This paper reassesses the European and Macaronesian species of Nephroma, analyses their chemistry, and provides a key to the 14 species accepted. The investigation employs chemical techniques which enable even fragmentary material to be identified. Seven chemical groupings are recognized in the genus of which four occur in the species discussed here. Particular emphasis is placed on the distribution of major hopane triterpenoids within the genus. N. areolatum, N. foliolatum, N. hensseniae and N. sulcatum spp. nov. are described from Macaronesia, and N. tangeriense (Maheu & A. Gillet) Zahlbr., is accepted as distinct.

An identification key to 128 macrolichen species from Tasmanian rainforest is presented. Additional data on the flora are also included. Five new species, Menegazzia caesiopruinosa P. James, M. confusa P. James, M. inactiva P. James & Kantvilas, M. minuta P. James & Kantvilas and M. subbullata P. James & Kantvilas, are described, and the new combination Leioderma amphibolum (Knight) P. M. Jørgensen & D. Galloway is made.

The lichen flora of the county of Gwynedd, north-west Wales, is described. The flora includes 851 species and 19 subspecies and varieties. The work comprises sections on: climate; geology; land use and vegetation; history of lichenology, 1680–1985; corticolous flora, with classification and description of the important woodland sites; inland saxicolous flora, dealing with acid, intermediate and basic rock, the effects of altitude and aspect, the flora of seepages, streams and lakes; heath and moorland flora; coastal flora classified into the recognized zones of the marine littoral, mesic, submesic and xeric supralittoral; aspects of conservation, pollution; and the lichen flora itself. The latter includes a brief description of the ecology and distribution of each species and all of the currently known 10-km2 records for the species in the county.

The epilithic lichen flora on the Beacon sandstone formation in Victoria Land consists of seven species: Acarospora gwynniiDodge & Rudolph, Buellia grisea Dodge & Baker, B. pallida Dodge & Baker, Carbonea capsulata (Dodge & Baker) Hale comb, nov., Lecanora fuscobrunnea Dodge & Baker, Leaded cancriformis Dodge & Baker, and L. siplei Dodge & Baker. The typification of the species is given along with descriptions and distribution in Antarctica.

The Southern Hemisphere genus Leioderma Nyl. contains seven species: L. amphibolum (Knight) P. M. Jørg & D. Galloway, L. applanatum sp. nov., L. duplication (Mull. Arg.) comb, nov., L. erythrocarpum (Nyl.) comb, nov., L. glabrum sp. nov., L. pycnophorum Nyl., and L. sorediatum sp. nov. The genus has two subgenera (Leioderma, and Fuscoderma subgen. nov.) distinguished by differences in thallus morphology and the structures of asci and ascospores. Leioderma is closely related to Erioderma but differs in thallus habit, structure of cortex and ascus, and chemistry. Leioderma appears to be a Gondwanan genus. A key is given, and details of anatomy, morphology, distribution, ecology, phytogeography and taxonomy are discussed. A new, Lewderma-like, sorediate Parmeliella, P. subgranulata sp. nov., is described from New Zealand, and the related P. granulata Lamb, is recorded from New Zealand for the first time.

The genus Psilolechia Massal. is reviewed; four species are accepted, including P. leprosa sp. nov. from copper-rich sites in north-west Europe and Greenland, and P. purpurascens sp. nov. from Tasmania. A hyphomycetous anamorph is described for P. clavulifera, and anomalous forms of P. lucida with a vicarious, Stichococcus photobiont are reported.

Notes are provided on the genus Vezdaea and its five species represented in the British Isles, including V. acicularis sp. nov. A key to the six European species is included.

The new species Lichinella japonica Harada & Henssen is described for the first time from Japan. L. japonica differs from known species in thallus structure and ecology. It is the first record of the genus from East Asia.

Choreospora tibellii P. Const. & R. Sant. gen. & sp. nov., a sporodochial hyphomycete with non-septate, tetraradiate conidia is described from Australia. The fungus grows on a sterile foliicolous lichenized thallus (?Echinoplaca sp.) on leaves of Cordyline.

Rich collections of foliicolous lichens were made, especially from submontane and montane areas, in the Usambara Mountains of Tanzania during the Usambara Rain Forest Research Project expeditions in 1982, 1984 and 1985. An enumeration of the identified species is provided together with taxonomic, ecological and geographical notes. This first part treats 36 species from the Arthoniaceae, Opegraphaceae and all genera with pyrenocarpous ascomata. New records include 14 species for the Usambaras, eight for Tanzania, and three to Africa. Porina sphaerocephaloides sp. nov., widely distributed in the study area, is described.

