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International audience; Amber is renowned for the exceptional preservation state of its inclusions, allowing detailed morphological analysis and providing relevant environmental, palaeoecological, geographical, and geological information. Amber deposits predominantly known from North America, Europe, and Asia, are considered to be rare on the continents that formed Gondwana. The recent discovery of fossiliferous amber deposits in Ethiopia therefore provides an inimitable opportunity to close gaps in the fossil record of African terrestrial biota, and to study organisms otherwise rare in the fossil record. Here we show that diverse cryptogams are preserved in highest fidelity in Miocene Ethiopian amber. We describe gametophyte fragments of four liverworts: Thysananthus aethiopicus sp. nov. (Porellales, Lejeuneaceae), Lejeunea abyssinicoides sp. nov. (Porellales, Lejeuneaceae), Frullania shewanensis sp. nov. (Porellales, Frullaniaceae), and Frullania palaeoafricana sp. nov. (Porellales, Frullaniaceae). Furthermore, we describe a pleurocarpous moss of the extant genus Isopterygium (Hypnales, Pylaisiadelphaceae) and a lichen representing the order Lecanorales. These new specimens represent the first amber fossils of liverworts, mosses, and lichens from the African continent and render Ethiopian amber one of the few worldwide amber deposits preserving bryophytes (mosses and liverworts) or lichens. Fossil species of Thysananthus were recorded in Eocene Baltic and Oligocene Bitterfeld as well as Miocene Dominican and probably also Miocene Mexican ambers. Fossils which can unequivocally be assigned to Lejeunea have only been found in Dominican amber, so far. Neotropical ambers contain only one taxon of Frullania to date, while the genus is most diverse in Baltic, Bitterfeld, and Rovno ambers, formed in temperate regions. The new fossils support a tropical to subtropical origin of Ethiopian amber. The new African liverwort fossils are included in an updated list of leafy liverworts described from worldwide Cenozoic ambers to date.

The number of available liverwort fossils substantially increased within the past decade, which is mainly due to new findings from Cretaceous and Cenozoic amber deposits. Many of them, however, are fragmentary and not predestined for consideration in evolutionary analyses. Here, we list those liverwort fossils that we suggest as suitable for calibrating phylogenetic reconstructions, along with brief descriptions, justification of their use, and age information. Our recommendations are based on thorough microscopic investigation of available fossils from worldwide amber collections including recent findings. We recommend that the following 42 fossil taxa can be used as confident minimum age constraints in phylogenetic reconstructions: Acrolejeunea ucrainica (35 Ma), Anastrophyllum rovnoi (35 Ma), Bazzania polyodus (34 Ma), Blepharolejeunea obovata (15 Ma), the genus Bryopteris with B. bispinosa and B. succinea (15 Ma), Calypogeia stenzeliana (34 Ma), Cephaloziella nadezhdae (35 Ma), the genus Ceratolejeunea with C. antiqua, C. palaeomexicana, and C. sublaetefusca (15 Ma), Cheilolejeunea latiloba (34 Ma), Cheirorhiza brittae (158 Ma), Cololejeunea sp. (15 Ma), Cyclolejeunea archaica (15 Ma), Dibrachiella grollei (15 Ma), Diettertia montanensis (112 Ma), Drepanolejeunea eogena (15 Ma), the genus Frullania with F. baerlocheri, F. cretacea, and F. partita (99 Ma), Frullania subgen. Frullania with F. casparyi (34 Ma) and F. riclefgrollei (35 Ma), F. subgen. Trachycolea with F. rovnoi (35 Ma) and F. schumannii (34 Ma), Gackstroemia cretacea (99 Ma), Geocalyx heinrichsii (34 Ma), the genus Lejeunea with L. hamatiloba, L. miocenica, L. resinata, and L. urbanioides (15 Ma), Lopholejeunea subnigricans (15 Ma), Marchantites cyathodoides (228 Ma), Marchesinia brachiata (15 Ma), Metzgeriothallus sharonae (383 Ma), Microlejeunea nyiahae (52 Ma), Neurolejeunea macrostipula (15 Ma), Nipponolejeunea europaea (34 Ma), Notoscyphus balticus (34 Ma), Odontoschisma (sect. Iwatsukia) dimorpha (34 Ma), Plagiochila groehnii (34 Ma), Porella subgrandiloba (34 Ma), Protolophozia kutscheri (34 Ma), Radula (subgen. Odontoradula) cretacea (99 Ma), R. (subgen. Amentuloradula) heinrichsii (99 Ma), Scapania hoffeinsiana (34 Ma), Solenostoma berendtii (34 Ma), Spruceanthus polonicus (34 Ma), Stictolejeunea squamata (15 Ma), Tetralophozia groehnii (34 Ma), Thysananthus auriculatus (15 Ma), Thysananthus contortus (34 Ma). Furthermore, we transfer Lophozia kutscheri to Protolophozia, Archilejeunea grollei to Dibrachiella, Frullania ucrainica to Acrolejeunea, and Mastigolejeunea extincta to Spruceanthus, based on new fossil evidence and morphological revisions.

