What is the most rarest spider in the world?

The Horrid Ground Weaver (Nothophantes horridus) is probably the most rare spider. It has only been found in two locations in Plymouth (UK), in limestone quarries. Very little is known about these arachnids, but it is believed that they may live entirely underground, and that the quarries simply exposed them.
Updated on Wednesday, February 01 2012 at 01:56PM EST
Collection: plymouth