Jörn Hentschel

World checklist of hornworts and liverworts

Abstract 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.

Phylogenetic biogeography and taxonomy of disjunctly distributed bryophytes

Abstract  More than 200 research papers on the molecular phylogeny and phylogenetic biogeography of bryophytes have been published since the beginning of this millenium. These papers corroborated assumptions of a complex genetic structure of morphologically circumscribed bryophytes, and raised reservations against many morphologically justified species concepts, especially within the mosses. However, many molecular studies allowed for corrections and modifications of morphological classification schemes. Several studies reported that the phylogenetic structure of disjunctly distributed bryophyte species reflects their geographical ranges rather than morphological disparities. Molecular data led to new appraisals of distribution ranges and allowed for the reconstruction of refugia and migration routes. Intercontinental ranges of bryophytes are often caused by dispersal rather than geographical vicariance. Many distribution patterns of disjunct bryophytes are likely formed by processes such as short distance dispersal, rare long distance dispersal events, extinction, recolonization and diversification.

One species or at least eight? Delimitation and distribution of Frullania tamarisci (L.) Dumort. s. l. (Jungermanniopsida, Porellales) inferred from nuclear and chloroplast DNA markers.

Frullania tamarisci is usually regarded as a polymorphic, holarctic-Asian liverwort species with four allopatric subspecies [subsp. asagrayana, moniliata, nisquallensis and tamarisci]. This hypothesis is examined using a dataset including sequences of the nuclear internal transcribed spacer region and the plastid trnL-trnF and atpB-rbcL regions of 88 accessions of F. tamarisci and putatively related taxa. Maximum parsimony and maximum likelihood analyses indicate the presence of at least eight main lineages within F. tamarisci s. l. The long branches leading to the tip nodes of the different F. tamarisci s. l. clades and their partly sympatric distribution reinforce species rank. Within F. tamarisci s. l. we recognize the Asian F. moniliata, the western North American F. californica and F. nisquallensis, the eastern North American F. asagrayana, the eastern North American-European F. tamarisci s. str., the Macaronesian F. sergiae, and two newly identified European lineages assigned to as F. calcarifera and F. tamarisci var. azorica. The considerable sequence differences are not reflected in conspicuous morphological disparities, rendering F. tamarisci s. l. the most explicit example of a complex of semi-cryptic and cryptic liverwort species. The temperate Frullania clades of this study likely went through recent extinction and expansion processes as indicated by the bottleneck pattern of genetic diversity. Species from tropical regions or regions with an Atlantic climate usually contain several geographical lineages. Our findings support frequent short-distance migration, rare successful long-distance dispersal events, extinction and recolonization as an explanation for the range formation in these Frullania species.

Goodbye or welcome Gondwana? – insights into the phylogenetic biogeography of the leafy liverwort Plagiochila with a description of Proskauera, gen. nov. (Plagiochilaceae, Jungermanniales)

Molecular phylogenies based on chloroplast gene rps4 sequences and nuclear ribosomal ITS sequences have been generated to investigate relationships among species and putative segregates in Plagiochila (Plagiochilaceae), the largest genus of leafy liverworts. About a fourth of the ca. 450 accepted binomials of Plagiochilaceae are included in these phylogenetic analyses, several represented by multiple accessions. A clade with Chiastocaulon, Pedinophyllum, and Plagiochilion is placed sister to a clade with numerous accessions of Plagiochila. Plagiochila pleurata and P. fruticella are resolved sister to the remainder of Plagiochilaceae and transferred to the new Australasian genus Proskauera which differs from all other Plagiochilaceae by the occurrence of spherical leaf papillae. The historical biogeography of Plagiochilaceae is explored based on the reconstructions of the phylogeny, biogeographic patterns and diversification time estimates. The results indicate that the current distribution of Plagiochilaceae cannot be explained exclusively by Gondwanan vicariance. A more feasible explanation of the range is a combination of short distance dispersal, rare long distance dispersal events, extinction, recolonization and diversification.

