The development of 12 litter and seven phylloplane fungal species was examined from spore germination to colony sporulation across a series of environmentally relevant UV-B doses. For the litter fungi all aspects of fungal development and morphology studied were affected. On the basis of the responses of mycelial extension rate and spore germination to increasing UV-B, the 12 litter fungi were divided into two groups. Group A (Aspergillus fumigatus, Penicillium hordei, P. janczewskii, P. spinulosum and P. purpurogenum) were sensitive to UV-B, with the predicted effects of a 15% ozone depletion resulting in 22–44% reductions in spore germination. Mycelial extension rate on the agar surface was similarly affected, with reductions ranging from 15 to 25%. In contrast group B (Mucor hiemalis, Cladosporium cladosporioides, Leptosphaeria coniothyrium, Trichoderma viride, Ulocladium consortiale, the Verticillium state of Nectria inventa and Marasmius androsaceus) were relatively insensitive to UV-B, with significant, but small, reductions in mycelial extension rate (<5%) and spore germination (0–22%). Spore production in response to UV-B in the litter species was very variable, reductions ranging from 5% to complete inhibition. Only P. hordei showed a significant increase in spore production in response to UV-B dose. In contrast, in all seven phylloplane species, spore germination was unaffected by increasing dose. Mycelial extension rate was slightly (2–12%), but significantly, inhibited by UV-B for the four phylloplane fungi tested. The contrasting responses of phylloplane and litter fungi to UV-B are discussed along with the implications for resource capture by competing fungal species and the possible effects of UV-B on decomposition processes.

Sequences of nuclear ITS (nrDNA) regions were obtained from 22 species of Tyromyces s.l., a group of important wood-rotting, poroid holobasidiomycetes, belonging to Coriolaceae. Different reference collections of a species generally produced identical molecular sequences. Parsimony analysis of these sequences resulted in trees compatible with the currently accepted delimitation of genera, but the alignment of sequences has proven to be difficult owing to regions of uncertainty. Analyses based on inclusion and exclusion of ambiguous regions in the alignment demonstrate that closely related taxes are, however, always clustered together, especially at the generic level. It is considered that ITS sequences are reliable in distinguishing genera and species of Tyromyces s.l., but not able to provide sufficient resolution for relationships between some formerly recognized genera. The taxonomic implications of ITS variation are also discussed. Species of Oligoporus and Postia clustered in one clade, indicating a close relationship as shown from morphological research. Species of Skeletocutis are characterized by encrusted hyphal ends in the hymenophore, but the type species of Tyromyces, T. chioneus, is embedded within the Skeletocutis clade, indicating a strong link between these two genera. Species of Antrodia and of Spongipellis included in this study were not well supported as monophyletic groups, although they are clustered together within the trees.

To test the validity of R. tauricus as a separate species, its carbon source utilization, isoenzyme patterns and PCR-coupled RFLP of the ITS of its rDNA were analysed. Whilst R. tauricus differed considerably from R. pusillus and R. miehei in morphological traits as well as its ability to row on single carbon sources, the results obtained from all other experimental approaches suggest extensive similarity between R. tauricus and R. pusillus. These findings lead us to believe that R. tauricus is a mutant heterothallic strain of R. pusillus.

