We studied the foliicolous mycobiota associated with Coussapoa floccosa. This is a tree belonging to the Cecropiaceae, endemic to the Brazilian tropical seasonal semideciduous montane forest. It is listed as an endangered species because of habitat destruction. Until now no fungus has been recorded in association with this plant species. This paper describes six foliicolous fungi associated with this plant that were collected during a survey of the mycobiota occurring in a locality where a small population of C. floccosa was discovered. All fungi described here are new to science, namely Dennisiella coussapoae, Mycosphaerella coussapoae, Pseudoallosoma nervisequens (which also represents a newly proposed genus), Pseudocercospora coussapoae, Pseudocercospora atrofuliginosa and Tripospermum acrobaticum. The high proportion of taxonomic novelties revealed in this study reflects the general lack of mycological information for forest ecosystems in Brazil and also indicates that vulnerable plant species such as C. floccosa may harbor unique mycobiota. Such mycobiota may depend on their nearly extinct hosts and consequently can be equally endangered with extinction and therefore also deserve consideration for in situ and ex situ conservation.