A morpho-molecular classification of the liverworts (Hepaticophytina, Bryophyta)
Frey, Wolfgang; Stech, Michael
Recent molecular analyses and a re-evaluation of morphological and ultrastructural characters provided new insights into relationships among liverworts (Hepaticophytina, Bryophyta), and mosses. Considering these results, a new suprageneric classification of liverworts is proposed. The liverwort classes are grouped into four superclasses. According to the paraphyly of simple thalloid liverworts, new classes, Pallaviciniopsida and Pelliopsida, are established for taxa formerly included in the Jungermanniopsida, which in the narrower circumscription comprise only the leafy liverworts (separated into Jungermanniidae with two new superorders, Jungermannianae and Porellanae, and Pleuroziidae subclass. nov.) and the Metzgeriidae s. str. (Aneurales ord. nov. and Metzgeriales). Pallaviciniopsida comprise two monotypic orders, Pallaviciniales and Hymenophytales, whereas Pelliopsida comprise a single order, Pelliales. Fossombroniopsida are treated here including Fossombroniaceae, Petalophyllaceae, Allisoniaceae, and Sandeothallaceae. Taxa of ambiguous position within superclass III according to morphological and molecular data include Makinoaceae, Noterocladaceae, and Phyllothalliaceae. The present classification on high taxonomic level reflects the early-divergent evolutionary history of the long-separated major liverwort groups. Selected morphological-anatomical and ultrastructural characteristics of the higher taxa are provided along with summaries of fossil records and recent molecular data.