Abstract
During the study of lignicolous freshwater fungi from Thailand, three pleurotheciaceous species were collected from freshwater habitats in Thailand. Two were identified as Pleurothecium aquaticum and Rhexoacrodictys fimicola, and the third is a new species Dematipyriforma muriformis sp. nov.. Rhexoacrodictys is accepted in Pleurotheciaceae based on phylogenetic analysis. Rhexoacrodictys nigrospora is transferred to Dematipyriforma based on phylogenetic analysis and morphological characters. Pleurothecium aquaticum and Rhexoacrodictys fimicola are reported from Thailand for the first time.