Are the people making the claim guilty of environmental hyperbole? Are we always overstating the environmental case in a form of jingoism (aka "belicose chauvanism")? Or is this like the south-west botanically - a hotspot of diversity? A special claim is extended for everything - which devalues all claims.
Do we protect places because they have a level of endemic species? Is that the same as saying they have a high level of biodiversity? Why are we protecting the Great Barrier Reef? Because it is big and beautiful, or because it has a high level of diversity?
I can't assess the validity of the claim so I'll go off and do some research.