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Mucormycosis is caused by fungi belonging to the order Mucorales. The term “Black Fungus” has been widely applied to human pathogenic Mucorales in India. They mainly infect the sinuses and brain, lungs, stomach and intestines, and skin. While this has been considered a rare disease, thousands of cases have been reported during the second wave of COVID-19 in India, between the months of April and June 2021. Hitherto, more than 45,374 cases and over 4300 deaths have been reported among COVID-19 patients across India from April 2021 to July 21, 2021. Though the mortality rate is estimated to be 50%, it could be above 90% if left untreated. In India, Rhizopus arrhizus has been related to be the most common species to cause human mucormycosis, followed by Apophysomyces variabilis, Rhizopus microsporus, and R. homothallicus. Accurate sample identification of human pathogenic Mucorales species is challenging especially due to the frequent lack of diagnostic morphological features. Traditionally, the culture-based approach has been extensively used to isolate and characterize human pathogenic Mucorales. However, this may not be an appropriate approach to objectively isolate and characterize all species, as the germination and growth of fungal spores are highly dependent on culture media and environmental conditions. Therefore, a robust approach to the accurate and rapid identification of human pathogenic Mucorales species is a prerequisite. The metagenomic approach comprehensively sequences and analyzes all genetic material in a complex biological sample and, consequently, this could be an appropriate approach to objectively characterize human pathogenic Mucorales taxa without the need for in vitro culture. The precise identification of the species will not only be useful for the correct diagnosis of this disease, but also for the development of antifungal drugs specific for each species. Accurate and rapid species identification is desperately needed to save lives in the mucormycosis outbreak among COVID-19 patients in India and neighboring countries.

An understanding of how biotic interactions shape species’ distributions is central to predicting host–symbiont responses under climate change. Switches to locally adapted algae have been proposed to be an adaptive strategy of lichen-forming fungi to cope with environmental change. However, it is unclear how lichen photobionts respond to environmental gradients, and whether they play a role in determining the fungal host’s upper and lower elevational limits. Deep-coverage Illumina DNA metabarcoding was used to track changes in the community composition of Trebouxia algae associated with two phylogenetically closely related, but ecologically divergent fungal hosts along a steep altitudinal gradient in the Mediterranean region. We detected the presence of multiple Trebouxia species in the majority of thalli. Both altitude and host genetic identity were strong predictors of photobiont community assembly in these two species. The predominantly clonally dispersing fungus showed stronger altitudinal structuring of photobiont communities than the sexually reproducing host. Elevation ranges of the host were not limited by the lack of compatible photobionts. Our study sheds light on the processes guiding the formation and distribution of specific fungal–algal combinations in the lichen symbiosis. The effect of environmental filtering acting on both symbiotic partners appears to shape the distribution of lichens.

Both macroclimate and evolutionary events may influence symbiont association and diversity patterns. Here we assess how climatic factors and evolutionary events shape fungal–algal association patterns in the widely distributed lichen-forming fungal genus Protoparmelia. Multilocus phylogenies of fungal and algal partners were generated using 174 specimens. Coalescent-based species delimitation analysis suggested that 23 fungal hosts are associating with 20 algal species. Principal component analysis (PCA) was performed to infer how fungal–algal association patterns varied with climate. Fungi associated with one to three algal partners whereas algae accepted one to five fungal partners. Both fungi and algae were more specific, associating with fewer partners, in the warmer climates. Interaction with more than one partner was more frequent in cooler climates for both the partners. Cophylogenetic analyses suggest congruent fungal–algal phylogenies. Host switch was a more common event in warm climates, whereas failure of the photobiont to diverge with its fungal host was more frequent in cooler climates. We conclude that both environmental factors and evolutionary events drive fungal and algal evolution in Protoparmelia. The processes leading to phylogenetic congruence of fungi and algae are different in different macrohabitats in our study system. Hence, closely related species inhabiting diverse habitats may follow different evolutionary pathways.

Species recognition in lichen-forming fungi has been a challenge because of unsettled species concepts, few taxonomically relevant traits, and limitations of traditionally used morphological and chemical characters for identifying closely related species. Here we analyze species diversity in the cosmopolitan genus Protoparmelia s.l. The ~25 described species in this group occur across diverse habitats from the boreal-arctic/alpine to the tropics, but their relationship to each other remains unexplored. In this study, we inferred the phylogeny of 18 species currently assigned to this genus based on 160 specimens and six markers: mtSSU, nuLSU, ITS, RPB1, MCM7, and TSR1. We assessed the circumscription of species-level lineages in Protoparmelia s. str. using two coalescent-based species delimitation methods--BP&P and spedeSTEM. Our results suggest the presence of a tropical and an extra-tropical lineage, and eleven previously unrecognized distinct species-level lineages in Protoparmelia s. str. Several cryptic lineages were discovered as compared to phenotype-based species delimitation. Many of the putative species are supported by geographic evidence.

