According to the Guinness World Record, the rarest snake is Alsophis antiguae, also called the Antiguan racer, which can be found in Antigua.

In 2004, this species, with less than 150 existing in the world, is classified as Critically Endangered on the World Conservation Union Red List. The reason for the extinction is mainly because of the introduction of non-indigenous predators in the island of Antigua. Read more here -www.bbc.co.uk/nature/18770570