Laboulbenia stenolophi is reported for the first time from Japan. Stenolophus iridicolor and S. propinquus are added as new hosts. The crowded antheridia and the protruding (bulging) cell IV are characteristic of this fungus, although thalli with an almost normal cell IV sometimes occur. Laboulbenia anoplogenii on Anoplogenius is easily distinguished from what has been called L. anoplogenii on Stenolophus, Astigis, Abacetus and Chlaeminus by the following characters: 1) no crowded antheridia can be observed throughout thallus development, but many sterile long branches can be observed instead; 2) cell IV starts to undergo cell division early in thallus development; 3) cell V extends downward to the level of cell VII, rather than extending only as far as the perithecial basal cells; and 4) cell VI is usually longer and extends farther distally than cell III. Anoplogenius is the host genus of L. anoplogenii and the records from other hosts represent misapplied names.

We examined the effects of chemical components and nitrogen sources on zygospore development, using 62 different ingredients based on Sutter's synthetic medium Sl, which has been widely used for studies of sexual physiology in Phycomyces. An increase of inorganic microelements such as ZnSO₄, NaMoO₄ and CaCl₂ promoted an increase in the number of zygospores per unit area. Glutamate (Glu) contained in Sl as the sole nitrogen source was indispensable for sexual development, and replacement of Glu with NH₄⁺(Am) strongly inhibited it, mainly because of growth inhibition. However, zygospore production was enhanced 1.8-fold by equivalent amounts of both Glu and Am as compared with Glu alone. A newly developed medium, mSI+Am, enriched with Am and the above-mentioned effective microelements doubled the number of zygospores formed per unit area (density), compared with Sutter's original SI, and increased both the density and the weight (volume) of zygospores, 1.6- and 2-fold, respectively, compared with potato-dextrose-agar medium enriched with yeast extract and casitone (PDAYC). Sexual stimulation by mSI+Am was also observed in the mating of a pair of β-carotene-deficient mutants. Methionine sulfoxime, an inhibitor of glutamine synthetase, strongly inhibited the progress of mating without significant growth inhibition.

Identifications of 29 species of polypores described by Corner were made by type examinations. Laetifomes gen. nov. is proposed, typified by Rigidoporus flammans. The following new combinations are proposed: Abortiporus zonatus, Antrodiella flava, Laetifomes flammans, Oligoporus perplexus, Trichaptum vinaceibrunneum and Tyromyces sublacunosus. The following names are accepted in the original genera: Microporellus fuliginosus, M. pahangensis, M. subumbonatus, Rigidoporus adnatus, R. erectus and R. incarnatus. The following names are considered synonyms: Heteroporus kinabaluensis, Microporellus brunneus, M. nigripes, Rigidoporus albiporus, R. ochraceicinctus, R. parvulus, R. patellarius, R. sulphureus, R. suppileatus, R. trametoides and R. vinaceus. The following species are dubious because of their poor or sterile conditions: Heteroporus odoratus, Microporellus labyrinthiformis, Oxyporus lilaceus and Rigidoporus hypobrunneides. No authentic specimens were traced for Microporellus grandiporus and Paratrichaptum accuratum. Descriptions and line drawings are given for most of the accepted species.

We isolated an Alternaria species from brown leaf spots of Japanese butterbur in Kanuma city, Tochigi Prefecture in August 1996, and in Akagi village, Gunma Prefecture in June 1997. The isolated fungus formed irregularly shaped colonies with yellow-brown pigment on potato sucrose agar (PSA) and potato dextrose agar (PDA). When Japanese butterbur leaf was inoculated with small fragments of mycelia, brown spot lesions were produced. Conidial suspensions of the fungus also produced similar spots on Japanese butterbur leaf. Under moist conditions, a small amount of conidia was produced on the spots. The conidia were somewhat variable in shape and size, measuring 102-362×9-22 μm for the Kanuma isolate and 70-392 × 11-27 µm for the Akagi isolate. Length of the conidial beak was also variable, being 30-280 μm for the Kanuma isolate and 30-302 μm for the Akagi isolate. The fungus could not be identified with any of Alternaria species hitherto known, suggesting that it was new to science. We proposed to designate the fungus as Alternaria petasitis, giving a Latin description of the new species.

