The new species, Termitomyces bulborhizus, is described from south-west China. The stipe of the basidiome is swollen into a prominent bulbous base at ground level, and this, together with the floccules on the stipe surface, distinguishes this species within the genus. T. bulborhizus is compared with closely related species, including three originally described from China, and a key to T. bulborhizus and related species is provided.

A taxonomic and ecological reassessment of the genus Cresporhaphis is presented, with a key to all 7 species currently known, including C. ulmi sp. nov. from Spain, on twigs of Ulmus minor. Species are facultatively lichenized with chlorococcoid algae, Trentepohlia and other algae, or saprobic.

Arthrowallemia anam. gen. nov., characterized by holothallic conidiogenesis, secession randomly schizolytic, and cylindrical, septate, brown conidia emerging from conspicuous unbranched conidiophores, is described and illustrated. The type species, A. formosa sp. nov., was collected on unidentified decaying leaves in Cuba. Notes on similar genera are given.

Axenic cultures of the aspen rust Melampsora larici-tremulae were established for the first time by seeding aeciospores artificially produced on larch onto three chemically defined media. Cultures were maintained for 9 months and evaluated for their appearance, growth rates and sporulation ability. Two types of colonies were observed. One, white and fluffy tending to felty, did not sporulate in culture. The other, white-orange with a more compact aerial mycelium, sporulated profusely producing various spore like bodies and other unusual structures. An initial lag phase, with reduced growth, characterised primary rust cultures in the first 4–5 weeks. After about one month, cultures seemed adapted to utilising exogenous nutrients for sustained growth and their development rate increased substantially. As a result of selection under unusual growing conditions, fast-growing genetic variants were also observed in the nutrient agar. Growth on all the three test media, containing different organic and inorganic constituents, suggested that nutritional requirements were non-specific. The importance of axenic cultures in the study of the nutritional requirements of aspen rust and the potential of these investigations to elucidate some physiological and genetic aspects of the host-parasite relationship are discussed.

The development of the peridioles of a Mycocalia sp., and the primordia of Scleroderma verrucosum and S. areolatum, has been studied, particularly in view of the presence of metamorphosed basidia. In the Mycocalia sp. and S. verrucosum spore-like bodies were formed exclusively by transformation of whole basidia. The ontogeny of S. verrucosum has been compared with that of S. areolatum. The structure of the exoperidium of S. verrucosum is much more complicated: hyphal knots play an important part in its construction. The processes giving rise to the exoperidium may be homologous with those constituting universal veils in Agaricales.

The rust fungus Chrysomyxa woroninii causes perennial witches' brooms on several species of Ledum in northern and subalpine regions of Europe, North America and Asia. Spruce bud rust has been assumed to be the aecial state of C. woroninii because of the close proximity of infected Ledum plants and systemically infected buds on Picea. The lack of experimental evidence for this connection, however, and the presence of other species of Chrysomyxa on the same hosts has led to confusion about the life-cycle of C. woroninii. In this study, infections on both spruce and Ledum were studied in the field and in a greenhouse. The link between the two states was proven by inoculating spruce with basidiospores from Ledum groenlandicum. After infection of spruce in spring, probably through the needles, the fungus overwinters in the unopened buds until the next spring, when the infected shoots are distinguished by stunting and yellow or red discolouration. Microscopic examination of dormant Ledum shoots showed that C. woroninii overwinters in this host in the bracts and outer leaves of the vegetative buds, and in the pith and cortex of the stem. The telia of C. woroninii, on systemically infected Ledum leaves of the current season, are easily distinguished from the telia of other Chrysomyxa species on the same hosts. The latter produce localized telia and uredinia only on overwintered leaves, produce aecia on spruce needles in the same year as infection occurs, and are not systemic in spruce. The restricted habitat distribution of C. woroninii and the need for overwintering outdoors suggest that this rust fungus has specific environmental requirements for survival.

Recent studies suggest that the antifungal agents itraconazole, bifonazole, and ketoconazole affect calcium-mediated signal transduction in Trichophyton rubrum. We have now examined the effects of azole-antifungal agents on cell membrane function in T. rubrum, by analysing the effects of itraconazole, bifonazole, ketoconazole, and lanoconazole on ionomycin-induced changes in intracellular calcium concentration ([Ca2+]i). Addition of 1 μm ionomycin to the culture medium produced a persistent increase in [Ca2+]i. While treatment with 1·5–15 nM of lanoconazole or bifonazole for 24 h did not affect this ionomycin-induced increase in [Ca2+]i, 30 nM of these agents resulted in a transient increase in [Ca2+]i rather than the usual sustained increase in [Ca2+]i. This transient ionomycin-induced increase in [Ca2+]i was also observed after treatment with only 1·5 and 3 nM of ketoconazole or itraconazole. Incubation in the presence of lanoconazole or bifonazole at [ges ]150 nM, and ketoconazole or itraconazole at [ges ]15 nM inhibited both the persistent and transient ionomycin-induced increase in [Ca2+]i. On the basis of these findings, it is suggested that azole antifungal agents disturb membrane function in T. rubrum, and that one manifestation of this effect is the disruption of the ionomycin-induced increase in [Ca2+]i. We report that the ionomycin-induced increase in [Ca2+]i is more sensitive to low concentrations of ketoconazole and itraconazole compared to bifonazole and lanoconazole.

