Slippery when wet: Phylogeny and character evolution in the gelatinous cyanobacterial lichens (Peltigerales, Ascomycetes)

Species in lichen-forming fungi: balancing between conceptual and practical considerations, and between phenotype and phylogenomics

Lichens are symbiotic associations resulting from interactions among fungi (primary and secondary mycobionts), algae and/or cyanobacteria (primary and secondary photobionts), and specific elements of the bacterial microbiome associated with the lichen thallus. The question of what is a species, both concerning the lichen as a whole and its main fungal component, the primary mycobiont, has faced many challenges throughout history and has reached new dimensions with the advent of molecular phylogenetics and phylogenomics. In this paper, we briefly revise the definition of lichens and the scientific and vernacular naming conventions, concluding that the scientific, Latinized name usually associated with lichens invariably refers to the primary mycobiont, whereas the vernacular name encompasses the entire lichen. Although the same lichen mycobiont may produce different phenotypes when associating with different photobionts or growing in axenic culture, this discrete variation does not warrant the application of different scientific names, but must follow the principle "one fungus = one name". Instead, broadly agreed informal designations should be used for such discrete morphologies, such as chloromorph and cyanomorph for lichens formed by the same mycobiont but with either green algae or cyanobacteria. The taxonomic recognition of species in lichen-forming fungi is not different from other fungi and conceptual and nomenclatural approaches follow the same principles. We identify a number of current challenges and provide recommendations to address these. Species delimitation in lichen-forming fungi should not be tailored to particular species concepts but instead be derived from empirical evidence, applying one or several of the following principles in what we call the LPR approach: lineage (L) coherence vs. divergence (phylogenetic component), phenotype (P) coherence vs. divergence (morphological component), and/or reproductive (R) compatibility vs. isolation (biological component). Species hypotheses can be established based on either L or P, then using either P or L (plus R) to corroborate them. The reliability of species hypotheses depends not only on the nature and number of characters but also on the context: the closer the relationship and/or similarity between species, the higher the number of characters and/or specimens that should be analyzed to provide reliable delimitations. Alpha taxonomy should follow scientific evidence and an evolutionary framework but should also offer alternative practical solutions, as long as these are scientifically defendable. Taxa that are delimited phylogenetically but not readily identifiable in the field, or are genuinely cryptic, should not be rejected due to the inaccessibility of proper tools. Instead, they can be provisionally treated as undifferentiated complexes for purposes that do not require precise determinations. The application of infraspecific (gamma) taxonomy should be restricted to cases where there is a biological rationale, i.e., lineages of a species complex that show limited phylogenetic divergence but no evidence of reproductive isolation. Gamma taxonomy should not be used to denote discrete phenotypical variation or ecotypes not warranting the distinction at species level. We revise the species pair concept in lichen-forming fungi, which recognizes sexually and asexually reproducing morphs with the same underlying phenotype as different species. We conclude that in most cases this concept does not hold, but the actual situation is complex and not necessarily correlated with reproductive strategy. In cases where no molecular data are available or where single or multi-marker approaches do not provide resolution, we recommend maintaining species pairs until molecular or phylogenomic data are available. This recommendation is based on the example of the species pair Usnea aurantiacoatra vs. U. antarctica, which can only be resolved with phylogenomic approaches, such as microsatellites or RADseq. Overall, we consider that species delimitation in lichen-forming fungi has advanced dramatically over the past three decades, resulting in a solid framework, but that empirical evidence is still missing for many taxa. Therefore, while phylogenomic approaches focusing on particular examples will be increasingly employed to resolve difficult species complexes, broad screening using single barcoding markers will aid in placing as many taxa as possible into a molecular matrix. We provide a practical protocol how to assess and formally treat taxonomic novelties. While this paper focuses on lichen fungi, many of the aspects discussed herein apply generally to fungal taxonomy. The new combination Arthonia minor (Lücking) Lücking comb. et stat. nov. (Bas.: Arthonia cyanea f. minor Lücking) is proposed.

