A new terncolous Micarea (M. viridiatra sp. nov.) is described from the Cairngorm Mountains. It is similar and apparently closely allied to M. turfosa.

A new species, Everniastrum diffractaicum the only member of the genus containing diffractaic acid, is described. It has much larger ascospores than those of any other member of the genus.

The question of whether or not some Trebouxia species have multinucleate cells is a controversial one. Trebouxia jamesii was re-examined and found to have multinucleate cells in cultures grown on rich, organic media. Possible reasons for this condition are discussed.

We present a robust, five-locus phylogeny of the Megasporaceae and, based on this, propose several taxonomic innovations. The new genus Antidea is erected for Aspicilia brucei, which occupies a position near the base of the phylogeny, and the new species Aspicilia indeterminata and A. suavis are described from Montana. We also show that all North American (and some European) records of Aspilidea myrinii are misidentifications with many representing a second species in the genus, differing from A. myrinii by having elevated apothecia and narrower ascospores and for which we make the new combination Aspilidea subadunans. Finally, we make the new combinations Lobothallia determinata and L. peltastictoides, and report the lichenicolous fungus Sagediopsis aspiciliae (on A. subadunans) as new to North America.

Gyalideopsis cochlerifer Lücking & Sérus. sp. nov. is a new, pantropical, commensalistic species restricted to foliicolous representatives of certain genera in the Gomphillaceae. It produces black spathulate hyphophores and small black apothecia.