The spatial distribution patterns of saproxylic beetles in Europe are shown in Figures 5 to 8. The intermediate latitudes of central Europe clearly stand out as areas of high species richness (Figure 5). Biodiversity hotspots seem to be located in mountainous areas such as the Pyrenees, Alps and Carpathians. The richness of endemic species is shown in Figure 6 and shows somewhat similar patterns to the overall species diversity.
The Mediterranean and Macaronesian islands have many range-restricted endemic saproxylic beetles, although these regions do not necessarily show up on the endemic species richness map since typically each particular island will only have one or a few endemic species.
The distribution of threatened species is shown in Figure 7, and shows that the greatest concentrations of threatened saproxylic beetle species are found in central and eastern Europe, with Hungary and surrounding countries having a high number of threatened species. The lack of threatened species in other regions of Europe can be explained by the fact that species found in these areas are quite widespread, due to the lack of biogeographical peculiarities in certain regions, and/or due to the lack of suitable habitat in areas dominated by arable agriculture.
|Figure 5. Species richness of European saproxylic beetles.||Figure 5. Species richness of European saproxylic beetles.|
|Figure 7. Distribution of threatened saproxylic beetles in Europe.||Figure 8. Distribution of Data Deficient saproxylic beetle species in Europe.|
The distribution of Data Deficient species is shown in Figure 8, and shows a very similar pattern to the general saproxylic beetle richness (Figure 5), with a particularly high number of Data Deficient species present in the Balkan Peninsula and in European Russia. In the Balkan Peninsula, some species have only been recently described or recorded, and there is no information to elucidate their trends and threats. In addition, the distribution of Data Deficient species also reflects a general lack of research or very limited knowledge about species’ ecology as a result of the small number of saproxylic ecologists in Europe. Finally, some species are only known from historical records and from a single locality, while the taxonomic status of others remains a matter of discussion.