Illustrated descriptions are provided for four new lichen species found in The Seychelles: Arthothelium feuereri Aptroot & Seaward, Dimerella straminea Aptroot & Seaward, D. subsquamosa Aptroot & Seaward and Fellhanera silhouettae Aptroot & Seaward.

A new lichenicolous fungus Buelliella lecanorae Suija & Alstrup, found on epiphytic Lecanora, is described from Estonia.

Specimens of Xanthoria parietina were collected from worldwide locations and ascospore discharge used to establish axenic cultures of the mycobiont. DNA was extracted and RAPD-PCR fingerprinting of 59 isolates was successfully achieved, resulting in 58 unique fingerprints. 110 multilocus RAPD markers were generated and used to construct a dendrogram. Two main groups were distinguished (75% bootstrap support): the first comprising samples from the Iberian Peninsula, the Balearic and Canary Islands; the second comprising all other worldwide samples including isolates from throughout Europe and North America. Samples from Australia and New Zealand clustered with the second group except one additional, phenotypically distinct specimen, not belonging to X. parietina, which formed an outgroup. However, comparative DNA sequence analyses are required to verify this interpretation.

The phylogenetic relationships of 16 species of Parmelia s. str. are presented based on sequences of nuITS rDNA from 56 specimens, and β-tubulin gene sequences from 29 collections. Parmelia serrana sp. nov. a Mediterranean species morphologically very close to P. saxatilis is described. Parmelia ernstiae is the sister-group to P. saxatilis s. str., and a further undescribed North American species of the P. saxatilis complex may require recognition. The isidiate P. squarrosa is closely allied to the sorediate P. sulcata, which is paraphyletic. Japanese samples of P. cochleata form a monophyletic group but too few collections of these were studied to reach firm conclusions regarding their relationships. An epitype is selected for the lectotype of Lichen saxatilis to unequivocally fix the application of that epithet.

An inventory of foliicolous lichens in Mexican lowland and montane rainforest revealed a total of 288 species, 238 of which are new records for the country, raising the number of reported lichen species to c. 1800. Among the new records, there are 29 recently described species and four new records for the Neotropics and the Americas, while five taxa are for the first time reported for Central America. The 293 species now known from Mexico comprise nearly two-thirds pantropical to cosmopolitan or intercontinentally distributed taxa, whereas little more than one-third are Neotropical or American, and only 6% are potentially endemic to the country. A comparison with other lowland and montane rainforest sites in Guatemala, Costa Rica and Ecuador shows that on average lowland sites have twice as many species as montane sites. Also, the differentiation in species composition between lowland and montane sites within the same region is more pronounced (63–75% similarity) than that between adjacent regions (96–99% similarity for lowland sites and 83–87% similarity for montane sites). This means that altitudinal preferences affect species composition more strongly than geographical differentiation. The latter is a function of distance, however, while Mexican and Guatemalan lowland (montane) sites share 96% (83%) of the species, these values drop to 74% (72%) when comparing Mexico with Ecuador. Nevertheless, overall floristic similarity is very high, with the lowest value of 54% shared species found between Mexican lowland and Costa Rican montane forest.

The anatomy of the endolithic, calcicolous lichen Verrucaria rubrocincta Breuss is described using optical and scanning electron microscopy. This lichen is locally abundant in caliche plates of open desert pavements in the Sonoran Desert of south-western Arizona. The endolithic growth of V. rubrocincta is distinctly layered. The upper layer is a fine-grained calcite (micrite). This layer is sparsely penetrated by hyphae and therefore cannot be interpreted as a lithocortex sensu stricto. Beneath the micrite is the photobiont layer. Below this photobiont layer hyphae form a pseudomedulla penetrating up to 1 cm into the caliche. Calcium oxalates occur in the pseudomedulla but are absent from uninhabited caliche. The analogy of a greenhouse describes the ecophysiological adaptations of this endolithic growth to the environmental extremes of the Sonoran Desert. The micrite acts as a roof and the photobiont layer and pseudomedulla represent the greenhouse interior. Verrucaria rubrocincta has thus evolved a strategy to successfully establish and survive within an extreme environment. Our study illustrates biodeterioration and biomineralization processes acting simultaneously within a single lichen species. Mineralogical evidence suggests that the micrite on the thallus surface is biologically induced. The hyphae of the lichen biodeteriorate the caliche thus forming the pseudomedulla. Simultaneously with this process micrite forms at the surface protecting the thallus from exposure and counter-balancing rock degradation. These combined effects of biodeterioration and biomineralization do not markedly accelerate erosion because inhabited and uninhabited areas of the same plate show similar surface heights.

