Rhizocarpon hochstetteri s. str. is shown to be an upland/montane species with relatively large ascospores. The name Rhizocarpon infernulum is resurrected for the species with smaller ascospores previously included within R. hochstetteri, but which is probably more closely related to R. cinereovirens. Lectotypes are chosen for a number of taxa, including R. cinereovirens and R. infernulum, and descriptions provided for two new taxa with small hyaline, 1–septate ascospores: R. caesium, which occurs on damp, mildly basic rocks in oceanic areas, and R. infernulum f. sylvaticum occurring on siliceous rocks in damp deciduous woodlands. All these taxa are known also from North America. Rhizocarpon discoense is shown to be a distinct species, not a synonym of R. cinereovirens. The different ascospore dimensions reported for R. hochstetteri by British and European authors are shown to be due to confusion between R. hochstetteri and R. polycarpum. A number of morphological characters are evaluated regarding their relevance to species separation in Rhizocarpon and the name Macrocarpa-green is proposed for the olivaceous pigment present in most species of Rhizocarpon and Porpidia. A key is provided for the species of Rhizocarpon with hyaline, 1– septate ascospores.

The genus Lethariicola is shown to be a synonym of Odontotrema. Fifteen lichenicolous species are recognized: O. bryoriae sp. nov. (on Bryoria), O. cuculare comb. nov. (on Parmeliopsis hyperopta), O. figulinum comb. nov. (on Lecanora polytropa) O. intermedium sp. nov. (on Thamnolia), O. lecanorae sp. nov. (on Lecanora), O. melaneliae sp. nov. (on Melanelia), O. ochrolechiae sp. nov. (on Ochrolechia), O. pertusariae sp. nov. (on Pertusaria hymenea), O. rhizocarpicola sp. nov. (on Rhizocarpon) O. santessonii sp. nov. (on Thamnolia), O. sipei comb. nov. (on Letharia), O. thamnoliae sp. nov. (on Thamnolia), and three undescribed species on Lecanora, Mycoblastus and Usnea. The type of O. cuculare has two distinct lichenicolous species of Odontotrema, and the name is lectotypified on the species growing on Parmeliopsis. A key is given to all lichenicolous species of Odontotrema and Paralethariicola.

Menegazzia neotropica sp. nov. is described from upper montane forest remnants and paramos in Ecuador, Colombia and Venezuela. It is characterized by short-pedicellate apothecia with ridged margins that partly obscure the discs, and by narrow, glossy lobes with brown-black margins. Menegazzia dissecta is recorded from South America for the first time and M. terebrata is recorded from Colombia and Ecuador for the first time.

ITS rDNA sequence data shows that Diploicia and Diplotomma species form a monophyletic clade distinct from other Buellia species. This indicates that Diplotomma merits acceptance as a genus, and suggests that Diploicia should be treated as a synonym of Diplotomma, the earlier name. The data also shows Diploicia subcanescens, considered the fertile counterpart in a species pair with D. canescens, is nested within D. canescens and should be treated as a synonym despite reported chemical differences. In addition, the molecular data support the distinctness of Diplotomma rivas-martinezii, a species restricted to gypsum rocks in Spain, from the widespread D. venustum, which grows on calcareous rocks. Aposymbiotic cultures suggest that D. rivas-martinezii also differs from D. venustum in its germination and isolation success rates. One new combination is made: Diplotomnta pulverulenta (Anzi) D. Hawksw. (syn. Abrothallus pulverulentus Anzi) for the lichenicolous species previously known as Buellia pulverulenta.

Four anthraquinones were isolated from the foliose lichen, Lasallia papulosa (Ach.) Llano. Two of the anthraquinones are known compounds, previously isolated from Lasallia papulosa, while the other two were reported previously as secondary metabolites from laboratory-cultured Nephroma laevigatum, and are isolated here for the first time from lichens in their natural habitat. All compounds were characterized by UV spectrophotometry, mass spectrometry, 1H NMR and 13C NMR. The products were identified as 7-chloroemodin, valsarin (7-chloro-5-hydroxyemodin), 5-chloro-1-O-methylemodin and 5-chloro-1-O-methyl-ω-hydroxyemodin.