The taxonomy of foliicolous representatives of the Porina epiphylla group is revised. As a result of our studies of world-wide material, a more subtle species concept within the Porina epiphylla aggregate, i.e. species with 7-septate ascospores, is given. Thallus structure, perithecial morphology and development, and ascospore shape and size proved to be most valuable for species delimitation. A key to all known foliicolous species of the Porina epiphylla group, including facultatively foliicolous taxa, is presented. Eight species and one variety are described as new to science: Porina andreana, P. atropunctata, P. guianensis, P. mazosioides, P. minutissima, P. mirabilis, P. subepiphylla, P. subnucula, and P. lucida var. australiensis. The combination Porina foliicola (Bas.: Clathroporina foliicola) is formally proposed. P. radiata is introduced as a new name for the illegitimate younger homonym P. rugosa. Porina atriceps is reinstated as an autonomous species, and P. multiseptata is reduced to synonymy with P. virescens. P. distans is a sterile taxon, which most probably belongs to one of the several species in the genus producing cylindrical isidia, but cannot be identified at present. Notes on the distribution and ecology of the species are given, and the systematics and evolution of the group is outlined.