Host specificity in the fungal plant parasite (, ) reveals three new species and indicates a potential split in the host plant .

The smut fungal genus contains more than 100 species that parasitize hosts predominantly in the sedge genus . species are mainly found in the boreal zones of the Northern Hemisphere and many species have an arctic-alpine distribution. Recent re-organization of the taxonomy of the main host genus questions current understanding of host associations in . Host specificity for many of the species in this genus is considered to be quite broad and a host spectrum of over 10 host species is common. One aim of the study is to understand the potential influence that host taxonomy has on the evolutionary patterns of . Additionally, by including more specimens, we clarify host specificity and species delimitation in , a prevalent species occurring on different host species in different subgroups using molecular data. Host colonization patterns within are complex, and different subclades of have been colonized several times independently, whereas clades of related species often occur on species from the same host clade. Parasites previously thought to be occurring on the different host are shown to be at least four distinct species that are restricted to individual host species. Three new species, on from the Alps and the Carpathians on from the Alps and on from mountains in the Balkan Peninsula, are described and illustrated. An emended description of is also provided. in its emended circumscription consists of two clades that correspond to respective clades within . The study shows that host colonization in is more complex than current host taxonomy suggests. Further, including several specimens per host species results in a much higher diversity within than previously assumed. Kemler M, Denchev TT, Feige A, Denchev CM, Begerow D (2024). Host specificity in the fungal plant parasite () reveals three new species and indicates a potential split in the host plant . : 91-110. doi: 10.3114/fuse.2024.13.04.