Fungi are ubiquitous and indispensable components of nearly all ecosystems on earth, including freshwater environments. A survey of fungal diversity in freshwater environments of Korea led to the identification of four unrecorded Pezizomycotina (Ascomycota) species in 2016 and 2017, based on morphology and molecular phylogeny; these included Cladorrhinum australe, Curvularia muehlenbeckiae, Curvularia pseudobrachyspora (Dothideomycetes), and Diaporthe longicolla (Sordariomycetes).