In an attempt to clarify the taxonomic status, geographical distribution and host relationships of Laboulbenia pterostichi and its close allies, especially in relation to the parasites found on European Pterostichini (Coleoptera, Carabidae), we have examined the type series and a wide range of material from the northern hemisphere. We conclude that the presence of L. pterostichi on European Carabidae is not confirmed and that most records are based on misidentifications of the variable species L. pseudomasei.

Eight new species of ascomycete, Anthostomella longispora sp. nov., Capronia glabra sp. nov., Dictyonella circinata sp. nov., Guignardia castanopsis sp. nov., G. clematidis sp. nov., Hysterographium longisporum sp. nov., Ophiodothella arengae sp. nov. Saccardoella miscanthi sp. nov. from Taiwan are described, illustrated and compared with closely related taxa. Keys to Anthostomella species on Smilax and to the recognized species of Dictyonella are also provided. The two Guignardia species are also associated with Phyllosticta anamorphs.

This paper sketches the origins and the history of the British Mycological Society over its first century with emphasis on the individuals and institutions which have nurtured it.

Zoospores of the nematode-parasitic Catenaria anguillulae (Chytridiomycota) were studied by videomicroscopy in sealed films of water on microscope slides in the presence or absence of freeze-inactivated nematodes (Panagrellus redivivus). Zoospores swam for more than 1 h at a mean velocity of 104 μm s−1, interspersed with repeated phases (1–2 min) of amoeboid crawling on glass or nematode surfaces. They were attracted to and encysted near the mouth, excretory pore, and anus of nematodes, or eventually encysted at random on glass and nematode surfaces. The single posterior flagellum was immobile during amoeboid crawling but resumed rapid beating when the last pseudopodium was being retracted. Zoospores encysted by adhesion of the anterior of an amoeboid cell to a surface; then the cell posterior was raised above the anterior so that the flagellum projected perpendicular to the surface, and the flagellum was retracted by rotation of the cell contents. Cysts germinated within 20–60 min by a narrow germ-tube at the site of adhesion. The germ-tube grew a short distance, then formed an intercalary vesicle into which the cyst contents emptied by expansion of a cyst vacuole. In several cases the germ-tube penetrated a nematode and formed the vesicle inside the host. Rhizoids or assimilative hyphae developed from the vesicle or by growth of the germ-tube tip. An increasing proportion of zoospores that remained motile after 1 h in water films had a globose body in contrast to the normal elongated form. This seemed to be caused by damage during repeated transitions between the amoeboid and swimming phases, because pseudopodia sometimes remained firmly attached to a glass surface.

C. anguillulae showed consistent orientation (polarity) of zoospore encystment and cyst germination. This parallels the behaviour of other zoosporic fungi or fungus-like organisms (Plasmodiophora brassicae, Rozella allomycis, Pythium, Phytophthora and Saprolegnia spp.) suggesting that it is a common feature of zoosporic parasites. Surface-recognition for encystment by C. anguillulae was mediated by the zoospore soma, not the flagellum. In addition, we redefine the early development of C. anguillulae, including flagellar retraction by rotation of cell contents, non-specific adhesion of zoospores and cysts to surfaces, and evacuation of cyst contents into a vesicle from which further growth occurs.

Osmotrophic eukaryotes with a cell wall during the assimilative phase are ‘fungi’: the term ‘fungus’ is an essentially physiological concept, thus flagellate fungi conforming to this definition are not ‘pseudofungi’. But mycologists may also work with flagellate organisms which are phagotrophic or lack a plasmodial cell wall and, therefore, are not strictly ‘fungi’. In fungi the flagellate stage is confined to planonts (asexual zoospores and gametes).

Flagellar form and function have many conserved characteristics, but although ultrastructural diversity, particularly in kinetosome/flagellar root structure, has been intensively studied, other morphological features of the zoospore have been less thoroughly explored. The numbers, lengths, orientations and structural ornaments of flagella all provide data for biodiversity assessments at the species and ecological levels. The structural and functional biodiversity of fungal flagella and zoospores are reviewed, particularly with respect to the isokont/anisokont flagellar lengths and the isokont/heterokont flagellar ornaments of the zoospore. The straminipilous ornamentation has particular functional significance.

