This issue of Mycological Research News features: In this issue; and Changing the biological clock in Neurospora crassa.

Original papers in this number include morphological and molecular investigations on: Endophyllum species on asteraceous plants; Melampsora rusts on Salicaceae; myxotoxin producing Fusarium chemotypes; host specificity and nutrient uptake in Eudarluca caricis; Ampelomyces populations on powdery mildews; salt marsh populations of Claviceps purpurea; the classification of Omphalina foliacea; and endophytes in different genera of native Australian orchids.

A gene encoding a malic enzyme involved in the anaerobic growth of Mucor circinelloides is characterized. In the ericoid mycorrhizal Hymenoscyphus ericae, one paper shows how carbon availability affects nitrogen source utilisation, and another the effects of copper toxicity in relation to phosphatase activity.

The colonization of wood by airborne spores has been studied in experimental forest plots, and the climatic and altitudinal factors correlated with spore catches of Alternaria and Cladosporium determined.

Early development of Morchella fruit bodies is described and documented by scanning electron microscopy.

The following new scientific names are introduced in this issue: Endophyllum dimorphothecae sp. nov.; E. elytropappi (syn. Aecidium elytropappi) comb. nov.

Lu et al. (2002) described a method for identifying Hericium species by PCR, using the primers HT-U1 and HT-L1 which they specifically designed for this purpose. In our hands these primers do not appear to discriminate between tooth fungi and other wood decay species. Therefore PCR primers were designed that discriminated Creolophus cirrhatus from other species (HER2F/HER3R), and which discriminate Hericium alpestre, H. coralloides and H. erinaceus from other wood decay Ascomycota and Basidiomycota but not from each other (HER2F/HER2R). Using the HER2F/HER3R primers together with traditional isolation and direct incubation procedures, the location of C. cirrhatus in Turkey oak logs was mapped. The PCR approach often detected C. cirrhatus in locations where it was suspected to be, based on patterns of staining and decay, but where it was not revealed by isolation onto agar media, emphasising the value of adopting several approaches to unravel fungal community structure in wood.

Endophyllum osteospermi is an autoecious, endocyclic rust fungus, which has only been recorded on Chrysanthemoides monilifera ssp. monilifera (Asteraceae, Calendulae), a perennial woody shrub. Both organisms are indigenous to South Africa. Because E. osteospermi is being considered for release in Australia as a biocontrol agent against C. monilifera ssp. monilifera, it was necessary to determine its host range and natural distribution in South Africa. To address this, natural stands of Chrysanthemoides species, as well as other South African asteraceous plants, were monitored for E. osteospermi between 1992 and 2003. A morphological and molecular comparison of specimens referable to Endophyllum was undertaken. Based on these results, E. osteospermi was recorded on C. monilifera sspp. monilifera, pisifera, rotundata, canescens, and subcanescens, C. incana, and an undescribed taxon. E. osteospermi was also recorded on Osteospermum ciliatum, O. polygaloides, and O. potbergense. Furthermore, a closely related but previously undescribed species, E. dimorphothecae sp. nov. is described on Dimorphotheca cuneata. Aecidium elytropappi is transferred to Endophyllum as E. elytropappi comb. nov., being recorded on Elytropappus rhinocerostis and Stoebe plumosa. This study shows that in South Africa E. osteospermi is restricted to a small group of related plant species in the Calenduleae. This rust is therefore considered suitable as a candidate agent for the biocontrol of C. monilifera ssp. monilifera, and pending the results of host specificity testing, would most likely be safe to introduce into Australia.

The foraging behaviour of Armillaria rhizomorph systems is poorly understood owing to their cryptic position within the soil. We investigated foraging in a homogeneous environment (i.e. agar), finding that rhizomorph systems of the more parasitic species, A. mellea, A. ostoyae, and A. tabescens, lacked melanin and the approximately cylindrical cord-like form observed in the field. In contrast, rhizomorph systems of the more saprotrophic species, A. calvescens, A. gallica, and A. sinapina, developed radially resembling those in the field. For the three saprotrophic Armillaria species, the number of rhizomorph tips, total rhizomorph length and total rhizomorph surface area were significantly positively correlated with increasing rhizomorph system diameter and elapsed time in two developmental tests. However, the fractal dimension (D), used as a measure of foraging intensity, was temporally invariable, suggesting that one component of foraging behaviour is innate. In a heterogeneous environment (i.e. sand) and in the absence of a potential nutrient source, we observed that rhizomorph systems of A. gallica most often developed asymmetrically. While rhizomorph foraging was unresponsive to the lateral placement of an uncolonised stem segment, we were able to demonstrate directional growth toward an uncolonised Quercus velutina stem segment placed above or below the colonised source stem segment. When neighboring rhizomorph systems were conspecific genets of A. gallica, we observed that the growth of one rhizomorph system was directed toward zones unoccupied by its neighbour. However, the foraging intensity of the neighbouring genets, as measured by fractal dimension (D), was unaffected by the proximity of a neighbour. When neighbouring rhizomorph systems represented different species (A. gallica and A. mellea), A. gallica rhizomorph systems produced more total length and more foraging tips but concentrated their rhizomorph production away from the neighbouring A. mellea genet. In contrast, A. mellea rhizomorph systems produced significantly more foraging tips per unit length, both overall and in the zone of confrontation with the neighbouring A. gallica genet. Our observations are consistent with field observations of territoriality among Armillaria genets, and provide evidence that rhizomorph systems of more parasitic Armillaria spp. are able to compete effectively with the larger rhizomorph systems of more saprotrophic Armillaria species.

The 5′ end of the large subunit (LSU) region and the entire internal transcribed spacer (ITS) region of ribosomal DNA were sequenced from 11 species or special forms of Melampsora on Salix, and three species on Populus. For all the species, except for M. larici-epitea and M. coleosporioides, the sequences in both the examined regions were identical within a species. Within M. larici-epitea, f. sp. larici-epitea typica and f. sp. larici-retusae shared the same sequences which slightly differed from that of f. sp. larici-daphnoides. In the LSU region, M. larici-epitea, M. capraearum and the stem-infecting form on S. viminalis shared the same sequence and the Far-Eastern species M. epiphylla differed from them only slightly (p distance 0.006), indicating that they may share a common ancestral lineage. M. amygdalinae and M. coleosporioides formed a distict group (bootstrap value 100% for combined ITS and LSU data). M. larici-epitea and M. ribesii-purpurea, both belonging to the M. epitea complex, appeared to be distinct. The molecular data also suggest that the differences in certain characteristics, such as the thickness of teliospore walls and host specificity, may have evolved relatively recently.