A new oomycete was found from intertidal fallen leaves of mangroves in Japan and Thailand and is described here as Halophytophthora porrigovesica. This species is characterized by having an epapillate, ovate zoosporangium with a lens-shaped dehiscence plug-like material at the apex, and by forming an expanding long cylindrical vesicle prior to zoospore release. A key to 14 species and 2 varieties of Halophytophthora including the new species is proposed. The subtropical (Iriomote Is., Japan) strains and tropical (Thailand) strains were different in physiological properties and especially in the asexual reproduction. The subtropical strains showed a lower optimal temperature and wider range of suitable temperature and salinity for zoosporangium formation, whereas the tropical strains showed a higher optimal temperature and narrower range of temperature and salinity. These differences are explained as adaptations of the strains to the environmental conditions of their respective habitats. From the subtropical mangroves, six strains of the new species have been isolated only from submerged leaves of Sonneratia alba, while several strains have been isolated from tropical mangroves from the leaves of three species of mangrove trees, S. alba, Bruguiera gymnorrhiza and Avicennia alba. This indicates a change of taxon selectivity (host specificity) with the geographical distribution.

Tricholoma matsutake was isolated into pure cultures from field samples of ectomycorrhizas on Pinus densiflora. The mycorrhizal tips were collected at different times of the year from a colony of T. matsutake in a P. densiflora stand. The mycorrhizal tips were continuously washed with sterilized distilled water and diluted Tween 80 solution, surface-sterilized with calcium hypochlorite solution, and inoculated on several kinds of nutrient agar media. Most of the mycorrhizal tips collected in winter and spring produced colonies that were morphologically similar to cultures of T. matsutake isolated from basidiocarps. The identity of isolates obtained from mycorrhizas was further confirmed to be T. matsutake based on fungal morphology and RFLP patterns of PCR amplified rDNA. The feasibility of T. bakamatsutake isolation into pure culture from ectomycorrhizas on Quercus serrata was also confirmed. These results indicated that mycelium of matsutake mushrooms can be isolated into pure culture from ectomycorrhizas at different times of the year. Mycorrhizas of both T. matsutake and T. bakamatsutake were not observed to have any specific association with soil fungi such as Mortierella spp.

A Calonectria sp. forming a Cylindrocladium anamorph was found to be commonly associated with leaf spot and cutting rot of Eucalyptus in Brazil, Colombia, Ecuador and Argentina. Based on morphology, isolates of this species resembled Cal. hederae, Cal. reteaudii and Cy. leucothoes, taxa that are commonly referred to as the Cal. reteaudii-complex. Using DNA sequence data of the ITS1, 5.8S and ITS2 of the rRNA gene, as well as the β-tubulin gene, this species was shown to represent a previously described, but rather poorly known species, Cal. spathulata, for which an emended description is provided. Furthermore, the recently described Cy. perseae was also shown to be synonymous with Cy. leucothoes, a species shown to be distinct from Cy. spathulatum. Based on vesicle and conidium morphology, as well as perithecial colour and ascospore morphology, it appears that Cal. hederae and Cal. reteaudii should also be retained as separate species. Additional collections and cultures would be required, however, to suitably characterise the latter two species in future studies.

A species of Mycosphaerella with a Pseudocercospora anamorph was collected on overwintered fallen leaves of Japanese beech, Fagus crenata. Based on comparison of morphology with Mycosphaerella species on Fagaceae, the fungus was newly described as Mycosphaerella buna. The Pseudocercospora anamorph derived from a single ascospore of the fungus was morphologically identical to an endophytic anamorph isolated from asymptomatic living leaves of Japanese beech.

Fruit-bodies of Agaricales are known to show positive phototropism during the early stage of development, but negative gravitropism at the later stage after the onset of basidiospore formation. However, when exposed to light from below, the fruit-bodies of Tephrocybe tesquorum and Coprinus spp. grew downward through all stages of development, even after the onset of basidiospore formation. Primordium formation, fruit-body development and basidiospore formation were not disturbed under such conditions. In these downward-growing fruit-bodies, gills stood straight upward. In T. tesquorum, caps often became swollen and stipes sometimes became twisted anticlockwise, contrary to those in light from above, while such behaviours were not observed in Coprinus spp.

Equilibrium, a concept of dynamics, is found to be applicable to the phototropic and gravitropic growth in agaric fruit-bodies. The fruit-bodies exposed to light from below grow straight downward without bending upward, and those exposed to light from obliquely below grow first downward and then upward by negative gravitropism. The fruit-bodies exposed to light from above grow upward. Fruit-bodies growing straight downward or upward do not change the direction of growth; they are in 'equilibria'. The straight downward growth can be regarded as an 'unstable equilibrium' having a higher potential, and the straight upward growth as a 'stable equilibrium' having a lower potential. The change in the direction of growth can be explained by the change in the potential; the upward bending in fruit-bodies that have grown obliquely downward can be regarded as a 'transition' from the unstable equilibrium to the stable one.

