The genus Caloplaca is taxonomically difficult. Many species are characterized by a combination of morphological traits, and there are only a few useful microscopic characters. The secondary chemistry is rather uniform and of little taxonomic value, notwithstanding the usually bright pigmentation.

As part of a revision of the genus Acanthothecis s. lat. (Graphidaceae) in Brazil, an updated world key to the known species of the genus is presented. From Brazil, the following ten new species are described: A. latispora, with single-spored asci, large, muriform ascospores, and norstictic and stictic acids; A. megalospora, with single-spored asci, very large, transversely septate ascospores, and norstictic and protocetraric acids; A. multiseptata, with 8-spored asci, medium-sized and narrow, transversely multiseptate ascospores, and lacking secondary substances except terpenoids; A. norstictica, with 1–2-spored asci, large, muriform ascospores, and norstictic acid; A. oryzoides, with 8-spored asci, medium-sized, transversely septate ascospores, and norstictic acid; A. rimosa, with 2-spored asci, small to medium-sized, muriform ascospores, and stictic acid; A. roseola, with 1–2-spored asci, large, muriform ascospores, and norstictic, stictic and subnorstictic acids; A. saxicola, with 8-spored asci, small, 3-septate ascospores, and norstictic acid; A. subfarinosa, with 8-spored asci, small, 6–8-septate ascospores, and norstictic acid; and A. submuriformis, with 8-spored asci, small, submuriform ascospores, and lichexanthone. In addition, three further species are formally validated, namely A. bicellulata, A. farinosa and A. subabaphoides, and the new combination A. bicellularis is proposed, based on Acanthotrema bicellularis.

Felihanera viridisorediata Aptroot, Brand & Spier, a corticolous sorediate species commonly found sterile, is described from fertile material on Juglans glabra in the Netherlands. It was also found with apothecia on, for example, twigs of Vaccinium myrtillus, Lonicera, and other trees. It seems to be common and rapidly spreading in sheltered habitats in Belgium, Germany and the Netherlands, also occasionally on wood, roofs, granite and brick. It is close to other Felihanera species, especially F. seroexpectata and F. viridis, but it differs in the paler soredia, smaller, 1-septate and constricted ascospores and the presence of roccellic acid.

Some enzymes, particularly esterases and phosphatases, are commonly variable within lichen populations. Mycobiont cultures of Cladonia cristatella Tuck, were examined electrophoretically in order to determine whether isozymes of these enzymes varied among 12 cultures initiated from single ascospores of the same apothecium. There were significant differences among mycobionts with respect to growth in liquid malt-yeast medium, and there was isozymic variability among them just as there is among intact thalli in natural lichen populations. These results are consistent with the idea that in nature ascospores could participate in the reproductive process. Enzymatic differences within a population may originate from propagules, including sexual ones, which initiate individual thalli.

Aspicilia excavata Thor & Timdal sp. nov. is described and reported from Austria, Finland, Norway and Sweden. It is usually sterile and mainly characterized by an indeterminate thallus composed of small, white pruinose squamules excavated from the margin by dark brown to black soralia. The species grows on calcareous rocks and mortar, mainly on steep to overhanging faces.

Strigula fossulicola sp. nov. and S. oceanica sp. nov. are described from Lord Howe Island, New South Wales, Australia. They inhabit the leaves of endemic shrubs and trees and are distinguished by ascospores that fracture at the septum prior to maturity.