The Zhangpu biota provides a new insight into biodiversity redistribution during the Mid-Miocene Climatic Optimum., During the Mid-Miocene Climatic Optimum [MMCO, ~14 to 17 million years (Ma) ago], global temperatures were similar to predicted temperatures for the coming century. Limited megathermal paleoclimatic and fossil data are known from this period, despite its potential as an analog for future climate conditions. Here, we report a rich middle Miocene rainforest biome, the Zhangpu biota (~14.7 Ma ago), based on material preserved in amber and associated sedimentary rocks from southeastern China. The record shows that the mid-Miocene rainforest reached at least 24.2°N and was more widespread than previously estimated. Our results not only highlight the role of tropical rainforests acting as evolutionary museums for biodiversity at the generic level but also suggest that the MMCO probably strongly shaped the East Asian biota via the northern expansion of the megathermal rainforest biome. The Zhangpu biota provides an ideal snapshot for biodiversity redistribution during global warming.

Motivation for this comment Recently, the Society of Vertebrate Paleontology (SVP) has sent around a letter, dated 21st April, 2020 to more than 300 palaeontological journals, signed by the President, Vice President and a former President of the society (Rayfield et al. 2020). The signatories of this letter request significant changes to the common practices in palaeontology. With our present, multi-authored comment, we aim to argue why these suggestions will not lead to improvement of both practice and ethics of palaeontological research but, conversely, hamper its further development. Although we disagree with most contents of the SVP letter, we appreciate this initiative to discuss scientific practices and the underlying ethics. Here, we consider different aspects of the suggestions by Rayfield et al. (2020) in which we see weaknesses and dangers. It is our intent to compile views from many different fields of palaeontology, as our discipline is (and should remain) pluralistic. This contribution deals with the aspects concerning Myanmar amber. Reference is made to Haug et al. (2020a) for another comment on aspects concerning amateur palaeontologists/ citizen scientists/private collectors.

An inclusion in Miocene Dominican amber is described as Cheilolejeunea lamyi, sp. nov. The fossil resembles the extant Cheilolejeunea rigidula but differs in the partly subacute leaf lobes, often apiculate underleaf lobes, and the slightly more acute lobes of the bracteole. The two other Cheilolejeunea species in Dominican amber, Cheilolejeunea antiqua and C. suzannensis, have entire rather than bifid underleaves.

DNA-based analyses as well as the fossil record indicate that liverworts date back to the early Paleozoic, but diverse specimens of lifelike three-dimensional fossils only occur as amber inclusions from the mid-Cretaceous onwards. Some Albian–Cenomanian ambers preserve elements of a diverse biota that existed during the rise of angiosperms, a time of fundamental change in terrestrial ecosystems that likely affected epiphytic taxa. Recent analyses have provided important insight into the phylogenetic diversification and morphological evolution of liverworts. They suggest that the mid- to Late Cretaceous was a transitional time with a significant species turnover. Here, we review all currently recognized leafy liverwort species from Cretaceous ambers based on the examination of previously described fossil specimens as well as newly discovered amber inclusions. Our survey includes a determination key. The study of 26 new fossils from Kachin amber, including fertile material, enabled us to emend descriptions for Frullania cretacea, F. baerlocheri, and Protofrullania cornigera. Mid-Cretaceous Frullaniaceae often possess some characters and character combinations that are absent in extant representatives, substantiating the assumption of a lineage turnover in the Cretaceous. Among the new fossils is Radula heinrichsii sp. nov., which expands the number of Cretaceous, amber-preserved liverwort species to eight.

With more than 300 extant species, Frullaniaceae represent a species-rich clade of the predominantly epiphytic order Porellales, occurring in humid tropical and subtropical forests as well as temperate regions. Earliest fossils of Frullaniaceae are known from mid-Cretaceous Burmese and Alaskan ambers. So far, evidence for four or five fossil species have been recovered in these ambers. The steady search for new fossils is important, since many liverwort fossils lack important characters and sometimes only the investigation of numerous specimens can provide all relevant characters. Based on two newly discovered and exquisitely preserved gametophytes from mid-Cretaceous Burmese amber, we provide a detailed investigation and re-appraisal of two previously described species of Frullaniaceae, namely Frullania baerlocheri and Protofrullania cornigera. The new discovery of a complete gametophyte of F. baerlocheri with both vegetative and fertile parts enables an emended morphological description, and demonstrates that F. baerlocheri and F. pinnata are conspecific. A new specimen of P. cornigera provides additional information concerning leaf lobule, stylus and leaf cells. The fossil record and phylogenetic analysis of the liverworts recovered in mid-Cretaceous Burmese and Alaskan amber clearly show that Frullaniaceae have already accumulated some notable diversity in the Cretaceous, including the extant genus Frullania with three species and the extinct monotypic genus Protofrullania from mid-Cretaceous Burmese amber and probably also the extinct monotypic genus Kaolakia from mid-Cretaceous Alaskan amber.

