–11 vs. 6–9 (rarely 10) in T. medoensis. (4) The ventrolateral stripe is uniformly white in females, in contrast to the red (below) and white (above) or white stripe observed in T. medoensis. (5) Iris golden-yellow in females vs. yellow or yellowish-green in T. medoensis.

Trimeresurus liqibini sp. nov. differs from T. vogeli by having: (1) Lower max SVL in females (522 mm vs. 947 mm); lower number of VEN in females (145–147 [146.0 ± 1.0] vs. 157–173 [166.3 ± 6.4]); slightly lower number of SC in females (55–60 [57.5 ± 2.5] vs. 59–65 [60.8 ± 2.0]); lower number of VEN + SC in females (200–207 [203.5 ± 3.5] vs. 218–233 [227.2 ± 5.5]). (2) Fewer dorsal scale rows at mid-body (19 vs. 21, rarely 20). (3) Lower number of cephalic scales (10–11 vs. 11–14). (4) Iris golden-yellow in females vs. yellow or yellowish-green in T. vogeli. (5) Tail mostly reddish-brown in life vs. mostly green in T. vogeli.

Trimeresurus liqibini sp. nov. differs from T. truongsonensis by having: (1) Higher max SVL in females (522 mm vs. 462 mm); lower number of VEN in females (145–147 vs. 165); lower number of SC in females (55–60 vs. 70); lower total number of VEN + SC in females (200–207 vs. 235). (2) MSR 19 vs. 21 in T. truongsonensis. (3) Fewer cephalic scales, 10–11 vs. 10–13 in T. truongsonensis. (4) Blotches, spots, bands, or crossbar absent in dorsum vs. present in T. truongsonensis.

Trimeresurus liqibini sp. nov. can be distinguished from T. mayaae by having: (1) A relatively small body size, with a maximum known SVL of 522 mm in females (vs. 590 mm in T. mayaae). (2) Lower number of VEN in females (145–147 vs. 153); slightly higher number of SC in females (55–60 [57.5 ± 2.5] vs. 54–55 [54.5 ± 0.5]); slightly lower number of VEN + SC in females (200–207 [203.5 ± 3.5] vs. 207–208 [207.5 ± 0.5]). (3) 19 dorsal scales at mid-body, weakly keeled vs. MSR 21 (rarely 19 / 20), moderately keeled in T. mayaae. (4) Postocular stripe absent in females vs. a faint white postocular stripe present or absent in T. mayaae. (5) Irises golden yellow in females vs. green eyes in T. mayaae.

Trimeresurus liqibini sp. nov. can be distinguished from T. pretiosus by having: (1) Higher max SVL in females (522 mm vs. 512 mm); higher number of VEN in females (145–147 vs. 142); higher number of SC in females (55–60 vs. 54); higher total number of VEN + SC in females (200–207 vs. 196). (2) Subcaudal scales all paired vs. partially arranged in a single row in T. pretiosus. (3) Females have golden yellow irises, distinctly different from the orange-yellow eyes of T. pretiosus.

Distribution and habitat.

Trimeresurus liqibini sp. nov. is currently known only from the type locality and its adjacent areas, which were found in the central Yunnan Plateau, at elevations reaching approximately 1,800 m in Kunming, Yunnan Province, China (Fig. 5). It is found in a typical subtropical mountain evergreen broad-leaved forest and deciduous broad-leaved mixed forest ecosystem, surrounded by karst landforms and humid climate, with high vegetation coverage and complex and diverse hillside habitats. In its typical locality, this species prefers to perch on branches, waiting for prey (Fig. 6).