Diel (24-h) time courses of microclimate, water relations, and CO2 exchange were measured under quasi-natural conditions at a forest edge in a lower montane, tropical rainforest in Panama for six Lobariaceae (Lobaria crenulata, L. dissecta, Pseudocyphellaria aurata, P. intricata, Sticta sublimbata, S. weigelii). Responses to experimentally controlled water content (WC), photosynthetic photon fluence rate (PPFR), and temperature were studied in most detail with P. aurata.

Photosynthesis was well adapted to high temperatures, and all species exhibited ‘shade plant’ characteristics with low light compensation points and low light saturation. Lobaria and Pseudocyphellaria species suffered from a strong depression of net photosynthesis (NP) at suprasaturating WC; suprasaturation depression was less in cyphellate Sticta species.

Photosynthetic capacity correlated with thallus nitrogen concentration, and maximal NP rates of the cyanobacterial Sticta species was 4 to 5 times higher than that of the green algal Lobaria species. However, high rates of NP were uncommon and brief events under natural conditions; the different environmental factors were rarely optimal simultaneously. Similar to earlier observations with other rainforest lichens, NP ceased during the period of highest irradiation on most days due to desiccation. During moist periods low light often limited carbon fixation, and high thallus hydration was often detrimental to NP. In spite of these limitations the maximal daily integrated net photosynthetic carbon income (ΣNP) was quite high especially for the Sticta species [17·3 and 24·1 mgC (gC)−1 day−1 for S. sublimbata and S. weigelii, respectively]. High nocturnal carbon loss, due to high night temperatures and continuous hydration, resulted in frequent negative diel carbon balances (ΣC) in all species. The average nocturnal carbon loss amounted to 83 and 70% ΣNP for P. aurata and P. intricata, respectively and to 64 and 59% of ΣNP for S. sublimbata and S. weigelii, respectively. Their average diel ΣC was as high as 3·7 and 5·3 mgC (gC)−1 day−1. In contrast, ΣC was much lower for the other species, it amounted to only 0·18 mgC (gC)−1 day−1 for L. crenulata. Thus, the Sticta species stood out amongst the species studied for their most successful adaptation of photosynthetic productivity to the habitat conditions in the lower montane rainforest.

In newly collected material from high altitudes in China and India three new species in the genus Fuscopannaria have been discovered: F. albomaculata, F. granulifera and F. hirsuta, all with unusual characters for the genus. The first one has remarkable tube-like structures exposing the white medulla above, the thallus thus appearing to be white-dotted. The second contains green algae, and the last one is the first regularly hairy species to be discovered in the genus.

Floristic, vegetational and ecological features of lichens in ultramafic environments are reviewed using a wide range of literature dating from the beginning of the 20th century. Co-presence of acidophytic (silicicolous) and basiphytic (calcicolous) species and the occurrence of species characterized by particular (disjunct) distribution patterns are features of lichens in ultramafic environments. It is not possible to detect consistent trends in data on other broadly accepted features, such as paucity of species, low cover and the occurrence of particular ecotypes because of the influence of several environmental factors in addition to the substratum. Some recent data about physico-chemical interactions between saxicolous lichens and ultramafic rocks are also reported.

Molecular sequence data of the nuclear ITS region was used to investigate the diversity of photobionts in Polish samples of Flavocetraria nivalis. The samples came both from alpine habitats, as well as from lowland localities near the coast. All green algal symbionts were identified as members of the Trebouxia simplex aggregate. These were compared with those of additional samples from Flavocetraria nivalis collected in different parts of Europe and also with photobionts assigned to T. simplex from other lichens. Within the T. simplex aggregate, the Trebouxia ITS sequences from F. nivalis formed four clades. In the Polish lowland populations only a single clade of T. simplex was detected which also occurs in Polish mountains, south Sweden and Austria. A further clade of T. simplex is present in F. nivalis from Polish mountains and is also known from F. nivalis further north in Scandinavia and Greenland, as well as from other lichens in Sweden, the Austrian Alps, and Antarctica.

