The evolution and biogeographic history of epiphytic thalloid liverworts.

Among liverworts, the epiphytic lifestyle is not only present in leafy forms but also in thalloid liverworts, which so far has received little attention in evolutionary and biogeographical studies. Metzgeria, with about 107 species worldwide, is the only genus of thalloid liverworts that comprises true epiphytes. In the present study, we provide the first comprehensive molecular phylogeny, including estimated divergence times and ancestral ranges of this genus. Analyses are based on a plastid marker dataset representing about half of the Metzgeria species diversity. We show for the first time with molecular data that Austrometzgeria is indeed a member of Metzgeria and that two morpho-species M. furcata and M. leptoneura are not monophyletic, but rather represent geographically well-defined clades. Our analyses indicate that Metzgeria started to diversify in the Cretaceous in an area encompassing today's South America and Australasia. Thus, Metzgeria is one of the few known epiphytic liverwort genera whose biogeographic history was directly shaped by Gondwana vicariance. Subsequent dispersal events in the Cenozoic resulted in the colonization of Asia, Africa, North America, and Europe and led to today's worldwide distribution of its species. We also provide the first reliable stem age estimate for Metzgeria due to the inclusion of its sister taxon Vandiemenia in our dating analyses. Additionally, this stem age estimate of about 240 million years most likely marks the starting point of a transition from a terrestrial to an epiphytic lifestyle in thalloid liverworts of the Metzgeriales. We assume that the Cretaceous Terrestrial Revolution played a key role in the evolution of epiphytic thalloid liverworts similar to that known for leafy liverworts.

Affinities of the fern genus Ptisana (Marattiaceae) in the Solomon Islands, with descriptions of two new species.

In the process of undertaking a comprehensive review of the pteridophytes of the Solomon Islands, multiple unidentified specimens of the fern genus Ptisana Murdock (Marattiaceae) were collected. Morphological and molecular phylogenetic analyses as well as field observations were required to identify the Solomon Islands taxa. Four species and one variety are recognized from the Solomon Islands: Ptisana ambulans Murdock & C.W. Chen, sp. nov., Ptisana decipiens Murdock & C.W. Chen, sp. nov., Ptisana decipiens var. delicata Murdock & C.W. Chen, var. nov., Ptisana papuana (Alderw.) Murdock & C.W. Chen, comb. nov., and Ptisana smithii (Mett. ex Kuhn) Murdock. The complexities in the identification of Solomon Islands collections show the limits of morphology in the genus and illuminate a path forward for untangling the Ptisana taxonomy on a broader scale.

World checklist of hornworts and liverworts.

A working checklist of accepted taxa worldwide is vital in achieving the goal of developing an online flora of all known plants by 2020 as part of the Global Strategy for Plant Conservation. We here present the first-ever worldwide checklist for liverworts (Marchantiophyta) and hornworts (Anthocerotophyta) that includes 7486 species in 398 genera representing 92 families from the two phyla. The checklist has far reaching implications and applications, including providing a valuable tool for taxonomists and systematists, analyzing phytogeographic and diversity patterns, aiding in the assessment of floristic and taxonomic knowledge, and identifying geographical gaps in our understanding of the global liverwort and hornwort flora. The checklist is derived from a working data set centralizing nomenclature, taxonomy and geography on a global scale. Prior to this effort a lack of centralization has been a major impediment for the study and analysis of species richness, conservation and systematic research at both regional and global scales. The success of this checklist, initiated in 2008, has been underpinned by its community approach involving taxonomic specialists working towards a consensus on taxonomy, nomenclature and distribution.

Transantarctic disjunctions in Schistochilaceae (Marchantiophyta) explained by early extinction events, post-Gondwanan radiations and palaeoclimatic changes.

The liverworts are the first diverging land plant group with origins in the Ordovician. The family Schistochilaceae exhibits diverse morphology and widely disjunct geographic ranges within the Southern Hemisphere. The family has been presented as a classic example of Gondwanan biogeographic distribution, with extant species ranges resulting from vicariance events. In this study, we present results that elucidate the origin and diversification of Schistochilaceae. We conducted a comprehensive time-calibrated, molecular-based phylogenetic analysis and different approaches for ancestral range inference of the family. Schistochilaceae is inferred to have originated in the Late Cretaceous, in an ancestral area including southern South America, West Antarctica and New Zealand. Despite a family origin at c. 100Ma, most of the diversification of Schistochilaceae occurred in New Zealand after the 80Ma opening of the Tasman Sea that isolated New Zealand from the rest of Gondwana. Most dispersals were transoceanic. The northward migration of the Schistochilaceae is probably linked with the spread of temperate vascular plant forest ecosystems that have Late Cretaceous southern origins and have maintained suitable environments for the family throughout the Cenozoic. The distribution and biogeographic history of the family is very similar to that of Nothofagaceae.

Illuminating the evolutionary history of liverworts (Marchantiophyta)-towards a natural classification.

The phylogenetic relationships of liverworts were reconstructed using the sequence data of four genome regions including rbcL, rps4 and trnL-F of the chloroplast and 26S large subunit ribosomal rRNA gene of the nucleus, and 90 characters of morphological, ultrastructural and developmental aspects. The taxa sampled consisted of 159 species including 135 liverworts (108 genera, 54 families and 29 suborders), 13 mosses, two hornworts, seven vascular plants and two charophyte algae. Analyses based on maximum parsimony using both direct optimization (POY) and static alignment (NONA), as well as Bayesian inference (MrBayes) were done. All the data sets were analyzed simultaneously. Our study confirms that liverworts compose a monophyletic group which consists of three classes. The class Treubiopsida including both Treubia and Haplomitrium is resolved as the earliest diverging liverwort lineage. Blasia and the complex thalloids are assigned to the Marchantiopsida, under which Blasiidae and Marchantiidae are divided. Marchantiidae include Sphaerocarpales and Marchantiales. The simple thalloid and leafy liverworts form the Jungermanniopsida, which is further divided to subclasses Pelliidae subclassis nov., Metzgeriidae and Jungermanniidae. Metzgeriidae here is defined to include only Metzgeriaceae, Aneuraceae and Vandiemeniaceae, and is the sister group to the leafy liverworts. The leafy liverworts Jungermanniidae include the orders Pleuroziales, Porellales and Jungermanniales. It is assumed that the Porellales and the Jungermanniales have split early, at least in the Jurassic period. In the Porellales, the diversification rate may have remained relatively constant for long periods of time but speeding up only recently within some of the families, associated with an explosive radiation of angiosperms. The Jungermanniales are most probably a recently diversified group which has attained the greatest profusion of structure and the most remarkable diversity of leaf development and protective devices for maturing sporophytes. A detailed classification scheme for liverworts is presented.