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.

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.

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.

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.

The distribution patterns of lichens belonging to the family Peltulaceae and procaryotic algae (cyanobacteria) were studied in a rock pool on a sandstone koppie (‘Inselberg’). situated in the mopane savanna of the northern Transvaal. The co-dominant lichen species along the wall of the pool were: Peltula clavata (Krempelh.) Wetmore, P. euploca (Ach.) Poelt ex Pisut, P. obscurans (Nyl.) Gyelnik, and P. placodizans (Zahlbr.) Wetmore. The cyanobacteria Gloeocapsa sanguinea (Ag.) Kütz. emend. Jaag, Plectonema tomasinianum Gom. ex Gom., Rivularia sp., Scytonema sp. and Tolypothrix sp. grew epilithically between the lichen thalli. Unicellular species of the genus Chroococcidiopsis Geitler or Myxosarcina Printz occurred cryptoendolithically. The distribution patterns of several lichen species are presented and statistical tests reveal distinct correlations of the habitats of some species with light levels and water supply; e.g. the olive-green P. placodizans preferred the fully exposed situation near and along the rim of the rock pool; the black species P. clavata was restricted to areas next to the water level.

Four enzymes were examined electrophoretically from each of seven stands of arctic umbilicate lichens in central Ellesmere Island. The species studied included Umbilicaria virginis Schaerer, which was prolifically apotheciate, and U. decussata (Vill.) Zahlbr. and U. hyperborea (Ach.) Hoffm., which were both sterile. Electrophoretic banding patterns were converted to presence/absence data reflecting the occurrence of electromorphs in each thallus, and enzyme polymorphism was assessed using three statistical methods, one based on frequency of individual enzyme forms, another on the number of banding patterns, and a third on the proportional representation of different band patterns within each collection site. Greater enzyme variability occurred in stands of apotheciate species than in stands of species which were asexual in the study area, suggesting that regular sexual reproduction contributes to greater diversity.