“Quality and Quantity: maintaining biological diversity in space and time”—Session II of the 5th Symposium of the International Association for Lichenology, Tartu, Estonia, 16–21 August 2004. As naturalists and especially as lichenologists, we would all agree that lichen diversity is desirable for its own sake. A species-poor forest looks ‘wrong’ to an experienced outdoors-person, and, conversely, a lichen-rich forest is a delight, even if the viewer knows nothing about lichens per se. This is why many people, not just lichen-lovers, agonize over the loss of lichen diversity in our natural landscape.

The new species Caloplaca tswaluensis is described from Tswalu Kalahari Reserve, Northern Cape Province, South Africa. Caloplaca tswaluensis occurs on the trunks of Vachellia erioloba (camelthorn) trees and is characterized by its 3-septate to quadrilocular ascospores. Molecular data indicate that the new species is placed in the subfamily Teloschistoideae but cannot be assigned to any existing genus and, because its systematic position is unclear, we choose to describe it in Caloplaca s. lat. Caloplaca tswaluensis is compared with other crustose Teloschistaceae species with plurilocular ascospores.

Chaenotheca degelii sp. nov. is described from New Zealand. The position of the species in the genus and the chemistry are discussed briefly. Chaenotheca degelii is a lignicolous species mainly occurring in the Central Plateau of North Island, but one isolated occurrence in the South Island is also known.

Morphogenesis of podetia in Cladonia subcervicornis is a non-linear, repeating process based upon a pattern of meristem enlargement and division. Variability in mature podetia of C. subcervicornis, which may appear branched or scyphoid, is the result of variation early in ontogeny. The growth pattern of C. subcervicornis represents a continuum of developmental stages. It is impossible to predict the form of the mature thallus of C. subcervicornis because growth in this species is fluid. The morphology of the mature thallus of C. subcervicornis is difficult to circumscribe using conventional Cladonia terminology, because the processes that form the thallus are dynamic and heterogeneous. The meristem shapes that are produced during early ontogeny in C. subcervicornis are relatively simple, and the processes by which they are formed are uncomplicated. Yet podetial form in C.subcercicornis is difficult to interpret.

The distribution of many Arctic lichens is well known but their place and time of origin is still conjectural. Land bridges are often suggested but continental drift suggests a possible tie to Gondwanaland and Pangaea. This review suggests consideration of the available evidence for such ideas and emphasizes the need for more exact data from molecular studies of living and amber materials to determine the antiquity of the lichen species involved.

The new species Ochrolechia splendens Lumbsch and Messuti, is described from Mexico, south-western North America, where it occurs on exposed siliceous rocks. It is characterized by relatively large apothecia with entire margins, the presence of the gyrophoric acid chemosyndrome in the thallus and apothecial disc and the presence of lichexanthone as major components.

Two species of lichenicolous fungi are described as new to science: Lichenotubeufia etayoi Zhurb. (on Trachyderma), with light orange perithecia up to 360 μm diam., non-fasciculate excipular hairs, and 10–13-septate ascospores, 110–162 × 3–5 μm; and L. tibellii Zhurb. (on Coccocarpia), with light orange perithecia up to 275 μm diam., non-fasciculate excipular hairs, and 5–12-septate ascospores, 50–100 × 3–4.5 μm. An updated key to the species of Lichenotubeufia is provided.

The phylogenetic relationships of the monospecific genus Paratricharia, with the single species P. paradoxa, within the family Gomphillaceae are resolved using newly generated sequences of the mtSSU and nuLSU markers for three specimens collected in Costa Rica. The results support placement as sister to the genus Caleniopsis, the two genera sister to a clade containing the genera Aulaxina and Aulaxinella. This placement confirms earlier studies based on cladistic analysis of phenotype characters and phenotype-based phylogenetic binning, suggesting that apothecial features are more informative for the phylogenetic placement of taxa within Gomphillaceae than thallus characteristics.