Montane old-growth forests on the windward slopes of interior mountain ranges in British Columbia support high loadings of arboreal lichens. These lichens represent a major source of readily labile plant material and potentially play an important role in ecosystem nutrient dynamics. Given the role of winter storms in scouring lichens from within the canopy and the extended length of winter snowpack, from November through to May or even early June, in these ecosystems, the decomposition of lichen litterfall should be heavily influenced by placement within the snowpack. We have examined this factor by placing litter bags containing samples of the hair lichens, Alectoria sarmentosa and Bryoria spp., on top of the winter snowpack in the Cariboo Mountains. Samples were set out in early- (8 Nov.) mid- (16 Jan.) and late- (22 Mar.) winter and subsequently retrieved on spring snow-melt (22 May). Lichen samples that were buried in the lower snowpack all winter long (196 days) lost two-thirds of their original mass. In contrast lichens placed on the snowpack in mid- (127 days) or late-winter (61 days) lost only 6-15% of their total mass, far less than would be predicted on the basis of time in snowpack alone. Spot measurements showed that the snowpack environment effectively buffers litter samples from extreme winter conditions. All lichen samples placed within the snowpack showed much higher C/N ratios on removal, indicating rapid leaching of readily soluble cellular constituents in the snowpack environment. These findings indicate that the snowpack environment plays a major role in decomposition processes in these high-elevation forests and reinforces our view that lichens are a readily labile nutrient source within these ecosystems.

Bacidina mendax, described here as a new lichen species, appears to be common and widespread, at least in Central Europe. Analyses of the ITS rDNA region and the morphology of specimens showed an intraspecific variation in the new taxon. It differs from B. neosquamulosa in the lack of a subsquamulose thallus, and from B. caligans in its longer and only slightly curved to apically hooked conidia and lack of a granular (sorediate) thallus. Since ITS rDNA data support the inclusion of Bacidia pycnidiata Czarnota & Coppins in the genus Bacidina, a new combination is proposed.

Lichen thallus fragments were maintained in a growth cabinet under four differing conditions of light intensity. Levels of usnic acid and atranorin did not differ significantly from the control under any of the treatments. However, perlatolic acid and fumarprotocetraric acid per unit dry weight of thallus were dependent upon light availability.

The weathering phenomena resulting from the growth of six foliose and crustose lichens (Parmelia subrudecta, Xanthoria ectaneoides, Parmelia conspersa, Aspicilia radiosa, Caloplaca sp. and Ochrolechia parella) on three mafic rocks have been studied. The bioweathering results in more or less extensive fragmentation and corrosion of the mineral surfaces immediately beneath the lichen thalli and in the formation, in the thallus or at the rock-lichen interface, of secondary products. The significant amounts of whewellite found in all interfaces, and the bipiramids of weddellite detected at the serpentine rock-Ochrolechia parella interface, suggest that the oxalic acid secreted by the mycobiont is the chemical substance principally involved. The capacity of the lichens to alter their rock substrata does not appear to be related to their thallus morphology.

Galactomannans were isolated from Cladonia signata, C. furcata, C. imperialis, and C. clathrata via successive alkaline extraction and precipitation with Fehling solution and Cetavlon. They were investigated using ⊃13C-NMR spectroscopy, methylation analysis, and Smith degradation, and their specific rotations and monosaccharide compositions determined. As with galactomannans of other Cladonia species, they contained (l →6)-linked main chains of α-mannopyranose, which were non-substituted (structure 4 in Fig. 2), monosubstituted at O-2 with α-mannopyranose (structure 6) or α-galactopyranose (structure 1), O-4 with β-galactopyranose (structure 2), and disubstituted at O-2 and O-4 with α-mannopyranosyl and β-galactopyranosyl units, respectively (structure 5). Disubstitution was present to a greater extent in the galactomannans of C. clathrata and C. imperialis than in those of C. signata and C. furcata. In the case of the galactomannans of C. furcata, C. clathrata, and C. imperialis, substitution also occurred at O-2 with O-β-galactofuranosyl-(l→6)-O-α-mannopyranosyl units (structure 7). As observed in previous investigations, the C-l portion of the ⊃13C-NMR of mannose-containing polysaccharides is typical of the lichen species. However, those of galactomannans of C. imperialis and C. clathrata are almost identical and, although other chemical data showed many structures in common, some differences were evident.

