Freshwater ascomycetes are a group of fungi of great ecological importance because they are involved in decomposition processes and the recycling of organic matter in aquatic ecosystems. The taxonomy of these fungi is complex, with representatives in several orders of the phylum Ascomycota. In the present study, we collected ninety-two samples of plant debris submerged in freshwater in different locations in Spain. The plant specimens were placed in wet chambers and developed several fungi that were later isolated in pure culture. A main phylogenetic tree using the nucleotide sequences of D1-D2 domains of the 28S nrRNA gene (LSU) was built to show the taxonomic placement of all our fungal strains, and, later, individual phylogenies for the different families were built using single or concatenated nucleotide sequences of the most suitable molecular markers. As a result, we found a new species of Amniculicola that produces a coelomycetous asexual state, a new species of Elongatopedicellata that produces an asexual state, a new species of Neovaginatispora that forms both sexual and asexual states in vitro, and the sexual states of two species of Pyrenochaetopsis, none of which have been reported before for these genera. In addition, we describe a new species of Pilidium characterized by the production of copper-colored globose conidiomata, and of Pseudosigmoidea, which produces well-developed conidiophores.
Keywords: Dothideomycete; Leotiomycetes; ascomycetes; freshwater; fungi; taxonomy.