Maria Prieto

Dating the diversification of the major lineages of Ascomycota (Fungi)

Establishing the dates for the origin and main diversification events in the phylogeny of Ascomycota is among the most crucial remaining goals in understanding the evolution of Fungi. There have been several analyses of divergence times in the fungal tree of life in the last two decades, but most have yielded contrasting results for the origin of the major lineages. Moreover, very few studies have provided temporal estimates for a large set of clades within Ascomycota. We performed molecular dating to estimate the divergence times of most of the major groups of Ascomycota. To account for paleontological uncertainty, we included alternative fossil constraints as different scenarios to enable a discussion of the effect of selection of fossils. We used data from 6 molecular markers and 121 extant taxa within Ascomycota. Our various ‘relaxed clock’ scenarios suggest that the origin and diversification of the Pezizomycotina occurred in the Cambrian. The main lineages of lichen–forming Ascomycota originated at least as early as the Carboniferous, with successive radiations in the Jurassic and Cretaceous generating the diversity of the main modern groups. Our study provides new information about the timing of the main diversification events in Ascomycota, including estimates for classes, orders and families of both lichenized and non–lichenized Ascomycota, many of which had not been previously dated.

Mazaedium evolution in the Ascomycota (Fungi) and the classification of mazaediate groups of formerly unclear relationship

Calicioid or mazaediate fungi constitute a heterogeneous assemblage of fungi sharing the presence of a mazaedium. These fungi were once treated as an order (Caliciales) of the Ascomycota but many are now known to be nested within the Arthoniomycetes, Eurotiomycetes, Lecanoromycetes and Leotiomycetes. In this study we employ multigene phylogenetic analyses of main mazaediate groups (based on nuclear 18S, 28S, 5.8S rDNA, mitochondrial 16S, and the protein coding RPB1 and Mcm7) of 116 taxa corresponding to most major groups of the inoperculate ascomycetes (“Leotiomyceta”) and a selection of Pezizomycetes, to trace the evolution of the mazaedium in the Pezizomycotina (the “Euascomycetes”). In particular, we studied the placement of three calicioid groups of uncertain position, Calycidiaceae, Coniocybaceae and Microcaliciaceae. Here, we show that the Calycidiaceae is closely related to the Sphaerophoraceae in the Lecanoromycetidae (Lecanoromycetes), as supported by overall morphology and the production of sphaerophorin. The Coniocybaceae constitute an early divergent line in the inoperculate ascomycetes and here we propose to recognize this group formally as the new class and order Coniocybomycetes, Coniocybales. The Microcaliciaceae is nested within the Ostropomycetidae (Lecanoromycetes). Both Coniocybaceae and Microcaliciaceae, although highly distinctive, lack morphological similarities to related main fungal groups. Ancestral state reconstruction suggests that the ancestor of all inoperculate ascomycetes and the ancestor of all main inoperculate ascomycete groups, with the exception of the Coniocybomycetes, was non‐mazediate, and thus confirms the large amount of parallel evolution and independent gains of the mazaedium in the history of the Ascomycota.

Multiple-scale environmental modulation of lichen reproduction

It is necessary to understand how environmental changes affect plant fitness to predict survival of a species, but this knowledge is scarce for lichens and complicated by their formation of sexual and asexual reproductive structures. Are the presence and number of reproductive structures in Lobaria pulmonaria, a threatened lichen, dependent on thallus size, and is their formation sequential? Does any size-dependence and sequential formation vary along a climate gradient? Generalized linear mixed models were used to explore the effect of environmental predictors on the size and presence/abundance of each reproductive structure and to determine the probability of a given-sized thallus to develop any reproductive structure. The largest individuals are more likely to develop reproductive structures, and the lichen uses a mixed strategy of early asexual reproduction and late sexual. Macro and microclimatic variables also influenced reproductive capacity. Relationships among climate conditions and lichen size and reproductive capacity can compromise the future viability of the species in the most southern populations of Europe.

Molecular phylogeny of Heteroplacidium, Placidium, and related catapyrenioid genera (Verrucariaceae, lichen-forming Ascomycota)

PREMISE OF THE STUDY Verrucariaceae is a fascinating lineage of lichenized fungi for which generic and species delimitation is problematic due to the scarcity of discriminating morphological characters. Members of this family inhabit rocks, but they further colonize soils, barks, mosses, and other lichens. Our aim is to contribute to the DNA-based inference of the Verrucariaceae tree of life and to investigate characters that could be useful for proposing a more natural classification. We focused on catapyrenioid genera, which are often part of biological soil crusts, a cryptogam-dominated ecosystem contributing to soil formation and stabilization in arid environments. Understanding their evolution and taxonomy is essential to assess their roles in these fragile and important ecosystems. METHODS A multigene phylogeny of Verrucariaceae including catapyrenioid genera is presented. We further examined the phylogenetic relationships among members of Heteroplacidium and Placidium. The evolution of selected characters was inferred using the latter phylogeny. KEY RESULTS Anthracocarpon and Involucropyrenium were closely related to Endocarpon. Placidium comprised two monophyletic clades sister to Heteroplacidium. Inferred ancestral states of diagnostic characters revealed that the type of medulla and the pycnidia location were homoplasious within the Placidium clade. In contrast, the presence of rhizines was a synapomorphy for Clavascidium. CONCLUSIONS Our results provide new information on the usefulness of characters for delineating groups in Verrucariaceae. Taxonomic changes are proposed to reflect more natural groupings: Heteroplacidium podolepis is transferred to Placidium, and Clavascidium is recognized as a different genus. Eight new combinations are proposed for Clavascidium.