The effect of the environment on the germination, survival and infection of sorghum by conidia of Peronosclerospora sorghi is unknown in Africa. Dew point temperature, and the effect of conidium age was characterized for an isolate of P. sorghi from Zimbabwe. Germination and germ tube growth took place in the range 10–34°C (optimal at 10–34 and 20–33°, respectively). Infection was optimal at 14–30°. Incidence of infection at different temperatures was correlated with germ tube growth (r=0·8, P<0·001). Germination and germ tube growth occurred from 5 h after commencing incubation of infected leaf material, although immature conidia harvested at 3 h caused a low incidence of infection. Plant age also affected the incidence of infection. Container grown sorghum plants older than 20 d, and maize plants older than 15 d were resistant to systemic infection by conidia. The results indicate that germination, germ tube growth and infection take place over a wide temperature range, and that some limited biotypic variation may exist when these data are compared to other reports of the environmental requirements of P. sorghi from the U.S.A. and India.

The genus Dioicomyces is reviewed on the basis of the examination of types, authentic material, or personal collections. Three new species from Spanish anthicids are described: D. denticulatus, D. ladoi, and D. leptalei spp. nov. Eleven taxa (including eight species, two forms, and one variety) are synonymized and included under D. anthici, which is considered a very variable species. With additions and changes, Dioicomyces currently includes 23 species. In this synopsis no taxa at infraspecific rank are recognised. For each accepted species synonyms are listed, mostly based on the study of type material. Types for each taxon are included and lectotypes designated when necessary. This monograph also includes descriptions, photographs and/or drawings for all species studied and a key for their determination.

Species of Rhizoctonia cause a blight of Lotus corniculatus, a perennial forage legume. We characterized genetic variation and virulence in populations of R. solani and binucleate Rhizoctonia's associated with diseased L. corniculatus in field plantings over several years. Isolates of anastomosis groups AG-1 and AG-4 accounted for the R. solani recovered from diseased leaf and shoot tissues. Isolates of binucleate Rhizoctonia were recovered predominantly from soil and associated plant debris. Isolates of R. solani were more virulent on leaves and shoots of L. corniculatus than were binucleate Rhizoctonia isolates. Numerous unique DNA restriction patterns were observed among binucleate isolates and anastomosis groups of R. solani. Variation in restriction patterns was greater among isolates of AG-1 from the lower plant canopy than from the upper canopy. No restriction pattern was shared by any isolate from AG-1 and AG-4. Allelic and genotypic heterogeneity of AG-1 isolates were also greater in the lower plant canopy. Binucleate isolates exhibited greater heterogeneity than AG-1 isolates from either canopy region. L. corniculatus offers significant opportunities for investigating temporal and spatial dynamics of genetic structure of Rhizoctonia populations in perennial plant systems.

Ultrastructural details of sporangial plasmodia and zoosporangia of Spongospora subterranea f. sp. nasturtii infecting the roots of watercress were observed using transmission electron microscopy. The plasmodial envelope, the interface between host and parasite, was found to be convoluted, having a large surface area. Pseudo-food vacuoles, formed by convolutions of the plasmodial envelope, contained portions of host cytoplasm. True-food vacuoles containing the remains of host organelles were seen within plasmodia. Similar remains also were seen in the central vacuole. The flagellar apparatus including the kinetosome, with microtubular rootlets, the transition zone, the flagellum and the tapering end-piece were examined and described. These observations are discussed in terms of the nutrition of S. subterranea f. sp. nasturtii, its original classification within the fungi (latterly Plasmodiophoromycetes) and affinities with the protists.

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.

Conidiogenesis in Septoria chrysanthemella was studied in vitro with light and transmission electron microscopy (TEM). For the first time, proof is given with TEM that both percurrent and sympodial proliferation can occur in a single conidiogenous cell. Ontogeny of conidia is holoblastic. After delimitation by a transverse, uniperforate septum, each conidium is liberated schizolytically. Three kinds of conidiogenous cells occur in S. chrysanthemella: (i) annellides, proliferating only percurrently; (ii) sympodulae, proliferating only sympodially, and (iii) cells proliferating either way. No influence of illumination by diffuse daylight or nuv, or medium was observed on qualitative aspects of conidiogenesis. The annellations in S. chrysanthemella seen with TEM are not resolved by light microscopy (LM). It is concluded that LM is not sufficient to assess conidiogenesis in species of Septoria with equally minute conidiogenous cells.