Twenty species and one variety of the genus Bactrospora Massal. are revised. The following new species are described: B. arthonioides sp. nov., B. brodoi sp. nov., B. carneopallida sp. nov., B. incana sp. nov., B. intermedia sp. nov., and B. spiralis sp. nov. Six species of Lecanactis and one of Bacidia are transferred to Bactrospora. A key is given.

Sections of the crustose saxicolous lichen, Caloplaca trachyphylla, were dated using 14C accelerator mass spectrometry (AMS). The data show a stron linear dependence of radial position on time (r=0.993), suggesting a constant radial growth rate. This specimen had averaged a marginal growth rate of 1.48 mm/year. Extrapolation of the growth curve yields a thallus age of 20 years. These data demonstrate the feasibility of using AMS technology to precisely date lichen tissues and determine growth rates of lichen thalli.

Eighteen species in the lichen genera Acanthothecis Clem. and Fissurina Fée (Graphidaceae) with colourless, trans-septate ascospores are recorded from India. Eight new species, namely Acanthothecis collateralis, Fissurina capsulata, F. coarctata, F. karnatakensis, F. khasiana, F. longiramea, F. taeniocarpoides and F. verrucosa, and a new variety, F. dumastioides var. salazinica, are described. Fissurina saxicola ad int., clearly distinguished from the other species is recorded, but is not formally described as new to science as the material is scanty. Acanthothecis consocians, F. globulifica, F. insidiosa and F. rugosa are reported for the first time from India. A key for the trans-septate species of Acanthothecis and Fissurina in India is provided.

A taxonomic revision of 15 taxa of Diploschistes from India and Nepal is presented. Two species, D. awasthii and D. nepalensis, are described as new. Diploschistes caesioplumbeus (Nyl.,) Vainio, D. diacapsis (Ach.) Lumbsch and D. eugatieus (Massal.) Steiner are new records for the lichen flora of India.

Fungi that are unrelated to the mycobiont species frequently colonize lichens. Some of these fungal colonists are described lichenicolous fungi, lichen parasites and pathogens that produce recognizable morphological characters, while others apparently produce no noticeable structures. Here we apply the single strand conformation polymorphism (SSCP) technique to directly assess the abundance of different fungi in lichens. Twenty-eight lichen thalli were chosen, some with and some without externally visible symptoms of parasite infection, and these were subjected to total DNA extraction. PCR was conducted with fungal-specific primers for the ITS region of ribosomal DNA. Single strands of the products were separated on native acrylamide gels. The majority of lichen specimens, both infected and those without symptoms, displayed more than one band in the stained gels. In one case, 14 bands were detected using SSCP. Some of these bands apparently represent other neighbouring lichens in the habitat, but many are apparently non-lichen-forming. Since few lichen-associated fungi have been cultured and sequenced, it is difficult to know if SSCP bands represent obligate lichenicolous fungi, other asymptomatic lichen parasites, or fungi not obligately associated with lichens, but our results indicate that large numbers of non-lichen-forming fungi commonly co-occur with lichens in nature. For specimens of the filamentous lichens Cystocoleus ebeneus and Racodium rupestre we used cloned sequences to compare the number of sequences obtained by the SSCP method to the number obtained by direct sequencing of thallus extracts, and we generally found that more sequences could be detected by SSCP than could be seen by direct sequencing.

The lichen genus Biatora comprises inconspicuous crustose lichens that are typically found on organic substrata such as tree bark, bryophytes and detritus. During the last 20 years many new species have been added to the genus making its delimitation more and more difficult. The infrageneric relationships of the 42 species have never been investigated thoroughly. Using DNA sequences from three gene loci (ITS, RPB2, mrSSU) and 59 OTUs, an attempt was made to reconstruct the phylogenetic relationships of Biatora and its infrageneric groups. Cliostomum appears to be the closest relative of Biatora. The position of Mycobilimbia in the Lecania-clade is confirmed. Phylogenetic relationships within Biatora are poorly supported, but six different species groups that are also phenotypically distinguished are more or less well supported: the vernalis-, meiocarpa-, hertelii-, ocelliformis-, beckhausii- and rufidula- groups. The analysis also confirms the presence of several undescribed taxa. Biatora subduplex as currently circumscribed appears to be heterogeneous, as does B. helvola. Based on the phylogeny, the distributional range of B. alaskana is extended to Japan. The new combinations Biatora ementiens (Nyl.) Printzen and Biatora hemipolia (Nyl.) S. Ekman & Printzen are made and both names are typified.