Correlations between molecular biology and flagellar ultrastructure indicate that several independent phylogenetic lines have evolved flagellate fungi. The strengths and weaknesses of the databases for these phylogenies are discussed in historical and current contexts.

Nine isolates of a Colletotrichum sp. collected in North America on yellow water-lily (Nuphar luteum subsp. polysepalum) at five locations in the Pacific Northwest (PNW) and one isolate from Nymphaea odorata in Rhode Island were compared to three isolates of C. nymphaeae occurring on Nymphaea alba and Nuphar luteum in Europe. The appressoria of all North American isolates were significantly wider than those of C. nymphaeae. Conidia of the nine PNW isolates were significantly wider than those of both the Rhode Island isolate and C. nymphaeae isolates. All isolates were compared using random amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism of the ITS region (RFLP-ITS). Two distinct clusters were differentiated in the dendrogram based on the RAPD analysis. The ten North American isolates formed one cluster and the European isolates of C. nymphaeae formed a second cluster. The separation of the North American isolates from the European isolates was supported by distinct restriction digest phenotypes of the ITS region. Based on morphological and molecular characterization the North American fungus is proposed as a new species, C. nupharicola.

In this investigation, we have determined the life span of the fruit bodies of Agaricus bisporus grown in a protected cultivation environment as 36 d. We describe the morphological changes occurring in ageing mushrooms and find that signs of senescence become visible around day 18; they steadily increase in amplitude towards the end of the fruit bodies' life. Cytologically, karyolysis and focal cytoplasmolysis were the first signs followed by indications of an increased permeability of the cytoplasmic membranes and by structural changes of the cell wall. These changes result in extracellular aggregations of the lytic cell remains encapsulating or bridging the hyphal cells. Cells of the stipe tissues were transformed to empty cylinders or had irregularly collapsed. Most basidia and subhymenial cells remained alive even on day 36. When the mushrooms were cultivated according to our usual growth procedures, about 50% of the fruit bodies were infected by Trichoderma harzianum and/or Pseudomonas tolaasii on day 18; all fruit bodies died on day 24 due to diffuse bacterial and mycotic infections manifesting themselves by tissue necrosis and discoloration of the caps and stipes. When none of the fruit bodies was harvested at the time of the first flush they soon formed a canopy of pilei and their growth ceased. On day 14, all these fruit bodies showed widespread mixed infections followed by a diffuse liquefaction necrosis of all tissues including the hymenium. Post-harvest fruit bodies kept at ambient temperature or at 2 °C at low r.h., or at 20° at high r.h. revealed a diffuse cell wall destruction which was followed by cytoplasmic degeneration in due course. Fruit bodies kept refrigerated had the least gross and cell structural changes during our observation period of 7 d. We conclude that the morphological changes occurring in post-harvest and in senescent fruit bodies of Agaricus bisporus are different.

Pronase E and tunicamycin, a putative inhibitor of protein glycosylation, strongly reduced the frequency of germlings adhering to smooth polystyrene and completely inhibited appressorium formation of adhering germlings without inhibiting germ-tube growth of the pathogen. Additionally, α-mannosidase or α-glucosidase, but not β-glucosidase or lipase, partly inhibited adhesion to smooth polystyrene and substantially inhibited appressorium formation by germlings adhering to this substrate. Infection structure formation was also reduced by the addition of either lectins binding to mannose or glucose residues (ConA and LCA), or by the addition of IgG. The presence of ConA- and IgG-binding (glyco)proteins among proteins obtained from the germination fluid, or from differentiated germlings, has been confirmed on Western blots. Removal of proteinaceous surface material by pronase E inhibited appressorium formation on smooth polystyrene. After the protease was removed, newly formed ConA-binding glycoproteins have been detected at the germ-tube apex with FITC-conjugated ConA. The (re)appearance of these glycoproteins was correlated with the time period when appressorium formation was observed. Interestingly, removal of proteinaceous materials from the germ-tube surface by pronase E, and also the addition of IgG had no inhibitory effect on appressorium formation on furrows in polystyrene.

Our results suggest ConA-binding surface glycoproteins present at the germ-tube apex as essential factors for infection structure formation on smooth polystyrene. In contrast, these glycoproteins are unlikely to be involved in appressorium induction over grooves in the same substrate.

