Leioderma subg. Fuscoderma D. Galloway & P. M. Jørg., is shown to be a distinct genus, confined to Tasmania and New Zealand and comprising three species: Fuscoderma amphibolum (Knight) comb, nov., F. applanatum (D. Galloway & P. M. Jørg.) comb, nov., and F. limbatum sp. nov. A key to the species is given. A revised key to Leioderma is also presented and a second locality (Ecuador) is reported for the Brazilian species L. glabrum D. Galloway & P. M. Jørg.

The new generic names Metamelanea Henssen and Strotnatella Henssen are described inthe Lichinaceae. They are denned by the developmental morphology of the ascocarp and thallus structure. In both genera the thallus is subfruticose, and the cyanobiont a single-celled member of the Chroococcales. The genus Metamelanea is based on the type species M.umbonata Henssen, newly described from the Alps, and M. melambola (Tuck.) Henssen comb, nov., found in North America. The genus Strotnatella is based on the single species, S. bermudana (Riddle) Henssen, formerly Psorotichia bermudana Riddle. The new genera are compared with species of other genera of the Lichinaceae: Gyrocollema, Lecidopyrenopsis and Porocyphus; some micrographs of Lecidopyrenopsis corticola Vainio. are also included. The new combination Porocyphus ocellatus(Th. Fr.) Henssen is made; Pyrenopsis triptococcus Nyl. is selected as lectotype of Pyrenopsis subgen. Cladopsis Nyl. (syn. Cladopsis (Nyl) Hue).

The Lepraria membranacea group is shown to constitute the genus Leproloma Nyl. ex Crombie, characterized by the presence of dibenzofurans. A full account of the genus and four species is given: L. angardianum (Øvstedal) Laundon comb, nov., L. diffusum Laundon sp. nov., L. membranaceum (Dickson) Vainio, and L. vouauxii (Hue) Laundon comb. nov. The species L. diffusum comprises var. diffusum and var. chrysodetoides Laundon var. nov. Fertile material of L. membranaceum was found in the 18th century; the morphology and chemistry of this suggests that the genus may tentatively be included in the ascomycete family Pannariaceae. Leproloma angardianum has a powdery thallus in shade but a granular thallus in sun. Lepraria arctica is a synonym of Leproloma vouauxii. The latter species contains a newly identified compound, methyl pannaric acid, and L. diffusum also contains a new compound, oxypannaric acid.

Arthonia anglica Coppins, A. anombrophila Coppins & P. James (syn. A. cinereopruinosa auct. brit.) and A. ligniariella Coppins are newly described, and Arthothelium ilicinum var. dictyosporum is given specific rank. British material of ‘Arthonia exilis’ is shown to be Bryostigma leucodontis Poelt & Döbb., which is transferred to Arthonia. Arthonia granitophila Th. Fr. (syn. Melaspilea subarenacea J. Nowak & Kiszka) is transferred to Melaspilea. Arthonia ligniaria Hellb. is added to the British list. Arthonia astroidestra Nyl. is lectotypified and shown not to be conspecific with A. stellaris Krempelh., while A. excipienda Nyl. (syn. A. hibernica Nyl.) is found not to be a synonym of A. dispersa (Schrader) Nyl. Catillaria ooliticola W. Watson is made a synonym of A. lapidicola (Taylor) Branth & Rostrup; Arthonia punctilliformis Leighton is excluded from that genus; and A. dispersa and A. patellulata Nyl. are excluded from the British list. In addition, four new lichenicolous species on corticolous hosts are introduced: Arthonia cohabitans Coppins, A. graphidicola Coppins, A. invadens Coppins and A. thelotrematis Coppins.

A broad generic concept is adopted for Catillaria, and the following new combinations made: C. aphana (Nyl.) Coppins, C. modesta (Müll. Arg) Coppins (the basionym, Lecidea modesta Müll. Arg., being lectotypified), C. picila (Massal.) Coppins, and C. scotinodes (Nyl.) Coppins. Lecidea botryiza Nyl. ex Stirton is added to the synonymy of Micarea lutulata. Catillaria rhypodiza is transferred to Halecania, and a new, sorediate, corticolous species of that genus, H. viridescens Coppins & P. James, is described.

