Abstract
Ingoldian fungi, or aquatic hyphomycetes, are asexual microfungi, mostly ascomycetes, commonly occurring in running freshwater. They grow on dead plant material, such as leaves and twigs, and play a major role in nutrient flows in stream ecosystems (Bärlocher, 1992). They were discovered and first extensively studied by Ingold (1942) and were thus named "Ingoldian" fungi. Ingold described their abundant multicellular asexual spores of sigmoid or, more typically, tetraradiate shape (Fig. 1). He recognized that they probably arose from multiple convergent evolutions, by secondary adaptation to aquatic life, as recently confirmed by molecular markers (Belliveau & Bärlocher, 2005; Baschien et al., 2006). Because of their apparent lack of sexuality, Ingoldian species were placed in asexual genera, such as Tricladium or Tetracladium, based on conidial morphology and/or mode of conidiogenesis. Unexpectedly, several lines of evidence now suggest that some Ingoldian fungi are also plant endophytes, that is, they grow in plants without producing symptoms.[...]