Growing fruit bodies of Agaricus bisporus and Amanita muscaria responded with regenerating white hyphae to cell and tissue injuries caused by intrapileal needle insertion and leucofuchsin injection. We point out reserve cells as a possible source of regenerating hyphae in the wound repair. Such reserve cells were not found in the partial veil and in the surface covering. Damage of the partial veil remained unrepaired and caused lamellar dysplasia. Hydrophilic, somatic tissues reacted immediately and strongly with leucofuchsin, whereas hyphae of the surface covering and partial veil showed a delayed and weak reaction. We explain this by the presence of an extracellular matrix, which consists of hydrophilic mucilaginous substances around tissue-forming hyphae. Transmission and scanning electron microscopical studies revealed that white hyphae were deprived of such matrix material. We conclude that for fungal tissue formation the hyphae have to be capable of producing a substantial amount of extracellular matrix material beyond the cell wall.

A method is described for identifying strains of Metarhizium suitable for use in field experiments. It involves the restriction endonuclease digestion of a PCR product derived from the Pr1 protease gene and the analysis of the fragments by electrophoresis. Using this technique, 40 Metarhizium strains produced 15 different profile types and were clustered into four groups. Correlation between the profile of restriction fragments and geographic origin was observed for certain groups of strains. This PCR strategy allowed the identification of fungal strains, using as samples spores scraped from the surface of single insects killed by the fungus or single whole dead insects with external mycelium. The sequence of the Pr1 PCR product from two strains revealed that Pr1 gene has at least three introns.

Twenty-nine field isolates of the broad host range pathogen Claviceps purpurea from various host plants and different geographical origin were compared by RAPD analysis. The RAPD patterns obtained showed considerable diversity; it was even possible to discriminate all strains tested with single primers, indicating an unusual high degree of genetic diversity within this species. A parsimony analysis using the PAUP software grouped most strains from specific host plants together, indicating some degree of host specificity in this fungus. Those strains derived from rye seem to be genetically less diverse than those from other host plants. However, the geographic origin also seems to be important.

Verticillium wilt in winter-sown oilseed rape (Brassica napus L. ssp. oleifera), which has not yet been reported in the U.K. but is widespread in Europe, was shown to be caused by the host-specific, ‘near-diploid’ Verticillium longisporum comb. nov. Thirty-one cruciferous isolates (plus one from sugarbeet) of V. longisporum, mainly from oilseed rape from Germany, Sweden, Japan, France and Poland, were characterized and compared with nine typical isolates of V. dahliae and five of V. albo-atrum. Isolates of V. longisporum were distinguished from those of V. dahliae by three morphological characters, i.e. elongate microsclerotia, long conidia (7·1–8·8 μm) and mainly three phialides per node on conidiophores, whereas those of V. dahliae had ±spherical microsclerotia, short conidia (3·5–5·5 μm), and 4–5 phialides per node. Isolates of V. longisporum lacked extracellular polyphenol oxidase activity (p.p.o.); they showed mean conidial nuclear diam. (DAPI fluorescence) of ca 1·85 μm, and ‘near-diploid’ standardized arbitrary DNA values (Feulgen DNA microdensitometry) of 0·89–1·17 (mean, 1·02). For isolates of V. dahliae, extracellular p.p.o. activity was detectable, and the corresponding figures for conidial nuclear diam. were ca 1·16 μm and DNA values of 0·45–0·65 (mean, 0·57), respectively. Using three oligonucleotide primers, isolates of V. longisporum were clearly distinguishable from those of V. dahliae and V. albo-atrum by their RAPD band profiles. Greenhouse pathogenicity tests, employing five winter oilseed rape cvs, confirmed the pathogenicity of V. longisporum, whereas V. dahliae was non-pathogenic. On the basis of all the above characters, this host-specific pathotype, V. longisporum, should now be considered as a distinct species. Evidence is presented to suggest that it may have evolved by parasexual hybridization between a strain of V. albo-atrum and a strain of V. dahliae, thus explaining its ‘near diploid’ state and the origin of four recombinants detected.

Epifluorescence microscopy and low temperature scanning electron microscopy were used to document the development of Uncinula necator on vine leaves and the antifungal effects of kresoxim-methyl and penconazole. Post-germinational growth and development followed a regular time course which was classified into 10 stages.