Chitin synthase genes of Tuber magnatum were sought in order to investigate the molecular bases of its growth. Primers designed from highly conserved Chs domains were used to identify a chs gene portion. A genomic library was used to obtain the full gene sequence (TMchs4) with an open reading frame which encodes a predicted protein of 1230 amino acids. The sequence is similar (62%) to the class IV chitin synthase from Neurospora crassa. The putative protein shows hydrophobicity pattern that suggests the presence of several intramembranous domains and other peculiar features common to the other chs of class IV. Northern experiments demonstrated that the gene is expressed in ascomata sampled at different maturation steps. These data suggest that ascomata growth requires new chitin deposition, which is based on a chs gene activation and not only on an enzymatic activity.

Harposporium arcuatum, H. dicorymbum and H. subuliforme were isolated from nematodes and grown in pure culture. All three species produced accessory conidia in culture and two species also produced arthroconidia. A comparative study of spore production within nematophagous members of the genus Harposporium was made.

The occurrence of disease outbreaks associated with the genus Sorosporella on grasshoppers and locusts (Orthoptera: Acridoidea) in Africa is reported. Infected hosts, representing ten genera within five acridoid subfamilies, are characterized by red, thick-walled chlamydospores which completely fill the cadaver. On selective media, the chlamydospores, up to seven-years-old, germinated to produce a Syngliocladium anamorph which is considered to be undescribed. The new species Syngliocladium acridiorum is described and two varieties are delimited: var. acridiorum, on various grasshopper and locust genera from the Sahelian region of West Africa; and, var. madagascariensis, on the Madagascan migratory locust. The ecology of these insect-fungal associations is discussed. Sorosporella is treated as a synonym of Syngliocladium.

Allelic genes hga1-1 and hga1-2, which encode G protein alpha subunit in the violet root rot fungus, Helicobasidium mompa, were sequenced and characterized. Restriction fragment polymorphism (RFLP) analysis determined that the gene is present as a single locus in the single basidiospore isolates, while strain V169 possessed both alleles of this gene. Therefore, although basidiospore isolates are dikaryon, they are homokaryotic. Field-isolated strain V169, the putative parent strain, is a dikaryotic heterokaryon. Allelic genes hga1-1 and hga1-2 segregated in almost a 1[ratio ]3 ratio among single basidiospore isolates from the same fruiting body. Moreover, the copy number of hga1-1 was found to be less than that of hga1-2 in the V169 strain. These results suggest that one of the nuclei in the V169 parent strain is homozygous diploid and the other heterozygous diploid. This parent strain produced four homokaryotic and dikaryon basidiospores on each basidium.

A key to 17 species in the genus Hygrocybe, subgenus Pseudohygrocybe, sections Coccineae and Neohygrocybe sensu Boertmann is provided for the Greater Antilles. Five new species and five taxa that are new reports for the region are described. The new species in section Coccineae are H. pseudoadonis, H. viridiphylla, and H. zonata. The new species in section Neohygrocybe are H. albomarginata and H. ovinoides. The new reports are H. caespitosa, H. coccinea, H. cf. miniata, H. papillata, and H. subovina. Three new combinations are proposed: Hygrocybe mycenoides, H. papillata and H. subovina.

Terrestrial invertebrates in central Amazonian floodplains must cope with annual long-term inundation. Parasites should be affected mainly indirectly through the specific life-cycles of their hosts. We studied the temporal structure of a beetle–fungus system at a central Amazonian blackwater floodplain (Rio Negro, Brazil). The host species Phaeoxantha aequinoctialis (Coleoptera, Carabidae, Cicindelinae) showed a seasonal, univoltine life-cycle triggered by the annual flood pulse. Infestation frequency of its fungal parasite, Laboulbenia phaeoxanthae (Ascomycota, Laboulbeniales), varied seasonally. However, the seasonality was opposed in host and parasite: the lowest infestation frequencies were observed during periods of highest beetle abundance and vice versa. Periods of lowest beetle abundance coincided with the end of the old generation, those with highest abundance with the appearance of new adults. The resulting annual patterns of a slow spread in the host population resembled the few records of temporal patterns from temperate regions. It is explicitly demonstrated that older adult female beetles are more frequently infested than younger ones. Future studies may reveal whether this is simply the result of specific host life-cycles (driven by a flood pulse, winter, or other factors), or might also be related to potentially easier infestation in older individuals.

Two new species of Wawelia are described from rabbit and hare dung incubated under conditions of restricted water supply. A key to the five known species of Wawelia is provided.