Taxonomic identifications in some groups of lichen-forming fungi have been challenge largely due to the scarcity of taxonomically relevant features and limitations of morphological and chemical characters traditionally used to distinguish closely related taxa. Delineating species boundaries in closely related species or species complexes often requires a range of multisource data sets and comprehensive analytical methods. Here we aim to examine species boundaries in a group of saxicolous lichen forming fungi, the Aspiciliella intermutans complex (Megasporaceae), widespread mainly in the Mediterranean. We gathered DNA sequences of the nuclear ribosomal internal transcribed spacer (nuITS), the nuclear large subunit (nuLSU), the mitochondrial small subunit (mtSSU) ribosomal DNA, and the DNA replication licensing factor MCM7 from 80 samples mostly from Iran, Caucasia, Greece and eastern Europe. We used a combination of phylogenetic strategies and a variety of empirical, sequence-based species delimitation approaches to infer species boundaries in this group. The latter included: the automatic barcode gap discovery (ABGD), the multispecies coalescent approach *BEAST and Bayesian Phylogenetics and Phylogeography (BPP) program. Different species delimitation scenarios were compared using Bayes factors species delimitation analysis. Furthermore, morphological, chemical, ecological and geographical features of the sampled specimens were examined. Our study uncovered cryptic species diversity in A. intermutans and showed that morphology-based taxonomy may be unreliable, underestimating species diversity in this group of lichens. We identified a total of six species-level lineages in the A. intermutans complex using inferences from multiple empirical operational criteria. We found little corroboration between morphological and ecological features with our proposed candidate species, while secondary metabolite data do not corroborate tree topology. The present study on the A. intermutans species-complex indicates that the genus Aspiciliella, as currently circumscribed, is more diverse in Eurasia than previously expected.

There is a long-standing debate on the extent of vicariance and long-distance dispersal events to explain the current distribution of organisms, especially in those with small diaspores potentially prone to long-distance dispersal. Age estimates of clades play a crucial role in evaluating the impact of these processes. The aim of this study is to understand the evolutionary history of the largest clade of macrolichens, the parmelioid lichens (Parmeliaceae, Lecanoromycetes, Ascomycota) by dating the origin of the group and its major lineages. They have a worldwide distribution with centers of distribution in the Neo- and Paleotropics, and semi-arid subtropical regions of the Southern Hemisphere. Phylogenetic analyses were performed using DNA sequences of nuLSU and mtSSU rDNA, and the protein-coding RPB1 gene. The three DNA regions had different evolutionary rates: RPB1 gave a rate two to four times higher than nuLSU and mtSSU. Divergence times of the major clades were estimated with partitioned BEAST analyses allowing different rates for each DNA region and using a relaxed clock model. Three calibrations points were used to date the tree: an inferred age at the stem of Lecanoromycetes, and two dated fossils: Parmelia in the parmelioid group, and Alectoria. Palaeoclimatic conditions and the palaeogeological area cladogram were compared to the dated phylogeny of parmelioid. The parmelioid group diversified around the K/T boundary, and the major clades diverged during the Eocene and Oligocene. The radiation of the genera occurred through globally changing climatic condition of the early Oligocene, Miocene and early Pliocene. The estimated divergence times are consistent with long-distance dispersal events being the major factor to explain the biogeographical distribution patterns of Southern Hemisphere parmelioids, especially for Africa-Australia disjunctions, because the sequential break-up of Gondwana started much earlier than the origin of these clades. However, our data cannot reject vicariance to explain South America-Australia disjunctions.

Lichen-forming fungi (LFF) are prolific producers of functionally and structurally diverse secondary metabolites, most of which are taxonomically exclusive and play lineage-specific roles. To date, widely distributed, evolutionarily conserved biosynthetic pathways in LFF are not known. However, this idea stems from polyketide derivatives, since most biochemical research on lichens has concentrated on polyketide synthases (PKSs). Here, we present the first systematic identification and comparison of terpene biosynthetic genes of LFF using all the available Lecanoromycete reference genomes and 22 de novo sequenced ones (111 in total, representing 60 genera and 23 families). We implemented genome mining and gene networking approaches to identify and group the biosynthetic gene clusters (BGCs) into networks of similar BGCs. Our large-scale analysis led to the identification of 724 terpene BGCs with varying degrees of pairwise similarity. Most BGCs in the dataset were unique with no similarity to a previously known fungal or bacterial BGC or among each other. Remarkably, we found two BGCs that were widely distributed in LFF. Interestingly, both conserved BGCs contain the same core gene, i.e., putatively a squalene/phytoene synthase (SQS), involved in sterol biosynthesis. This indicates that early gene duplications, followed by gene losses/gains and gene rearrangement are the major evolutionary factors shaping the composition of these widely distributed SQS BGCs across LFF. We provide an in-depth overview of these BGCs, including the transmembrane, conserved, variable and LFF-specific regions. Our study revealed that lichenized fungi do have a highly conserved BGC, providing the first evidence that a biosynthetic gene may constitute essential genes in lichens.