Reinstatement of Lophocoleaceae (Jungermanniopsida) based on chloroplast gene rbcL data: exploring the importance of female involucres for the systematics of Jungermanniales

Maximum likelihood analysis of 113 rbcL sequences leads to a well resolved phylogeny of Jungermanniales. All species with perigynia or marsupia are found in one clade, whereas species with coelocaules are placed in several lineages. The broadly circumscribed Geocalycaceae (including Lophocoleaceae) of most recent authors are resolved as polyphyletic. Geocalycaceae genera which develop female involucres without involvement of stem tissue (Chiloscyphus, Heteroscyphus, Leptoscyphus, Physotheca) form a robust clade which is placed sister to Plagiochilaceae whereas the genera with involucres originating at least partly from stem tissue (Geocalycaceae s.str., Geocalyx, Harpanthus, Saccogyna) are nested within the paraphyletic Jungermanniaceae. This topology leads to the exclusion of the strictly perianth-bearing species from Geocalycaceae and the reinstatement of Lophocoleaceae. Campanocolea is nested within Chiloscyphus. Physotheca and Chiloscyphus breutelii are placed within an unsupported clade with several accessions of Leptoscyphus. Heteroscyphus forms a paraphyletic grade at the base of Chiloscyphus.

DNA taxonomy, cryptic speciation and diversification of the Neotropical-African liverwort, Marchesinia brachiata (Lejeuneaceae, Porellales)

The Neotropical-African liverwort Marchesinia brachiata has long been regarded as a polymorphic species. This hypothesis is examined using a dataset including sequences of the nuclear internal transcribed spacer region and the plastidic trnL-trnF region of 39 Marchesinia accessions. Maximum parsimony, maximum likelihood and Bayesian analyses indicate that Marchesinia robusta is nested within M. brachiata s.l. The molecular topologies support at least three partly sympatric biological species within M. brachiata s.l., the Neotropical M. bongardiana and M. languida, and the Neotropical-African M. brachiata s.s. These species are incompletely separated by subtle differences in underleaf shape and leaf dentation. Long branches within M. brachiata s.s. suggest ongoing speciation processes that are not yet reflected in distinguishable morphological variation. Divergence time estimates based on nrITS sequence variation and the liverwort fossil record indicate an establishment of the species M. bongardiana, M. brachiata, M. languida, M. madagassa, and M. robusta in the Late Oligocene and Miocene. The intraspecific diversity shows distinctive patterns with evidence for constant accumulation of genetic diversity in M. robusta and M. brachiata whereas M. bongardiana and M. languida likely went through a recent extinction or expansion process as indicated by the bottleneck pattern of genetic diversity. The tropical American-African disjunction of M. brachiata is the result of dispersal rather than Western Gondwanan vicariance.

Steady diversification of derived liverworts under Tertiary climatic fluctuations.

Tropical forests contain the majority of extant plant diversity and their role as a cradle and/or museum of biodiversity is an important issue in our attempts to assess the long-term consequences of global climate change for terrestrial biomes. Highly diverse groups of liverworts are an often ignored but extremely common element in rainforests, and thus their evolution may shed light on the ecological robustness of rainforest biomes to climate fluctuations. We record a remarkable constant accumulation of diversity through time for the most species-rich family of liverworts, Lejeuneaceae, inferred by divergence time estimates. The observed pattern supports the recently developed concept of a dual role of the tropics as both a museum and a cradle of biodiversity.

