Evolution of freshwater Diaporthomycetidae (Sordariomycetes) provides evidence for five new orders and six new families

Abstract

Cancellidium is a remarkable fungal genus which has been collected from wood submerged in freshwater and has unique conidia that are important in dispersal in running streams. With such a remarkable morphology, one would have expected it to be a distinct family or order. However, due to the dearth of molecular evidence in related taxa, this genus has previously been placed in the order Hypocreales, subclass Hypocreomycetidae of Sordariomycetes. In this study, we made three new collections of this remarkable aquatic genus from streams in China and Thailand, isolated them into culture, extracted DNA and carried out multigene phylogenetic analysis and divergence time estimation which placed the genus in Diaporthomycetidae. This is one of the seven subclasses of Sordariomycetes and contains 30 lineages that are only known from freshwater. The subclass is therefore of interest when considering the evolution of freshwater fungi. Several lineages of Diaporthomycetidae are morphologically unique and taxa cluster with strong support, but have weak support at the base of the trees. The phylogenetic and MCC trees generated in this study indicate that Aquapteridospora, Barbatosphaeriaceae, Bullimyces, Cancellidium, Ceratolenta, Conlarium, Phialemoniopsis, Pseudostanjehughesia and Rhamphoriaceae are distinct genera/families that evolved in the family/order time frame. The new orders Barbatosphaeriales (177 MYA), Cancellidiales (137 MYA), Ceratolentales (147 MYA), Conlariales (138 MYA) and Rhamphoriales (133 MYA) and six new families, Aquapteridosporaceae (110 MYA), Cancellidiaceae (137 MYA), Ceratolentaceae (81 MYA), Bullimycetaceae (81 MYA), Phialemoniopsaceae (59 MYA), and Pseudostanjehughesiaceae (111 MYA) are introduced with evidence from phylogenies, divergence estimates and distinct morphologies. Of these families, Aquapteridosporaceae, Cancellidiaceae, Bullimycetaceae, and Pseudostanjehughesiaceae are only known from freshwater.