The dice snake,Natrix tessellata (Serpentes: Colubridae) in Pakistan: Analysis of its range limited to few valleys in the western Karakoram

Based on the recent rediscovery of a dice snake (natrix tessellata) in the karakoram mountains of north-central pakistan (western karakoram) and the only other records from northwestern pakistan we utilize contemporaneous information on the ecology of n. tessellata and climate fluctuations during the holocene to analyze its limited distribution to a few mountain valleys. we elaborate several plausible expansion routes from a glacial refugium in northern afghanistan through the hindu kush mountain range into pakistan and the western karakoram. the apparent range restriction of n. tessellata to the mountains of northern pakistan is discussed in regards to postglacial expansion speed and routes,available period during the holocene,habitat requirement,competition with another semi-aquatic water snake,xenochrophis piscator,and potential misidentification with the latter species. copyright 2013 zoological society of pakistan.