Hans-Peter Kreier

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.

Formalizing morphologically cryptic biological entities: New insights from DNA taxonomy, hybridization, and biogeography in the leafy liverwort Porella platyphylla (Jungermanniopsida, Porellales)

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 (atpB-rbcL, trnL-trnF) 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. reflects 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.

Phylogeny of the leafy liverwort Ptilidium: Cryptic speciation and shared haplotypes between the Northern and Southern Hemispheres

The small, phylogenetically isolated liverwort genus Ptilidium has been regarded as of cool-Gondwanic origin with the bipolar, terrestrial Ptilidium ciliare giving rise to the Northern Hemisphere epiphytes Ptilidium pulcherrimum and Ptilidium californicum. This hypothesis is examined using a dataset including three chloroplast DNA regions from 134 Ptilidium accessions and one accession each of its closest relatives Trichocoleopsis and Neotrichocolea. Maximum likelihood and parsimony analyses point to a close relationship between P. ciliare and P. pulcherrimum, whereas P. californicum is placed sister to the remainder of the genus, separated by a long branch. Haplotype analysis and our phylogeny indicate the presence of Southern Hemisphere haplotypes of P. ciliare in the Northern Hemisphere, and shared haplotypes of P. ciliare and P. pulcherrimum between Europe and North America. Based on our findings, we reject the Gondwana-scenario and propose recent long distance dispersal as an explanation for the bipolar disjunct range. Ptilidium ciliare is resolved as paraphyletic with P. pulcherrimum nested within it. An isolated Ptilidium lineage with the morphology of P. ciliare from the Himalaya region likely represents a hitherto unrecognized cryptic species. Ptilidium pulcherrimum splits into a Japanese clade and a clade with accessions from Europe and North America.

Serpocaulon (Polypodiaceae), a new genus segregated from Polypodium

We describe the neotropical fern genus Serpocaulon (Polypodiaceae), segregated from Polypodium, and make new combinations for the forty known species. Serpocaulon has been recognized previously as a putatively natural group by several authors, based on morphological evidence, but never accorded generic rank. The monophyly of Serpocaulon is strongly supported in chloroplast DNA-based phylogenetic analyses, using the genes rbcL, rps4, rps4-trnS intergenic spacer, and trnL-F intergenic spacer on 29 samples from 22 species. Serpocaulon is readily separated from other subclades within Polypodiaceae, and especially from Polypodium, which is less closely related to Serpocaulon than are several other genera. Serpocaulon differs from other New World polypods in the combination of usually long-creeping, sparingly branched rhizomes with clathrate (sometimes strongly so), usually peltately attached scales; regularly anastomosing (goniophlebioid) veins with individual areoles chevron-shaped and each with a single, free, included excurrent veinlet; and non-paraphysate sori in one to 10 rows between costae and pinna margins. In Polypodium, the rhizome scales are not clathrate, ± concolorous, and invaginated at the base, with somewhat overlapping basal lobes, and rhizomes are generally shorter-creeping and more frequently branched, the veins are free or forming a single row of areoles, and the sori uniseriate on each side of the costae. Most species of true Polypodium are north-temperate, Mexican, or Mesoamerican in distribution, while Serpocaulon is entirely neotropical or subtropical, with the greatest number of species in South America. There appears to be no convenient infrageneric division of the species within Serpocaulon, although the most widespread species, S. triseriale, is somewhat isolated at the base of the clade. Species with the thinnest rhizomes also have the fewest scales, and generally grow at high elevations. Species having the scaliest rhizomes, with scales spreading and strongly overlapping, form a weakly supported subclade, as do species with multiseriate rows of areoles between costae and pinna margins.

Origin and diversification of African ferns with special emphasis on Polypodiaceae

Although Africa harbors low species diversity compared to the neotropics or South East Asia, the African fern flora is of interest because of its specific composition and geographic location between the neotropics and Asia. We address the question of how the evolution of the African fern flora may have been enriched by repeated input from the neotropics and Asia. For the purpose of this paper we consider ihree major biogeographic regions: the neotropics, Africa and Madagascar, and Asia including Malesia and Australasia. We interpret distribution data for six clades of Polypodiaceae in a molecular phylogenetic framework. We conclude that African fern taxa shared with or closely related to ones in the neotropics or Asia have been brought about by ancient and recent dispersal events with or without subsequent speciation. The African fern flora is interpreted as being composed of endemic, neotropical, and Asian elements and as being situated in a zone of overlap of typical neotropical and Asian fern floras.

The Synammia Enigma: Evidence for a Temperate Lineage of Polygrammoid Ferns (Polypodiaceae, Polypodiidae) in Southern South America

Abstract Evidence for a southern South American lineage of polygrammoid ferns was inferred from analyses using four cpDNA markers. The lineage corresponds to the genus Synammia, which has usually been treated as a synonym of the polyphyletic genus Polypodium. Seven specimens of two of the three recognized species were sampled to infer the phylogenetic relationships of this lineage to other polygrammoid ferns and the diversity within this lineage. All approaches found Synammia clearly separated from other polygrammoid ferns, but the exact relationships are still unclear. Model-based methods recovered Synammia as sister to a mainly Neotropical clade of polygrammoid ferns, but support for this hypothesis was provided only by Bayesian inference of phylogeny. The deletion of nearly the whole rps4-trnS IGS is a synapomorphy of Synammia. The lineage is separated from other extant polygrammoid ferns, but very low to zero sequence diversity was found among the seven samples of Synammia. The results strongly support an independent lineage of polygrammoid ferns in southern South America.