Diversity of Leptogium (Collemataceae, Ascomycota) in East African Montane Ecosystems

Tropical mountains and especially their forests are hot spots of biodiversity threatened by human population pressure and climate change. The diversity of lichens in tropical Africa is especially poorly known. Here we use the mtSSU and nuITS molecular markers together with morphology and ecology to assess Leptogium (Peltigerales, Ascomycota) diversity in the tropical mountains of Taita Hills and Mt. Kasigau in Kenya and Mt. Kilimanjaro in Tanzania. The sampled habitats cover a wide range of ecosystems from savanna to alpine heath vegetation and from relatively natural forests to agricultural environments and plantation forests. We demonstrate that Leptogium diversity in Africa is much higher than previously known and provide preliminary data on over 70 putative species, including nine established species previously known from the area and over 60 phylogenetically, morphologically, and/or ecologically defined Operational Taxonomic Units (OTUs). Many traditional species concepts are shown to represent morphotypes comprised of several taxa. Many of the species were only found from specific ecosystems and/or restricted habitats and are thus threatened by ongoing habitat fragmentation and degradation of the natural environment. Our results emphasize the importance of molecular markers in species inventories of highly diverse organism groups and geographical areas.

Hispidopannaria and Phormopsora, two new and small, but evolutionary old Pannariaceae lichen genera from southern South America

Based on phylogenetic analyses of the ITS, nuclear large subunit rRNA, mitochondrial small subunit rRNA, and MCM7 genes, species previously treated as Pannaria hispidula and P. isabellina are shown to represent two new Pannariaceae genera, Hispidopannaria and Phormospsora. Each genus forms monophyletic clades, both in multilocus phylogeny and in single gene phylogenies. In the multilocus phylogeny, both genera together formed a monophyletic clade as a sister group to the genus Pannaria, whereas this monophyly was not maintained in single gene phylogenies. Hispidopannaria differs from Pannaria in having large, geotropically arranged, hispid squamules, IKI+ internal ascus structures, and perispores with irregular pulvinate verrucae and apical extensions. The southern South American, TLC-negative species H. hispidula is generitype and is concentrated to trunks in the evergreen Nothofagus forests of south-central Chile. Psoroma dasycladum, a similar endemic species from the Juan Fernández Archipelago, is also transferred to Hispidopannaria. Phormopsora is monospecific and is the only member of Pannariaceae which contains norstictic and connorstictic acids. Its thallus of large, branched squamules with large, foliose cephalodia and its bullate perispores with long-apiculate apical extensions also separate it from Pannaria. Its species, Phormopsora isabellina, has a similar distribution as H. hispidula on the South American mainland, but is more widespread. The position of these two small genera as a sister group to the large and diverse genus Pannaria, indicates a long period of slow evolutionary rate, with the island endemic Hispidopannaria dasyclada as an exception. Reproductive isolation and photobiont specialization are partly suggested to explain their slow evolution and lack of surviving speciation.

Species delimitation in the cyanolichen genus Rostania

Background

In this study, we investigate species limits in the cyanobacterial lichen genus Rostania (Collemataceae, Peltigerales, Lecanoromycetes). Four molecular markers (mtSSU rDNA, β-tubulin, MCM7, RPB2) were sequenced and analysed with two coalescent-based species delimitation methods: the Generalized Mixed Yule Coalescent model (GMYC) and a Bayesian species delimitation method (BPP) using a multispecies coalescence model (MSC), the latter with or without an a priori defined guide tree.

Results

Species delimitation analyses indicate the presence of eight strongly supported candidate species. Conclusive correlation between morphological/ecological characters and genetic delimitation could be found for six of these. Of the two additional candidate species, one is represented by a single sterile specimen and the other currently lacks morphological or ecological supporting evidence.

