This issue is dedicated to John Webster, a former President of the International Mycological Association, and twice President of the British Mycological Society. It includes 17 papers from close colleagues, former students, and other mycologists. A list of John Webster's scientific publications is also provided.

Mycological Research News contains: A tribute to John Webster: holomycologist extraordinaire; John Webster: reflections; Fire, hypogeous fungi and mycophagous marsupials; and Palaeopyrenomycites devonicus: a 400 Myr old pyrenomycete.

The research papers address conidiogenesis types in Agaricales (with a key), and provide an overview of propagule types in Ingoldian fungi, observations on helicoid aero-aquatic conidia, a synopsis of Pseudaegerita, a polyphasic approach to classification in Rosellinia, and a study on Basifimbria aurea. Molecular phylogenetic methods are used to provide a reappraisal of the Lulworthiales, justify the re-introduction of the entomopathogenic genus Isaria, and investigate Phragmidium rusts on dog roses. The endophyte Acremomium zeae produces antifungal compounds, and the production of sordarin in Podospora pleiospora is examined. Other contributions address stipe elongation biomechanics in Coprinopsis cinerea, endophytic fungi of cacti, and septa in Peronosporaceae.

The following new scientific names are introduced in this issue: Lulwoana and Lulwoidea gens. nov.; Pseudaegerita conifera, and P. websteri spp. nov.; Isaria cateniannulata (syn. Paecilomyces cateniannulatus), I. cateniobliqua (syn. P. cateniobliquus), I. coleopterora (syn. P. coleopterorus), I. ghanensis (syn. P. ghanensis), I. javanica (syn. Spicaria javanica), Kohlmeyeriella crassa (syn. Lulworthia crassa), Lulwoana uniseptata (syn. Lulworthia septata, and Lulwoidea lignoarenaria (syn. Lulworthia lignoarenaria) combs. nov.

A personal perspective of John Webster, with an emphasis of studies of aero-aquatic hyphomycetes and the techniques pioneered to enable them to be studied, illustrated by examples particularly from the genera with helicoid conidia, Helicodendron and Helicoon, showing flotation devices.

Dikaryotic and haploid mycelia of more than 150 gilled species of euagarics were studied morphologically and by molecular phylogenetic methods. The morphological investigations revealed anamorphs in more than 90 species that were often specific at the genus or family level. Thallic conidiogenesis dominated and varied from fragmentation of normally branched hyphae to the formation of differentiated sympodially branched conidiophores. Secession modes, coiling of the conidiogenous hyphae or the swelling of the conidia were additional distinguishing features. Phylogenetic analysis of the D1–D3 domains of the nuclear gene for the ribosomal large subunit using a Bayesian Markov chain Monte Carlo approach resulted in several well-supported groups that are consistent with anamorph morphology. These results indicate that the anamorphs provide valuable characters for a natural classification of the Agaricales.

This first contribution of a planned series on the morphology of the Ingoldian fungi discusses three aspects useful for conidial identification, something needed principally in stream ecology and biodiversity surveys: (1) types of propagules found; (2) release organ remnants found on propagules; and (3) conidial tails (or caudal appendages).

(1) Propagules can be unexpectedly varied, and difficulty may be encountered in distinguishing, for example, misshapen conidia from expected ranges in conidial form, or in recognizing the outcome of post-release morphogenesis (involving elongation, branching or fragmentation, the latter resulting in part-conidia of several kinds); autonomous hyphal branching systems resembling branched conidia may undergo disorganized in situ fragmentation; propagules may be compound, the components covering more than one generation of the same morph or even more than one morph; conidial aggregations may behave as single dispersal units; and in one case it may be difficult to distinguish between thalli and propagules.

(2) Conidia secede by means of various specialized structures (release organs) which leave behind remnants of diagnostic value. Among ascomycetous anamorphs are scars (half-septa resulting from schizolysis of release septa), basal collars (portions of lateral walls resulting from rhexolysis or fracture of release or separation cells), and in one case mucilaginous masses (probably the result of the gelification of release cells). The location of scars can sometimes only be inferred by means of other diagnostic characters, and in some instances it cannot even be inferred. This may lead to problems in orientating conidial and consequently in their identification. In the case of release cells, the remnants on the conidium frequently disappear or become indistinct. Among basidiomycetous anamorphs are twin scars (the result of paired schizolysis of the two septa, i.e. the axial and bridge septa, in the release clamp), excentric collars (seemingly the result of a combination of schizo- and rhexolysis of clamp components) and basal collars (the outcome of lysed evacuate conidiogenous cells).

(3) The presence of tails is often inconstant, but where recognizable three types occur which may significantly aid in conidial orientation and hence identification.

In addition, three methodological aspects are emphasized: the effect of the position of the conidium on the appreciation of some diagnostic characters, the need to observe spent conidiogenous structures, and in some cases the necessity of directly observing morphogenesis in order to interpret the conidial form.

