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Three new species are described in the small genus Stirtonia, all from NE Brazil, and all from one reserve of Caatinga forest in Paraíba. Stirtonia microsporais characterized by the small macrocephalic ascospores, S. nitidaby the smooth thallus even covering the ascigerous areas and S. niveaby the pruinose, elongated ascigerous areas. This is an unexpected diversity of this mostly palaeotropical genus in the neotropics. A revised worldwide key to the known species is presented.

A refined species concept is applied in the tropical corticolous lichen genus Polymeridium(Trypetheliaceae). While up to now many species were considered to be variable in phenotypical characters, such as hamathecium inspersion and/or presence of lichexanthone, these characters are here accepted as species-specific characters. This classification is in line with the taxonomy in other groups of lichenized fungi. The monotypic genus Exiliseptumis included here in Polymeridium, as it differs in only one character from several species of Polymeridiumand has no unique characters. The number of accepted species is thus raised from 27 to 53, including 13 new species, viz.: Polymeridium albidoreagens, P. albidovarians, P. alboflavescens, P. catapastoides, P. costaricense, P. inspersum, P. multiforme, P. multiseptatum, P. neuwirthii, P. pyrenastroides, P. submuriforme, P. tribulationis, and P. xanthoreagens.The following new combinations are proposed: Polymeridium albopruinosum, P. amylosporum, P. bengoanum, P. brachysporum, P. jordanii, P. microsporum, P. ocellatum, P. refertum, P. siamense, P. stramineoatrum, P. subvirescens, and P. suffusum. An identification key is provided to all accepted species.

The new species Coenogonium chloroticumis described from a tree that also supports another Coenogoniumspecies that was not known from Brazil before, viz. C. siquirrensef. denticulatum. This new species was collected during an ecological study about the corticolous microlichens in high altitude rainforest enclaves in the middle of Caatinga vegetation, known as Brejo de Altitudes, in Paraiba State, NE Brazil.