A new corticolous species belonging to the lichen family Pertusariaceae, Pertusaria grassiae Messuti & A.W. Archer, is described from Tucumán Province, Argentina. It is characterized by disciform apothecia covered by a white to greyish white pruina, single-spored asci, ellipsoid and double-walled ascospores and the presence of atranorin.

The aim of this investigation was to determine the NH4Cl concentration threshold, above which negative physiological effects would occur in the nitrophytic lichen Xanthoria parietina. Over a 10 month period, X. parietina thalli growing on roof tiles were exposed weekly to NH4Cl concentrations of 0·04, 0·17, 0·34 or 0·69 M. Nitrogen (N) uptake from ammonium and the concentrations of total thallus N and biont markers (chlorophyll a, ergosterol and chitin) were measured on four occasions, over the experimental period. Xanthoria parietina was able to assimilate a significant quantity of the applied ammonium. However, lichens exposed to the two higher concentrations suffered damage to both the photobiont and the mycobiont, as evidenced by reduced chlorophyll a and ergosterol concentrations, while lichens exposed to the two lower concentrations showed no significant changes in either chlorophyll a or ergosterol that could be related to the ammonium inputs. Xanthoria parietina tolerated a weekly irrigation of at least 0·17 M NH4Cl, corresponding to an N deposition of c. 1000 kg ha−1 yr−1, suggesting that this species has a very high tolerance to N pollution.

While studying the taxonomy of the non-yellow species of Rhizocarpon DC., with hyaline and muriform ascospores, in the Nordic countries (Ihlen 2004), some specimens of Rhizocarpon from the Svalbard archipelago were also examined. Among this material, we discovered six specimens of Rhizocarpon anaperum (Vain.) Vain. that had been labelled “R. obscuratum”. As R. anaperum is not listed in the recent checklist from Svalbard (Elvebakk & Hertel 1996) or, to our knowledge, in any other paper dealing with the lichen flora of Svalbard, it is here reported new to this archipelago.

Two shade-adapted (Lobaria pulmonaria and Cetraria islandica) and two sun-adapted lichen populations (Xanthoria parietina and Cetraria nivalis) were exposed to three irradiance regimes (1: photosynthetic radiation—PAR, 2: PAR+UV-A, 3: PAR+UV-A+UV-B) and two hydration regimes (1: no hydration, 2: daily hydration) in a growth cabinet for three weeks. Shade-adapted thalli had transparent upper cortices without coloured pigments, whereas sun-adapted thalli had coloured UV-B absorbing cortical pigments masking the photobiont. Manipulation of pigment concentration was the third factor used in the factorial design (1: pigments intact, 2: pigments non-destructively extracted from air-dry living thalli by acetone). Inhibition of the photobiont due to PAR alone was severe in the two shade-adapted populations, but no applied UV wavelength bands caused additional aggravation of photoinhibition. Shade-adapted thalli of the ubiquitous C. islandica were more PAR-susceptible than of the rare old forest lichen L. pulmonaria, suggesting that screening by the mycobiont rather than photobiont characteristics, account for their different success in sun-exposed localities. Hydration of shade-adapted species during exposure reduced their photoinhibition substantially, probably because of moisture-activated repair mechanisms. On the contrary, the sun-adapted X. parietina was most phototolerant in the desiccated state, whereas hydration caused increased photoinhibition. When removing the orange cortical pigment parietin, the photoinhibition in moist thalli was aggravated, confirming a PAR-protective function of parietin. No effects of irradiance treatment, pigment extraction (usnic acid), or hydration level were observed in C. nivalis.

