Two new species of Lichenothelia, both from Iran, are described. Lichenothelia iranica is characterized by a black thallus with often finely lobate, slightly effigurate, not areolate margins, eight non-amyloid spores per ascus and 1–3-septate ascospores with 1–2 longitudinal or oblique septa. Lichenothelia ilamensis is distinguished by a black areolate, fissured, slightly effigurate or rarely lobulate thallus. The areoles are confluent and aggregated in the centre, becoming dispersed towards the margin, and the asci contain (4–)6(–8) non-amyloid, 1-septate spores.

The lichen Pyrenula minutissima is described as new to science from the Hyrcanian forests in northern Iran. In addition, three further, essentially tropical, Pyrenula species are reported for the first time from Iran. An identification key is provided for all eight Pyrenula species now known from Iran.

The new species Megaspora rimisorediata Valadbeigi & A. Nordin is described from Iran, where it mainly grows on tree bark but also on calciferous rocks and mosses. It is characterized by a pale ochraceous to bluish grey, cracked and sorediate thallus, very rarely producing ascomata. It appears to be rather commonly distributed in Iran. Its close affinity with Megaspora verrucosa is illustrated in a graph resulting from a phylogenetic network analysis of nuclear rDNA ITS1-5.8S-ITS2 sequences from specimens representing the different genera of Megasporaceae.

The species of the genus Immersaria in Iran are reviewed. Immersaria iranica is described as a new species in the Lecideaceae, characterized by pycnoconidia opening by stellate, winding cracks and 2′-O-methylsuperphyllinic acid as major secondary metabolite. The characters separating it from other taxa of the Lecideaceae are discussed. Immersaria athroocarpa and I. cupreoatra are new records for Iran. An identification key and a table with diagnostic characters of the species hitherto known from Iran are provided.