Abstract:Over the past decades, the snakes of the genus Gloydius with 23 rows mid-back scales (except for Gloydius saxatilis, G. shedaoensis and G. lijianlii) have been identified as G. intermedius by most Chinese herpetologists consistently. However, different populations of so called “G. intermedius” in the north of China exhibit highly variable in morphological characters and behavioral traits (Fig. 2, Fig. 3 and Fig. 4). Therefore, it is necessary to investigate the systematic relationships between different populations of “G. intermedius”. In this study, we conducted a comparative study on different populations of “G. intermedius” in the north of China (Table 1 and Table 2) by combining several approaches such as field exploration (Fig. 1), morphological comparison and molecular phylogenetics. The results indicated that there are significant morphological difference between different populations of “G. intermedius” from the north of China (Table 3), which indeed belongs to three subspecies of G. halys, i.e. G. h. halys, G. h. cognatus and G. h. stejnegeri, respectively (morphological comparison in Table 4 and type locality comparison in Table 5). The mean genetic divergence (uncorrected p-distance) among these three subspecies of G. halys is higher than those among the recognized congeneric species, suggesting that G. h. cognatus and G. h. stejnegeri should be elevated as species status (Fig. 5 and Fig. 6). Accordingly, “G. intermedius” from the north of China should be regarded as three distinct species, i.e. “Siberian Pitviper (G. h. halys)”, “North China Pitviper” (G. stejnegeri) and “Alashan Pitviper” (G. cognatus), respectively. The haplotype network also suggested that G. h. caraganus should be elevated as species status (G. caraganus, Fig. 6). In addition, this study reveals that G. shedaoensis, which was considered as an insular endemic species, also occur in Liaodong Peninsular Mountains, thus we suggest to recover the validity of G. sh. qianshanensis Li, 1999. Finally, we provided a thorough review and supplement of the taxonomy, distribution and biology of the Gloydius halys-G. intermedius complex in China.