The new crustose lichen genus Tasmidella, containing the species, T. variabilis sp. nov with two varieties, var. variabilis and var. inactiva var. nov., is described. Tasmidella is most closely related to Megalaria, from which it differs chiefly by having simple ascospores with a layered wall. Relationships with superficially similar genera are discussed. A revised circumscription of the family Megalariaceae is provided to take into account the inclusion of a second genus.

Pyrenocollema montamnn P. M. McCarthy & Kantvilas sp. nov. (Xanihopyreniaceae) is described from moist and aquatic alpine rocks in south-western Tasmania.

The new species, Schaereria bullata Kantvilas from alpine Tasmania, is described and illustrated, with notes on its characterization, distribution and habitat. A key to the seven known species of the genus is provided.

Three species of Porina (Trichotheliaceae), P.kansriae P. M. McCarthy, P. siamensis P. M. McCarthy and P. wolseleyae P. M. McCarthy, are described from aquatic and semi-aquatic rocks in montane rainforest in north-eastern Thailand.

The new species Peltigera phyllidiosa Goffinet & Miadlikowska from the Southern Appalachians, eastern U.S.A., is closely related to P. collina and P. neckeri. Like these species it has a glabrous upper cortex and black fingernail- or saddleshaped apothecial discs, but differs in its laminal phyllidia. Variation in nucleotide sequences of the Internal Transcribed Spacer (ITS) of the nrDNA repeat region correlates with the presence or absence of phyllidia, supporting the distinction of P. phyllidiosa from P. collina and P. neckeri.

A protocol is described to enable the production of reliable genetic fingerprints of lichen-forming fungi using randomly amplified polymorphic DNA (RAPD) markers. Key features of the method are the use of mycobiont DNA extracted from axenic cultures by a phenol-chloroform procedure, and PCR amplification using DyNAzyme II DNA polymerase. RAPD-PCR fingerprints of Graphis scripta, G. elegans and Phacographis dendritica were successfully generated using this protocol and individual isolates could be identified on the basis of differences in banding patterns produced. DNA extracted from whole thalli of G. scripia was also subjected to RAPD-PCR but the fingerprints produced differed from those given by axenic cultures of the mycobiont. Therefore difficulties of interpretation may arise when whole thalli are used in RAPD analysis.

A community ecology approach using an association of species test and a principal component analysis resulted in the recognition of two major and two minor foliicolous lichen communities in a neotropical rainforest. The major communities arc governed by microclimatic factors, one characteristic of the shady understorcy and the other confined to light gaps. The minor communities are due to subtle phorophyte preferences towards palm and dicot leaves. The shady understorey community is dominated by the families Anhoniaceae, Opegraphaceae, Tnchoihdiaceae and Pilocarpaceae, which predominantly have Phycepeltis as their phycobiont, thin thalli, abundant sexual reproduction, small ascospores produced in high numbers, and pyenidial conidiomata. The light-gap community is mainly composed of the families Gomphillaceae and Ectolechiaceae, with Trebouxia as their phycobiont, thickly crystalline or whitish, dispersed thalli, frequent asexual reproduction, large ascospores produced in low numbers, and specialized campylidia and hyphophores as conidiomata. Phycobiont, thallus structure, and the mode of reproduction are considered as adaptations to different microsites, whereas the shape and size of ascospores and conidia seem to be of less importance. The foliicolous lichen communities reflect the spatial and temporal structure of the forest, in particular the continuity of the shady understorey in comparison to the discontinuity of the light gaps. While the formation of the shady understorey community follows more deterministic patterns, the light-gap community exhibits high stochasticity.

The phytosociology of lichens colonizing granitic churches and dolmens in Galicia (N.W. Spain) and Alentejo (central Portugal) was studied so as to identify (a) a group of species whose frequency on these structures would make them potentially useful as test species for the evaluation of biocides used for conservation, (b) environmental factors likely to control species distribution, and (c) species that may be useful as bioindicators of environmental factors in this kind of construction in the region studied. Chief among the factors correlating with species distribution is the class of structure (church or dolmen), which is attributed to the probable influence of this factor on environmental parameters affected by structural complexity, the presence of non-granitic materials and the influence of man in the immediate surroundings. The bioindicator species most sensitive to this complex of parameters appear to be three species found only on churches (Caloplaca citrina, Sarcogyne davits and Verrucaria macrostoma) and the most widespread of the species found only on dolmens (Lasallia pustulata). Other important factors, probably affecting the influence of class of structure, are pH and the availability of nitrogen and moisture.

It has been suggested that the host specificity exhibited by some lichenicolous fungi depends on their ability to tolerate the secondary chemistry of potential host lichens. For example, the lichen parasite Marchandiomyces corallinus is able to degrade the tissues of the lichen Flavoparmelia baltimorensis irrespective of the presence or absence of endogenous phenolic compounds. In contrast, the degradation of tissues from the lichen Lasallia papulosa is suppressed when endogenous phenolics are not removed. We have investigated the physiological basis of this inhibition in order to understand more about how lichen chemistry infiuences host preference in lichenicolous fungi. Results showed that the secondary compounds from L. papulosa inhibit the overall growth of M. corallimis, but not the catalytic activity of its tissue-degrading polysaccharidases. This effect is different from that shown by another lichen parasite, Nectria parmeliae, where lichen compounds specifically inhibited polysaccharidase activity. Compared with the compounds of L. papulosa, the endogenous phenolics of F. baltimorensis inhibited the growth of M. corallimis substantially less and exhibited little or no inhibition of polysaccharidases. For M. corallimis, host preference appears to be associated with physiological adaptation to the chemistry of F. baltimorensis.