Freshwater fungi, especially the freshwater hyphomycetes, have been observed as early as the 1880s. The tetraradiate, sigmoid and branched conidia were an interesting character that caught the attention of pioneer mycologists. Heliscus lugdunensis was the first described freshwater hyphomycete species (Saccardo 1880), while Flagellospora penicillioides was the first aquatic hyphomycete where the sexual state was known (Ranzoni 1956). An important contribution to aquatic hyphomycete research is that of de Wildeman (1893, 1894, 1895) who described four new fungal species, three with tetraradiate and one with sigmoid conidia, from ponds, ditches and marshy areas on different substrates (algae, willow leaves, aquatic macrophytes Hippuris vulgaris). The first prolific sporulation of freshwater hyphomycete in vitro was by Kegel (1906) for Varicosporium elodeae, wherein the induction of sporulation occurs when overgrown agar blocks were placed in nutrient-poor water. Some authors who worked on freshwater were Grove (1912), Fragoso (1920), Huber-Pestalozzi (1925, 1938), Brutschy (1927) and Lowe (1927). A major breakthrough occurred when Ingold (1942) discovered a typical habitat for freshwater fungi, growing on submerged decaying leaves of broad-leaved trees in well-aerated waters and introduced the taxa Alatospora acuminata, Anguillospora longissima (≡ Amniculicola longissima), Articulospora tetracladia (≡ Hymenoscyphus tetracladius), Clavariopsis aquatica, Flagellospora curvula, Heliscus aquaticus (≡ Nectria lugdunensis), Heliscus longibrachiatus (≡Clavatospora longibrachiata), Lemonniera aquatica, Lunulospora curvula, Margaritispora aquatica, Tetracladium marchalianum, Tetrachaetum elegans, Tetracladium setigerum, Tricladium angulatum, Tricladium splendens, Varicosporium elodeae, almost 50 years after Wildeman observed their conidial morphology. At the time, Ingold was studying chytrids in a stream behind his house, and coincidentally found a large fungal spore collection trapped in scum behind a barrier of twigs (Bärlocher 1992). After a long experimental period, he discovered their structure and detailed 16 species of which ten were novel (Ingold 1942, 1953). Ainsworth (1976) considered this discovery as a “minor mycological industry” as the discovery of Ingold paved the way for an era where reports of the fungal occurrence multiplied. Presently, these hyphomycetes are popularly known as Ingoldian fungi, in honour of C.T. Ingold (Webster & Descals 1981a, b). Ingoldian fungi were previously known as “aquatic hyphomycetes” (de Wildeman 1895, Ingold 1942), freshwater hyphomycetes (Nilsson 1964), and “amphibious hyphomycetes” (Michaelides & Kendrick 1978). In the 1950s, Ingold (Ingold 1951, 1954, 1955) noted that aquatic ascomycetes were abundant in freshwater particularly on stalks of reed swamp plants with many of the ascospores with variously developed appendages (e.g. Ceriospora caudae-suis, Loramyces macrospora). A vast number of comprehensive studies were published after the initial work of Ingold (Ranzoni, 1953, Tubaki 1957, Petersen 1962, 1963a, b, Nilsson 1964, Webster & Descals 1981a, b, Dudka 1985, Goh & Hyde 1996, Chan et al. 2000, Sivichai et al. 2000, 2006, Pinnoi et al. 2006). Since Ingold’s early research, numerous studies, both on sexual and asexual taxa, have been published from all over the world (Tubaki et al. 1983, Hyde 1992, Sridhar et al. 1992, Jones et al. 1999, Hyde & Wong 2000, Tsui et al. 2001b, Tsui & Hyde 2003, Pinruan et al. 2004, Shearer et al. 2004, 2007, 2014, Zhang et al. 2011, Liu et al. 2015). The most recent major publications on freshwater ascomycetes and hyphomycetes are from Shearer et al. (2014), Luo et al. (2019) and Dong et al. (2020), while those on Ingoldian fungi on leaves are by Chan et al. (2000), Selosse et al. (2008), Sudheep & Sridhar (2013), Ghate & Sridhar (2015), Fiuza et al. (2017), Fiuza et al. (2019) and Tarda et al. (2019).