Iberian records of Buellia triseptata A. Nordin are presented. This corticolous and lignicolous species was recently described from North America. A description based on the Iberian material is given, together with notes on ecology and distribution. Specimens belonging to B. triseptata were previously reported as B. disciformis, B. lauricassiae, B. pharcidia and B. triphragmia. The main distinguishing features between these taxa and B. triseptata are pointed out, and background to the misapplied names is given. Illustrations of the ascospores of B. triseptata and B. lauricassiae are presented. A distribution map of B. triseptata in the Iberian Peninsula is also provided.

The new species Rhizocarpon timdalii, is described from north-west Europe and north-east North America. The ecology and distribution of the new species are also discussed.

The fruticose lichen Cavernularia hultenii exhibits a strongly disjunct distribution between north-western North America, Newfoundland and north-western Europe. An investigation of its population structure, based on nuclear ITS and IGS DNA sequences, shows that western North America has a higher number of haplotypes than the two other areas. Most of the haplotypes confined to this region are rare and occur outside the area that was affected by Pleistocene glaciations. Three haplotypes are common in all three areas. The high number of haplotypes in western North America might be due to a combination of events during the Pleistocene and Holocene epochs, viz. increased lineage survival by repeated fragmentation of populations and reduced lineage extinction through rapid postglacial expansion and population growth.

The lichen family Thelotremataceae was studied in Thailand and Malaysia (including one specimen from Indonesia). Of the 30 new species recognized, 26 are recorded from Thailand: Myriotrema grandisporum, M. khaoyaianum, M. khuntanense, M. rongklaense, M. subanamaliense, M. subgranulosum, M. subminutum, M. thailandicum, M. whalleyanum, Ocellularia brunneospora, O. diospyrosis, O. flavescens, O. inthanonensis, O. kansriae, O. krathingensis, O. melanophthalma, O. neoleucina, O. peremergens, O. pluriporoides, O. rhicnoporoides, O. subleucina, O. wolseleyana, Thelotrema laemense, T. mongkolsukii, T. phliuense and T. rhododiscum; and 4 from Sarawak: M. coppinsii, M. muluense, O. neoperforata, and O. roseotecta.Additional notes are provided on Ocellularia palaeoamplior Aptroot & Sipman and Thelotrema isidiophorum (Kremp.) Zahlbr.

There is evidence to suggest that part of the recent changes in the lichen flora of the Netherlands is attributable to an increase in temperature. Changes which have occurred over the last 22 years were studied in detail, and were subjected to a statistical treatment by comparing the change of species to their latitudinal distribution and to ecological determinants.

All 329 epiphytic and terrestrial lichen species occurring in the Netherlands were considered in relation to their world distribution. Arctic-alpine/boreo-montane species appear to be declining, while (sub)tropical species are invading. The proportion of increasing species is by far the largest among the wide-tropical lichens (83%), and smallest among the arctic-alpine/boreo-montane lichens (14%). None of the wide-tropical species was found to decrease, while 50% of the arctic-alpine/boreomontane species show a decline.

Long-term monitoring of the epiphytic lichen flora in the province of Utrecht from 1979 onwards shows that the total number of taxa present increased from 95 in 1979 to 172 in 2001, while the average number of taxa per site increased from 7·5 to 18·9. The rate of increase was greatest by far between 1989 and 1995. The majority of the species (152 taxa or 85%) show a gross increase, only 17 species (10%) show a decrease.

A detailed analysis of these data using multiple regression suggests global warming as an additional cause for recent changes, next to decreasing SO⊂2 and increasing NH⊂3. Changes appear to be correlated initially (1979-1995) only with toxitolerance and nutrient demand. Changes between 1995 and 2001, however, appear positively correlated to both temperature and nutrient demand, indicating a recent and significant shift towards species preferring warm circumstances, independent from, and concurrent with changes due to nutrient availability.

This is the first paper reporting long-term floristic changes for lichens that appear to be correlated significantly with increasing temperatures. We suggest that future lichen monitoring programmes also pay attention to effects of climatic change, instead of focusing on air pollution effects only.

The chemical and ultrastructural features of the interface formed by different biotypes of saxicolous lichen species with their rock substrata were investigated in the semiarid habitat of the SE Iberian Peninsula and the relationships between the bioweathering patterns observed and lichen colonization selectivity towards the different rock substrata evaluated. Xanthoria parietina was able to fix to the rock substratum by the adherence of single cell walls from the lower cortex. Neofuscelia pulla used rhizines and loose groups of hyphae for attachment of the thallus to the rock. Colonization by the foliose lichen species was confined to the rock surface, while Diploschistes diacapsis was also able grow below the surface showing two types of hyphal growth. Minerals in close contact with cell walls were biochemically and biophysically weathered, but hyphae showing calcium oxalate crystals did not appear to be directly involved in the patterns observed. The textural characteristics of the substratum seemed to be related to the type of microorganism colonization: sedimentary rocks were more deeply colonized by lichens and other chasmolithic microorganisms than volcanic material. Calcium oxalate crystals were found in the medulla of N. pulla but not at the lichen-substratum interface. Crustose lichens such as D. diacapsis showed calcium oxalate crystals in the upper cortex and over the outside of fungal medullary hyphae but not in direct contact with the rock surface. Calcium oxalate precipitation seems to be related to the different metabolic activities of the mycobiont within the lichen thallus and to different species. D. diacapsis inhibits the growth of other microorganisms in close proximity to the thallus, whereas foliose species were associated with several communities of microorganisms.

14C/C ratios in samples from radial transects across individual thalli of Caloplaca trachyphylla collected at two sites were measured and the results used to investigate whether 14C/C data might provide some insight into the magnitude of carbon turnover in this lichen species. The 14C/C data suggest that significant internal recycling/translocation of carbon is unlikely in the sampled thalli. However, converting the 14C/C data for the larger intact thalli sampled at each site to calendar years, using the atmospheric ⊃14C record, does not yield constant or even monotonically varying growth rates. Since crustose lichen growth rates are constant or decrease with thallus size, and since the 14C/C data from these larger thalli show a relatively small spread in 14C/C data values compared to the Northern Hemisphere atmospheric ⊃14C record over the past 50 years, the 14C/C data suggest that carbon turnover may be occurring. Carbon turnover was modelled starting with the atmospheric ⊃14C record. Turnover was incorporated so that for each year in the record a constant percentage of the total carbon was lost annually and replaced by new photosynthetically fixed carbon with a 14C/C ratio equal to that of the contemporary atmosphere. The 14C/C data from the radial samples were then converted to a calendar year using the model record. Constant annual carbon turnover values of 0, 0·5, 1, 1·5, 2, 2·5, 3, 3·5, 4, 4·5, 5, 5·5, 6, 7, 8, 9, 10, 15, 20, 25 and 50% were modelled. Carbon turnover values between 3 and 6% created ⊃14C model records that when applied to 14C/C data from the thalli produced constant radial growth rates that were: (1) identical for all lichens at a given site, and (2) independent of lichen size at a given site. The 14C/C data further indicate that annual carbon turnover in this species of lichen is <10%, independent of the nature of thallus radial growth. The data and modelling suggest that carbon turnover might provide a simple explanation for the 14C/C data from the thalli and might explain the discrepancies between the standard atmospheric ⊃14C record and the 14C/C ratios observed in C. trachyphylla.