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.

There are approximately 70000 species of described fungi, representing about 5% of the estimated 1·5 M species world-wide. Proportionally there are numerous undescribed species and most habitats and hosts should provide a bounty of novel fungi that can be exploited in a wide variety of ways. Where, however, are these missing fungi? Data indicates that they may occur in poorly studied countries, hosts, habitats, niches or tissues, and are mostly microfungi. Host specificity and/or tissue recurrence are important considerations in biodiversity estimates. We are a long way from establishing where we can find the missing 1·43 M fungi, but evidence presented here resulting from data from Hong Kong indicates many places where we could look.

A 909 bp region containing a genomic clone encoding for hydrophobin (ssgA) from the entomopathogenic fungus Metarhizium anisopliae has been sequenced and the regulatory motifs analysed against those recognized in other fungi. The genomic clone was also compared with the open reading frame of the hydrophobin ssgA (starvation stress gene) cDNA sequence. The genomic clone contained a 291 bp coding sequence with one intron of 64 nucleotides. From this sequence primers were established that could be used to amplify the hydrophobin. Restriction fragment polymorphism analysis of hydrophobin amplified by the polymerase chain reaction from 80 isolates of M. anisopliae showed no variability. Analysis of the potential regulatory elements 313 bp upstream from the transcriptional start site revealed typical TATAA and CCAAT boxes. CT or GC motifs were not found. Upstream regulatory elements were also found with sequence homologies to the AREA, CREA, CRE (cAMP response element) and BRLA regions of Aspergillus nidulans as well as the CYS3 and AmyB regions of Aspergillus oryzae. The promoter regions of other fungal hydrophobins were also assessed for the presence of regulatory elements. Upstream regulatory elements are also present for the gene encoding a cuticle-degrading protease (Pr1) from M. anisopliae. We suggest that nutrient levels and cAMP mediation of thigmotropic signals in the entomopathogenic fungus, M. anisopliae, co-ordinate the regulation of the gene products required for morphological development and secretion of ‘penetration’ enzymes.

Pseudotulostoma volvata gen. sp. nov. is described from the south-central Pakaraima Mountains of Guyana. Pseudotulostoma volvata is associated with ectomycorrhizal Dicymbe corymbosa trees (Caesalpiniaceae) and placed in the Ascomycota, Eurotiales, Elaphomycetaceae. Included are a description of the genus and species, illustrations of the macroscopic and microscopic features, and a discussion of the distinctive features and phylogenetic placement of this fungus.

This paper presents an experimental test of a model that predicts the outcome of intraspecific competition between unit-restricted decomposer fungi. The model was tested using two isolates each of two species of the mushroom genus Coprinus (Basidiomycota). The fungi were grown on yeast extract agar at several resource densities. The effect of intraspecific competition was measured as the reduction of stipe dry weight (an indicator of spore production) when an individual grows in competition with a second individual of the same species as compared to the stipe dry weight when it grows alone. Additionally, competition often caused a significant change in the growth rate of the isolates. In general, the model accurately predicted the stipe dry weight of the isolates growing in competition, but it incorrectly predicted the outcome of competition for at least one resource density for each isolate.

Eleven enzymes from 139 specimens of thirteen Italian populations of Tuber magnatum were analysed with multilocus horizontal starch gel electrophoresis. The research was carried out to obtain insight into the genetic variability of this species across its geographic range. All the gene-enzyme systems scored appear to be fixed in homozygosity in accordance with what is hitherto known in the genus Tuber; nine seemed monomorphic, whereas two, that is MDH-1 and ME-2, showed three alleles each. These results indicated a self-reproductive system and the low genetic variability is in agreement with the restricted endemism of the white truffle. The distribution of the electrophoretic types is discussed as a basis for further molecular applications.