An inclusion in Cretaceous amber from Myanmar is described as a new fossil species in the extant liverwort genus Frullania. The name Frullania pinnata is proposed for the taxon that is characterized by entire underleaves paired with a conspicuous pinnate branching pattern, two distinctive and stable morphological features. Entire underleaves are known in several extant Frullania species but had not previously been documented in Frullania in amber. The combination of morphological characters in this new fossil species is unknown in any crown group lineage of Frullania, and may very well represent a stem lineage element of the genus. This discovery is important because it expands our understanding of the diversity of Frullaniaceae in the Burmese amber forest as well as important ramifications for the phylogenetic reconstruction of extant Frullania lineages.

Classification of incompletely preserved fossils is a challenging task. We describe a moss fossil preserved in a piece of Miocene Dominican amber and assign it to the monospecific extant genus Helicophyllum. According to the published divergence time estimates, Helicophyllum originated in the Late Cretaceous, but so far no Helicophyllum fossils have been found. The Helicophyllum fossil consists of several sterile gametophytes with dimorphic leaves in two lateral and one ventral series;the lateral leaves being lingulate and obtuse and the shorter ventral leaves ovate-lanceolate. All leaves have a percurrent single costa and hexagonal to subquadrate, papillose cells. The fossil differs from extant Helicophyllum torquatum only by its slightly narrower leaf costa. Based on the extensive morphological overlap of the fossil and extant Helicophyllum specimens in other gametophytic characters and considering the Mesozoic origin of the genus, we propose an assignment of the fossil to the extant species H. torquatum, thereby accepting a minimum age of the species of 15 My. We discuss the problems of assigning fossils to extant species and propose to take into account not only morphological evidence but also evidence from divergence time estimates.

Recent findings established the Albian-Cenomanian amber of Myanmar (Burmese amber) as an important source of Mesozoic cryptogams. Here, we describe an inclusion within Burmese amber as Protofrullania cornigera gen. et sp. nov. in the extant family Frullaniaceae (Porellales, Jungermanniopsida). Diagnostic characters include its incubous leaves consisting of a dorsal lobe and a ventral lobule forming a watersac, and strap-shaped, prominent underleaves producing a rhizoid bundle from the uppermost sector of the long, narrow disc. Bark fragments connected to some of the rhizoid bundles provide evidence that the fossil was an epiphyte.

We present molecular data demonstrating that the New Zealand endemic Plagiochila caducifolia represents an isolated population of Plagiochila (sect. Arrectae) spinulosa, a species previously thought confined to the eastern Holarctic but which also occurs in Lesotho, southern Africa. In New Zealand, the wide distribution of P. spinulosa in undisturbed and relatively isolated habitats throughout the South Island is consistent with an indigenous, rather than adventive, species. Plagiochila spinulosa is the first reported bipolar disjunct species within the Plagiochilaceae. Although other bipolar disjunctions are known in vascular and non-vascular plants, they usually involve species with wider circumboreal or circumarctic distributions, presumably indicating an origin in the Northern Hemisphere. Most species of Plagiochila sect. Arrectae reproduce asexually by caducous leaves and have disjunct distributions; the significance of this correlation and biogeographic patterns in this lineage both require ...

A revision of the Baltic and Bitterfeld amber fossils assigned to Cylindrocolea dimorpha (Cephaloziellaceae) has yielded evidence of the presence of multicellular, bifid underleaves, which have not previously been reported for this species and conflict with the current circumscription of the family. We transfer the fossil species to Odontoschisma (sect. Iwatsukia) and propose the new combination O. dimorpha of the Cephaloziaceae. Characteristics of the fossil include an overall small size of the plant, entire-margined, bifid leaves and underleaves, more or less equally thickened leaf cell walls, ventral branching that includes stoloniform branches with reduced leaves, and the lack of a stem hyalodermis and gemmae. Placement of the fossil in Cephaloziaceae profoundly affects divergence time estimates for liverworts based on DNA sequence variation with integrated information from the fossil record. Our reclassification concurs with hypotheses on the divergence times of Cephaloziaceae derived from DNA sequence data that provide evidence of a late Early Cretaceous to early Eocene age of the Odontoschisma crown group and an origin of O. sect. Iwatsukia in the Late Cretaceous to Oligocene.

Allopolyploidy is an important mode of speciation in angiosperms, ferns and mosses, but has been considered of little importance in liverworts. The few known examples include taxa of the simple thalloid genus Pellia, the complex thalloid genera Corsinia, Reboulia and Targionia and the leafy liverworts Barbilophozia, Calypogeia and Porella. The diploid Plagiochila britannica has alternatively been considered an autopolyploid derivative of Plagiochila porelloides or an allopolyploid of Plagiochila asplenioides and P. porelloides;however, experimental evidence is still lacking. Here we present phylogenetic analyses of the P. asplenioides-P. britannica-P. porelloides complex based on a sampling of 37 accessions and plastid DNA rps4 and rbcL and nuclear ribosomal ITS1-5.8S-ITS2 sequences. Plastid DNA sequences of four accessions of P. britannica cluster with P. asplenioides, whereas nrITS sequences of P. britannica cluster with P. porelloides. We thus conclude that P. britannica is an allopolyploid hybrid of P. asplenioides and P. porelloides, with P. asplenioides the probable donor of the plastome and P. porelloides of the nuclear DNA. Contrary to earlier belief, P. britannica is not closely related to Plagiochila arctica. European and North American accessions of P. porelloides form sister lineages. A putative accession of P. asplenioides from Canada forms a separate lineage and may represent another taxon.