Conclusions

We conclude that Rostania includes a minimum of six species: R. ceranisca, R. multipunctata, R. occultata 1, R. occultata 2, R. occultata 3, and R. occultata 4,5,6. Three distinct Nostoc morphotypes occur in Rostania, and there is substantial correlation between these morphotypes and Rostania thallus morphology.

The First Finding of the Lichen Solorina saccata at an Algific Talus Slope in Korea

An algific talus slope is composed of broken rocks with vents connected to an ice cave, releasing cool air in summer and relatively warmer air in winter to maintain a more stable microclimate all year round. Such geological features create a very unusual and delicate ecosystem. Although there are around 25 major algific talus slopes in Korea, lichen ecology of these areas had not been investigated to date. In this study, we report the first exploration of lichen diversity and ecology at an algific talus slope, Jangyeol-ri, in Korea. A total of 37 specimens were collected over 2017-2018. Morphological and sequencing analysis revealed 27 species belonging to 18 genera present in the area. Of particular interest among these species was Solorina saccata, as it has previously not been reported in Korea and most members of genus Solorina are known to inhabit alpine regions of the Northern Hemisphere. We provide here a taxonomic key for S. saccata alongside molecular phylogenetic analyses and prediction of potential habitats in South Korea. Furthermore, regions in South Korea potentially suitable for Solorina spp. were predicted based on climatic features of known habitats around the globe. Our results showed that the suitable areas are mostly at high altitudes in mountainous areas where the annual temperature range does not exceed 26.6 °C. Further survey of other environmental conditions determining the suitability of Solorina spp. should lead to a more precise prediction of suitable habitats and trace the origin of Solorina spp. in Korea.

The genus Massalongia (lichenised ascomycetae) in the Southern Hemisphere

The species of Massalongia recorded and described from the Southern Hemisphere are revised and it is shown that only one is present; M. patagonica which is widespread, with populations in Australia and New Zealand that differ from the South American populations, but at present best regarded as part of the variation of that species. Records from this hemisphere of all other species placed in the genus are incorrect. The type species, M. carnosa, is restricted to the Northern Hemisphere. Two species, M. antarctica and M. novozelandica cannot be identified precisely due to lack of sufficient type material and with the types as the only collections known of these, but none belongs in Massalongia according to available data. Massalongia griseolobata (from Gough Isl.) is shown here to belong in the Pannariaceae and is part of the parmelielloid clade. M. intricata (from South Georgia) and M. olechiana (from South Shetland) have both recently been correctly transferred to the genus Steinera in the Arctomiaceae.

The cellular cortex in Collemataceae (lichenized Ascomycota) participates in thallus growth and morphogenesis via parenchymatous cell divisions

According to a widely held view, fungi do not produce parenchymatous tissues. Following up on recent transmission electron microscopy (TEM) evidence that challenged this paradigm in several lichens, we employed scanning electron microscopy (SEM) to investigate the orientation of new anticlinal walls in the single-layered fungal cortex of six species of Collemataceae, a family of gelatinous cyanolichens with diverse surface morphologies. Examination of thallus surfaces in four species of Leptogium (L. austromericanum, L. burnetiae, L. chloromelum, L. marginellum) and two species of Scytinium (S. gelatinosum, S. lichenoides) revealed that recently formed septa adjoin to preceding septa in parenchymatous division. These cortical divisions were evident in the formation and development of thallus wrinkles, folds, isidia, and lobules in the six morphologically distinct taxa. Tomentum, by contrast, arose as filamentous outgrowths of the cortical cells. We conclude that the monostromatic cellular cortex in Collemataceae participates in surface growth and morphogenesis by means of parenchymatous cell divisions, in a remarkable parallel to plant meristems. Cortical cell divisions do not appear to drive morphogenesis, however, as very similar morphologies are achieved in the closely related genus Collema, which lacks a cortex altogether. These results provide evidence that parenchymatous cell division can indeed play a role in morphogenesis of fungal structures and show that SEM is a useful tool for distinguishing the orientation of anticlinal divisions in the cortex of gelatinous lichens.

