Phylogenetic study of Catapyrenium s. str. (Verrucariaceae, lichen-forming Ascomycota) and related genus Placidiopsis

The current classification of what used to be called Catapyrenium comprises eight genera belonging to distinct lineages in the Verrucariaceae. Previous phylogenetic studies have shown that the redefined genus Catapyrenium (Catapyrenium s. str.) is monophyletic and sister of Placidiopsis within the Staurothele group, but this relationship was based on only two species from each genus. We conducted a phylogenetic study of Catapyrenium and Placidiopsis as currently delimited to evaluate the monophyly of each genus and infer infrageneric relationships. An initial family level phylogenetic analysis based on the nuLSU locus and implementing a backbone constraint tree (with both weighted maximum parsimony and bootstrap maximum likelihood approaches) was performed to infer phylogenetic placements of Catapyrenium and Placidiopsis taxa not included in previous molecular systematic studies. The results of this analysis were used to define the ingroup for a second phylogenetic analysis based on nuITS and nuLSU and centered on Catapyrenium s. str. and Placidiopsis. Placidiopsis was found to be monophyletic, whereas Catapyrenium s. str. was not. Catapyrenium dactylinum was found to be closely related to Placopyrenium caeruleopulvinum and Placopyrenium stanfordii, all of which were closely related to Placocarpus schaereri and Verrucula. In addition we found genus Placopyrenium to be polyphyletic. The resulting trees confirmed that Catapyrenium s. str. (excluding C. dactylinum) and Placidiopsis constitute two sister monophyletic entities. The data do not support Placidiopsis cinerascens and P. tenella as two distinct species because no characters can be used to distinguish them. Thus P. tenella is here reduced to synonymy with P. cinerascens.