Cephaloziaceae represent a subcosmopolitan lineage of largely terrestrial leafy liverworts with three-keeled perianths, a reduced seta, capsules with bistratose walls, filamentous sporelings, large, thin-walled cells, and vegetative distribution by gemmae. Here we present the most comprehensively sampled phylogeny available to date based on the nuclear ribosomal internal transcribed spacer region and the chloroplast markers trnL-trnF and rbcL of 184 accessions representing 41 of the 89 currently accepted species and four of the five currently accepted subfamilies. Alobielloideae are placed sister to the remainder of Cephaloziaceae. Odontoschismatoideae form a sister relationship with a clade consisting of Schiffnerioideae and Cephalozioideae. Cephalozioideae are subdivided in three genera, Fuscocephaloziopsis, Cephalozia, and Nowellia, the last two in a robust sister relationship. Most morphological species circumscriptions are supported by the molecular topologies but the Cephalozia bicuspidata complex and the Cephalozia hamatiloba complex require further study. A Neotropical clade of Odontoschisma originates from temperate ancestors. Odontoschisma yunnanense is described as new to science.

The Lophocoleaceae-Plagiochilaceae-Brevianthaceae clade is a largely terrestrial, subcosmopolitan lineage of jungermannialean leafy liverworts that may include significantly more than 1000 species. Here we present the most comprehensively sampled phylogeny available to date based on the nuclear ribosomal internal transcribed spacer region and the chloroplast markers rbcL and rps4 of 372 accessions. Brevianthaceae (consisting of Brevianthus and Tetracymbaliella) form a sister relationship with Lophocoleaceae; this lineage is in turn sister to Plagiochilaceae. Plagiochila is resolved monophyletic subsequent to exclusion of Plagiochila radiculosa; this species is placed in a new genus Cryptoplagiochila. Chiastocaulon and a polyphyletic Acrochila nest in Plagiochilion; these three genera are united under Chiastocaulon to include the Plagiochilaceae species with dominating or exclusively ventral branching. The generic classification of the Lophocoleaceae is still unresolved. We discuss alternative approaches to obtain strictly monophyletic genera by visualizing their consistence with the obtained consensus topology. The presented phylogeny will serve as a basis for follow-up studies including several thousand accessions. These studies will enable revision of current hypotheses on species diversity and distribution of Lophocoleaceae-Plagiochilaceae-Brevianthaceae and allow for a reconstruction of their evolution in time and space.

Amber, a fossilized angiosperm or conifer tree resin, is a valuable source of new information on the diversity of liverworts in the Late Cretaceous and Cenozoic. This chapter reviews the fossil record of liverworts in amber, and discusses several problems with regard to the classification of incompletely preserved specimens of these plants. Putative epiphytic species assignable to the order Porellales are disproportionally well represented; other species probably grew on the trunk bases of the resiniferous trees or in their close proximity. Divergence time estimates based on a comprehensive cp DNA dataset of extant liverworts and a root calibration derived from earlier studies yield age intervals that are in good accordance with current taxonomic hypotheses on amber fossils, and provide evidence of a general congruence of both data sources. Lineage-through-time plots indicate the occurrence of increased diversification of the largely epiphytic Porellales since the Cretaceous and a constant accumulation of diversity in the predominantly generalistic sister clade Jungermanniales. These findings underline the prime importance of amber fossils to understand accurately crown group evolution in epiphytic liverwort lineages, and call for the expansion of efforts to find additional fossils of these plants in Cretaceous amber deposits.

DNA-based divergence time estimates suggested major changes in the composition of epiphyte lineages of liverworts during the Cretaceous; however, evidence from the fossil record is scarce. We present the first Cretaceous fossil of the predominantly epiphytic leafy liverwort genus Radula in ca. 100 Myr old Burmese amber. The fossil's exquisite preservation allows first insights into the morphology of early crown group representatives of Radula occurring in gymnosperm-dominated forests. Ancestral character state reconstruction aligns the fossil with the crown group of Radula subg. Odontoradula; however, corresponding divergence time estimates using the software BEAST lead to unrealistically old age estimates. Alternatively, assignment of the fossil to the stem of subg. Odontoradula results in a stem age estimate of Radula of 227.8 Ma (95 % highest posterior density (HPD): 165.7–306.7) and a crown group estimate of 176.3 Ma (135.1–227.4), in agreement with analyses employing standard substitution rates (stem age 235.6 Ma (142.9–368.5), crown group age 183.8 Ma (109.9–289.1)). The fossil likely belongs to the stem lineage of Radula subg. Odontoradula. The fossil's modern morphology suggests that switches from gymnosperm to angiosperm phorophytes occurred without changes in plant body plans in epiphytic liverworts. The fossil provides evidence for striking morphological homoplasy in time. Even conservative node assignments of the fossil support older rather than younger age estimates of the Radula crown group, involving origins for most extant subgenera by the end of the Cretaceous and diversification of their crown groups in the Cenozoic.