Phylogeographic divergences of four coprinoid species, Coprinus comatus, Coprinellus disseminatus, Coprinellus micaceus and Coprinopsis lagopus were investigated using nuclear ITS sequences. Each taxon showed genetic variation that corresponds with the geographic origins of collections. Groupings produced from ITS1 and ITS2 sequences were similar together. In C. comatus, East Asian strains were well separated from New Zealand and North American strains. In C. disseminatus, Hawaiian strains formed an independent clade with that from Nepal, separating those from East Asia. And there were two distinct East Asian groups for C. disseminatus. East Asian C. micaceus strains constituted a distinct group from Hawaiian strains. In C. lagopus, Hawaiian and European strains were clearly separated from each other. There was a great genetic diversification in C. disseminatus and C. micaceus from East Asia, suggesting divergence process of these taxa in that region. However, Hawaiian strains lacked genetic variation, which indicated their recent origin in Hawaii.

Mortierella tsukubaensis sp. nov., isolated from uncultivated soil at Tsukuba, Japan, is described and illustrated as a new homothallic species. Simple, large sporangiophores with terminal, many-spored sporangia, large chlamydospores and naked zygospores are characteristic of M. tsukubaensis. A key of the 13 known homothallic species is provided.

Merimbla humicoloides sp. nov. was isolated after heat treatment of soil collected in a pine forest of Veracruz state, Mexico. The fungus is characterized by pale buff to cinnamon colonies that become dark brown to black in reverse and conidiophores that vary from irregularly asymmetrical penicilli to symmetrical penicilli with inflated metulae, and Humicola-like chlamydospores on the submerged hyphae. Phylogenetic inferences made from the ITS1-5·8S-ITS2 rDNA sequences indicate that M. humicoloides is a member of the Trichocomaceae and that it is related to M. ingelheimensis, Hamigera avellanea, and Penicillium species.

A recent report of an aflatoxin producing isolate of Aspergillus tamarii prompted a taxonomic re-examination of aflatoxigenic and non-aflatoxigenic isolates identified as A. tamarii as well as the closely related A. caelatus. Representatives of each species, including atypical isolates, were compared morphologically, for mycotoxin production, and for divergence in ITS, 28S, β-tubulin and calmodulin gene sequences. Because of genetic, morphological, and mycotoxin differences, the aflatoxin producing isolates of A. tamarii are given species rank as Aspergillus pseudotamarii sp. nov.

This revision of cuboid-spored Entoloma in Madagascar is based on the examination of type material described earlier by Romagnesi and new collections made by the first two authors. Entoloma pseudoheimii sp. nov. and E. rufovinascens sp. nov. are described, and two new combinations made: E. cuboidosporum var. chromostomum, and E. heimii combs nov. A key to the madagascarian cuboid-spored species of Entoloma is provided.

Myconymphaea yatsukahoi gen. sp. nov. is described in the Kickxellaceae (Kickxellales, Zygomycetes). The fungus is characterised by unicellular sporocladia formed on apical vesicles of sporangiophores, conspicuously long sporangiospores and peculiar septal plugs with prominent protuberances. In addition, a key to all known genera of the Kickxellales is provided.

Seven new species of smut fungi from the neotropics are described. The new species are remarkable for their special morphological development, as new representatives of small genera, or by interesting host plants and contribution to our knowledge of neotropic biodiversity. Aurantiosporium pallidum from Bolivia is the third species known in its genus. Its sori develop in the hypertrophied tissue of the rachillae of female and male spikelets. Kuntzeomyces ruizianae from Colombia is the second species known in its genus, characterized by relatively small teliospores. Moreaua bulbostylidis from Bolivia and Venezuela is the first record of a species of this genus (formerly Tolyposporium) on the genus Bulbostylis (Cyperaceae). Thecaphora amaranthicola from Ecuador differs from the known species T. amaranthi on the same host genus by smaller balls of teliospores. Thecaphora smallanthi is the first species of Thecaphora known to include hyaline globose sterile cells in the centre of teliospore balls. Tilletia boliviana is the first species of Tilletia infecting a species of Bromus (Poaceae) and forming warty teliospores. Species of Urocystis on Poaceae are known as agents of stripes on leaves, stems, and inflorescences. Urocystis reinhardii from Bolivia is the first species of this genus with sori in the interior of hypertrophic peduncles of a grass.