Analysis of Amplified Fragment Length Polymorphisms (AFLP) in a sample population of Epichloë and Neotyphodium was conducted to evaluate the usefulness of this technique in estimating phylogenetic relationships among these fungi. A total of 963 unique restriction fragments were identified with 13 selective primer combinations. Neighbour-joining and parsimony analysis produced phylogenetic trees with high bootstrap support. All Epichloë festucae isolates were monophyletic, and clades of E. festucae were identified that correspond to the host species from which they were isolated. These groups may indicate the importance of coevolution in the development of the fine fescue-E. festucae symbiosis. The grouping of E. festucae isolates from hard fescue and Chewings fescue into one clade conflicts with the current taxonomy of these host grasses. Sequencing of ribosomal DNA spacer regions ITS1 and ITS2 was conducted for comparisons to the phylogenetic relationships estimated by AFLP. Using the maximum likelihood test, a significant difference was detected between AFLP and rDNA trees due to discrepancies in the association of anamorphs (Neotyphodium) and teleomorphs (Epichloë). This discrepancy may be due to some mechanism of genetic recombination, such as hybridization or parasexual recombination, that occurs in Neotyphodium populations. It is concluded that AFLP markers are useful for producing meaningful phylogenies among a diverse group of fungi and for identifying groups of closely related individuals that are genetically and biologically similar. Further investigation is needed to determine how AFLP markers change over short periods of time in populations and over evolutionary time.

Ultrastructural and morphological studies have been carried out on M. tumidum, the type species of Myelosperma. Asci are provided with a distinctive refractive subapical ring, which differs from that found in other unitunicate families. The ascospores are reniform in all species and surrounded by mucilaginous sheaths of various shapes. Numerous ascomata also develop in a circle around a common central pore. At the ultrastructural level the ascus apex comprises an electron-transparent thickening incorporating a subapical electron-dense hemispherical ring-like structure and the ascus wall is continuous over the apex. This type of ring is compared with those found in representative species in other related families. Based on these observations, a new family, the Myelospermaceae, is introduced, to accommodate Myelosperma. The rationale behind this is discussed, and M. alata is described to accommodate a remarkable new species from the Seychelles. Arguments for the possible inclusion of Manokwaria, Palmicola and Pemphidium in the Myelospermaceae are given.

In experimental microcosms, three Glomus spp. were subjected to heating to over 200°C at the soil surface and 70° at 5 cm to determine the effect of fire on survival of arbuscular mycorrhizal fungi. Heating reduced the quantity of propagules surviving at the soil surface and the effect declined with depth. While all propagules are likely to be affected by heat, we argue that the hyphal network is most severely disturbed and probably responsible for declines in density of fungi observed in the field following fire.

Genetic relationships of twenty strains of Scedosporium, Petriella and Pseudallescheria were studied by sequencing a 370 bp part of the gene which encodes the large subunit ribosomal RNA (LSU rDNA). This study confirms and specifies earlier results from the small subunit ribosomal RNA gene (SSU rDNA).

It was confirmed that the pathogenic Scedosporium prolificans is closely related to Petriella, as is Graphium tectonae. Petriella setifera, which includes clinically isolated Scedosporium strains, can be divided into several groups inside the same genus.

The main part of Pseudallescheria is clearly distinguished from Petriella. Pseudallescheria is heterogeneous, however: Ps. africana is referred to Petriella and Ps. fimeti is more closely related to Microascus.

Three hypotheses of the phylogeny of the lichenized Parmeliaceae are constructed, using sequences of the nuclear ribosomal gene cluster (SSU, ITS, 5·8S rDNA) from Bryoria capillaris, Cetraria islandica, Evernia prunastri, Hypogymnia physodes, Parmelia saxatilis, Platismatia glauca, Pleurosticta acetabulum, Usnea florida, Vulpicida juniperina, V. pinastri and Xanthoparmelia conspersa. The first analysis, based on SSU sequences, shows the representatives of the Parmeliaceae to form a monophyletic group within the order Lecanorales. Usnea florida and Bryoria capillaris, sometimes classified in the families Usneaceae and Alectoriaceae, respectively, are also members of the Parmeliacceae. Cetraria and Vulpicida form a well-supported monophyletic group together with Usnea, but there is little support for any other groupings within Parmeliaceae. The second analysis is based on ITS an 5·8S sequence data of the representatives of the Parmeliaceae included in the first analysis, and supports the close relation of Cetraria and Vulpicida. Other groupings are not supported, and the topology also varies greatly with minor alignment changes. This is attributed to the included taxa being too distantly related to each other, causing alignment difficulties of the variable ITS region when a relatively small number taxa are included. It is predicted that a larger sample of phylogenetically intermediate taxa will overcome this problem. When combining the two datasets, the results are similar to the ITS results. The present study is one of the first phylogenetic studies utilizing the information in more than one gene alone in lichenized ascomycetes.