We describe a bryophyte community in a piece of Eocene Baltic amber housed in the American Museum of Natural History in New York. Five gametophytic plant fragments with zig-zagged stems, rounded-obtuse, bordered leaves with shortly and narrowly decurrent bases, non-mamillose, rhomboidal or elongate-hexagonal cells and a single costa are described as Rhizomnium dentatum, sp. nov., differing from extant species by some leaves with shortly-dentate margins. Syninclusions are Pyrrhobryum sp. and a pleurocarpous moss of the order Hypnales. The ecology of the extant representatives of these taxa and the presence of a chilopod suggest that the preserved bryophyte community grew in short distance to the amber-procucing tree or on its root plate, rather than epiphytically.

We describe a sterile gametophyte fragment of a leafy liverwort preserved in Cretaceous amber from Myanmar, and place it in the extant genus Gackstroemia, as G. cretacea sp. nov., representing the second extant genus of leafy liverworts reported from the Mesozoic. The complicate bilobed leaves of the fossil have a ventral lobule forming a ciliately toothed, Frullania-type water sac, and a dorsal lobe carrying a single apical cilium, as well as bifurcate underleaves being either flat or developed as a pair of ciliately toothed water sacs. Gackstroemia cretacea is the first fossil record of Lepidolaenaceae, a family being at the present time confined to the southern temperate zone. The new fossil adds to growing evidence that southern disjunctions cannot exclusively be explained by Gondwanan vicariance and that the range of Lepidolaenaceae once included parts of Laurasia.

A sterile liverwort inclusion in a piece of Miocene Mexican amber is described and assigned to the extant genus Ceratolejeunea. The inclusion has entire leaves with a basal group of 2–4(– ca. 7) ocelli, rather thin-walled leaf cells, large ovoid lobules and bifid, suborbicular underleaves. This combination of characters does not fit the morphology of extant species. Accordingly, the fossil is described as Ceratolejeunea antiqua, sp. nov., making it the second liverwort species known from Mexican amber.

The Neotropical genus Bromeliophila includes two species that grow exclusively in the water-filled leaf axils of Bromeliaceae. Phylogenetic analyses of a three marker dataset (chloroplast genome rbcL gene and trnL-F region, and nuclear ribosomal ITS1-5.8S-ITS-2 region) confirmed the monophyly of Bromeliophila and provided evidence for a sister relationship of Bromeliophila and Prionolejeunea; this clade is in turn sister to Cyclolejeunea. Despite remarkable morphological similarities, Bromeliophila is not closely related to Lejeunea and its close relatives Harpalejeunea and Microlejeunea. Based on the molecular topology and morphological evidence, Cyclolejeunea is subdivided in subgenus Cyclolejeunea and the monospecific subgenera Hyalolejeunea and Nephrolejeunea. Genetic relationships among multiple accessions of the same species support currently accepted morphological–typological species concepts.

In this study, we evaluate the impact of fossil assignments and different models of calibration on divergence time estimates carried out as Bayesian analyses. Estimated ages from preceding studies and liverwort inclusions from Baltic amber are used as constraints on a molecular phylogeny of Cephaloziineae (Jungermanniopsida) obtained from sequences of two chloroplast coding regions: rbcL and psbA. In total, the comparison of 12 different analyses demonstrates that an increased reliability of the chronograms is linked to the number of fossils assigned and to the accuracy of their assignments. Inclusion of fossil constraints leads to older ages of most crown groups, but has no influence on lineage through time plots suggesting a nearly constant accumulation of diversity since the origin of Cephaloziineae in the early to Middle Jurassic. Our results provide a note of caution regarding the interpretation of chronograms derived from DNA sequence variation of extant species based on a single calibration point and/or low accuracy of the assignment of fossils to nodes in the phylogeny. peerReviewed

Diplasiolejeunea is a pantropical, epiphytic genus of leafy liverworts that occurs from the lowlands to more than 4000m altitude. Phylogenetic analyses of a molecular dataset consisting of three markers (nuclear ribosomal ITS region, plastidic trnL-F region and rbcL gene) and 122 accessions (plus two outgroups, Colura and Cololejeunea) indicate that the evolutionary diversity of Diplasiolejeunea is underestimated by current morphology-based classification. Four morphologically semi-cryptic species have been recovered. The molecular phylogenies support a deep split into a Neotropical and a Paleotropical clade, the latter structured into Australasian, Asian and Afromadacascan lineages. Presented results confirm the ranges of two pantropical species (D. cavifolia, D. rudolphiana), provide evidence for dispersal from the Neotropics into the Paleotropics, indicate speciation along altitudinal gradients and demonstrate extensive morphological homoplasy. We propose a revised supraspecific classification of Diplasiolejeunea into a predominantly Paleotropical subgenus Physolejeunea and predominantly Neotropical subgenera Austrolejeuneopsis and Diplasiolejeunea, the former containing mainly epiphytic species, the latter mainly epiphylls. Several clades are supported by combinations of morphological character states, and could be assigned to sections at some later point. This is the first comprehensive phylogeny of a largely epiphyllous genus of liverworts.