The microsoroid ferns: Inferring the relationships of a highly diverse lineage of Paleotropical epiphytic ferns (Polypodiaceae, Polypodiopsida)

The relationships of the microsoroid ferns were studied using a DNA sequence-based phylogenetic approach. Nucleotide sequences for up to four chloroplast genome regions were assembled for 107 samples from 87 species. Microsoroids s.l. include six lineages of which two are species rich. The results indicate that several genera are not monophyletic (e.g. Microsorum), several controversial genera are confirmed to be monophyletic (e.g. Leptochilus), and some genera new to science should be recognized (M. membranaceum clade). Unique insights were gained into the biogeographic history of this highly diverse epiphytic vascular plant lineage that is widespread in continental Asia to Australasia. Evidence was found for splits into lineages diversifying in parallel in continental Asia and Malesia. No evidence was recovered for an African radiation because all African microsoroid species either also are found in Asia or have sister species in continental Asia. In contrast, evidence for independent radiations were discovered for the Australasian region.

A phylogeny of the northern temperate leafy liverwort genus Scapania (Scapaniaceae, Jungermanniales).

Scapania is a northern temperate genus with a few disjunctions in the south. Despite receiving considerable attention, the supraspecific classification of this genus remains unsatisfactorily solved. We use three molecular markers (nrITS, cpDNA trnL-F region, atpB-rbcL spacer) and 175 accessions belonging to 50 species (plus eight outgroup taxa) to estimate the phylogeny and to test current classification systems. Our data support the classification of Scapania into six rather than three subgenera, rearrangements within numerous sections, and inclusion of Macrodiplophyllum microdontum. Scapania species with a plicate perianth form three early diverging lineages; the most speciose subgenus, Scapania s.str., represents a derived clade. Most morphological species concepts are supported by the molecular topologies but classification of sect. Curtae requires further study. Southern lineages are nested in northern hemispheric clades. Palearctic-Nearctic distribution ranges are supported for several species.

A New Species of Microgramma (Polypodiaceae) from Brazil and Recircumscription of the Genus Based on Phylogenetic Evidence

Abstract We describe a new species of Microgramma (M. microsoroides) from the Atlantic Forest of Brazil, present a phylogeny of Microgramma, and provide a new generic circumscription. Microgramma comprises ca. 30 species in the Neotropics and perhaps two species in Africa and on islands in the Indian Ocean. Several species are contentious with regard to generic placement, and have been treated within Pleopeltis, Polypodium, and Solanopteris. From all known species of Microgramma, the new species differs by the sori forming irregular rows between adjacent primary veins. This finding is quite surprising, inasmuch as all other species in the genus have sori in two very strict rows, one row on each side of the midrib. The monophyly of Microgramma, as newly redefined, is strongly supported in chloroplast DNA-based phylogenetic analyses, using the genes rbcL and rps4, the rps4–trnS intergenic spacer, and the trnL–trnF intergenic spacer on 13 samples from 12 species. The new species is nested within Microgramma as sister to Microgramma megalophylla. Recognition of the relationships of M. microsoroides calls into question certain soral characters traditionally used to define genera of Polypodiaceae, as well as genera of ferns in other families. Sorus placement is notoriously variable in some genera and in many different families of Polypodiales.

Key Innovations Versus Key Opportunities: Identifying Causes of Rapid Radiations in Derived Ferns

Biological radiations, e.g., adaptive radiations and rapid radiations, are widely accepted as one of the major events contributing to the diversification of the tree of life, but many aspects of these events are poorly understood (Schluter 2000; Gavrilets and Losos 2009). The classical examples for biological radiations are adaptive radiations, in which a lineage occupies a range of niches by diversifying in a relative short time until all niches are filled. However, not all radiations necessarily fulfil this pattern and alternative scenarios such as rapid radiations are widely considered. A major setback is the lack of a generally accepted definition of biological radiations (Schluter 2000). Empirical studies on the frequency and contribution of radiation, however, need concise theoretical concepts and criteria such as temporal increase of diversification rate or the absolute number of species to define biological radiations (Schluter 2000; Gavrilets and Losos 2009). Thus, our knowledge is limited by both the disparity of applied concepts and the limited amount of studies scrutinizing evidence for as many lineages of organisms as possible. It is therefore impossible to estimate quantitatively the contribution of radiations to the diversity of life on earth today. A recent study on 101 phylogenies discovered evidence for a hypothesis that explains the constant accumulation of biodiversity through rare single speciation events instead of species radiations (Venditti et al. 2010).