The genus Usnea is a conspicuous component of the macrolichen vegetation in Macaronesia. Ten species are recognized in the Azorean archipelago: Usnea cornuta Körb., U. esperantiana P. Clerc, U. flammea Stirt., U. geissleriana P. Clerc sp. nov., U. krogiana P. Clerc sp. nov., U. macaronesica P. Clerc sp. nov., U. rubicunda Stirt., U. silesiaca Motyka, U. subflammea P. Clerc sp. nov., and U. subscabrosa Motyka. All these species occur in the Canary Islands as well. Descriptive, chemical, ecological and distributional data for each species are provided. Species that have been recorded once for the Azores but not seen, or that are doubtful or excluded in this work, are briefly discussed.

The new species Lepraria santosii Argüello & Crespo is described from the Canary Islands. It is characterized by a crustose to subsquamulose thallus with slightly raised rim and the presence of atranorin and the stictic acid chemosyndrome. It is currently known from Tenerife (Canary Islands), where it grows on soil over basaltic rocks in the laurel forest. Twelve new sequences of the ITS region from this species and L. isidiata were obtained and analysed with sequences downloaded from GenBank. Maximum parsimony and Bayesian analyses suggest that Lepraria santosii is closely related to L. isidiata. The latter name is here lectotypified and the characters for the distinction of the two species from similar taxa are discussed.

Caloplaca badioreagens is a new endolithic species of subgenus Pyrenodesmia characterized by a greyish brown, K+ reddish brown epithecium, and simple, non-capitate paraphyses. It is readily distinguishable from other endolithic Pyrenodesmias (C. agardhiana, C. alociza, C. erodens) by the presence of an unknown lichen substance in the excipulum and the subhymenium, forming large, rectangular crystal plates in GAW and GE. The new species was collected on hard limestone in three localities of central and southern Italy.

Anisomeridium calcicolum Upreti & Nayaka (Monoblastiaceae) from India is described as new to science. Lithothelium hyalosporum (Nyl.) Aptroot, and Polymeridium albocinereum (Krempelh.) R. C. Harris are reported as new records for the Indian lichen flora.

Revision of world-wide material of Cryptothecia candida sensu Santesson (1952) revealed that three different species are involved, differing in the shape of their ascomata, chemistry, and distribution. C. candida (Kremp.) R. Sant. s. str. [syn.: Arthonia lacerata Vain.; C. epiphylla R. Sant.] contains 2′-O-methylperlatolic acid and 2′-O-methylanziaic acid (thallus and ascomata C+ red) and has rounded to slightly irregular ascomata; it is a paleotropical species occurring in Africa and SE Asia (absent in Australia). All neotropical populations previously identified as C. candida contain perlatolic acid (thallus and ascomata C−) and are further characterized by their well-delimited, regularly rounded ascomata. The name Cryptothecia filicina (Ellis & Everh.) Lücking & G. Thor comb. nov. [bas.: Ascomycetella filicina Ellis & Everh.; syn.: Myxotheca hypocreoides Ferd. & Winge] is taken up for this taxon. A third species was discovered in material from Australia and China (Hong Kong) and is here described as Cryptothecia irregularis Lücking, Aptroot, Kalb & Elix sp. nov. Its ascomata are radiately elongate and it contains psoromic, subpsoromic, 2′-O-demethylpsoromic, and confluentic acids.

A phylogenetic study using large subunit ribosomal DNA sequence data of several species of Siphula, representing all phenotypically recognized species groups, suggests that Siphula is not monophyletic. One lineage, including the core group related to S. ceratites and the S. decumbens group, is placed with members of the Icmadophilaceae, whereas a second distinct lineage, comprising S. complanata, S. fragilis and their relatives, has evolved within the Coccotremataceae. To accommodate these species, the new genus Parasiphula is described as new to science. Parasiphula consists of species restricted to cool to cold latitudes of the Southern Hemisphere. The results show a remarkable case of parallel evolution of lineages that have lost sexual stages and propagate via thallus fragments.

The genus Haematomma is treated as part of the Ticolichen biodiversity inventory in Costa Rica. Together with literature reports, fourteen taxa are recognized as occurring in the country (plus three species to be expected), and three of them are new to science: Haematomma nicoyense Nelsen, Lücking & Chaves, with a sorediate thallus, russulone and atranorin, and zeorine apothecia with a split between proper excipulum and thalline margin, Haematomma staigeriae Nelsen, Lücking & Umaña, with a sorediate thallus, russulone and lichexanthone, and submuriform ascospores, and Haematomma fluorescens var. longisporum Nelsen, Lücking & Navarro, with russulone and lichexanthone and ascospores up to 120 μ m in length with up to 27 septa. A key is presented for the 17 taxa known or expected from Costa Rica.