Morphologically cryptic biological species within the liverwort Frullania asagrayana

UNLABELLED PREMISE OF THE STUDY The Frullania tamarisci complex includes eight Holarctic liverwort species. One of these, F. asagrayana, is distributed broadly throughout eastern North America from Canada to the Gulf Coast. Preliminary genetic data suggested that the species includes two groups of populations. This study was designed to test whether the two groups are reproductively isolated biological species. • METHODS Eighty-eight samples from across the range of F. asagrayana, plus 73 samples from one population, were genotyped for 13 microsatellite loci. Sequences for two plastid loci and nrITS were obtained from 13 accessions. Genetic data were analyzed using coalescent models and Bayesian inference. • KEY RESULTS Frullania asagrayana is sequence-invariant at the two plastid loci and ITS2, but two clear groups were resolved by microsatellites. The two groups are largely reproductively isolated, but there is a low level of gene flow from the southern to the northern group. No gene flow was detected in the other direction. A local population was heterogeneous but displayed strong genetic structure. • CONCLUSIONS The genetic structure of F. asagrayana in eastern North America reflects morphologically cryptic differentiation between reproductively isolated groups of populations, near-panmixis within groups, and clonal propagation at local scales. Reproductive isolation between groups that are invariant at the level of nucleotide sequences shows that caution must be exercised in making taxonomic and evolutionary inferences from reciprocal monophyly (or lack thereof) between putative species.

A phylogeny of Adelanthaceae (Jungermanniales, Marchantiophyta) based on nuclear and chloroplast DNA markers, with comments on classification, cryptic speciation and biogeography

Adelanthaceae (including Jamesoniellaceae) represent a major lineage of jungermannialean liverworts that is characterized by ventral-intercalary, often flagelliform branches, succubous leaves, ovoid to cylindrical, plicate perianths with a contracted mouth, often connate bracts and bracteoles, and 4-7 stratose capsule walls. Here we present the first comprehensive molecular phylogeny of Adelanthaceae using five markers (rbcL, psbA, trnL-trnF region, atpB-rbcL spacer, nrITS1-5.8S-ITS2) and 108 accessions from throughout the geographic range of the family. The molecular data support the separation of subfamilies Adelanthoideae and Jamesonielloideae. The Adelanthoideae include the genera Adelanthus, Pseudomarsupidium and Wettsteinia. The Jamesonielloideae include representatives of the genera Anomacaulis, Cryptochila, Cuspidatula, Jamesoniella, and Syzygiella in five main clades. The monophyly of taxa in current morphological classification schemes of Jamesonielloideae is not supported by the molecular data. Based on the outcome of the molecular phylogenetic analyses we propose to include Anomacaulis and Jamesoniella kirkii in Cuspidatula, and to place Cryptochila, Roivainenia, and Jamesoniella in the synonymy of Syzygiella. Molecular data support intercontinental ranges for several species and a range formation of Adelanthaceae by frequent short-distance dispersal, rare long-distance dispersal, extinction, and diversification. Disjunct distribution patterns within the Adelanthaceae cannot be explained by Gondwanan vicariance.

Molecular insights into the phylogeny and subgeneric classification of Frullania Raddi (Frullaniaceae, Porellales)

With an estimated 300-375 species, Frullania is the largest genus of Porellales and forms a major clade of leafy liverworts. The cosmopolitan genus includes mostly epiphytes and represents an important component of the cryptogamic vegetation in various, especially tropical, habitats. There have been abundant changes and modifications to the infrageneric classification of Frullania, with up to fifteen subgenera and numerous sections solely based on morphology. Here we present the first molecular phylogeny of Frullania using four markers (rbcL, psbA, trnL-trnF region of cp DNA, nr5.8S-ITS-2 region) and 171 accessions from throughout the range. The molecular data provide evidence for the monophyly of several subgenera and support intercontinental ranges of these clades. Previous subgeneric assignment for a suite of taxa based on morphological evidence is not supported by the molecular data. Representatives of the genera Amphijubula, Neohattoria and Schusterella are nested in robust subclades of Frullania. Basal relationships within Frullania are largely unsupported. Based on the outcome of the phylogenetic analyses we present a revised supraspecific classification and provide evidence for the monophyly of some morphological species. Disjunct distributional patterns within Frullania cannot be explained by Gondwanan vicariance.