Biodiversity of biological soil crusts from the Polar Regions revealed by metabarcoding

Biological soil crusts (BSCs) are amalgamations of autotrophic, heterotrophic and saprotrophic organisms. In the Polar Regions, these unique communities occupy essential ecological functions such as primary production, nitrogen fixation and ecosystem engineering. Here, we present the first molecular survey of BSCs from the Arctic and Antarctica focused on both eukaryotes and prokaryotes as well as passive and active biodiversity. Considering sequence abundance, Bryophyta is among the most abundant taxa in all analyzed BSCs suggesting that they were in a late successional stage. In terms of algal and cyanobacterial biodiversity, the genera Chloromonas, Coccomyxa, Elliptochloris and Nostoc were identified in all samples regardless of origin confirming their ubiquitous distribution. For the first time, we found the chrysophyte Spumella to be common in polar BSCs as it was present in all analyzed samples. Co-occurrence analysis revealed the presence of sulfur metabolizing microbes indicating that BSCs also play an important role for the sulfur cycle. In general, phototrophs were most abundant within the BSCs but there was also a diverse community of heterotrophs and saprotrophs. Our results show that BSCs are unique microecosystems in polar environments with an unexpectedly high biodiversity.

Rostania revised: testing generic delimitations in Collemataceae (Peltigerales, Lecanoromycetes)

Here, we test the current generic delimitation of Rostania (Collemataceae, Peltigerales, Ascomycota) utilizing molecular phylogeny and morphological investigations. Using DNA sequence data from the mitochondrial SSU rDNA and two nuclear protein-coding genes (MCM7 and β-tubulin) and utilizing parsimony, maximum likelihood and Bayesian phylogenetic methods, Rostania is shown to be non-monophyletic in the current sense. A new generic delimitation of Rostania is thus proposed, in which the genus is monophyletic, and three species (Rostaniacoccophylla, R.paramensis, R.quadrifida) are excluded and transferred to other genera. Rostaniaoccultata is further non-monophyletic, and a more detailed investigation of species delimitations in Rostania s. str. is needed. The new combinations Leptogiumparamense and Scytiniumquadrifidum are proposed.

Lichenized Fungi and the Evolution of Symbiotic Organization

Lichen symbioses comprise a fascinating relationship between algae and fungi. The lichen symbiotic lifestyle evolved early in the evolution of ascomycetes and is also known from a few basidiomycetes. The ascomycete lineages have diversified in the lichenized stage to give rise to a tremendous variety of morphologies. Their thalli are often internally complex and stratified for optimized integration of algal and fungal metabolisms. Thalli are frequently colonized by specific nonlichenized fungi and occasionally also by other lichens. Microscopy has revealed various ways these fungi interact with their hosts. Besides the morphologically recognizable diversity of the lichen mycobionts and lichenicolous (lichen-inhabiting) fungi, many other microorganisms including other fungi and bacterial communities are now detected in lichens by culture-dependent and culture-independent approaches. The application of multi-omics approaches, refined microscopic techniques, and physiological studies has added to our knowledge of lichens, not only about the taxa involved in the lichen interactions, but also about their functions.

Multi-gene phylogeny of the genus Lobaria: Evidence of species-pair and allopatric cryptic speciation in East Asia

PREMISE OF THE STUDY

Accurate species delimitation has critical implications for ecological and conservation studies. The lichen genus Lobaria is widely distributed in old-growth forests. Particularly in East Asia, this genus includes many rare and poorly known taxa that are circumscribed as morpho- or chemospecies, as well as species-pairs.

METHODS

To critically examine the relationships between species identified via morphological and chemical criteria, phylogenetic species recognition (PSR) was applied to the genus Lobaria. Morphological and chemical patterns of 87 individuals were examined and three independent nuclear loci were sequenced. The East Asian L. meridionalis-group was additionally studied using split decomposition and haplotype network analysis.