The genus Sagenidiopsis gen. nov. of uncertain family in the order Opegraphales is erected for a byssoid lichen which occurs in the cool temperate rainforests of the Macpherson Range of eastern Australia, S. merrotsii sp. nov. The genus is characterized by its byssoid thallus and bitunicate asci which have no amyloid structures apparent in the tholus. A byssoid thallus is without taxonomic significance at the family level, but is an ecological key character.

The lichen Diploschistes muscorum (Scop.)R.Sant. starts its thallus development as a parasite of the squamules of different Cladonia species, but fully developed Diploschistes thalli live independently. D. muscorum develops apothecia in the Cladonia squamules and is associated at that stage with the phycobiont of Cladonia, Trebouxia irregularis. Augmentation of the Cladonia phycobiont and growth of the D. muscorum hyphae result in a development of young Diploschistes thalli from the Cladonia squamules. As the Cladonia increasingly disintegrates, D. muscorum becomes independent. In fully developed thalli the Cladonia phycobiont can be exchanged for T. showmanii, an alga different in morphology and reproduction from T. irregularis. In one case, a fully developed D. muscorum thallus with both phycobionts was demonstrated. A fully established thallus can also be formed by the growth of small thallus swellings, which cover Cladonia squamules.

The lichen substances of 64 Danish specimens of the Cladonia macilenta bacillaris aggregate were analysed by thin layer chromatography. Nine chemical types were found. The presence of thamnolic acid was not found to be correlated with any of the examined morphological parameters.

SEM observations of the surface of branch tips of Bryoria fuscescens, before and after treatment to remove the matrix produced by the cortical hyphae, are described. Cortical hyphae are arranged in a simple, apical bundle, parallel to the long axis of the branch, which becomes, behind the apex, a hollow cylinder containing the algal population. The cortical structure is less complex than that of Usnea subfloridana. Substantial amounts of extracellular matrix are produced and the significance of this is discussed.

Notes are provided on the genus Ramonia and its four species represented in the British Isles, including R. dictyospora sp. nov. and R. nigra sp. nov.

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.

The lichen vegetation on exposures of gabbro near Letterfrack, Co. Galway, western Ireland is described. Species abundance and vigour relate primarily to the geochemical composition of the gabbro substratum rather than to microclimatic factors. Lichens may be useful as geochemical indicators when mapping rocks with similar textures and mineralogies.

The localization of norstictic acid and copper in green, copper-rich specimens of Acarospora smaragdula and Lecidea lactea from cupriferous substrata was studied by optical microscopy, scanning electron microscopy, and electron probe microanalysis. Infrared absorption spectroscopy of lichen material and a synthetic Cu-norstictic acid complex, and the other studies, provide evidence that complexing of copper by norstictic acid occurs within the cortex of these lichens and leads to their unusual surface coloration. Preliminary observations suggest that copper may also form a complex with psoromic acid and colour lichen thalli green. There is a strong possibility that other metal-lichen acid complexes may occur.

The genera Hypotrachyna (Vainio) Hale and Pseudoparmelia Lynge are emended to include species previously accommodated in the genus Parmelina Hale. Pseudoparmelia endochromatica sp. nov., P. singularis sp. nov., Xanthoparmelia glomerulala sp. nov., X. karamojae sp. nov., and X. meruensis sp. nov. are described. The following combinations are proposed: Hypotraehyna afrorevoluta (Krog & Swinscow) comb, nov., H. aurulenta (Tuck.) comb, nov., H. damaziana (Zahlbr.) comb, nov., H. horrescens (Taylor) comb, nov., H. meyeri (Zahlbr.) comb, nov., H. minarum (Vainio) comb, nov., H. spathulata (Kurok.) comb, nov., H. spumosa (Asah.) comb, nov., H. swinscowii (Hale) comb, nov., Parmotrema vividum (Krog & Swinscow) comb, nov., Pseudoparmelia chlorea (Stizenb.) comb, nov., P. simplicior (Hale) comb, nov., P. usambarensis (Steiner & Zahlbr.) comb, nov., P. wallichiana (Taylor) comb, nov., Xanthoparmelia interrupta (Stizenb.) comb, nov., and X. kiboensis (Dodge) comb. nov. Xanthoparmelia cylindriloba Knox is reduced to synonymy with X. kiboensis.