A new anamorph genus, Acarocybiopsis, with A. cubitaensis as type species, is described. It is characterized by an unusual combination of indeterminate synnemata having two kinds of hyphae and terminal head composed of a single conidium.

Colletotrichum dematium is the cause of a new fungal stem disease on cowpea in South Africa. The pre-penetration and infection process of this fungus on cowpea stems was studied by light microscopy and SEM. Conidia began germinating at 6 h post inoculation (hpi), forming appressoria directly or at the ends of germ-tubes. By 14 hpi appressoria had melanized and direct penetration of host tissue had begun. At 20 hpi infection vesicles formed in epidermal cells. Thick, knotted primary hyphae formed from these vesicles and entered adjacent cells. At ±40 hpi C. dematium produced secondary hyphae which were highly branched, and grew extensively inter- and intracellularly. After approximately 48 hpi light brown lesions appeared on the stem, associated with the invasion of secondary hyphae into cells and cell necrosis. Acervuli with one or two melanized setae were visible on lesions by 70 hpi.

Batcheloromyces spp. are dematiaceous hyphomycetes which cause leaf spots on members of the Proteaceae in South Africa. The leaf spots are non-necrotic and composed of numerous sporodochial conidiomata. Conidiogenesis is holoblastic with percurrent, enteroblastic proliferation producing conidiogenous cells with ragged and irregular annellations. Brown, verrucose, aseptate and multiseptate conidia are produced. Conidia produced percurrently, can remain adhered to each other in fragile chains, disarticulating to produce aseptate conidia or, in some cases, they remain as multiseptate conidia where further schizolytic cleavage, at the delimiting septa, may or may not occur. This paper compares Batcheloromyces with the morphologically similar Stigmina, discusses the current members of Batcheloromyces and introduces the new species B. leucospermi.

Field isolates of Rhizoctonia solani are presumed to consist of heterokaryotic cells, but the number of different nuclear types present in each cell is unknown, nor is it known if there is any regulation of the heterokaryotic state. To investigate the nature of heterokaryosis in AG 4, hyphal tip subcultures of two strains were examined using vegetative compatibility as a marker. Upon subculture, each isolate could be placed into one of two VCGs, members of which were compatible within the group but incompatible with those of the other group and the parent strain. No other phenotype could distinguish these groups from each other or the parents. Pairing of hyphal tip isolates never resulted in regeneration of the parental strain. Examination of nuclei in the tip cells of incompatible strains by DAPI staining and fluorescence microscopy showed variation in nuclear numbers in different parts of the fungal colony and a significant tendency for some adjacent branch tips to have a similar number of nuclei. These results suggest a mosaic of nuclear, and perhaps mitochondrial, types within the colony, and that subcultures of components of the mosaic retain their differences. This variation implies that regulation of nuclear number within a colony is loosely controlled.

Penicillium verrucosum is one of the main producers of ochratoxin A (OA) in agricultural commodities. To forecast the risk of OA contamination, there is a need to improve our knowledge on the ecology of P. verrucosum in the field. Dilution plating on ‘dichloran yeast extract sucrose 18% glycerol agar’ (DYSG) offers a simple and very sensitive method of detecting P. verrucosum propagules in soil. The properties of DYSG are illustrated in a suspension mixture experiment and confirmed in a soil mixture experiment. In the latter, P. verrucosum could be detected in conidial concentrations below 200 colony forming units (cfu) g−1 soil even when it constituted no more than 0·3% of the cfu. Furthermore, the DYSG method can be used to estimate the abundance of P. verrucosum propagules in soil with good precision. In some of the analysed cases, however, it was necessary to use appropriate mathematical models to treat results with high numbers of cfu on the Petri dishes.