Phylogenetic study of Catapyrenium s. str. (Verrucariaceae, lichen-forming Ascomycota) and related genus Placidiopsis

The current classification of what used to be called Catapyrenium comprises eight genera belonging to distinct lineages in the Verrucariaceae. Previous phylogenetic studies have shown that the redefined genus Catapyrenium (Catapyrenium s. str.) is monophyletic and sister of Placidiopsis within the Staurothele group, but this relationship was based on only two species from each genus. We conducted a phylogenetic study of Catapyrenium and Placidiopsis as currently delimited to evaluate the monophyly of each genus and infer infrageneric relationships. An initial family level phylogenetic analysis based on the nuLSU locus and implementing a backbone constraint tree (with both weighted maximum parsimony and bootstrap maximum likelihood approaches) was performed to infer phylogenetic placements of Catapyrenium and Placidiopsis taxa not included in previous molecular systematic studies. The results of this analysis were used to define the ingroup for a second phylogenetic analysis based on nuITS and nuLSU and centered on Catapyrenium s. str. and Placidiopsis. Placidiopsis was found to be monophyletic, whereas Catapyrenium s. str. was not. Catapyrenium dactylinum was found to be closely related to Placopyrenium caeruleopulvinum and Placopyrenium stanfordii, all of which were closely related to Placocarpus schaereri and Verrucula. In addition we found genus Placopyrenium to be polyphyletic. The resulting trees confirmed that Catapyrenium s. str. (excluding C. dactylinum) and Placidiopsis constitute two sister monophyletic entities. The data do not support Placidiopsis cinerascens and P. tenella as two distinct species because no characters can be used to distinguish them. Thus P. tenella is here reduced to synonymy with P. cinerascens.

The genus Placidiopsis in the Iberian Peninsula and the Balearic Islands

A taxonomic revision of the genus Placidiopsis in the Iberian Peninsula and the Balearic Islands is provided. A total of 500 specimens were studied. A detailed description of the morphology, anatomy, ecology, and distributional rank is presented for each species. Additionally, a key to Placidiopsis species is included. The genus is represented by four species in the studied region, with P. cavicola and P. cinereoides known only from the type localities and P. cinerascens and P. custnani common in the eastern half of the region. These data expand considerably the ecological and distributional range of these species in the Iberian Peninsula.

Epiphloea belongs to Collemataceae (Lecanoromycetes, lichenized Ascomycota)

The cyanolichen genus Epiphloea is currently included within the Heppiaceae (Lichinomycetes) based on ascus characteristics. The presumed presence of a prototunicate ascus has been used as support for this classification, despite the incongruence with other characters (e.g. spores). Here, we use a molecular phylogeny of the two markers mtSSU rDNA and Mcm7 to investigate the position of Epiphloea . In addition, we have re-investigated the ascus characteristics. Our results place the two species, Epiphloea byssina and E. terrena, within the Collemataceae , nested in Leptogium s. str. The ascus type in both species is shown to be Lecanoralean and similar to the ascus in other Collemataceae , with a strongly amyloid tube-like structure. This observation supports the placement within Lecanoromycetes and refutes the earlier suggested affinities with Heppiaceae and Lichinomycetes. The correct names for these species are Leptogium byssinum and Leptogium terrenum .

A New Species of Anthracocarpon (Verrucariaceae) from Argentina

Abstract Anthracocarpon andinum, a new terricolous species, is described from northern Argentina. The most important differences from A. virescens (Zahlbr.) Breuss are in thallus morphology and size and shape of the ascospores. Anthracocarpon andinum develops a squamulose thallus covered by a sulcate epinecral layer. The squamules of A. virescens are smaller, thinner and covered by a thin and continuous epinecral layer. In addition, A. andinum has paler rhizines than A. virescens. Thallus thickness, spore width and length/width ratio of ascospores are significantly different for the two species.

New Records of Lichinomycetes in Sweden and the Nordic Countries

Abstract: Prieto, M., Westberg, M. & Schultz, M. 2015. New records of Lichinomycetes in Sweden and the Nordic countries. — Herzogia 28: 142–152. Six species of Lichinomycetes are newly reported for Sweden, of which three are also new for the Nordic countries. Lichinella stipatula is the first species of the mainly Mediterranean genus Lichinella s.str. found in the Nordic countries. The new records increase the number of Psorotichia species in Sweden and the Nordic countries to three (previously only one), Lichinella to two (considering Thallinocarpon nigritellum as belonging to Lichinella s.l.), and Anema species in Sweden to two (A. tumidulum and A. nummularium). The genus Metamelanea is recorded for the first time in Sweden with two species (M. caesiella and M. umbonata). Four of the six species were collected on the Baltic islands of Gotland or Öland in Sweden, growing on calcareous rocks in alvar habitats.

Records of terricolous lichens from páramos of southern Ecuador

Ecological studies of five paramos in Azuay and Loja provinces recorded one lichen species new to South America (Bryoria nitidula), five new to Ecuador (Cladonia halei, C. melanopoda, C. merochlorophaea, C. subreticulata, Diploschistes diacapsis), two new to mainland Ecuador (Cladonia grayi, C. pyxidata), and 20 new provincial records. Brief morphological descriptions, with remarks on distribution and ecology, are provided.