Examination of two pieces of amber from the mid-Cretaceous of Myanmar revealed seven inclusions of leafy liverworts that we assign to the extinct Frullania cretacea Hentschel et al. 2009. These inclusions show a suite of characters that were not visible in the type specimen of F. cretacea . The new gametophytes consistently display rectangular to ovate underleaves that have two long-ciliate apical teeth in addition to 0–2 blunt lateral teeth. A narrow stylus is present on at least some leaves. The lobules usually form water sacs that are 1.2–2.3 times longer than wide, and are arranged at some distance from the stem. The observed combination of character states is not present in extant crown group lineages of Frullania . A syninclusion in one of the amber pieces is interpreted as a detached gynoecium of a second Cretaceous Frullania species and is described as F. baerlocheri , sp. nov. The subgynoecial underleaves of the syninclusion are suborbicular in shape, and allow for a separation of this species from F. cretacea . The described amber inclusions are the oldest representatives of an extant genus of leafy liverworts known so far.

The generitype Syzygiella perfoliata and S. concreta share the same gross morphology but are only loosely related in molecular phylogenies. Based on an nrITS maximum likelihood phylogeny we identify accessions belonging to either the Syzygiella concreta or the S. perfoliata lineage. We use these DNA vouchers to recircumscribe both species and present morphological characters that allow for their identification. Differences have been seen in the development of the stem cortex, the insertion of the leaves, presence or absence of rudimentary amphigastria, size and shape of the leaf cell wall trigones, and papillosity of the leaf cuticle.

 Premise of the study : Recognition and formalization of morphologically cryptic species is a major challenge to modern taxonomy. An extreme example in this regard is the Holarctic Porella platyphylla s.l. ( P. platyphylla plus P. platyphylloidea ). Earlier studies demonstrated the presence of three isozyme groups and two molecular lineages. The present investigation was carried out to elucidate the molecular diversity of P. platyphylla s.l. and the distribution of its main clades, and to evaluate evidence for the presence of one vs. several species.  Methods : We obtained chloroplast ( atp B- rbc L, trn L- trn F) and nuclear ribosomal (ITS) DNA sequences from 101 Porella accessions ( P. platyphylla s.l., P. × baueri , P. cordaeana , P. bolanderi , plus outgroup species) to estimate the phylogeny using parsimony and likelihood analyses. To facilitate the adoption of Linnean nomenclature for molecular lineages, we chose a DNA voucher as epitype.  Key results : Phylogenies derived from chloroplast vs. nuclear data were congruent except for P. platyphylla s.l., including a North American lineage that was placed sister to P. cordaeana in the chloroplast DNA phylogeny but sister to the Holarctic P. platyphylla s.str. in the nuclear DNA phylogeny. European and North American accessions of P. cordaeana and P. platyphylla form sister clades.  Conclusions : The genetic structure of P. platyphylla s.l. refl ects morphologically cryptic or near cryptic speciation into Holarctic P. platyphylla s.str. and North American P. platyphylloidea . The latter species is possibly an ancient hybrid resulting from crossings of P. cordaeana and P. platyphylla s.str. and comprises several distinct molecular entities.

Mesozoic bryophyte fossils are rare and often assigned to form genera only. Here, we describe a fragment of a leafy liverwort preserved in Cenomanian amber from northern Alaska, and place it in a new genus, Kaolakia. The extinct species Kaolakia borealis resembles the extant Frullaniaceae in having perianths with a beak, as well as complicate-bilobed incubous leaves with a Frullania-type water sac; however, two water sacs are consistently present on each side of the stem. This character resembles Lepidolaenaceae and Goebeliellaceae, although the extant members of these families have coelocaules or truncate perianths. Thus our fossil likely represents an extinct lineage with affinities to Porellales, the primarily epiphytic clade of the leafy liverworts, and is possibly closely related to Frullaniaceae.

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.

Maximum parsimony and Bayesian analyses of a chloroplast DNA rbcL dataset indicate a position of Gottschelia schizopleura in Scapaniaceae (Jungermanniales suborder Cephaloziineae). Gottschelia grollei, G. patoniae and Scaphophyllum speciosum are nested in Solenostoma (Solenostomataceae, Jungermanniales suborder Jungermanniideae) and are transferred to this genus. Accessions of G. schizopleura from Africa and Asia are separated by long branches. peerReviewed

