The definition of endemism is a relative concept, and is relative to the size of the territory and the hierarchical rank of the taxon one is referring to. The more the territory is small, less you would expect to find in it the whole areal of taxa which ranks are high as a family or an order. Here is the case to cite FAVARGER (1969): "It is the scale that creates the phenomenon." The criterion for the definition of endemism is therefore the exclusive membership to a certain geographical territory taken as a reference, not the size of the range of taxon.