The new species, Pertusaria huanicola Messuti & A. W. Archer (Pertusariaceae, Ascomycota), is described. It is distinguished from Pertusaria phlyctaenula Nyl., P. subambigens Dibben and P. suboculata Brodo & Dibben by the chemistry and the number of ascospores per ascus. The new species is known only from Valdivian rainforest in south-western Argentina.

Cellular responses to copper stress were investigated for the first time in a saxicolous lichen species, Lecanora polytropa (Hoffm.) Rabenh. Bright blue-green apothecia accumulated up to 1·3% Cu on a dry weight basis (205 μ mol Cu g−1), c. 50% in an exchangeable form. A bright turquoise-blue layer extended beneath the hymenium into the medulla, above and between a dentate photobiont layer. Oxalic (1·88 μ mol g−1), citric (0·83 μ mol g−1) and lower concentrations of malic (0·45 μ mol g−1) acids were determined by GC/MS analysis. Short-term exposure to high Cu2+ concentrations (40 and 400 μ mol g−1) under non-complexing conditions caused a dose-dependent decrease in chlorophyll a content; chlorophyll b and total carotenoid contents remained constant. The phaeophytinization quotient remained unchanged during Cu2+ exposure. Analysis of thiol peptides confirmed glutathione was reduced (GSH) in native L. polytropa (0·538 μ mol g−1), and phytochelatins (PC2 and PC3) oxidised. Short-term exposure to 40 μ mol g−1 Cu2+ oxidised c. 28% of the glutathione pool; oxidised phytochelatin concentrations remained unchanged. This is the first report of phytochelatin production and thiol peptide status in a crustose lichen. These represent two possible detoxification mechanisms in this Cu-tolerant species. Copper complexation by low molecular mass organic acids and non-protein thiols do not entirely account for its tolerance.

The delimitation of the genus Parmelia s.lat. has been a subject of controversy for the past 30 years. Originally this large group of lichens was split into smaller genera for convenience, based mainly on the colour of the thallus and the presence of marginal cilia (Hale 1974); later conidial and other vegetative characters were used (Hale 1984: 18–20). With time several quite small genera of parmelioid lichens were recognized by a number of authors (e.g. Elix 1994), whilst others, because of the sparsity of characters, continued to regard most of them as still belonging to Parmelia (Purvis et al. 1992). Recent molecular studies have ended this polarization, and an agreed classification is now being adopted (Blanco et al. 2004a, 2004b, 2005).

The species included in the recently reinstated genus Bilimbia De Not. (Veldkamp 2004) are usually associated with temperate and cold regions in both hemispheres, where they are muscicolous, terricolous or develop on plant debris (Wirth 1995; Nimis & Martellos 2004; Søchting et al. 2004; Hafellner et al. 2005; Kantvilas et al. 2005). Occasionally, taxa inhabiting corticolous bryophytes extend to adjoining bark, but no species has been described as exclusively corticolous.

After revising the order Pertusariales in Tierra del Fuego (Messuti & Vobis 2002), Teuvo Ahti drew my attention to some nomenclatural problems concerning Pertusaria pachythallina (Räsänen) Messuti. This name was based on Pertusaria grisea var. pachythallina Räsänen. However, the new combination was invalidly published since the page of publication was not indicated (Art. 33.3, Ex 5 ICBN 2000) and the lectotypification originally performed by Lamb (in herb.) did not meet the Code requirements (Art. 7.11). The correct nomenclature and typification are indicated below.

Lichens are colourful organisms owing to numerous combinations of algal and fungal pigments (as reviewed by Rikkinen 1995). Colour is often used in taxonomic studies to aid species identification but it is sometimes over-used as a characteristic to discriminate related genera such as, Xanthoparmelia and Neofuscelia (Poelt & Leuckert 1993). However, colour variations within species can be significant (Solhaug et al. 2003) because of spatial (Gauslaa & Solhaug 2001; Gauslaa & Ustvedt 2003) and temporal variations (Gauslaa & McEvoy 2005) in environmental factors. There are few experimental studies on lichen colours so far; as a result we do not know the relative importance of genetic versus environmental factors. Our study aimed to assess the effect of ultraviolet radiation (UVR) on the colour of the widespread foliose lichen Xanthoparmelia stenophylla (Ach.) Ahti & D. Hawksw. (until recently known as X. somloensis (Gyeln.) Hale, see Ahti & Hawksworth 2005). Usnic acid is responsible for the yellowish appearance of its upper cortex, but other colour variations are also mentioned in taxonomic literature (Brodo et al. 2001). More specifically, we wanted to discover if UVR and the photosynthate ribitol supplied by the photobiont would cause changes in pigmentation in a Xanthoparmelia species. These factors have been shown to induce and stimulate the synthesis of the orange parietin in Xanthoria parietina (Solhaug & Gauslaa 2004; Solhaug et al. 2003).