Sixty-two samples of Asahinea chrysantha from different localities in the Soviet Union were analysed by TLC. Three different chemotypes are recognised, each with a different geographical distribution. The most restricted of the three is an usnic acid deficient chemotype (I), with atranorin, alectoronic and α-collatolic acids, which is chemically the same as A. scholanderi and A. kurodakensis. Chemotype II contains usnic acid in addition to the basic chemistry, and chemotype III is α-collatolic acid deficient and has the widest geographical range. A centre of speciation of Asahinea in Soviet Primorje or Japan is proposed.

Verrucaria elaeomeleana (Massal.) Arnold s.str. is confirmed for the British Isles and its separation from V. funckii (Sprengel) Zahlbr. is discussed. Additional records are provided for V. latebrosa Körber. Verrucaria aquilella Nyl. and V. fuscocinerascens Nyl. are confirmed as synonyms of V. aethiobola Wahlenb., while V. conturmatula Nyl. is shown to be based on immature material of Polycoccum microsticticum (Leighton ex Mudd) Arnold growing on Hymenelia lacustris. The British record of V. amylacea Hepp is referred to V. praetermissa (Trevisan) Anzi, and that of V. collematodes Garov. is referred to V. fusconigrescens Nyl.

Three lichen species, Hypogymnia physodes, Bryoria capillaris and Peltigera canina were fumigated with 215 μig m−3 of SO2 (6 h per day, 5 days per week) in exposure chambers under three different moisture conditions. The treatments were (1) low humidity (40–50° r.h. continuously), (2) high humidity (80–90° r.h. continuously) and (3) high humidity + water (80–90° r.h. + daily moistening). The value of light microscopy, fluorescence microscopy and electron microscopy in assessing the SO, injury in the lichens was compared. The three lichen species studied were all damaged by this level of SO, fumigation, and injury increased with increased duration of exposure. Electron microscopy was the most sensitive method of revealing cellular injuries after 5 days of exposure in all the species studied. Fluorescence microscopy revealed changes in the colour and intensity of fluorescence after 10 days of exposure in the two epiphytic species, but no clear changes in the cyanobacterial cells of P. canina could be detected by this method. Light microscopy revealed plasmolysis of the algal cells in the two epiphytic species after 10–15 days of fumigation. All the species studied were clearly more sensitive to SO2 when cultured in air of high humidity, although slight cellular injuries also occurred in the dry air treatment (40–50° r.h.). Additional daily moistening tended to protect against injury in the lichens cultured at high humidity. In the present continuous flow fumigation chamber P. canina proved to be sensitive to SO2 in regard to ultrastructural injuries that could be observed in both the cyanobacterial and fungal cells.

Macentina stigonemoides sp. nov. is described from trees in Great Britain and Ireland; it is characterized by a filamentous to granular thallus with papillose cortical cells and pale perithecia with 3–5-septate spores.

Cladonia arbuscula subsp. squarrosa (Wallr.) Ruoss and C. stygia (Fr.) Ruoss are reported for the first time from the Southern Hemisphere. Populations of C. arbuscula in New Zealand and Australia are recognized as subsp. stictica Ruoss, subsp. nov., usually containing stictic acid, norstictic acid (first report in subg. Cladina), and sometimes also the fumarprotocetraric acid complex. C. laevigata (Vainio) Gyelnik is reinstated in Cladonia subg. Cladina sect. Tenues, while C. stygia is considered to belong to sect. Crustaceae rather than to sect. Tenues. C. confusa R. Sant. is morphologically highly variable, although chemically uniform, usually containing usnic acid and perlatolic acid. An usnic acid-deficient chemodeme is reported as new to New Zealand.

Xanthoria elegans has a broad ecological amplitude, world-wide distribution and includes morphological variants which differ markedly with respect to colour, form and frequency of apothecia. Distinctive thallus forms are associated with different habitats. Samples from two contrasting habitats were studied on Ellesmere Island in the Canadian High Arctic. Carotenoids, polyphenolic products and isoenzymes were examined to establish whether two thallus types were biochemically distinct. Pigments were comparable in both morphological variants, as were approximately half of the most frequently occurring enzyme forms. Enzymatic similarity between the two resembled that between conspecific populations of other lichens. On the basis of the chemical attributes investigated, the thallus forms did not warrant recognition as fundamentally distinct entities, but were merely variants of an ecologically versatile and extremely plastic species.

