The formation of sclerotia is inhibited by certain chemicals. These resting fungal structures are also parasitized by mycoparasites. This study reports results of experiments on the effect of four sclerotial inhibitors on the sclerotial mycoparasite Coniothyrium minitans and was carried out in an attempt to determine possible compatibilities between sclerotial inhibitors and mycoparasites. Thioglycolic acid was the most toxic to mycelial growth while its sodium salt was totally non-toxic. Mercaptoethanol and mercaptoethylamine were intermediate. At low concentrations, pycnidial formation by C. minitans was not hindered by any of the compounds tested. All four compounds inhibited the formation of sclerotia in Sclerotinia sclerotiorum. Sclerotia are also parasitized by C. minitans. Na-thioglycolate should be tested further as it had no adverse effect on the mycelial growth and pycnidium formation in C. minitans, while it inhibited extensively the formation of sclerotia in S. sclerotiorum. These data suggest that Na-thioglycolate and C. minitans should be considered for use in integrated control.

The influence of Fosetyl-Al and Metalaxyl on the diversity of arbuscular mycorrhizal fungi (AMF) was evaluated on naturally established citrus plants. Thirteen AMF species were recovered from rhizospheres of Citrus sinensis/C. limon treated or not with Fosetyl-Al and/or Metalaxyl. Spores of AMF were obtained from 100 g of rhizospheric soil at two sites in São Paulo state, Brazil. The soil samples were treated by the wet-sieving technique and the spores were quantified and identified. The number of spores was low at both sites. Fosetyl-Al reduced the number of spores and the diversity of AMF in one site but not in the other. Metalaxyl at low concentration increased the diversity of species in some experiments, but at higher concentration it tended to reduce the number of spores of AMF. Scutellospora was the genus that presented the largest number of species (7) followed by Acaulospora (3), Glomus (2) and Gigaspora (1). Gigaspora ramisporophora was the dominant species in one site, Glomus macrocarpum and Scutellospora gilmorei were dominant at the other.

Coniochaeta polymegasperma sp. nov. is described from hare dung from Sutherland, Orkney and Inverness. With 64-spored asci, it differs from other Coniochaeta spp. with asci with more than eight spores by its much larger spores. Delitschia trichodelitschioides sp. nov. is described from hare dung from Sutherland and Inverness, differing from other Delitschia spp. in its distinctively setose pseudothecial neck.

A violet root rot fungus recently found in Japan was identified as Helicobasidium brebissonii. The fungus was compared with another violet root rot fungus, H. mompa, which is distributed throughout Japan, in terms of morphological characteristics of the basidiospores and the conidial state, sequences of rDNA ITS regions, and pathogenicity on carrot, sweet potato and apple rootstock. The two species were clearly discriminated by these features and the taxonomic status of both species is discussed.

The orientation of individual urediniospores and spore clusters of Uromyces viciae-fabae, during fall and after landing in still air, was recorded using high-speed video microscopy. Individual spores and aggregates fell in a variety of orientations. On landing spore clusters attached to the substratum without rebounding or fragmenting and typically retained their orientation during fall. Some aggregates landed and attached in orientations in which their mass was asymmetrical with respect to their point of contact. Attachment also occurred when spores fell onto spore aggregates which had previously landed on the substratum. Rate of fall was influenced by the orientation and size of cluster. When dispersed and collected on substrata under simulated field conditions, the orientation and attachment of urediniospore clusters were similar to those of aggregates deposited in still air.

A study of the holotype and several collections of Cercospora zeyrae on leaves of Zeyheria digitalis from the Brazilian cerrado showed that it is actually a Pseudocercospora species with amphigenous fruit structures, here designated as P. zeyheriae (Henn.) comb. nov.

In Melanospora zamiae a total of five nuclear divisions took place during ascosporogenesis. The first and second divisions were meiotic in which the single diploid nucleus divided into four haploid nuclei. The mitosis that followed gave rise to eight nuclei which characteristically assumed a 1[ratio ]4[ratio ]3 (apical[ratio ]middle[ratio ]basal) spacing in the clavate ascus. After ascospore delimitation, each nucleus in the young ascospore underwent two successive mitoses producing four haploid nuclei in each spore. Equatorial arrangement of these nuclei was observed in the mature ascospores.

Type collections of Cercospora byrsonimatis and Ramularia ligustrina have been re-examined. Cercospora byrsonimatis is transferred to Pseudocercospora while a second hyphomycete, found on the type material, is described as Ramalia byrsonimatis sp. nov. Ramularia ligustrina is redescribed and its status as a true member of Ramularia is confirmed.

The Sistotremateae of the southern forests of Argentina are reviewed. Fourteen species are reported, collected on Nothofagus spp. and Drymis winteri. Sistotrema botryobasidioides and S. globosa are described as new. S. athelioides, S. efibulatum s. lat., S. porulosum and S. sernanderi are reported for the first time from Argentina. A key to the 14 species now known in the area is provided.

This month Mycological Research News features recent work on generic concepts in cantharelloid fungi, and ectomycorrhizal fungi raiding saprotrophic ones for nutrients. Amongst topics covered by the 18 research papers in this issue are molecular systematics of Craterellus, variation at the molecular level in Chondrostereum purpureum and Monascus, genetic exchange between Metarhizium strains, β-1,3-glucanase regulation in Trichoderma harzianum, specific isozymes in Botrytis cinerea, lipid and fat composition of arbuscular mycorrhizal fungi, PCR detection of Verticillium chlamydosporium, the storage of Erynia, destruxin production by Metarhizium strains, ultrastructure of Entomosporium mespili, utilization of various substrates by Aspergillus fumigatus, Tuber melanosporum inoculation and molecular detection, and studies on freshwater ascomycetes from Thailand and Crepidotus species in Mexico. New scientific names introduced are: Botryobasidium musaisporum, Deltosperma oblongum, Melanochaeta garethjonesii, Ophiostoma setosum, Unguiculariopsis changbaiensis, and C. damingshanica spp. nov.; and Craterellus ignicolor (syn. Cantharellus ignicolor) comb. nov.

