Boulenger's keelback

Description

Boulenger's keelback or Sri Lankan keelback, (Xenochrophis asperrimus) is a nonvenomous and common water snake endemic to Sri Lanka. The holotype of Xenochrophis asperrimus measures 820 mm,of which 210 mm for the tail. X. asperrimus is found in Sri Lanka, in both dry and wet climatic zones up to 1000 m above mean sea level. It is abundant in waterways, such as flooded rice fields, ponds, lakes, marshes, rivers and streams. The body of the X. asperrimus is short and cylindrical, and has a clear neck and slightly pointed head. The eyes have rounded pupils, and the nostrils are narrow, directed slightly upwards. The tail is long. At birth, they are 100 mm and grow to an adult length of 400–700 mm. The female is longer. It has one pair of internasals; the posterior parts are narrow. One loreal, preocular, postocular and three temporals are found. Of the 9 supralabials, 4 and 6 connect with the eye. Ventrals number 131–146, and the undividedsubcaudals are 73–93 in count. The midbody consists of 19 rows of scales. The dorsal scales are strongly keeled and rough.