Needles of Pinus strobus (white pine) were cleared and stained to survey the occurrence and location of Lophodermium sp., a fungal endophyte. Cytoplasmically dense endophytic hyphae with a pronounced lobed morphology and containing lipid bodies were localized intercellularly between the epidermis and hypodermis. These fungal infections did not appear quiescent, but rather exhibited signs of continual slow growth. A few associated host cells exhibited a hypersensitive response. Material embedded in resin and examined by light microscopy and transmission electron microscopy confirmed the location of hyphae between epidermal and hypodermal cells, and the presence of lipid bodies within the hyphae. In senescing needles, aggressive colonization of needle tissues occurred. Thus, for Lophodermium in white pine, endophytic infection is active rather than quiescent, and displays an alternate hyphal strategy to that seen in the reproductive phase.

Pycnothryria of Tubakia dryina on naturally infected sweet gum (Liquidamber styraciflua) leaves were examined using transmission electron microscopy. The conidioma was attached to mycelium within the leaf tissue by a multicellular columella. Columellar cells were multinucleate. The surface layer of the pycnothyrium, the scutellum, was composed of thick walled prosenchymatous hyphae. Numerous conidiogenous cells were associated with the ventral surface of the scutellum and the columella. Conidia were produced enteroblastically from conidiogenous cells exhibiting a prominent collarette at their apex.

The two Mycosphaerella and Sphaerella species described from filmy ferns (Hymenophyllaceae) turned out to be lichenized and to belong to different ascomycete orders, the Trichotheliales and Pyrenulales. As one epithet antedates the names currently in use for the taxon, the following new combination is proposed: Trichothelium assurgens (syn. Sphaerella assurgens Cooke, Trichothelium marianense Harada, T. nanum Malcolm & Vězda). These unexpected redispositions serve as an example of the current state of knowledge about the taxonomy of foliicolous ascomycetes, both non-lichenized and lichenized. They also show that type studies are essential to evaluate the identity of Mycosphaerella and Sphaerella species, and that the resulting number of accepted species in the huge genus Mycosphaerella, and consequently in the ascomycetes as a whole, might be lower than currently thought. Strigula phyllogena and Porina albicera are reported as new for Samoa.

An undescribed species of the heterobasidiomycetous genus Chionosphaera is carried by the bark beetles Dryocoetus autographus, Hylurgops palliatus, Ips acuminatus, Ips sexdentatus, Ips typographus, Orthotomicus laricis, Pityogenes chalcographus, Pityokteines spinidens, and Polygraphus poligraphus infesting conifers in Europe (Abies alba, Larix decidua, Picea abies, and Pinus sylvestris). Chionosphaera cuniculicola sp. nov. differs morphologically from C. apobasidialis in the more slender basidiospores. The segregation of the two species is supported by comparison of partial sequences of the large subunit of the ribosomal gene. Isotype material of Chionosphaera lichenicola was re-examined. In contrast to C. cuniculicola and C. apobasidialis, C. lichenicola exhibits clamps at the septa. Fibulostilbum phylacicola is considered as a clamp-bearing species of Chionosphaera.

The genus Tulasnella is surveyed in the Patagonian Andes forests of southern Argentina based on specimens collected from Austrocedrus chilensis, Nothofagus antarctica, N. betuloides and N. pumilio. Five species are recorded, namely T. robusta sp. nov., T. allantospora s.lat., T. calospora, T. helicospora and T. violea, all of which represent new records for Argentina.

Aspects of the ecology of oospores of Phytophthora infestans were studied in the highlands of central Mexico. From an investigation of a random sample of strains, it was found that isolates differed in their average capability to form oospores when engaged in compatible pairings. Most crosses produced large numbers of oospores but a few yielded none and some yielded only a few oospores. The results reveal that oospore production and fecundity is dependent on both isolates and the combining ability of a specific combination of parental strains. On average, 14% of the oospores produced were viable as determined by the plasmolysis method. Viability ranged from a low 1% in one cross to a high of 29% in another cross. Oospores were found in 10–20% of naturally infected Solanum demissum leaves from two different collections, and leaflets with two lesions per leaflet produced more oospores than did leaflets with 3–5 lesions per leaflet. There was no consistent trend for preferential mating between isolates from the same location or host.