During a survey of freshwater fungi in China and Thailand, seven fresh collections representing four species in Chaetosphaeriaceae are described and illustrated based on morphological characters and phylogenetic analyses of combined LSU and ITS sequence data. Cryptophiale udagawae, Cryptophialoidea fasciculata and Nawawia filiformis were re-collected and are reported with the first sequence data. Two collections of Phialosporostilbe from China and Thailand are identified and introduced as a new species named P. scutiformis with the first sequence data for the genus. A new genus Neonawawia is introduced to accommodate Ne. malaysiana. New combinations are proposed for the genera Neonawawia and Phialosporostilbe. Descriptions and illustrations of the new taxa and identified species are provided. Reference specimens of Cryptophiale udagawae, Cryptophialoidea fasciculata and Nawawia filiformis are designated in this study. Phylogenetic placements of the genera Cryptophiale, Cryptophialoidea, Nawawia, Neonawawia and Phialosporostilbe are discussed.