Kresoxim-methyl was applied at a range of concentrations and at different times before and after inoculation. In glasshouse trials at moderate relative humidity (60%), all pre-infectional applications completely inhibited conidial germination. Lower efficacies were observed with detached leaves at high humidity in Petri dishes. Post-infectional applications of at least 8 mg a.i. l−1 inhibited sporulation and mycelial growth and 67 mg a.i. l−1 caused a partial collapse of surface structures.

Penconazole applied at 17 mg a.i. l−1 did not inhibit germination, but prevented hyphal development and caused growth distortion with hyphal tip swelling. Pre- and post-infectional treatments had similar effects. Applications made 3 d after inoculation increased multiple appressoria and conidiophore formation.

DNA was extracted from dried specimens of nine taxa of the Cantharellaceae. Approximately 325 bases near the 5′ end of the nuclear 28S ribosomal gene were sequenced, and the sequences were compared. Sequence analyses demonstrated that Cantharellus and Craterellus should be treated as distinct genera. The phylogeny generated using parsimony suggests that Cantharellus tubaeformis and Pseudocraterellus sinuosus should be considered species of Craterellus. As a result of this study, we recognize the first placement of these two species in Craterellus by Fries and Quélet. A reassessment of the morphological characters used to separate Cantharellus and Craterellus is indicated.

Saprobic fungi were identified among the material collected during the Benelux Lichenological Expedition to Papua New Guinea in 1992. These include many widespread species, especially those found on high altitude, some of which are reported here for the first time from the Southern Hemisphere. Papilionovela albothallina gen. et sp. nov. is described and illustrated. Xylopezia is referred to the Hyponectriaceae.

During investigations of microfungi occurring on submerged plant material in tropical streams, seven species of Sporoschisma and one species of Sporoschismopsis were recorded. Three are newly described: Sporoschisma parcicuneatum, S. phaeocentri and Sporoschismopsis australiensis. Each of these species is described and illustrated in detail and a synopsis of remaining species of Sporoschismopsis is provided. Generic concepts and connections to teleomorphs are discussed and a key is provided to accepted species in both genera.

A new species of Zoophagus, Z. cornus, capturing loricate rotifers on short peg-like traps, was isolated from paddy field mud in Ibaraki, Japan. The fungus produced long, narrow, cylindrical, aseptate conidia. Azygospores containing a large vacuole were produced directly from the hyphae.

Stilbohypoxylon is resurrected. The type species, S. moelleri, is redescribed and S. samuelsii is described as new. The third species, S. quisquiliarum, represents a new combination. A key to these taxa is provided.

The performance of isolates of the ectomycorrhizal fungi Coltricia perennis, Laccaria bicolor, Lactarius hepaticus and Paxillus involutus originating from Scots pine stands was studied on solid media with different concentrations of ammonium, glycine and glucose as inorganic nitrogen, organic nitrogen and carbon source. Laccaria bicolor was able to grow on both ammonium- and glycine-containing media. Biomass and growth rate of L. hepaticus and P. involutus on media with ammonium were generally higher than on media with glycine as nitrogen source. Coltricia perennis did not clearly show preference for either ammonium or glycine. Fractal dimensions, calculated from the biomass and radii of the fungi, were in the range 1–3. Fractal dimensions provided extra information about the foraging strategy of mycelia not obtained from growth rate and biomass production measurements, but cannot replace those because the use of fractal dimensions alone may lead to misinterpretation.

The yeast–mycelial dimorphic Aureobasidium pullulans var. pullulans was grown in chemostat culture under zinc-limitation at pH values in the range 2–7. Steady state was obtained and the growth yield with respect to zinc was independent of pH. The culture grew entirely as yeast, independently of the pH in the pH interval 3–7. The exopolysaccharide (EPS) production from the yeast cells was highest in the pH range 3–6 with a maximum at pH 4·0. Only little EPS was produced at pH 7·0 and no EPS was produced at pH 2·1. At pH 2·1 about 20% of the total biomass was in the filamentous growth form and some chlamydospores were present. A change in the carbon source from glucose to sucrose resulted in a more than doubling of the steady-state EPS concentration from 3·1 to 6·9 g l−1. A simple mass balance on carbon was constructed which could account for more than 95% of the carbon.