Soil-associated lichen species characteristic of north-eastern Patagonia are classified by cluster analysis into six groups using ecological and morphological characters. The constancy of species, the total number of species, the number of species per crust and the relative frequency of species are analysed at sites with different grazing levels: three non-grazed, three regulary grazed, and three heavily grazed. Using the results, the potential use of lichen groups as bioindicators of rangeland conservation and degradation are explored. Species of three lichen groups (group A: lichens growing on calcareous gravels; group C: terricolous lichens with pale, crustose non-areolate thalli; group F: terricolous lichens with pale, areolate thalli) are identified as sensitive to grazing, and most of the species forming these groups are suggested as potential bioindicators of grazing disturbance. Thus, Rinodina bischoffii, Caloplaca holocarpa, Catillaria lenticularis, Acarospora heppii (group A); Lecanora dispersa and Rinodina mucronatula (group C); and Psora decipiens (group F) are the species most sensitive to grazing disturbance. Conversely, species of group D (terricolous lichens with dark, foliose thallus: Collema coccophorum), and group B (lichens growing on siliceous gravels: Aspicilia contorta) may be indicated as the most resistant to grazing disturbance.

Juvenile development has been investigated for the first time in an Antarctic lichen species—Usnea antarctica—in the northern maritime Antarctic, Livingston Island (South Shetland Islands, 62°27′–62°48′S, 59°45′–61°15′W). Here, U. antarctica grows on rocks and forms the dominant vegetation on this site together with a few other macrolichens. This species reproduces mainly by vegetative diaspores (soredia), which include both the photobiont and the mycobiont. To understand the early ontogenetic strategies in U. antarctica, culture experiments were performed in an Antarctic field site where the species occurs naturally. This paper focuses on the different developmental steps seen between the initial colonization of soredia to the formation of a small well-developed thallus, and also on the growth rate of the respective juvenile stages. Compared with growth rates of lichens from temperate European regions the early development of U. antarctica is extraordinarily slow, taking 5–6 years until an adult thallus has been formed. The low photobiont content in the juvenile stages probably limits the growth rate. It is suggested that juvenile development of U. antarctica is controlled by a combination of ecophysiological and morphological adaptations that are required for success in extreme environments such as the terrestrial habitats of the Antarctic.

Jørgensen & James (1983) in their detailed study of the Leptogium azureum group in western Europe, pointed out that L. azureum (Swartz) Mont. was absent from Europe and that most of the European material so named belongs to L. cochleatum (Dicks.) P. M. Jørg. & P. James. Although both species show some morphological similarity, they also show a great number of differences. Leptogium cochleatum develops a darker and thicker thallus than L. azureum, with a finely striate upper surface, a different arrangement of the photobiont in the thallus, apothecia with persistent±wrinkled margins, proper euparaplectenchymatous exciples, the presence of paraplectenchymatous tissue at the base of apothecia and muriform ascospores which are larger than in L. azureum. For a summary of the most important characters distinguishing these two species see Jørgensen & James (1983). Leptogium valdivianum M. Lindström, a species from cool temperate South America, has also been confused with L. azureum, however, it can be distinguished by its distinctly thicker and dark leaden grey­blue thallus, apothecia with persistent thalline margins and its larger and broader distinctly muriform ascospores (Galloway & Jørgensen 1995; Lindström 1996).

The taxonomic position of the Neuropogon group, as inferred from the morphology of representative species of the group and ITS sequences from Usnea antarctica and U. sphacelata, is discussed. Morphological observations revealed that the Neuropogon group does not have annular-pseudocyphellae, which are characteristic of the subgenus Dolichousnea, or a fistulose axis, which is characteristic of the subgenus Eumitria. In addition, the hypothecium of Neuropogon is thin, and the iodine reaction in the axis is negative. These features are consistent with those of the subgenus Usnea. Within the subgenus Usnea, Neuropogon is morphologically distinct from sections Usnea and Ceratinae (i.e. having a sphacelata-type cortex, black pigmentation of the upper thallus and a dark brown apothecial disc). The molecular data suggest that U. antarctica and U. sphacelata are members of the subgenus Usnea and are less closely related to subgenera Dolichousnea and Eumitria. The morphological and molecular phylogenetic analysis suggest that the Neuropogon group is a member of the subgenus Usnea at the level of a section, and the appropriate name for this group is subgenus Usnea section Neuropogon (Nees & Flot.) Mont.

Each reference is numbered progressively and is characterized by publication details, a brief abstract and one or more abbreviations referring to specific themes. The list is followed by an Analytical Index of the different themes, showing the numbers corresponding to the appropriate references in the Bibliographic list. A new topic (RV) has been introduced to identify the review articles.