黑背白环蛇Lycodon ruhstrati
形态特征:(依据北京标本描述)小型无毒蛇,全长725mm。鼻间鳞1对,前额鳞1对,额鳞1枚。顶鳞1对。眶上鳞左右各1枚。眶前鳞1枚,眶后鳞2枚,颞鳞2+2枚,颊鳞1枚,入眶。上唇鳞8枚,下唇鳞10枚。颌片2对,具颌沟。背鳞微起棱。体中段背鳞17行,近尾端15行。腹鳞219枚。肛鳞完整。尾下鳞双行,94对。头及体背黑色,头枕部有一对白斑纹,体背自颈部至尾端有60个左右白色环纹,颈部较窄,向后逐渐加宽且变密集。头颈区分明显,头近三角形,吻端圆钝,吻鳞头背部可视。
生活习性:多为夜间活动,捕食蜥蜴及小型两栖类。
地理分布:国内见于北京、天津、陕西、江苏、安徽、浙江、江西、湖南、福建、台湾、广东、香港、广西、四川、贵州等省区;国外分布于日本琉球群岛南部。
环渤海地区分布:北京、天津(蓟县)。
生存现状:无危(LC)。
注:2005年王宁和郑光美在北京小龙门首次发现并报道;2009年莫训强等在天津蓟县拍摄到本种照片(路杀个体);2016年又有徒步者在北京与河北交界处的野三坡拍摄到该蛇的照片。鉴于此,黑背白环蛇在华北地区的分布可初步确定。
59.Lycodon ruhstrati
Description Adults up to 725 mm TOL, body is small and non-toxic.Scales between the nose are one pair; 1 pair of forehead scales; one head scale; one pair of top scales;supraorbital scales on both sides; 1 pair of anterior orbital scales; two pairs of posterior orbital scales; temporal scales arranged in 2+2; a buccal scale in the orbits.8 supralabials and 10 infralabials.two pairs of jaw pieces with groove; dorsal scales are slightly ribbed;17 rows of dorsal scales are in the middle part of the body; 15 rows near the tail end; 219 ventral scales; anal plate complete; 94 pairs of subcaudals arranged in two rows; the head and the body are black, with a pair of white stripe at the occipital part; nearly 60 white circle stripes from the neck to the tail end, the stripes on the neck are narrow, gradually dense and wide backwards; head and neck are obviously separated; head is slightly in triangle-shaped; snout is round and blunt; snout scales are seen from the head dorsum.
Behaviour Lycodon ruhstrati often move at nights and prey lizards and small amphibians.
Distribution China: in Beijing, Tianjin, Shaanxi, Jiangsu, Anhui, Zhejiang, Jiangxi,Hunan, Fujian, Taiwan, Guangdong, Hong Kong, Guangxi, Sichuan, Guizhou and other provinces.At abroad: in the south of Japan's Ryukyu Islands.Distribution around Bohai Sea: in Beijing, Jixian of Tianjin.
Conservation Least Concern (LC).
Notes Wang and Zheng (2005) reported Lycodon ruhstrati at Xiaolongmen in Beijing.Mo Xunqiang and others took pictures of this species (kill the one on the road) in Jixian of Tianjin in 2009.Some hikers took pictures of this species at hillsides yesanpo on the border of Beijing and Hebei in 2016.Due to the evidence above, Lycodon ruhstrati are preliminarily found in north China.
黑背白环蛇幼体