The inhibitory action of aqueous extracts from detached podetia of heathland Cladonia spp. and leachates from transplanted Cladonia turfs was tested using seeds of Avena fatua, Calluna vulgans and Deschampsia flexuosa. Significant inhibitory effects were found for each species. Further evidence from a field experiment suggests that patches containing a mixture of Cladonia spp. can inhibit germination or establishment of vascular species, probably through both chemical and physical processes, and thus maintain intact lichen patches in otherwise closed heathland stands.

Nine new species of foliicolous lichens are described from Los Tuxtlas Tropical Biology Station, Veracruz, Mexico: Asterothyrium atromarginatum sp. nov. (Asterothyriaceae), Enterographa perez-higaredae sp. nov. (Roccellaceae), Gyalectidium barbatum sp. nov., G. pallidum sp. nov., G. ulloae sp. nov. (Gomphillaceae), Opegrapha heliabravoa sp. nov., O. tuxtlensis sp. nov. (Roccellaceae), Pocsia alvari sp. nov. (Verrucariaceae) and Tricharia sublancicarpa sp. nov. (Gomphillaceae). Pycnidia are reported for the first time in Coenogonium hypophyllum (Vězda) Kalb & Lücking.

Phoma fuliginosa sp. nov. is described and illustrated from apothecia of Caloplaca trachyphylla (Teloschistaceae) collected in Nebraska, USA. The species is distinguished from other lichenicolous fungi referred to the genus in the shape and size of the conidia. It is considered pragmatic to continue to use the generic name Phoma for this group of lichenicolous coelomycetes until cultural and molecular information is available, although these fungi may later prove not to be congeneric amongst themselves nor with the species occurring on plants. A key to the 14 lichenicolous species now accepted in Phoma is provided, and notes on reports of some additional collections referred to the genus are included.

Ambient CO2 concentration (together with CO2 exchange and microclimate) was recorded every 30 min for 15 months for Lecanora muralis growing in the Botanical Garden Würzburg (Germany, northern Bavaria), a habitat on the outskirts of the city. Annual mean CO2 was around 17 ppm higher than the global average reported for the time of measurement (361 ppm; 1995/96), and daily values ranged from 317 to 490 ppm. Diel courses of CO2 could be classified into three different types. Type A, when CO2 levels rose overnight and then fell strongly to below global levels during the day, which predominated in the summer (about 75 of days); Type B, irregular diel courses occurred during all seasons with often very rapid changes apparently due to advective CO2 transport; Type C, CO2 concentration was typically almost stable at generally between c. 330 and 430 ppm which predominated in the winter (63 of days).

Under controlled conditions, CO2 saturation of net photosynthesis (NP) of L. muralis at optimal hydration and light occurred at around 1000 ppm. NP was also affected by low CO2 at limiting light and thallus water contents. Based upon these data, we estimated the improvement of NP of L. muralis due to transient increase of ambient CO2 (as compared with the global average) for one selected combination of environmental factors (nocturnal dew or frost). This combination is an important source of water for the lichen, resulting in 40 of its annual production and, especially in these situations, photosynthesis was increased by high ambient CO2 in the early morning under prevailing Type A conditions. After dew activation, light compensation point of NP occurred at an average concentration of 413 ppm and diel maxima of NP at 402 ppm. This allows a rough estimate that the transiently elevated CO2 increased the photosynthetic gain of the lichen after dew of 7, or an improvement to its annual carbon balance of about 3. Conditions, especially interrelationships between lichen hydration, light and CO2 are so complex that we are not yet able to extend our estimates to other environmental situations of photosynthetic activity of L. muralis.