Lichen communities at four sites of copper sulphide mineralization and associated secondary oxidation products are described from an old mining area at Coniston in the English Lake District. Five lichen species new to Britain, Stereocaulon symphycheilum, Lecanora handelii, Rhizocarpon furfurosum, Lecidea atrofulva and L. inops, are briefly described, the last mentioned being a specific indicator of copper mineralization. The species complex, Lecidea auriculata, L. diducens and L. inops, is discussed in some detail. Toninia leucophaeopsis and the non- British Bilimbia tornensis are distinct species and are both referred to the genus Stereocaulon.

The examination of the surface deposit of various lichens with X-ray diffraction methods, correlated with scanning electron microscopical (SEM) studies, have shown that calcium oxalate is present as two different hydrates; weddellite (CaC2O4-(2 + x)H2O), in three slightly different morphologies, and whewellite (CaC2O4H2O). The reason for the formation of calcium oxalate is not known and the presence of the various crystal forms is yet to be explained. However, the various hydrates may have some role in the water balance as they are different in dry and humid sites.

The growth and development of several lichens under natural conditions are studied with the SEM. The results permit observations on the influence of the microclimate and of pollution on thalline development and on some principles of lichen systematics.

The endemic African lichen Parmelia hottentotta (Ach.) Ach. and related species are placed in a new genus, Xanthomaculina Hale, on the basis of cortical chemistry and a combination of conidial and morphological characters, including umbilicate growth form, presence of cilia and a vaulted cortex.

A new saxicolous genus and species, Glyphopeltis eburina Brusse, is described from southern Africa. The genus differs from Lecidea s. lat. in the peltate thallus.

Lichenostigma rugosa sp. nov. is reported from Europe, North Africa, Asia and the USA. Only one species of Lichenostigma, L. maureri, from Europe and Asia, was previously known. L. rugosa differs chiefly in having spores with deep irregular fissures. L. maureri is reported for the first time from South America (Argentina, Peru), the British Isles and Sweden.

Under favourable climatic conditions the mycobiont of Coniocybe furfuracea bears masses of conidia in chains on macronematous conidiophores. The same type of conidia were also formed by axenically grown mycobionts which had been isolated from single ascospores. Germinating conidia were found on the thalli. Coniocybe furfuracea is one of the very few lichen mycobionts so far known with a teleomorph and hyphomycetous anamorph.

The formation of vegetative cells from zoospores and the morphogenesis of the multilayered cell walls during this process was observed in some Trebouxia and Pseudotrebouxia species. In Trebouxia species, e.g. Trebouxia erici, the wall of the vegetative cell is formed around the zoospore while in Pseudotrebouxia species, e.g. Pseudotrebouxia corticola, firstly an autosporangium with its wall is formed then the autosporangium further divides.

Macentina aurantiaca sp. nov. (Verrucariaceae) is described from the Burren, western Ireland. A sciophilous lichen, it is characterized by its comparatively large, orange ascomata and by its mostly 7-septate, elongate-ellipsoid ascospores.