Abstract:
The fern flora of the world (Pteridophyta) has direct evolutionary links with the earliest vascular plants
that appeared in the late Devonian. Knowing the mycobiota associated to this group of plants is critical for a full
understanding of the Fungi. Nevertheless, perhaps because of the minor economic significance of ferns, this niche
remains relatively neglected by mycologists. Cercosporoid fungi represent a large assemblage of fungi belonging to
the Mycosphaerellaceae and Teratosphaeriaceae (Ascomycota) having cercospora-like asexual morphs. They are
well-known pathogens of many important crops, occurring on a wide host range. Here, the results of a taxonomic
study of cercosporoid fungi collected on ferns in Brazil are presented. Specimens were obtained from most Brazilian
regions and collected over a 7-yr period (2009–2015). Forty-three isolates of cercosporoid and mycosphaerellalike
species, collected from 18 host species, representing 201 localities, were studied. This resulted in a total of 21
frond-spotting taxa, which were identified based on morphology, ecology and sequence data of five genomic loci
(actin, calmodulin, ITS, LSU and partial translation elongation factor 1-α). One novel genus (Clypeosphaerella) and
15 novel species (Cercospora samambaiae, Clypeosphaerella sticheri, Neoceratosperma alsophilae, N. cyatheae,
Paramycosphaerella blechni, Pa. cyatheae, Pa. dicranopteridis-flexuosae, Pa. sticheri, Phaeophleospora pteridivora,
Pseudocercospora brackenicola, Ps. paranaensis, Ps. serpocaulonicola, Ps. trichogena, Xenomycosphaerella
diplazii and Zasmidium cyatheae) are introduced. Furthermore, 11 new combinations (Clypeosphaerella quasiparkii,
Neoceratosperma yunnanensis, Paramycosphaerella aerohyalinosporum, Pa. dicranopteridis, Pa. gleicheniae, Pa. irregularis,
Pa. madeirensis, Pa. nabiacense, Pa. parkii, Pa. pseudomarksii and Pa. vietnamensis) are proposed.
Finally, nine new host associations are recorded for the following known fungal species: Cercospora coniogrammes,
Cercospora sp. Q, Ps. abacopteridicola, Ps. lygodiicola and Ps. thelypteridis.
