Molecular data challenge traditional subgeneric divisions in the leafy liverwort Radula

Abstract

AbstractWith approximately 200 species, the genus Radula is one of the most speciose genera of leafy liverworts. Although the genus is well delimited, its subdivision into subgenera and sections has been controversial. None of the subgeneric subdivisions have been the subject of an explicit test of internal consistency or monophyly based on molecular data and a comprehensive view of evolutionary relationships within the genus is thus still lacking. In the present paper we propose, based on a molecular phylogeny of the genus, a new subgeneric classification for Radula, and create three new subgenera. While the reconstructions of ancestral gametophytic characters allow for a morphological description of each of the seven lineages identified in our phylogeny, synapomorphies for these lineages are mostly lacking. Uncertainty of morphological state reconstructions at the deepest nodes of the phylogeny, which point to a rapid morphological diversification of the genus in its early history, do not allow for pinpointing when morphological changes occurred. The classification scheme proposed here is therefore mostly based on molecular features.