High levels of cryptic diversity have been documented in lichenized fungi, especially in Parmeliaceae, and integrating various lines of evidence, including coalescent-based species delimitation approaches, help establish more robust species circumscriptions. In this study, we used an integrative taxonomic approach to delimit species in the lichen-forming fungal genus Punctelia (Parmeliaceae), with a particular focus on the cosmopolitan species P. rudecta. Nuclear, mitochondrial ribosomal DNA and protein-coding DNA sequences were analyzed in phylogenetic and coalescence-based frameworks. Additionally, morphological, ecological and geographical features of the sampled specimens were evaluated. Five major strongly supported monophyletic clades were recognized in the genus Punctelia, and each clade could be characterized by distinct patterns in medullary chemistry. Punctelia rudecta as currently circumscribed was shown to be polyphyletic. A variety of empirical species delimitation methods provide evidence for a minimum of four geographically isolated species within the nominal taxon Punctelia rudecta, including a newly described saxicolous species, P. guanchica, and three corticolous species. In order to facilitate reliable sample identification for biodiversity, conservation, and air quality bio-monitoring research, these three species have been epitypified, in addition to the description of a new species.

Although classification at supra-specific ranks is inherently arbitrary, comparable taxonomic ranks within clades can facilitate more consistent classifications and objective comparisons among taxa. Different circumscriptions of the hyper-diverse lichen-forming fungal family Parmeliaceae and widely different generic circumscriptions among authors have been proposed. For this study, we use a recently developed temporal approach that uses time-calibrated chronograms to identify temporal bands for specific ranks in Parmeliaceae and allied groups with the overarching goal of establishing a consistent, stable classification. A data set of 330 species, representing 73 genera in the family and 52 species of related families was used to address the circumscription of Parmeliaceae and its genera following the proposed temporal approach. Based on the results of this study, we propose a revised, temporal-based classification for Parmeliaceae, including all clades that share a common ancestor 102.13–112.88 Ma for families and a time window of 29.45–32.55 Ma for genera. Forty-five of the currently accepted genera in Parmeliaceae were supported in their current circumscription. Two subfamilies are accepted within Parmeliaceae: Protoparmelioideae Divakar et al. subfam. nov., including Protoparmelia and the resurrected genus Maronina, and Parmelioideae, including the bulk of genera in the family. The new genus Austromelanelixia Divakar et al. is proposed to accommodate a clade of southern Hemisphere species previously included in Melanelixia. Eumitria and tentatively Dolichousnea are resurrected as genera separate from Usnea . The following genera are reduced to synonymy: Allocetraria, Cetrariella, Usnocetraria , and Vulpicida with Cetraria; Arctocetraria, Cetreliopsis, Flavocetraria, Kaernefeltia, Masonhalea, Tuckermanella , and Tuckermannopsis with Nephromopsis ; and the lichenicolous genera Nesolechia and Raesaenenia with the lichen-forming genera Punctelia and Protousnea, respectively. A total of 47 new combinations and three new names at the species level are proposed.

The phylogenetic relationship of lecanoroid lichens is studied using two data sets: 1) a 2-locus data set including 251 OTUs representing 150 species, and 2) a 6-locus data set with 82 OTUs representing 53 species. The genus Lecanora as currently circumscribed is shown to be highly polyphyletic and several genera, including Adelolecia, Arctopeltis, Bryonora, Carbonea, Frutidella, Lecidella, Miriquidica, Palicella, Protoparmeliopsis, Pyrrhospora, and Rhizoplaca are nested within Lecanora sensu lato. A core group of Lecanora is supported as monophyletic and includes species of the L. carpinea, L. rupicola, and L. subcarnea groups, and a core group of the L. subfusca group. Three monophyletic clades that are well supported in our analyses and well characterized by phenotypical characters are accepted here: 1) Myriolecis to accommodate the Lecanora dispersa group and Arctopeltis; 2) Protoparmeliopsis for the L. muralis group; and 3) Rhizoplaca is emended to include three placodioid taxa previously classified in Lecanora (L. novomexicana. L. opiniconensis, L. phaedrophthalma), whereas R. aspidophora and R. peltata are excluded from Rhizoplaca. The latter is transferred into Protoparmeliopsis. Lecidella is strongly supported as a monophyletic group. Our studies indicate the presence of additional clades of species currently placed in Lecanora sensu lato that warrant taxonomic recognition but additional data will be necessary before the circumscription of these entities is fully understood. 37 new combinations are proposed into the genera Myriolecis (30), Protoparmeliopsis (2), and Rhizoplaca (5).