The type locality of Gloydius lateralis sp. nov. in Jiuzhaigou National Nature Reserve, denoted by a black square, with the collection localities of some other congeneric species.

Holotype of Gloydius lateralis sp. nov. in life, adult female, CIB 119377 (JZ02) A dorsolateral view B ventral view.

Head squamation of holotype of Gloydius lateralis sp. nov. CIB 119377 (JZ02) A lateral view B ventral view C dorsal view. Scale bar: 10 mm.

Paratypes of Gloydius lateralis sp. nov. in life A, B CIB 119379 (JZ04), adult female in dorsolateral and ventral views C, D CIB119378 (JZ03), adult female in dorsolateral and ventral views.

Lateral (dorsolateral) heads of the alpine pitvipers (Gloydius) distributed in Sichuan and Tibet (not to scales) A G. lateralis sp. nov., CIB 119377 (JZ02), female, from Jiuzhaigou National Nature Reserve, Sichuan B G. swild, IVPP OV 2725, female, from Heishui, Sichuan C G. angusticeps, IVPP OV 2634, male, from Zoige, Sichuan D G. liupanensis, male, from Longnan, Gansu E G. qinlingensis, male, from Ningshaan, Shaanxi F G. strauchi, SYNU1508G4, male, from Litang, Sichuan G G. lipipengi, IVPP OV 2720, male, from Zayu, Tibet H G. rubromaculatus, male, from Yushu, Qinghai (not included in this study) I G. huangi, CIB 533422012, male, from Hola, Mangkang. Copyright: Sheng-Chao Shi (A, I), Jing-Song Shi (B, C, E, F, G, H), Zu-Yao Xia (D).

Lateral (dorsolateral) view of the alpine pitvipers (Gloydius strauchi complex) that distributed in Sichuan and Tibet (not to scales); the lateral stripes are pointed by arrows A G. lateralis sp. nov., CIB 119377 (JZ02), female, from Jiuzhaigou, Sichuan B G. swild, IVPP OV 2725, female, from Heishui, Sichuan C G. angusticeps, male, from Golog, Qinghai (not included in this study) D G. liupanensis, male, from Longnan, Gansu E G. qinlingensis, male, from Ningshaan, Shaanxi F G. strauchi, from Sichuan G G. lipipengi, IVPP OV 2720, male, from Zayu, Tibet H G. rubromaculatus, male from Yushu, Qinghai I G. huangi, CIB 533422012, male, from Hola, Mangkang. Copyright: Sheng-Chao Shi (A, I), Jing-Song Shi (B, E, G, H), Hong Zhao (C), Zu-Yao Xia (D) and Zhi-Yuan Tang (F).

Maximum-likelihood tree of the genus Gloydius based on 12S, 16S, COI, ND4 and cytb sequences, with the maximum likelihood bootstrap supports (left, regular) and Bayesian posterior probabilities (right, italic) displayed on the nodes (those < 50% are displayed as “-”).

A, C Macrohabitats and D microhabitats of Gloydius lateralis sp. nov. at the Jiuzhaigou National Nature Reserve. Note that another Protobothrops jerdonii sympatric to G. lateralis sp. nov. is shown in B.