Towards a natural classification of liverworts (Marchantiophyta) based on the chloroplast gene rbcL

Maximum likelihood analysis of 212 rbcL sequences leads to a robust phylogeny of liverworts. Our results indicate a subdivision of Marchantiophyta into three well sup- ported classes assigned as Haplomitriopsida, Marchantiopsida and Jungermanniopsida. Haplomitriopsida (incl. Treubiopsida) are resolved as sister to the remainder of liverworts and may represent the oldest extant lineage of land plants. The proximate clade is assigned to Marchantiopsida (including Blasia). The robust Jungermanniopsida comprise the para- phyletic Metzgeriidae (including Pleurozia) and the monophyletic Jungermanniidae. The Jungermanniidae are split into two clades which correspond to the orders Jungermanniales and Porellales. The latter two groups are separated by morphological and ecological trends. Porellales are predominantly epiphytes with specialized lobules or watersacs and endo- sporous protonemata, while Jungermanniales are frequently terrestrial, lack watersacs, and normally develop exosporous protonemata. Liverwort phylogeny / Haplomitriopsida / Marchantiopsida / Jungermanniopsida / Junger- manniales / Porellales / rbcL / maximum likelihood