Rarely seen extreme host specificity across the Neotropics between the lichens Pyrenula psoriformis, Pyrenula sauria sp. nov. (Eurotiomycetes: Pyrenulaceae), and Bonellia trees.

In tropical ecosystems specificity of lichen species to their phorophyte is rarely seen. Instead, lichen communities show a loose preference for groups of tree species that share bark characteristics. In this study we analyzed the lichens present on more than 200 trees from 57 species in a Mexican tropical dry forest. We describe an extreme case of host specificity between the Pyrenula psoriformis agg. and Bonellia trees. The lichen species grow exclusively on Bonellia trees, change the bark characteristics of the tree, and were present in every analyzed individual of Bonellia across the forest. We found evidence that this association is maintained across the Neotropics and could become a useful model in the wild to study fungal dispersal, species interactions, and the continuity of ecological patterns at different geographical scales. Lastly, we describe Pyrenula sauria sp. nov., the second species in the P. psoriformis agg., it is distinguished by having semi-immersed perithecia that are covered by a thalline layer, narrower ascospores, a less pronounced verrucose thallus, and molecular data.