During a survey for fungal pathogens associated with ferns in Brazil, a tar spot-causing fungus was found on fronds of Pleopeltis astrolepis. This was recognised as belonging to Inocyclus (Parmulariaceae). After comparison with other species in the genus, it was concluded that the fungus on P. astrolepis is a new species, described here as Inocyclus angularis sp. nov.
Keywords: Ascomycota; Brazil; Neotropics; tropical ferns.