KEY RESULTS

The genus Lobaria and most of its species were strongly supported statistically. Split decomposition and haplotype networks suggest complex evolutionary histories of species within the East Asian L. meridionalis-group.

CONCLUSIONS

Phylogenetic analyses confirmed the monophyly of the genus Lobaria, including L. anomala. Within Lobaria, three major clades were found. These clades associate with different photobionts and comprise 18 known species and 5 undescribed species. Several chemical compounds were found to be neither stable nor invariant characters. Some taxa of the L. meridionalis-group appear to be monophyletic but remain as allopatric cryptic species. In three clades, this study found evidence for diversification processes between isidiate and nonisidiate specimens (species-pair). These findings are discussed in the context of evolutionary hypotheses for speciation processes.

A Molecular Phylogeny of the Lichen Genus Lecidella Focusing on Species from Mainland China

The phylogeny of Lecidella species is studied, based on a 7-locus data set using ML and Bayesian analyses. Phylogenetic relationships among 43 individuals representing 11 Lecidella species, mainly from mainland China, were included in the analyses and phenotypical characters studied and mapped onto the phylogeny. The Lecidella species fall into three major clades, which are proposed here as three informal groups-Lecidella stigmatea group, L. elaeochroma group and L. enteroleucella group, each of them strongly supported. Our phylogenetic analyses support traditional species delimitation based on morphological and chemical traits in most but not all cases. Individuals considered as belonging to the same species based on phenotypic characters were found to be paraphyletic, indicating that cryptic species might be hidden under these names (e.g. L. carpathica and L. effugiens). Potentially undescribed species were found within the phenotypically circumscribed species L. elaeochroma and L. stigmatea. Additional sampling across a broader taxonomic and geographic scale will be crucial to fully resolving the taxonomy in this cosmopolitan genus.

A multigene phylogenetic synthesis for the class Lecanoromycetes (Ascomycota): 1307 fungi representing 1139 infrageneric taxa, 317 genera and 66 families

The Lecanoromycetes is the largest class of lichenized Fungi, and one of the most species-rich classes in the kingdom. Here we provide a multigene phylogenetic synthesis (using three ribosomal RNA-coding and two protein-coding genes) of the Lecanoromycetes based on 642 newly generated and 3329 publicly available sequences representing 1139 taxa, 317 genera, 66 families, 17 orders and five subclasses (four currently recognized: Acarosporomycetidae, Lecanoromycetidae, Ostropomycetidae, Umbilicariomycetidae; and one provisionarily recognized, 'Candelariomycetidae'). Maximum likelihood phylogenetic analyses on four multigene datasets assembled using a cumulative supermatrix approach with a progressively higher number of species and missing data (5-gene, 5+4-gene, 5+4+3-gene and 5+4+3+2-gene datasets) show that the current classification includes non-monophyletic taxa at various ranks, which need to be recircumscribed and require revisionary treatments based on denser taxon sampling and more loci. Two newly circumscribed orders (Arctomiales and Hymeneliales in the Ostropomycetidae) and three families (Ramboldiaceae and Psilolechiaceae in the Lecanorales, and Strangosporaceae in the Lecanoromycetes inc. sed.) are introduced. The potential resurrection of the families Eigleraceae and Lopadiaceae is considered here to alleviate phylogenetic and classification disparities. An overview of the photobionts associated with the main fungal lineages in the Lecanoromycetes based on available published records is provided. A revised schematic classification at the family level in the phylogenetic context of widely accepted and newly revealed relationships across Lecanoromycetes is included. The cumulative addition of taxa with an increasing amount of missing data (i.e., a cumulative supermatrix approach, starting with taxa for which sequences were available for all five targeted genes and ending with the addition of taxa for which only two genes have been sequenced) revealed relatively stable relationships for many families and orders. However, the increasing number of taxa without the addition of more loci also resulted in an expected substantial loss of phylogenetic resolving power and support (especially for deep phylogenetic relationships), potentially including the misplacements of several taxa. Future phylogenetic analyses should include additional single copy protein-coding markers in order to improve the tree of the Lecanoromycetes. As part of this study, a new module ("Hypha") of the freely available Mesquite software was developed to compare and display the internodal support values derived from this cumulative supermatrix approach.

