Nuclear and plastid phylogenies suggest ancient intersubgeneric hybridization in the fern genus Pyrrosia (Polypodiaceae), with a classification of Pyrrosia based on molecular and non-molecular evidence

摘要

The Old World fern genus Pyrrosia is one of the largest genera in Polypodiaceae. It is estimated to contain up to 100 species distributed in tropical and subtropical South and East Asia, from New Zealand to Siberia and from Africa to Polynesia. The monophyly of Pyrrosia has frequently been questioned, previous molecular analyses have produced conflicting results, and earlier infrageneric classifications have been controversial. We tested the monophyly of the genus and resolved the relationships within the genus using nuclear DNA data and combined plastid and nuclear DNA data. Our study shows that the recently established genus Hovenkampia is confirmed to be sister to Platycerium. Nuclear data do not recover the monophyly of the Niphopsis clade identified by plastid data pointing to the possibility of ancient hybridization between the Niphopsis and the Niphobolus clades. The combined plastid and nuclear data resolve Pyrrosia into four major clades confirming earlier findings. Three of the four major clades are further resolved into four, four, and six subclades, respectively, and the relationships among the major clades and subclades are well resolved. Based on molecular and non-molecular evidence Pyrrosia is classified into four subgenera: P. subg. Pyrrosia, P. subg. Neoniphopsis, P. subg. Niphobolus, and P. subg. Niphopsis, and the latter three are further classified into four, six, and four sections, respectively. A key to the infrageneric taxa is given. A nomenclatural account of each infrageneric taxon is provided.