Maximum parsimony (MP) and maximum likelihood (ML) analyses of 67 nrITS sequences of various genera of the liverwort families Lophocoleaceae and Plagiochilaceae as well as Herbertaceae (outgroup) lead to a fully resolved phylogeny with the separation of Lophocoleaceae and Plagiochilaceae having a bootstrap support of 93 to 99. The monospecific genus Leptophyllopsis is placed sister to the remainder of Lophocoleaceae. Heteroscyphus is found to be monophyletic (ML) or paraphyletic (MP) with Chiloscyphus polychaetus nested in a robust subclade of Heteroscyphus. Leptoscyphus is nested in Chiloscyphus and placed sister to a clade including Chiloscyphus subgenera Chiloscyphus, Lophocolea and Notholophocolea (Chiloscyphus clade I). Chiloscyphus subg. Connati is placed sister to this Leptoscyphus/Chiloscyphus clade. Several accessions of Chiloscyphus, which have also been treated as genus Clasmatocolea are nested in Chiloscyphus clade I. The generitype ofPachyglossa is part of Chiloscyphus clade I and placed sister to Chiloscyphus subg. Notholophocolea. Pachyglossa differs only by its multistratose leaves from Chiloscyphus subg. Notholophocolea. Based on morphological similarities and the outcome of the molecular investigation, Pachyglossa is transferred to Chiloscyphus and Chiloscyphus polychaetus to Heteroscyphus. Five new combinations are introduced.

Aim The cosmopolitan genus Herbertus is notorious for having a difficult taxonomy and for the fact that there is limited knowledge of species ranges and relationships. Topologies generated from variable molecular markers are used to discuss biogeographical patterns in Herbertus and to compare them with the geological history of continents and outcomes reported for other land plants. Location Africa, Asia, Azores, Europe, southern South America, northern South America, North America, New Zealand. Methods Phylogenetic analyses of nuclear ribosomal internal transcribed spacer and chloroplast (cp) trnL–trnF sequences of 66 accessions of Herbertus and the outgroup species Triandrophyllum subtrifidum and Mastigophora diclados were used to investigate biogeographical patterns in Herbertus. Areas of putative endemism were defined based on the distribution of species included in the analyses. Maximum parsimony analyses were undertaken to reconstruct ancestral areas and intraspecies migration routes. Results The analyses reveal species-level cladograms with a correlation between genetic variation and the geographical distribution of the related accessions. The southern South American Herbertus runcinatus is sister to the remainder of the genus, which is split into two main clades. One contains the Neotropical–African Herbertus juniperoideus and the New Zealand/Tasmanian Herbertus oldfieldianus. An African accession of H. juniperoideus is nested within Neotropical accessions. The second main clade includes species that inhabit Asia, the Holarctic, Africa, and northern South America. Maximum parsimony analyses indicate that this clade arose in Asia. Herbertus sendtneri originated in Asia and subsequently colonized the Holarctic and northern South America. An Asian origin and colonization into Africa is indicated for H. dicranus. Main conclusions The current distribution of Herbertus cannot be explained by Gondwanan vicariance. A more feasible explanation of the range is a combination of short-distance dispersal, rare long-distance dispersal events (especially into regions that faced floral displacements as a result of climatic changes) extinction, recolonization, and diversification. The African Herbertus flora is a mixture of Asian and Neotropical elements. Southern South America harbours an isolated species. The molecular data indicate partial decoupling of molecular and morphological variation in Herbertus. Biogeographical patterns in Herbertus are not dissimilar to those of other groups of bryophytes, but elucidation of the geographical ranges requires a molecular approach. Some patterns could be the result of maintenance of Herbertus in the inner Tropics during glacial maxima, and dispersal into temperate regions in warm phases.

A revision of Neotropical Herbertus leads to the recognition of two species (H. sendtneri, H. juniperoideus), the latter with four subspecies (H. juniperoideus ssp. juniperoideus, ssp. acanthelius, ssp. bivitattus, ssp. pensilis). A key to the taxa, morphological descriptions, specimen lists, and extensive synonymy are provided. Maximum likelihood and parsimony analyses of nuclear ribosomal internal transcribed spacer (nrITS) and chloroplast (cp) trnL-trnF sequences result in well-resolved topologies with H. sendtneri placed sister to a clade with Asian, Holarctic, and African species. H. juniperoideus constitutes a separate clade made up of polyphyletic H. juniperoideus ssp. acanthelius and ssp. pensilis, monophyletic H. juniperoideus ssp. bivitattus, and several accessions that could be identified to species level only. It is unclear whether the H. juniperoideus topology reflects plasticity of a variable species, occasional hybridization between morphologically clearly distinct populations or cryptic speciation. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society, 2006, 151, 309–332.

Plagiochila (sect. Arrectae) punctata, previously known from the Neotropics, Africa and Europe, has been collected on a sandstone cliff in a rockhouse type environment in Tennessee, new to North America. Maximum likelihood analyses based on nrITS1–5.8S-ITS2 sequences of several species of Plagiochila sect. Arrectae resolve the Tennessee specimen in a robust P. punctata subclade with accessions from Ecuador and the Democratic Republic of the Congo.

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.

Based on morphology and phylogenetical analyses of nrITS sequences, the Andean endemic Plagiochila (Jamesoniella) dependula is placed in Plagiochila sect. Fuscoluteae. Perianths, oil bodies and sporophytes are described for the first time. Morphologically, P. dependula is characterized by entire, dorsally mostly shortly decurrent, laterally appressed, reniform leaves which are covered by irregular papillae and membranous wax platelets, papillose oil bodies, intercalary androecia with opposite bracts that overlap dorsally, a plagiochilid perianth with an entire mouth, a 250 μm thick capsule wall with thickenings in all layers, large 1–4 celled spores, and bispiral elaters. Morphotypes of Plagiochila fuscolutea with laterally appressed leaves differ from P. dependula by an at least moderately decurrent, broad dorsal leaf base, a ±smooth upper leaf surface, and by its often toothed leaf apices. Plagiochila wolframii is placed in the synonymy of P. fuscolutea. Maximum likelihood and parsimony analyses...