Do photobiont switch and cephalodia emancipation act as evolutionary drivers in the lichen symbiosis? A case study in the Pannariaceae (Peltigerales)

Lichen symbioses in the Pannariaceae associate an ascomycete and either cyanobacteria alone (usually Nostoc; bipartite thalli) or green algae and cyanobacteria (cyanobacteria being located in dedicated structures called cephalodia; tripartite thalli) as photosynthetic partners (photobionts). In bipartite thalli, cyanobacteria can either be restricted to a well-delimited layer within the thallus ('pannarioid' thalli) or spread over the thallus that becomes gelatinous when wet ('collematoid' thalli). We studied the collematoid genera Kroswia and Physma and an undescribed tripartite species along with representatives of the pannarioid genera Fuscopannaria, Pannaria and Parmeliella. Molecular inferences from 4 loci for the fungus and 1 locus for the photobiont and statistical analyses within a phylogenetic framework support the following: (a) several switches from pannarioid to collematoid thalli occured and are correlated with photobiont switches; the collematoid genus Kroswia is nested within the pannarioid genus Fuscopannaria and the collematoid genus Physma is sister to the pannarioid Parmeliella mariana group; (b) Nostoc associated with collematoid thalli in the Pannariaceae are related to that of the Collemataceae (which contains only collematoid thalli), and never associated with pannarioid thalli; Nostoc associated with pannarioid thalli also associate in other families with similar morphology; (c) ancestors of several lineages in the Pannariaceae developed tripartite thalli, bipartite thalli probably resulting from cephalodia emancipation from tripartite thalli which eventually evolved and diverged, as suggested by the same Nostoc present in the collematoid genus Physma and in the cephalodia of a closely related tripartite species; Photobiont switches and cephalodia emancipation followed by divergence are thus suspected to act as evolutionary drivers in the family Pannariaceae.

Convergent evolution of a symbiotic duet: the case of the lichen genus Polychidium (Peltigerales, Ascomycota)

PREMISE OF THE STUDY

Thallus architecture has long been a powerful guide for classifying lichens and has often trumped photobiont association and ascomatal type, but the reliability of these characters to predict phylogenetic affinity has seldom been tested. The cyanolichen genus Polychidium unites species that have strikingly similar gross morphology but consort with different photobiont genera. If Polychidium were found to be monophyletic, photobiont switching among closely related species would be suggested. If, however, species were found to arise in different lineages, a convergent body plan and ascomatal type evolution would be inferred.

METHODS

We tested the monophyly of Polychidium with a multilocus phylogeny based on nuclear and mitochondrial sequence data from all known Peltigeralean families and reconstructed ancestral states for specific thallus architecture and ascomatal ontogeny types relative to Polychidium and other clades.

KEY RESULTS

We found that Polychidium consists of two species groups that arose independently in different suborders within the Peltigerales, associated with Nostoc and Scytonema photobionts, respectively. We infer from ancestral character state reconstruction that dendroid thallus architecture evolved independently in these two lineages.

CONCLUSIONS

The independent development of similar dendroid thallus architecture in different fungal suborders with different photobionts represents a clear and previously overlooked example of convergent evolution in lichens. Our results also suggest a pattern of character state conservation, loss, and reversion in ascomatal ontogeny types, hitherto considered conserved traits useful for higher level ascomycete systematics.