Twelve species of Rhizocarpon coexist with 94 other species of saxicolous lichens at Jonas Rockslide, Jasper National Park, Alberta, Canada. The position of each Rhizocarpon species in the community is assessed with respect to environmental factors and biotic relationships. Each species shows distinct correlations with measured environmental factors and a different set of interactions with other species. Rhizocarpon bolanderi and R. superficiale stand out as opposites with regard to their biotic associations and environmental correlations. Competition between pairs of Rhizocarpon species is predicted to vary in intensity, as some species pairs never occupy the same microenvironment, whereas others frequently occur in similar locations. Using thallus diameter as a measure, there is evidence of high recruitment rates into populations of the sub-genus Phaeothallus and lower recruitment rates in the sub-genus Rhizocarpon.

The present occurrence and vitality of Lobaria scrobiculata (Scop.) DC. were investigated at 67 localities (50 old and 17 new) in southern Sweden. Before 1950 L. scrobiculata was found at more than 300 localities in southern Sweden. However, it was only confirmed at two out of 50 thoroughly investigated old localities. An investigation of recently found localities (new) and confirmed ‘old’ sites showed that there have been decreases in population size, thallus size, fertility, number of phorophytes, and cliff colonization. In southern Sweden today L. scrobiculata is confined to old deciduous trees in regions with comparatively low air pollution and a high relative humidity. Apothecia have not been found in southern Sweden since 1947, although in the past, fertile material was collected from 35 localities in this region. The author suggests that this species, like many other lichens with the cyanobacterium Nostoc as photobiont, is currently more endangered by air pollution than by any other human activity and that it is seriously endangered in the southern part of Sweden.

Evernia prunastri thalli were homogenized and separated into algaland fungal-rich fractions. The former was shown to contain most β-l,4-glucanase (cellulase) activity. The significance of this localization in field material is discussed.

Most British collections hitherto identified as Lecidea cinnabarina Sommerf. are shown to belong to either Pertusaria pupillaris (Nyl.) Th. Fr. or to a sterile species tentatively assigned to Schismatomma as S. quercicola Coppins & P. James sp. nov. Notes are also provided on a problematical Pertusaria, resembling P. pupillaris and Lecidea cinnabarina s. str.

Lasallia hispanica (Frey) Sancho & Crespo comb. nov. is proposed as a result of anatomical and morphological comparisons between it and the related species, L. brigantium Zsch. and L. rossica Dombr. For all three species ecological notes, data on world distributions, and a key are provided.

Fifty-five new lichen taxa from the Azores are discussed. Of these, 30 taxa are new records for Macaronesia and 15 are new records for Europe.

Lichens of the most highly stressful habitats in Sverdrup Pass, Ellesmere Island, Northwest Territories, Canada, were examined for reproductive structures, as were lichens of less extreme sites within the same landform features. The study areas included twenty-two stands in a calcareous erosional mountain system and two microhabitats within the ablation zone of a valley glacier. In the most limited stands in the erosional mountains 83% of the lichens were apotheciate species and 93% of these were represented by specimens bearing apothecia. On stressful rock surfaces in the glacier fellfield most species also produced sexual fruiting bodies.

In Norway three species are recognized in the genus Bryoria sect. Implexae, B. capillaris (Ach.) Brodo & D. Hawksw., B. implexa (Hoffm.) Brodo & D. Hawksw., and B. nadvornikiana (Gyeln.) Brodo & D. Hawksw. Notes on their morphology, chemistry, ecology and distribution are given. Bryoria friabilis Brodo & D. Hawksw., B. pseudofuscescens (Gyeln.) Brodo & D. Hawksw., and B. vrangiana (Gyeln.) Brodo & D. Hawksw. are considered to be conspecific with B. implexa. Bryoria setacea (Ach.) Brodo & D. Hawksw. is considered to be conspecific with B. capillaris.