RESUMO
A severe leaf spot, turning to foliage blight, was observed on leaves of Maranta leuconeura growing in a garden in Brazil (state of Rio de Janeiro) in 2015. A dematiaceous hyphomycete bearing a morphology typical of a helminthosporoid fungi was regularly found in association with diseased tissues. The fungus was isolated and pathogenicity was demonstrated through the completion of Koch's postulates. A morphology and molecular analysis led to the conclusion that the fungus belonged to the genus Bipolaris, which is characterized by having fusiform conidia, externally thickened and truncate hila and a bipolar pattern of germination. Additionally, homology of internal transcribed spacer and GAPDH sequences with sequences of other Bipolaris species, confirmed its generic placement. A phylogenetic study also indicated clearly that the fungus on M. leuconeura is phylogenetically distinct from related species of this genus, leading to the proposal of the new species Bipolaris marantae.
RESUMO
During a survey of the mycobiota of selected Brazilian ferns we discovered a new genus of Parmulariaceae causing tar spot-like symptoms on leaves of Thelypteris serrata (Thelypteridaceae). The new genus and species, decribed as Rhagadolobiopsis thelypteridis, differs from morphologically similar species of Rhagadolobium in possessing colorless, aseptate ascospores and a hymenial gel that does not become blue with iodine. In addition this is the first record of a fungus on T. serrata, and the first Parmulariaceae recorded on a member of the Thelypteridaceae. The ontogeny of the ascomata is described and illustrated here for the first time for the Parmulariaceae.