Richness and composition of foliicolous lichens from the northeastern part of Puebla, Mexico

Currently, only 52 species have been reported to the montane rainforests of Puebla. To enhance our knowledge and expand the checklist of the state, we aimed to determine the foliicolous lichen species richness and composition at three sites in Tlatlauquitepec, Puebla: a secondary montane rainforest with coffee plantations (site 1), a lowland rainforest fragment (site 2), and a secondary montane rainforest (site 3). A total of 94 species were identified with 52 being new records for the state, such as Aptrootidea marginata, Calopadia puiggarii, and Chroodiscus coccineus; apart from that, we report 10 new records for the country, among which are Porina fulvelloides, Byssoloma tricholomum, and Calenia atlantica. Most foliicolous species were rare (60.63%) and restricted to less than 10% of the sampled phorophytes, among these we found Porina kameruniensis, Calopadia fusca, and Fellhanera subternella; in contrast, the most frequent species were Fouragea filicina, Actinoplaca strigulacea, Segestria rubentior, Porina karnatakensis, and P. pseudoapplanata. The dissimilarity in species composition between sites was notably high (> 0.8) and could be explained by species replacement between sites 2 and 3, and 1 and 3; whereas between sites 1 and 2 can be explained by differences in species richness. Site 2 exhibited the highest species richness, followed by site 3 and site 1; we attribute this low foliicolous richness in site 1, to the presence of sun-growth coffee plantations. However, despite the conditions of the sites, these findings significantly contribute to the knowledge of foliicolous lichen biota in Puebla and Mexico, raising the total richness of the state to 104 and of the country to 303 species. We advocate for continued exploration of the country's tropical ecosystems to better understand the foliicolous lichen diversity that persists in these habitats, which are increasingly threatened by various anthropogenic pressures and are in danger of extirpation.