Cannonia gen. nov. is introduced to accommodate three collections of an unusual taxon, originally described as Ceratostoma australe. Cannonia is thought to be xylariaceous, due to its globose immersed ascomata with the stroma reduced to a clypeus, well-developed paraphyses, unitunicate asci lacking an apical apparatus, and dark brown, aseptate ascospores with a germ slit. Cannonia is compared with other possibly related genera and illustrated with interference contrast micrographs.

Emericella indica sp. nov. and a peculiar morphological variant of E. quadrilineata are described and illustrated. The former is characterized by large, smooth, violet ascospores and the latter by apparently budding ascospores. Analysis of the sequences of the nuclear rDNA ITS region gene of these species and E. nidulans and E. variecolor support our concepts based on morphological criteria.

Video microscopy was used to examine a genetically tagged mutant (T30) of Glomerella graminicola whose conidia have a propensity to burst during the germination process. Before the germ tube is produced, the cell wall ruptures and the cytoplasm is extruded. The bursting takes place in less than 0.1 second. Bursting can be prevented by adding osmotica to the germination medium. By phase-contrast microscopy of alkali-washed conidia, we found that each ruptured conidium had a single gaping hole that was oriented parallel to the long axis of the spore. The holes were more frequent in the middle region of the conidia than at the apices. A mathematical model for stress based on conidial shape indicated that conidia ruptured where the stress on the wall was greatest. The microscopic observations on the orientation and distribution of the rupture sites are consistent with the hypothesis that T30 conidia have weaker walls than the wild-type. Comparative tests of resistance to mechanical breakage support this hypothesis.

Rubukia splendida sp. nov. from Mauritius is described, illustrated and compared to the only other species in the genus, R. samsonii from Honduras.

Three fungicolous hyphomycetes are described and illustrated. Anastomyces gen. nov., with the type species A. microsporus sp. nov., is described on ascomata of Apiospora sp. on dead culms of a grass from China. It differs from comparable genera by its fungicolous habitat, sporodochial conidiomata and polylocal conidiogenous cells mostly with 2 loci. Each locus produces one conidium but two conidia formed from the same conidiogenous cells join together to form H-shaped conidia in the earliest stages of their development. Idriella rhododendri sp. nov. grows over other microfungi and is described from leaf litter of Rhododendron ponticum from England. Infundibura adhaerens was found to be commonly associated with ascomata and conidiomata on dead leaves of R. ponticum in England.

Torrubiella dimorpha sp. nov. on an infected spider from Taiwan is described and illustrated. It is characterized by producing perithecia on an orange white, pulvinate, lanose mycelial mat covering the host. The anamorph, Gibellula dimorpha sp. nov., produces gibelluloid and granulomoid synanamorphs on aspergillate, distinctly roughened or warty conidiophores, or sometimes produces both synanamorphs on the same aspergillate vesicle. The differences between T. dimorpha and the closely related T. globosa, T. globoso-stipitata, T. arachnophila, T. ratticaudata and T. clavata are briefly discussed.

Pseudorobillarda magna sp. nov. from bark of Geoffroea decorticans, a native tree of Argentina, is described and illustrated. It is compared with the known species in the genus. This is the first report of a species of Pseudorobillarda from South America.

Antrodia taxa sp. nov. and Perenniporia celtis sp. nov. found growing saprotrophically on the decayed stems of Taxus mairei and Celtis sinensis, respectively, in Taiwan, are described and illustrated. A. taxa is distinguished by effused-reflexed to pileate basidiomes and small oblong ellipsoid basidiospores 4×2·5 μm. P. celtis is characterized by large, subglobose to tear-shaped, non-truncate basidiospores 8·5–10×5–7 μm and encrusted cystidia. Cultural characteristics are described for the two species.

The haplophase of the pine blister rust Cronartium flaccidum was used to grow mycelial clones axenically from single genotypes. Single telia were suspended over the media in order to obtain a direct cast of uninucleate basidiospores, providing nurse cultures from a mass basidiospore inoculum. Nurse culture and medium composition were crucial factors in successful germination and establishment of single-spore colonies. Significant differences in percentage germination between treatments and controls suggested that an extracellular matrix secreted by high density seeded basidiospores could be involved in the germination of single propagules. Proteins present in this matrix could exert a surface contact stimulus triggering germination of newly seeded basidiospores. Pre-production of extracellular enzymes in the medium could also initiate early substrate catabolism and thus create a favourable environment to support subsequent colony establishment. Growth was good on various media, and excellent on HG1Y+BSA medium. Primary mother colonies were divided into several smaller ones, re-grown axenically, then macerated. Aliquots of the resulting mycelial fragments were dispensed with a micropipette into fresh agar media. Clones derived from each pure culture were in general morphologically similar in texture, margin, compactness, and surface topography. These genetically pure lines grew at a faster rate and rapidly produced a considerable amount of mycelium. The significance of culturing rust fungi from single genotypes is discussed in relation to potential applications and new directions of research.