The species of Hemigrapha (lichenicolous Ascomycetes, Dothideales) on Peltigerales

The species of Hemigrapha (lichenicolous Ascomycetes, Dothideales) growing on Peltigerales are revised. H. atlantica sp. nov., on the cyanobacterial morph of Sticta canariensis from the Azores and the British Isles, H. nephromatis sp. nov., on Nephroma australe from Tasmania and New Zealand, and H. pseudocyphellariae sp. nov., on Pseudocyphellaria from Papua New Guinea are described and compared with the type species, N. asteriscus, which grows on species of Peltigera in the southern hemisphere and in Europe. Hemigrapha is shown to belong to the Microthyriaceae (Dothideales). Pycnothyrial anamorphs, morphologically identical to the thyriothecia, with hyaline, non-septate microconidia and/or macroconidia, and conidiogenous cells arising from the upper conidiomatal wall, are known in H. asteriscus, H. atlantica and H. pseudocyphellariae. A key is given for the species of Hemigrapha on Peltigerales.