ABSTRACT
Although there is now a good deal of information available for the Kingdom, it would be totally unrealistic to expect the existence of detailed distributional and ecological data that are available in Western Europe and North America. The biogeography of many taxa is still unknown and can only be guessed at. Furthermore, it is likely that some species have gone undiscovered. This is partly due to the exceptional difficulties of exploration, not so much in the desert areas, with their few ecological niches, but more particularly in the high recesses of the Asir where many mountain peaks and widyan have simply not been investigated.
