Taxonomy, phylogeny and evolution of freshwater Hypocreomycetidae (Sordariomycetes)

Abstract

AbstractHypocreomycetidaeis a highly diverse group with species from various habitats. This subclass has been reported as pathogenic, endophytic, parasitic, saprobic, fungicolous, lichenicolous, algicolous, coprophilous and insect fungi from aquatic and terrestrial habitats. In this study, we focused on freshwater fungi ofHypocreomycetidaewhich resulted 41 fresh collections from China and Thailand. Based on morphological and phylogenetic analyses, we identified 26 species that belong to two orders (HypocrealesandMicroascales) and six families (Bionectriaceae,Halosphaeriaceae,Microascaceae,Nectriaceae,SarocladiaceaeandStachybotryaceae). Ten new species are introduced and 13 new habitats and geographic records are reported.Mariannaea superimposita, Stachybotrys chartarumandS. chlorohalonatusare recollected from freshwater habitats in China. Based on phylogenetic analysis of combined LSU, ITS, SSU,rpb2 andtef1-α sequences data,Emericellopsisis transferred toHypocrealesgeneraincertae sedis;Pseudoacremoniumis transferred toBionectriaceae;Sedecimiellais placed inNectriaceae;NautosphaeriaandTubakiellaare excluded fromHalosphaeriaceaeand placed inMicroascalesgeneraincertae sedis; andFaurelinais excluded fromHypocreomycetidae.Varicosporellais placed underAtractiumas a synonym ofAtractium. In addition, phylogenetic analysis and divergence time estimates showed thatAscocodina,Campylospora,CornuvesicaandXenodactylariaceaeform distinct lineages inHypocreomycetidaeand they evolved in the family/order time frame. Hence, a new order (Xenodactylariales) and three new families (Ascocodinaceae,CampylosporaceaeandCornuvesicaceae) are introduced based on phylogenetic analysis, divergence time estimations and morphological characters. Ancestral character state analysis is performed for different habitats ofHypocreomycetidaeincluding freshwater, marine and terrestrial taxa. The result indicates that marine and freshwater fungi evolved independently from terrestrial ancestors. The results further support those early diverging clades of this subclass, mostly comprising terrestrial taxa and freshwater and marine taxa have been secondarily derived, while the crown clade (Nectriaceae) is represented in all three habitats. The evolution of various morphological adaptations towards their habitual changes are also discussed.