Bacidia coprodes (Körb.) Lettau, until now treated as a synonym of Bacidia trachona (Ach.) Lettau, is resurrected. Morphological, chemical and ecological characteristics place this species close to Toninia in the Ramalinaceae, but we retain it in Bacidia because of uncertainties in the generic taxonomy of this family. Bacidia coprodes is fairly widespread on calcareous and enriched siliceous rock in Europe and eastern North America. In North America the species has also been known under the synonyms Bacidia granosa (Tuck.) Zahlbr. (basionym: Lecidea granosa Tuck.) and Bacidia pammellii (Fink) Zahlbr. (basionym: Bilimbia pammellii Fink). Morphological and chemical features, together with molecular data, suggest that B. trachona does not belong to Bacidia, but rather in the Pilocarpaceae.

An examination of the holotype or lectotype of eight taxa, first described from Australia, in the genus Cladonia has shown that the names are, with the exception of Cladonia fruticulosa Krempelh., synonyms of previously described taxa. The taxa examined were as follows (with the correct name in parentheses); C. cariosa var. diffissa F. Wilson (C. enantia Nyl.); C. conchata Nyl. (C. pyxidata (L.)Hoffm.); C. cornucopioides var. grandis Krempelh. (C. pleurola (Flörke) Schaerer); C. deformis var. tasmanica Krempelh. (C. subdigitata Nyl.); Cenomyce firma Laurer, Cladonia firma (Laurer) Krempelh. (C. murrayi W. Martin); C. lepidula Krempelh. (C. ochrochlora Flörke); C. pergracilis Krempelh. (C. ochrochlora Florke); C. subsquamosa var. pulverulenta Vainio (C. squamosula Müll. Arg.) Homosekikaic acid is reported to occur with thamnolic acid in C. squamosula Müll. Arg.

Twenty-nine species of foliicolous lichens are reported from Zimbabwe. Arthonia nigratula (Müll. Arg.) R. Sant. is mentioned for the first time in Africa, and Catillaria vandenberghenii sp. nov. is described.

Schismalomma ceylanicum sp. nov. is described from Sri Lanka, and an account is given of two species from California previously assigned to Dirina: S. calijornicum(Tuck.) Zahlbr. and S. rediunta (Hasse) comb. nov.

Seven Neofuscelia species have been identified from Italy. A key to the species is provided and the distinguishing morphological and chemical characters, distribution, ecology, substratum preference and interrelationships of each are discussed. Neofuscelia perrugata is new to Italy. N. pyrenaica is new to Greece and Cyprus. New data on the distribution and ecology of N. perrugata, N. delisei and N. luteonotata are presented and these are consistent with their taxonomic rank.

Stereocaulon virgatum Ach. has colonized lava flows deposited on the west flank of the volcano La Soufrière. The mean annual rate of acetylene reduction was 43·4 nmol C2H4 gdw−1 h−1 with maximum rates during the prevalent cloud/shroud meteorology of 101 and minimum rates during rare high insolation events of 0·63 nmol gdw−1 h−1. Percentage thallus moisture was the major variable controlling nitrogenase activity. During cloud/shroud conditions the upper 90% of the lichen canopy reduced 85% of the acetylene. Canopy shading reduced intra-canopy temperatures allowing the basal 10% of the canopy to fix nitrogen during insolation shocks. Basal portions of pseudopodetia exhibited reduced rates of ethylene production when exposed to canopy surface light intensities during cloud/shroud conditions. The recovery pattern of nitrogenase following desiccation during an insolation shock is presented. Rates of photosynthesis during cloud/shroud conditions were high, reaching 50% of those attained during saturating light intensities.

Pyrenocollema elegans sp. nov., a widespread lichen on the Atlantic coast of Europe and the Pacific coast of North and South America, is distinguished from other members of the genus by a thallus bearing numerous black ridges and warts.

Lepraria eburnea is shown to comprise three morphologically indistinguishable chemotypes, containing either protocetraric acid, psoromic acid, or neither substance, in addition to alectorialic acid. The holotype of L. frigida contains protocetraric acid and alectorialic acid, and is thus united with L. ebumea under the latter name.

Micarea confuse, a species easily confused with M. denigrate, is described from heavy-metal contaminated ground in Belgium and The Netherlands. Additional information is provided on the main locality at Budel-Dorplein.

Usnea viktoriana P. Clerc & Otte is described as new. It is characterized by the presence of alectorialic acid as major secondary compound mainly present in the aggregated efflorescent soralia with long isidiofibrils. Usnea parafloridana K. Mark, Will-Wolf & Randlane is synonymized with U. praetervisa (Asahina) P. Clerc. Both U. viktoriana and U. praetervisa are supported by molecular analysis. A key to the shrubby-subpendulous sorediate Usnea species in Europe is provided.

Two new species, Mazosia lueckingii Kr. P. Singh & Pinokiyo and Sporopodium awasthianum Kr. P. Singh & Pinokiyo and a new variety, Aspidothelium scutellicarpum R. Lücking var. indicum Kr. P. Singh & Pinokiyo, are described.