Maximum likelihood and parsimony analyses of nrITS1-5.8S-ITS2 sequences place Austrian Herbertus sendtneri in a well boot- strap supported clade with Herbertus azoricus and Neotropical accessions which were alter- natively assigned to Herbertus subdentatus or Herbertus dicranus. Asian and African Herber- tus dicranus form a separate lineage which is placed sister to several European Herbertus taxa. Herbertus borealis from the British Isles is placed sister to H. stramineus in a robust sister relationship, indicating that the species does not belong in the synonymy of H. dicranus. As a result of the molecular investigation, the range of Herbertus sendtneri is extended to the Neotropics and H. azoricus is placed into the synonymy of H. sendtneri. Without much doubt, Herbertus dicranus does not occur in tropical America. Morphologi- cally, H. sendtneri and H. dicranus can at most be separated by weak tendencies. Herbertus sendtneri is characterized by the frequent occurrence of coarse appendages at the leaf margins and often completely papillose leaves. H. dicranus often has small appendages and a nearly smooth basal leaf half. Herbertus borealis, which is nonmonophyletic with H. dicranus in the molecular trees, cannot be separated morphologically from forms of H. dicranus with small appendages. Herbertus subdentatus is not identical with H. sendtneri. Morphological homoplasy and cryptic specia- tion are obviously common in Herbertus.

 Premise of the study: Closing gaps in the fossil record and elucidating phylogenetic relationships of mostly incomplete fossils are major challenges in the reconstruction of the diversifi cation of fern lineages through time. The cosmopolitan family Dryopteridaceae represents one of the most species-rich families of leptosporangiate ferns, yet its fossil record is sparse and poorly understood. Here, we describe a fern inclusion in Miocene Dominican amber and investigate its relationships to extant Dryopteridaceae.  Methods: The morphology of the fossil was compared with descriptions of extant ferns, resulting in it being tentatively assigned to the bolbitidoid fern genus Elaphoglossum . This assignment was confi rmed by reconstructing the evolution of the morphological characters preserved in the inclusion on a molecular phylogeny of 158 extant bolbitidoid ferns. To assess the morphology-based assignment of the fossil to Elaphoglossum , we examined DNA-calibrated divergence time estimates against the age of the amber deposits from which it came.  Key results: The fossil belongs to Elaphoglossum and is the fi rst of a bolbitidoid fern. Its assignment to a particular section of Elaphoglossum could not be determined; however, sects. Lepidoglossa , Polytrichia , and Setosa can be discounted because the fossil lacks subulate scales or scales with acicular marginal hairs. Thus, the fossil might belong to either sects. Amygdalifolia , Wrightiana , Elaphoglossum , or Squamipedia or to an extinct lineage.  Conclusions: The discovery of a Miocene Elaphoglossum fossil provides remarkable support to current molecular clock-based estimates of the diversifi cation of these ferns.

Recent studies have provided evidence for pulses in the diversification of angiosperms, ferns, gymnosperms and mosses as well as various groups of animals during the Cretaceous revolution of terrestrial ecosystems. However, evidence for such pulses has not been reported so far for liverworts. Here we provide new insight into liverwort evolution by integrating a comprehensive molecular dataset with a set of 20 fossil age constraints. We found evidence for a relative constant diversification rate of generalistic liverworts (Jungermanniales) since the Palaeozoic, whereas epiphytic liverworts (Porellales) show a sudden increase of lineage accumulation in the Cretaceous. This difference is likely caused by the pronounced response of Porellales to the ecological opportunities provided by humid, megathermal forests, which were increasingly available as a result of the rise of the angiosperms.

Dominican amber is an important source for Early Miocene bryophytes. We report the moss Macromitrium richardii Schwägr., an extant representative of the Orthotrichaceae, from the Dominican amber collection of the American Museum of Natural History. This species is currently a widespread Neotropical epiphyte. The specimen includes several gametophytes and sporophytes, and represents the first fossil record of Orthotrichaceae. Alongside the Macromitrium shoots we observed several fragments of the liverworts Cheilolejeunea antiqua and Frullania sp. The unusual thermal behavior of the resin sample initially led to doubts about the Miocene age of the specimen, but chemical analyses of the Hymenaea resin provides evidence that the specimen represents a highly oxidized sample of Miocene Dominican amber rather than an artificially thermally-treated subfossil resin (copal). Our inclusion demonstrates the exceptional preservation potential of tree resin, but our observations also suggest that provenance (including any possibility that a modern resin has been thermally treated to make it appear older) should be scrutinized when single pieces with atypical thermal behavior and exceptionally well-preserved extant morphotypes come to light.