The diminutive species Gyalidea praetermissa is described from Central Sweden. At the only known locality it grows on the sheltered and shaded vertical north side of a large boulder in an open pine forest. The species is mainly characterized by the 4-5-septate spores.

Thelopsis foveolata Renob. & Barreno sp. nov., is described from Northern Spain. It appears to be very rare and easily overlooked, but has a well-defined ecology. It grows on limestone within sciaphilous and humidity-loving communities, such as Gyalectetum leucaspidis and Petractinetum hypoleucae. The pycnidia and conidiogenous cells are described and illustrated, this being the first detailed account of these structures in the genus Thelopsis.

The lichen flora of high ground in the west of Ireland is described by reference to four localities (Brandon Mountain, Muckanaght, Ben Bulben, Slieve League). These were selected on the basis of their reputation for calcicolous alpine vascular plants and for being some of the most highly oceanic mountains in Europe. The montane element in the lichen flora is strictly limited, populations being small and isolated, although sub-montane species are more frequent. A small group of 44 species has been identified, which is 30% fewer than is found in either the Lake District or Snowdonia; their distribution and ecology are described. The margin of high-level tarns on Brandon Mountain support communities of outstanding importance, including Rinodina fimbriata, new to the British Isles. Seventeen lichens are reported as being new to Ireland.

The distribution and succession of epiphytic and other associated lichens on blackthorn (Prunus spinosa) growing on the shingle at Dungeness is described. Some 33 epiphytic species, which exhibited a range of ecological strategies from pioneer to late colonizers, were recorded. Both the rate of change of status (age) of blackthorns and the progress of lichen colonization seemed to depend on whether the bushes were growing directly on shingle or on adjacent alluvial soil; both processes seeming to be more rapid on the former substratum. Terricolous lichens, of which 18 were recorded, generally appeared late in the succession and mostly amongst bushes growing on shingle. Rabbits often invaded the blackthorns, especially those on alluvium, and probably contributed to the lack of terrestrial lichens under these bushes. Blackthorns growing on shingle tended to be more prostrate in form than those on alluvium.

The results of a nationwide survey of lichens associated with streams on chalk and limestone are reported. The lichen communities are present as a series of overlapping bands related to length of submergence. These have been named the submerged, fluvial mesic, fluvial xeric and fluvial terrestrial zones. The flora involves around 50 lichens, many of which are rarely recorded specialists restricted to this habitat. The richest sites for submerged species are headwaters, especially around springs. Active tufa deposition and disturbance of the stream bed by farm stock are detrimental to aquatic lichens. Diversity further downstream is related to the amount of exposed limestone available for colonization, with topographical complexity also important. An investigation of the influence of water quality suggests that suspended solids (silting) is a significant determinant of lichen distribution together with eutrophication.

Lichens were cultured by attaching a thallus fragment to a nylon monofilament loop with silicone sealer. Two effective methods for adjusting lichen mass to a standard moisture content were developed (the ‘reference-sample’ and ‘sacrificial’ methods). These corrections for moisture content allow detection of very small changes in dry mass without having to oven dry (and kill) all transplants. Average annual biomass growth rates for non-fragmenting species were typically between 5 and 30%. Annual biomass growth rates of healthy, vigorous individuals, as indicated by the 75th percentile, were mostly between 10 and 40%. Alectoria sarmentosa was prone to fragmentation despite the maintenance of healthy thalli. The other species can be ranked by biomass growth rates as follows: Evernia prunastri> Lobaria pulmonaria=Usnea longissima> Pseudocyphellaria rainierensis=Lobaria oregano.

Cladina subtenuis is the most commonly found ‘ reindeer lichen ’ in the southeastern United States. In the present study C. subtenuis was examined for polymorphism in the small subunit (SSU) ribosomal DNA (rDNA) within and among small clumps of podetia, here referred to as mats, from five geographical locations. Polymorphism in the SSU rDNA was not detected among podetia within mats, but polymorphism was detected among mats from a single location. Therefore, mats of C. subtenuis may represent a single genetic individual, although genetically distinct mats may occur in close proximity. Their proximity couldencourage sexual reproduction between genetically distinct individuals, which would maintain variation in these populations. The SSU rDNA types represented three different lengths and restriction-site patterns, reflecting the presence of sequence insertions of at least 200 nucleotides in the SSU rDNA coding region. Thei nsertions, differing in position, number and sequence, are group I introns similar to those previously reported in the Cladonia chlorophaea complex. The intron variation among the SSU rDNA types indicates that molecular evolution has occurred within this species, perhaps since its divergence from related taxa and dispersal across the southeastern United States.