A detailed examination of the rediscovered type of Tulostoma volvulatum leads to the conclusion that it represents an earlier name for T. giovanellae. The former name will be proposed for rejection and the latter for conservation. Tulostoma volvulatum s. auct. becomes T. obesum.

We try to explain the large differences observed in the proportion of needles colonized by fungal species in coniferous litter by spore dispersal properties. We constructed a population dynamics model, assuming that litter is a resource that is fragmented into ephemeral units, periodically produced. Spore dispersion on needles on a small spatial scale was assumed to follow a Poisson distribution. The model was compared with an experimental system using Thysanophora penicillioides on Abies alba needles and its relevance to field conditions is discussed.

Species of Gondwanamyces are unusual amongst the ophiostomatoid fungi in that they are associated with the infructescences of Protea in South Africa. These fungi are distinguished from other ophiostomatoid genera by their Knoxdavesia anamorphs. Knoxdavesia spp. are peripherally similar, but distinct from Stachybotrys and Phialocephala. They are, however, morphologically identical to Custingophora. Custingophora olivaceae, was isolated from compost in Germany, a niche very different from that associated with fungi from Protea spp. The similarity of Custingophora and Knoxdavesia is such that they cannot be distinguished morphologically. The notion that Gondwanamyces might represent a teleomorph for Custingophora is intriguing. To determine whether an anamorph–teleomorph connection exists between Knoxdavesia and Custingophora, we determined the sequence of approximately 1100 nucleotides from the large subunit (LSU) ribosomal RNA gene. Results suggest that species of Gondwanamyces and C. olivaceae are phylogenetically related. This, as well as their morphological similarity suggests that Gondwanamyces and C. olivaceae have a shared ancestry. They are, however, sufficiently different that Gondwanamyces is probably not a teleomorph for Custingophora olivaceae.

Two new species of Wawelia are described from rabbit and hare dung incubated under conditions of restricted water supply. A key to the five known species of Wawelia is provided.

Most species of Ceratocystis sensu stricto are virulent pathogens of a wide variety of plants including forest and fruit trees, sweet potato, pineapple and sugar cane. Confusion exists regarding the taxonomy of the species in this genus. The aim of this study was to develop a rapid and reliable PCR-based RFLP identification method and to consider phylogenetic relationships among the better-known species of Ceratocystis. A 1·6 kb fragment within the ribosomal DNA operon was directly amplified from living fungal tissue, without extracting DNA. The amplified fragment included part of the small (SSU) and large (LSU) sub-unit rRNA genes, the 5·8S rRNA gene and the internal transcribed spacers (ITS) 1 and 2. The PCR fragments were digested with eighteen restriction enzymes. Four of these (Alu I, Dra I, Hae III and Rsa I) produced RFLPs that separated the species of Ceratocystis. The amplification products from the best-known species were sequenced, and the delimitation of taxa based on this phylogenetic analysis generally agreed with results of previous studies using isozymes and rDNA sequence analysis. This study provides an extended understanding of the relationships among species of Ceratocystis and will form a sound foundation for further taxonomic studies of the group.

Coemansia aciculifera, C. scorpioidea and C. thaxteri were found in the rhizosphere of wheat and a fungus resembling C. spiralis was found in the rhizosphere of barley from two fields in eastern England when serially washed root pieces were incubated on low nutrient agar (SNA).

Mating type and RG57 fingerprints were determined for 141 isolates of Phytophthora infestans from 63 fields in all the important potato growing areas in Norway and Finland. Seventy-six multilocus genotypes were identified, of which 53 were detected only once. Norwegian and Finnish isolates were similar in terms of genotypic diversity and the genetic distances between the genotypes. The large number of genotypes and the high genetic distances between the genotypes indicate that sexual reproduction is contributing significantly to the genetic variation of P. infestans in Norway and Finland.