Mycorrhizas of Entoloma clypeatum f. hybridum on Rosa multiflora in the field in Japan were studied by stereo, light and electron microscopy. In most mycorrhizas, the root cap, meristem, and apical region of the cortex disappeared, but in a few mycorrhizas, these tissues remained. Fungal hyphae of the mycorrhizas invaded root tissues and branched palmately. Hyphae in contact with cortical cells were larger than those far from the root cells and contained many mitochondria, cisternae of endoplasmic reticulum and transitional vesicles. Invading hyphae were undulate in the apical part of the mycorrhiza, and some of them lacked distinct organelles. Electron-dense granules accumulated in the root cells adjacent to the fungal hyphae. Both the remnants of the plant cells and the fungal hyphae were included in the amorphous materials on the tip of the stele. These observations suggest the destructive infection by fungal hyphae of the root cells and their collapse near the tip of the stele.

Among the isolates from soil of grassland in Roraima State, Brazil, a new species of Neosartorya, N. takakii is described and illustrated. Neosartorya takakii differs from the other known species of the genus in having lenticular ascospores with two distinct equatorial crests and with roughly circularly arranged projections on the convex walls. A comparative SEM view of ascospores from six related Neosartorya species is also provided.

Lanceispora phyllophila is described based on specimens of petioles from an unidentified dicotyledonous host collected at Bukid Timan, Singapore. It is illustrated with interference contrast micrographs and compared with the type species L. amphibia. Lanceispora phyllophila differs from L. amphibia in having smaller ascomata and longer ascospores.

Uredinial-telial Puccinia fungi on Carex shimizuensis in Nagano Pref. and on C. dimorpholepis in Ibaraki Pref. were proven to host-alternate on Petasites japonicus by field observations and inoculation experiments. These fungi from the two localities were morphologically similar and were compared with three described Puccinia species that host-alternate between Carex species and P. japonicus in Japan, i.e., P. caricis-petasitidis, P. caricis-flabellatae and P. caricis-podogynae. The three previously described species and the newly found Puccinia fungi were morphologically indistinguishable at all stages of the life cycle; therefore, it was concluded that three species and the two newly found fungi are taxonomically identical, in which P. caricis-petasitidis has nomenclatural priority.

Two morphologically distinct strains, 63-76 and 63H1, were isolated from a protoplast and a hyphal tip of the parental Sclerotium rolfsii strain S-63, respectively. Strains 63-76 and 63H1 showed reduced mycelial growth and lacked clamp connections on hyphae. The two strains also differed from each other and from their parent in RAPD patterns generated by several primers, suggesting that 63-76 and 63H1 were homokaryons isolated from the hetereokaryon S-63. Whereas the parent S-63 belonged to ITS-RFLP group 1, RFLP patterns of internal transcribed spacer (ITS) regions of rDNA of 63-76 and 63H1 were similar to those of ITS-RFLP groups 5 and 3, respectively. The sequence similarity of ITS regions were more than 99% between 63-76 and group 5 strains, 100% between 63H1 and the group 3 strain, and 96.3% between 63-76 and 63H1. Direct sequencing failed in the parental strain S-63. S-63 was considered to contain ITS types of groups 5 and 3.

Surculiseries rugispora gen. et sp. nov. is described as an endophytic fungus from leaves of Bruguiera gymnorrhiza in mangrove forests in the Iriomote Is., Okinawa, Japan. This fungus develops peculiar conidiogenous cells that resemble octopus legs with obvious sucker-like scars, and produces lentiform conidia with lines on surface. Sequence analysis of 18S rDNA places this new fungus in the family Xylariaceae and shows its close affinity to the genus Ascotricha (anamorph: Dicyma).

AFLP (amplified fragment length polymorphism) analysis was applied to Armillaria ostoyae isolates (single-spore isolates and field isolates from the same forest). For detection of AFLP, we have developed a modified method using DNA sequencer with Texas Red-labeled selective primer. In analysis of single-spore isolates, this technique provided large numbers of highly polymorphic DNA markers, which can be used to identify genets. The results suggested that outbreeding might be common in A. ostoyae.

Stage-specific nucleolytic activity was identified in cell-free extracts (CFEs) of Phycomyces. Such activity was not detected in spore germlings or mycelia for the first 36 h after the start of cultivation. However, it was detected in mycelia more than 48 h after the start of cultivation, as well as sporangiophores and sporangia. The nucleolytic activity was completely inhibited by the addition of EDTA or G-actin to the CFE, and the various results together suggest that the activity was due to deoxyribonuclease I (DNase I).

Four PCR primers that are useful to determine the nucleotide sequences of the rDNA of the powdery mildew fungi were newly designed. These primers provide both enough stability to work on a wide range of powdery mildews and enough specificity to eliminate contaminating DNA by PCR. DNA sequences of the rDNA ITS region were successfully obtained from specimens that were contaminated by other fungi. In addition, sequence results of the 18S and 28S rDNA were dramatically improved by using these primers in most of the specimens examined.