Miracula einbuarlaekurica sp. nov., a new holocarpic endoparasitoid species from pennate freshwater diatoms in Iceland.

Holocarpic oomycetes infecting freshwater diatoms are obligate endobiotic parasites reported from a wide range of habitats. So far, the taxonomy of and phylogeny of most species remains unresolved, since most have not been reported throughout the past decades and sequence data are available for only the four species, , and the recently-discovered species . In the current study, a new freshwater diatom parasite resembling in the sense of Scherffel was discovered from pennate diatoms () collected from the small stream Einbúalækur on Víkurskarð, North Iceland and investigated for its life cycle and phylogenetic placement. In contrast to the original description, Scherffel reports an achlya-like spore discharge for . The phylogenetic reconstruction and morphological characterisation in this study revealed that Scherffel's is largely unrelated to the epitype of the species and is a member of the early-diverging genus . Consequently, the new species is described as in the present study. This adds a second freshwater member to the genus, demonstrating the high ecological adaptability of the genus, which thrives in both freshwater and marine ecosystems.