First European record of Sticta arenosella and new Central European records of Sticta fuliginoides

The genus Sticta has recently undergone significant taxonomic revisions in Europe, yet central regions such as Switzerland were not included in those revisions. To assess the diversity of the species complex Sticta fuliginosa in Switzerland, we used an integrative taxonomic approach combining morphological and genetic analyses. We sampled both the well-known localities, as well as newly discovered localities along the Doubs River. Our results showed that S. fuliginosa is presently absent from Switzerland. Instead, we confirmed the presence of S. fuliginoides, and reported the first occurrence of S. arenosella, a species previously known only from North and South America. Morphological, phylogenetic, and haplotype network analyses confirmed that the Swiss specimen identified as S. arenosella is morphologically and genetically indistinguishable from its holotype. Additionally, we also documented the presence of apothecia on S. fuliginoides for the first time. This expands the known phenotypic variation in this species and allows for a more complete taxonomic description. Finally, we provide a taxonomic key for the Central European species of Sticta to facilitate future research and monitoring.