Xanthoria calcicola (Teloschistaceae, Ascomycota) still present on bark in Sweden

For almost twenty years Xanthoria calcicola was considered extinct on bark in Sweden. Here, we report X. calcicola growing on bark at 14 localities in Skåne, southernmost Sweden. In total, ca 300 thalli were observed on bark, and the populations vary from 1 to 200 thalli. In all localities except one X. calcicola was also present and more abundant on neighboring substrates made of stone, such as churchyard walls, church walls or tombstones. Preliminary results from fungal ITS data reveal that haplotypes found on bark are always present in the surrounding wall populations. We conclude that trees are suboptimal habitats for X. calcicola and only colonized when in close vicinity of an established wall population. The most obvious threat to epiphytic X. calcicola is the cutting down of host trees.