A NEW SNAKE OF THE GENUS TRI^fERESURUS FROM SiCHUAN, CHINA l^O) 



ZHAO Er Mi 

 (Chengdu Institute of Biology, Academia Sinicd) 



About thirty species are recognized in the genus Trimeresurus Lacepede, 1804, which occur in the 

 souhem part of the Asian continent, mainly in southern and southeastern Asia, in southern China and in 

 Japan (Ryukyus Archipelago). This genus is reported from the southwestern, southern and central regions 

 of China as well as in the Indochinese part of the Oriental Region. In 1992, researchers of the Fifth 

 Laboratory of our Institute collected ten specimens of Trimeresurus at Xiangcheng, in the Hengduan 

 Mounts, western Sichuan Province. After examination, it proved to be a new species, which is described 

 below. 



Xiangcheng laotietou I'^' Trimeresurus xiangchengensis new species (Fig. 1) t^'J 



Diagnosis: The new species is closely related to T. elegans (Gray) 1'^' from which it differs by 1) the 

 presence of two loreals in the new species, against a single loreal in T. elegans, 2) the presence of a single 

 scale row between third and fourth supralabials and the subocular in the new species, versus two rows in T. 

 elegans; 3) the new species has 11-14 (mean: 12.3) infralabials, whereas T. elegans has 10-12 

 (mean: 10.5) infralabials; 4) 25 dorsal scale rows at midbody, with the two external rows smooth in the 

 new species, whereas T. elegans has 23 or 25 rows at midbody, of which only the outermost row is smooth; 

 5) 17 scale rows before vent in the new species, instead of 19 rows in T. elegans; 6) the new species has 

 189-194 (mean: 191.5) ventral scales, versus 179-191 (mean: 185.5) in T. elegans; 7) the new species has 

 50-66 (mean: 59.3) pairs of subcaudal scales, versus 63-79 (mean: 71.7) pairs in T. elegans; 8) the color of 

 the blotches are much different in these two species. 



Types: Holotype male (CIB Nr 725050, 1972-10-17, Sichuan Province, Xiangcheng, Qianjinxiang, 

 altitude 3100 m), cotypel'^l female (CIB Nr 725049, 1972-10-10, Sichuan Province, Xiangcheng, 

 Qianjinxiang, altitude 3200 m), paratypes 1 male, 5 females, 2 juveniles (CIB Nr 725048, 725051-725057, 

 1972-10-1-28, Sichuan Province, Xiangcheng, Qianjinxiang and Jiefangxiang, altitude 3000-3200 m). The 

 types are deposited in the Chengdu Insitute of Biology, Academia Sinica.t^^l 



Description: A triangular head, with a relatively sharp canthus rostralis; rostral slightly higher than 

 wide, with only its top visible from above; upper surface of head covered with small scales, the 

 supraoculars being the largest, followed in size by the scales on the top of the snout; the left and right 

 intemasals are separated by 1-4 (mean: 2.8) small scales in contact wih the upper margin of the rostral 

 scale; supraoculars longer than wide, their width being inferior to half of the distance between the left and 

 right supraoculars, which are separated by 10-12 (mean: 10.8) small scales in a row; nasals relatively 

 large, slightly constricted in their middle, sometimes each divided on its lower part into one anterior and one 

 posterior scales; nostrils nearly rounded, located on the posterior margin of the posterior nasal and directed 

 slightly obliquely backwards; eyes moderate, with a vertical, oval pupil; 7-8 (mean: 7.6) supralabials, of 

 which the first one is completely separated from the nasal, the second is high and forms the anterior border 

 of the loreal pit, the third is the largest, the third and fourth located just below the eye and separated from 

 the subocular by a small scale row; the foveal I^^l is separated from the nasal by 2-6 (mean: 3.5) small 

 scales; the superior preocular is separated from the nasal by two loreals I^''!; the temporals are smooth; 1 1- 

 14 (mean: 12.3) infralabials, the first pair in contact behind the mental, the 2nd or 3rd anterior infi-alabials 

 (sometimes the first) in contact with the anterior chin shields. The dorsal scales are rhombohedral or 