Molecular phylogenetic studies on the lichenicolous Xanthoriicola physciae reveal Antarctic rock-inhabiting fungi and Piedraia species among closest relatives in the Teratosphaeriaceae

The phylogenetic placement of the monotypic dematiaceous hyphomycete genus Xanthoriicola was investigated. Sequences of the nLSU region were obtained from 11 specimens of X. physciae, which formed a single clade supported both by parsimony (91 %), and maximum likelihood (100 %) bootstraps, and Bayesian Posterior Probabilities (1.0). The closest relatives in the parsimony analysis were species of Piedraria, while in the Bayesian analysis they were those of Friedmanniomyces. These three genera, along with species of Elasticomyces, Recurvomyces, Teratosphaeria, and sequences from unnamed rock-inhabiting fungi (RIF), were all members of the same major clade within Capnodiales with strong support in both analyses, and for which the family name Teratosphaeriaceae can be used pending further studies on additional taxa.

Phylogeny and character evolution in the jelly fungi (Tremellomycetes, Basidiomycota, Fungi)

The Tremellomycetes (Agaricomycotina, Basidiomycota, Fungi) are a nutritionally heterogeneous group comprising saprotrophs, animal parasites, and fungicolous species (fungal-inhabiting, including lichen-inhabiting). The relationships of many species, particularly those with a lichenicolous habit, have never been investigated by molecular methods. We present a phylogeny of the Tremellomycetes based on three nuclear DNA ribosomal markers (nSSU, 5.8S and nLSU), representing all main taxonomic groups and life forms, including lichenicolous taxa. The Cystofilobasidiales, Filobasidiales, Holtermanniales, and Tremellales (including the Trichosporonales) are recovered as monophyletic, but this is not the case for the Tremellomycetes. We suggest, however, that the Cystofilobasidiales tentatively continue to be included in the Tremellomycetes. As currently circumscribed, the Filobasidiaceae, Sirobasidiaceae, Syzygosporaceae and Tremellaceae are non-monophyletic. Cuniculitremaceae, Sirobasidiaceae and Tetragoniomycetaceae are nested within Tremellaceae. The lichenicolous species currently included within the Tremellomycetes belong in this group, distributed across the Filobasidiales and Tremellales. Lichen-inhabiting taxa do not form a monophyletic group; they are distributed in several clades and sometimes intermixed with taxa of other nutritional habits. Character state reconstruction indicates that two morphological traits claimed to characterize groups in the Tremellomycetes (the basidium habit and basidium septation) are highly homoplastic. Comparative phylogenetic methods suggest that the transitions between single and catenulate basidia in the Tremellales are consistent with a punctuational model of evolution whereas basidium septation is likely to have evolved under a graduational model in the clade comprising the Holtermanniales, Filobasidiales, and Tremellales.

Roselliniella revealed as an overlooked genus of Hypocreales, with the description of a second species on parmelioid lichens

Based on newly obtained 28S rDNA sequences from Roselliniella atlantica and R. euparmeliicola sp. nov., the genus Roselliniella has to be placed in Hypocreales and not in Sordariales; however, the family placement could not be resolved from the sequences obtained. The mature ascospores are single-celled and brown, but young ascospores are hyaline and sometimes have a median septum. The new species occurs on a Parmelia s.str. species in China, and differs in 24 nucleotide substitution positions in the nu-LSU rDNA region and ascospore size from R. atlantica. In this case, small variations in ascospore sizes and shape prove to be phylogenetically and taxonomically informative. The two species occur in the same clade with 95 % jack-knife support. Roselliniella atlantica occurs on Xanthoparmelia and Melanohalea species in Europe, whereas R. euparmeliicola was found on the species of Parmelia s.str. DNA was successfully recovered from a dried specimen of R. atlantica collected in 1992. Two unidentified fungi were also recovered from the Chinese specimen, and these belong to Sordariomycetidae and Dothideomycetes; whether these two are additional fungi living endolichenically in the lichen host, saprobes, or contaminants could not be ascertained.