The Lulworthiales consists of four genera: three that were removed from the Halosphaeriales, namely Lulworthia, Lindra, and Kohlmeyeriella; and Spathulospora, reassigned from the Spathulosporales. However, studies have shown that neither Lulworthia nor Lindra are monophyletic genera. This study was therefore undertaken to re-evaluate the genera of the Lulworthiales based on the SSU and LSU rDNA genes. Taxonomic revisions are proposed here for Lulworthia crassa, L. lignoarenaria, L. uniseptata and Lindra marinera: Lulworthia crassa is transferred into the genus Kohlmeyeriella; Lulwoidea gen. nov. is established for L. lignoarenaria; Lulwoana gen. nov. is established for L. uniseptata; and Lindra marinera is reduced to synonymy with L. thalassiae. Taxonomic descriptions are emended for the genus Lulworthia s. str., and for L. grandispora and Lindra thalassiae. A neotype is designated for Lulworthia grandispora.

More than 90 species are accepted in the xylariaceous genus Rosellinia. Thorough morphological characterisation of all known species will provide a taxonomic hypothesis that can be later tested by DNA sequence analysis. Exploratory analyses of ascospore morphology, shape of ascus apical structure, and anamorph genus suggest six morphological groups in the genus.

Phylogenetic relationships of Paecilomyces sect. Isarioidea species were analysed using the β-tubulin gene and ITS rDNA. Maximum parsimony analyses showed that the section does not form a natural taxonomic group and is polyphyletic within the Hypocreales. However, a group was recognized, designated as the Isaria clade, to be monophyletic comprising of the following Paecilomyces species: P. amoeneroseus, P. cateniannulatus, P. cateniobliquus, P. cicadae, P. coleopterorus, P. farinosus, P. fumosoroseus, P. ghanensis, P. javanicus and P. tenuipes. Some of these species have teleomorphs in Cordyceps.

Two new species of the aero-aquatic anamorph genus Pseudaegerita, P. conifera sp. nov. and P. websteri sp. nov. are described and illustrated. Both species were found on submerged plant material in Spain. The new species are compared morphologically with the seven species now accepted in the genus.

The variability in conidiogenesis of the coprophilous Basifimbria aurea, type species of the genus, is redescribed and illustrated, and is similar to that of B. spinosa. The distinction of the species from Stenocephalopsis subalutacea (syn. Rhinotrichum subalutaceum) is emphasized.

Rust fungi in the genus Phragmidium are frequent pathogens of both wild and cultivated roses. We investigated the occurrence and relationships of rusts on dog roses, Rosa sect. Caninae (Rosa canina, R. corymbifera and R. rubiginosa) in Germany. Two Phragmidium species, P. mucronatum and P. tuberculatum, were able to infect each of the three dog rose species examined. However, the overall infection of R. rubiginosa was significantly lower, which could be important for rose breeding. Despite overlapping host ranges, the evolutionary background of P. tuberculatum and P. mucronatum is quite distinct. Phylogenetic analyses of the D1/D2 region of the LSU rDNA suggest that P. mucronatum shares a common ancestor with other rose rusts, whereas P. tuberculatum evolved from a Rubus-Sanguisorba rust clade and must have undergone a host shift to Rosa spp.

The maize endophyte Acremonium zeae is antagonistic to kernel rotting and mycotoxin producing fungi Aspergillus flavus and Fusarium verticillioides in cultural tests for antagonism, and interferes with A. flavus infection and aflatoxin contamination of preharvest maize kernels. Chemical studies of an organic extract from maize kernel fermentations of Acremonium zeae (NRRL 13540), which displayed significant antifungal activity against Aspergillus flavus and F. verticillioides, revealed that the metabolites accounting for this activity were two newly reported antibiotics pyrrocidines A and B. Pyrrocidines were detected in fermentation extracts for 12 NRRL cultures of Acremonium zeae isolated from maize kernels harvested in Illinois (4/4 cultures), North Carolina (5/5), Georgia (1/2) and unrecorded locations within the USA (2/2). Pyrrocidine B was detected by LCMSMS in whole symptomatic maize kernels removed at harvest from ears of a commercial hybrid that were wound-inoculated in the milk stage with A. zeae (NRRL 13540) or (NRRL 13541). The pyrrocidines were first reported from the fermentation broth of an unidentified filamentous fungus LL-Cyan426, isolated from a mixed Douglas Fir hardwood forest on Crane Island Preserve, Washington, in 1993. Pyrrocidine A exhibited potent activity against most Gram-positive bacteria, including drug-resistant strains, and was also active against the yeast Candida albicans. In an evaluation of cultural antagonism between 13 isolates of A. zeae in pairings with A. flavus (NRRL 6541) and F. verticillioides (NRRL 25457), A. zeae (NRRL 6415) and (NRRL 34556) produced the strongest reaction, inhibiting both organisms at a distance while continuing to grow through the resulting clear zone at an unchanged rate. Maximum colony diameters for A. zeae (NRRL 6415) and (NRRL 13540), on potato dextrose agar after 14 d, were attained within the range of 25–30 °C, with less growth recorded at 15 ° and 37.5 ° and no growth at 5 °. Potential interactions between A. zeae and other maize endophytes are considered and the significance of these interactions relative to the aflatoxin and fumonisin contamination of preharvest maize is presented. This is the first report of natural products from Acremonium zeae.

