Disentangling generic limits in Chionoloma, Oxystegus, Pachyneuropsis and Pseudosymblepharis (Bryophyta: Pottiaceae): An inquiry into their phylogenetic relationships

Pottiaceae is the largest known moss family, with one of the most complex taxonomies among the bryophytes. The circumscription of genera within the Pottiaceae is challenging. Here, we elucidate the relationships among four related traditional genera of the Pottiaceae: Chionoloma, Oxystegus, Pachyneuropsis and Pseudosymblepharis, all sharing a complex taxonomic history. In order to resolve phylogenetic relationships among the four genera, a phylogeny derived from nuclear ITS and the plastid markers atpB-rbcL, trnG and trnL-F is inferred. Putative monophyly of these four genera is investigated using maximum likelihood and Bayesian inference analyses. Ancestral state reconstruction shows high levels of homoplasy in the characters historically used for the generic division of Chionoloma s.l. Based on our results, we suggest that Chionoloma, Oxystegus and Pseudosymblepharis should be merged into a single genus, for which the oldest name Chionoloma has priority. Additional analyses are needed to clarify the taxonomic status of Pachyneuropsis. New combinations are provided for those species where required, and lectotypes are designated for five names.