Lichinodium is a new lichenized lineage in the Leotiomycetes

Abstract

Here, we show that Lichinodium (Lichinaceae, Lichinomycetes, Ascomycota) constitutes a formerly unrecognized lineage within the Leotiomycetes, thus being the first lichenized lineage recognized in the superclass Sordariomyceta (Leotiomycetes, Laboulbeniomycetes and Sordariomycetes). To infer the position of Lichinodium, we constructed two multilocus phylogenies based on six and five gene regions (nuLSU rDNA, nuSSU rDNA, mtSSU rDNA, RPB1, RPB2 and MCM7) including main Pezizomycotina groups in the first analysis and focusing secondly on a comprehensive selection of Sordariomyceta. The results show that Lichinodium is sister to Leotiaceae. We discuss the morphological and ecological similarities between Lichinodium and other Leotiomycetes, and describe the new order Lichinodiales and family Lichinodiaceae. The sister relationship between Sordariomycetes and Laboulbeniomycetes is here supported as it is the relationship between this clade and the Leotiomycetes. The results also support the polyphyly of Helotiales, the recognition of the Leotiales in a strict sense or the inclusion of the Triblidiales in Leotiomycetes. The photobionts of Lichinodium were sequenced for two genetic markers (rbcLX and 16S rDNA) and identified as Rhizonema, a recently described genus of filamentous cyanobacteria belonging to Nostocaceae. TEM studies revealed that the mycobiont-cyanobiont interface in Lichinodium does not produce haustoria, thus differing from a typical Lichinomycete (e.g. Ephebe).

Placement of Triblidiaceae in Rhytismatales and comments on unique ascospore morphologies in Leotiomycetes (Fungi, Ascomycota)

“…Based upon the results of their analysis, they placed Triblidiaceae within Rhytismatales. The results reported by Prieto et al (2018) and Johnston et al (2019) support the inclusion of Pseudographis within Rhytismatales. However, conclusions regarding the placement of Triblidiaceae within Rhytismatales are speculative.…”

“…Two molecular phylogenetic studies of Leotiomycetes have included isolates of Pseudographis elatina. These are Prieto et al (2018) and Johnston et al (2019). In their fivegene phylogeny, Prieto et al (2018) used two genes derived from a P. elatina genome, but did not provide an accession number identifying the source of this data.…”

“…These are Prieto et al (2018) and Johnston et al (2019). In their fivegene phylogeny, Prieto et al (2018) used two genes derived from a P. elatina genome, but did not provide an accession number identifying the source of this data. Their phylogeny demonstrated that this P. elatina isolate grouped with three other species of Rhytismatales in a well-supported clade and they claimed that their results "confirmed" inclusion of Triblidiales within Leotiomycetes.…”

Three new species and a new combination of Triblidium

“…In brief, Magnes (1997) placed Triblidiaceae in Rhytismatales and treated Triblidiales as a synonym of Rhytismatales. Recent five-locus (Prieto et al 2019) and 15-locus (Johnston et al 2019) phylogeny analyses found high support for Pseudographis (Triblidiaceae) within Rhytismatales. The results of a three-gene phylogenetic analysis with expanded sampling by Karakehian et al (2019) supported Magnes classification and the authors emended Triblidiaceae to include Triblidium and Huangshania .…”

Phylogenetic Advances in Leotiomycetes, an Understudied Clade of Taxonomically and Ecologically Diverse Fungi

“…Other species associated with animals are species of Pseudogymnoascus such as P. destructans (the causal agent of white-nose syndrome in bats) (Gargas et al, 2009) and P. pannorum (a pathogen of humans) (Gianni et al, 2003). There are many so-called lichenicolous taxa (e.g., Epicladonia), which fruit epiphytically on lichens, and the newly described lichen-forming leotiomycete, Lichinodium (Prieto et al, 2019). In addition, one species of Trochila is a potential mycoparasite on rusts (Gómez-Zapata et al, 2021).…”