Rabbit pellets collected from the field were colonized by Podospora pleiospora at the exclusion of other coprophilous fungi, suggesting antibiosis. In liquid culture, P. pleiospora produced sordarin (1); sordarin B (2), a new compound in which sordarose is replaced by rhamnose; hydroxysordarin (3); and sordaricin (4). The major compounds 1 and 2 exhibited minimum inhibitory concentrations of 0.5–2.5 μg ml−1 against the yeasts Nematospora coryli and Sporobolomyces roseus, but showed little or no activity against bacteria or coprophilous filamentous fungi. In liquid culture, the production of 1 and 2 together amounted to 2.7 μg ml−1, whereas in rabbit dung only 1 was produced at a similar concentration (2.3 μg g−1 fresh weight). The biosynthesis of these substances was unaffected by the presence of inoculum of other fungi tested (Sporobolomyces roseus or Penicillium claviforme) in liquid culture or on dung. Sordarin-type natural products are therefore synthesized by P. pleiospora at sufficiently high concentrations to account for antibiosis against yeasts, but not against filamentous fungi.

Stipe elongation in fruit bodies of Coprinopsis cinerea (syn. Coprinus cinereus) was examined from a biomechanical perspective. Two strains were studied: the self-compatible Amut Bmut homokaryon that produces normal fruit bodies with relatively short stipes, and mutant B1918 that produces abnormally elongated stipes. Measurements of the pressure exerted by developing mushrooms were made using strain gauges, and these data were compared with measurements of the pressures exerted by vegetative hyphae of the same strains. The experiments demonstrate that AmutBmut hyphae elongating within stipe tissue push with the same pressure (approx. 0.5 atmosphere) as vegetative hyphae growing through their food sources. In purely biomechanical terms, the fruit body may therefore be viewed as a relatively uncomplicated sum of its parts. Analysis of the mutant strain B1918 demonstrated that hyperelongation of the stipe is not associated with any difference in the pressure exerted by the fruit body. The fault in the mechanism of stipe extension in B1918 may be reflected in the increased fluidity of the cell wall of vegetative hyphae of this strain, but further work is necessary to resolve this.

21 cactus species occurring in various localities within Arizona were screened for the presence of fungal endophytes. 900 endophyte isolates belonging to 22 fungal species were isolated. Cylindropuntia fulgida had the maximum endophyte species diversity, while C. ramosissima harboured the maximum number of endophyte isolates. Alternaria sp., Aureobasidium pullulans, and Phoma spp. were isolated from several cactus species. The diversity of the endophyte assemblages was low and no host specificity among endophytes was observed. However, the frequencies of colonization of the few endophyte species recovered were high and comparable to those reported for tropical plant hosts. Species of Colletotrichum, Phomopsis, and Phyllosticta, which are commonly isolated as endophytes from plants of more mesic habitats, were absent from these cacti.

Although Plasmopara viticola causes grape downy mildew in most, if not all, wine producing countries, many basic biological or chemical aspects are still unknown and thus the histopathological changes during development of this oomycete pathogen were studied. The fluorochromes Aniline blue and Uvitex 2B were successfully used in whole leaf stainings to visualise intercellular hyphae and to investigate septal-development in sporangiophores. The occurrence and transfer of cytoplasm in sporangiophores was studied with the aid of Chlorazole Black E and Phloxin B. Application of Chlorazole Black E was the most reliable method to differentiate between cytoplasm and septa in sporangiophores due to a high contrast between the dark cytoplasm and the pale septa. In P. viticola, septa were found in the stem and branches of the sporangiophores, but not in the intercellular hyphae, which was in contrast to other oomycetes, such as P. tabacina, Pseudoperonospora cubensis and P. humuli, where septa were frequently found in the mycelium. In order to verify chemical composition of septa, sporangiophores were digested using chitinase and β-1,3-glucanase. After staining with Aniline blue and Uvitex 2B, the intense fluorescence of septa was conserved after the application of chitinase but not after β-1,3-glucanase, indicating that septa are mainly composed of β-1,3-glucans. Pretreatments of infected vine leaves with 2-deoxy-D-glucose (2-DOG) at low concentrations (1–5 mM) led to a disorganisation of the sporangiophore structure of P. viticola, whereas the production of septa was unaffected. Application of 2-DOG at higher concentrations resulted in a reduced length of intercellular hyphae (10 mM) or total inhibition (50 mM) of the intercellular mycelium. Thus, 2 DOG or its analogues interferes with morphogenesis in Plasmopara viticola and may have a deleterious effect on the spread of this downy mildew between plants.

A list of the 242 scientific publications authored, co-authored, or edited by John Webster from 1951 to the end of 2004 is presented. The list includes papers, books, book chapters, films, and videos.