Roy Watling

Chloromethane production by wood-rotting fungi and an estimate of the global flux to the atmosphere

The production of chloromethane (CH 3 Cl) by wood rotting fungi of the Hymenochaetaceae is discussed with particular emphasis on emissions by species of Phellinus and Inonotus . Recent work on the metabolic role of CH 3 Cl as a methyl donor in the biosynthesis of secondary metabolites both in the Hymenochaetaceae and other families of white-rot fungi is reviewed. The parameters affecting the fungal emissions of CH 3 Cl in forest ecosystems are considered and where possible quantified. The annual global input to the atmosphere from this source is provisionally estimated at 160 000 t of which 75% is released from tropical and subtropical forests and 86% is attributable to Phellinus . The possible impact of the contribution from fungi and other biological sources on the atmospheric CH 3 Cl burden and stratospheric ozone depletion is assessed.

Global diversity and distribution of macrofungi

Data on macrofungal diversity and distribution patterns were compiled for major geographical regions of the world. Macrofungi are defined here to include ascomycetes and basidiomycetes with large, easily observed spore-bearing structures that form above or below ground. Each coauthor either provided data on a particular taxonomic group of macrofungi or information on the macrofungi of a specific geographic area. We then employed a meta-analysis to investigate species overlaps between areas, levels of endemism, centers of diversity, and estimated percent of species known for each taxonomic group for each geographic area and for the combined macrofungal data set. Thus, the study provides both a meta-analysis of current data and a gap assessment to help identify research needs. In all, 21,679 names of macrofungi were compiled. The percentage of unique names for each region ranged from 37% for temperate Asia to 72% for Australasia. Approximately 35,000 macrofungal species were estimated to be “unknown” by the contributing authors. This would give an estimated total of 56,679 macrofungi. Our compiled species list does not include data from most of S.E. Europe, Africa, western Asia, or tropical eastern Asia. Even so, combining our list of names with the estimates from contributing authors is in line with our calculated estimate of between 53,000 and 110,000 macrofungal species derived using plant/macrofungal species ratio data. The estimates developed in this study are consistent with a hypothesis of high overall fungal species diversity.

Armillaria species from South-Eastern Australia

Armillaria hinnulea sp.nov. and A. fumosa sp.nov. are described. Armillaria novae-zelandiae is fully described and its occurrence in Australia documented. Armillaria novae-zelandiae and A. hinnulea occur widely in wet forests in south-eastern Australia, the former in cool temperature rainforest and mixed forest, the latter in mixed forest and wet sclerophyll eucalypt forest. Armillaria fumosa is so far only known from poorly drained or seasonally wet locations within dry sclerophyll eucalypt forest. Morphological characteristics of vegetative isolates can be used to differentiate between A. hinnulea, A. novae-zelandiae and A. fumosa although isolates of the latter species cannot be differentiated from those of another Australian species, A. luteobubalina. The new combinations Armillaria bulbosa, A. fellea, A. griseomellea, A. montagnei and A. sparrei are proposed.

Poisoning by Cortinarius speciosissimus.

Severe renal failure caused by the mushroom Cortinarius speciosissimus was first recognised in 1972 and has been reported only from Scandinavia. In the summer of 1979 and following the consumption of the wild mushroom in Scotland, three previously healthy young adults developed the recognised features of cortinarius poisoning-namely, gastrointestinal upset after 36-38h, followed by nausea, anorexia, headache, rigors, severe burning thirst, muscle aching, and oliguria. One patient had a diuresis after 8 days and recovered completely. The two other patients did not present to hospital until 10 days after ingestion and severe renal failure had already developed. Both had a severe interstitial nephritis and neither recovered renal function. They were maintained on intermittent haemodialysis until they received renal transplants 9 months later. This form of mushroom poisoning has not so far been reported in the British Isles. With the increasing popularity of wild-mushroom eating, posters and publications on wild edible foods should contain warnings about the toxic nature of species of the genus Cortinarius.

The genus Armillaria -- nomenclature, typification, the identity of Armillaria mellea and species differentiation.

The nomenclatural history of the genus Armillaria is given and its acceptance over Armillariella argued. The identity of the type species, A. mellea, is determined and a full description of material from the probable locality in Denmark of the original collection is offered. It is suggested that this material be used as a neotype for Agaricus melleus Vahl ex Fr. The true identity of many species formerly placed in Armillaria is given, along with a discussion on species differentiation within the genus as it is now defined.

Taxonomy and toxicity of Conocybe lactea and related species

Conocybe lactea was examined as part of a larger study on the distribution of amatoxins and phallotoxins in fungi, and the taxonomic relationships between these fungi. As amatoxins are present in the congener C. filaris, the locally abundant C. lactea was examined using HPLC and mass spectroscopy. Amatoxins were not found in C. lactea, but the related phallotoxins were present in small quantities making it the first fungus outside of the genus Amanita in which phallotoxins have been detected. Despite the presence of a related toxin, C. lactea was found not to be taxonomically close to C. filaris. Phylogenetic analyses using nuclear ribosomal RNA genes indicated that North American specimens of C. lactea were conspecific with North American specimens of C. crispa in Conocybe sect. Candidae. European C. crispa was a distinct taxon. The implications of the use of the name C. albipes for these taxa are discussed. Nucleotide data confirmed placement of the sequestrate taxon Gastrocybe lateritia in sect. Candidae, but as a distinct taxon. It is hypothesized that the unique sequestrate morphology of G. lateritia may be caused by a bacterial infection.

Identification and occurrence of Australian Armillaria species, including A. pallidula sp. nov. and comparative studies between them and non-Australian tropical and Indian Armillaria

Interfertility studies with single-basidiospore isolates showed that the Australian species Armillaria luteobubalina, A. novae-zelandiae, A. fumosa, A. hinnulea and A. pallidula sp.nov. are biological species. Single-basidiospore isolates of A. novae-zelandiae from Australia and New Zealand were interfertile, confirming the occurrence of this species in both countries. The occurrence of A. novae-zelandiae, A. futnosa and A. hinnulea in New South Wales and Queensland and A. luteobubalina in South Australia, New South Wales and Queensland is documented. The host range of the latter species has been extended. A. pallidula is described from a plantation of Pinus caribaea on a former subtropical eucalypt forest site in Queensland. The affinities between it, other Australian species, the tropical species A. fuscipes, A. fellea, A. mellea var. camerunensis and a number of Indian species of Armillaria are considered. Detailed descriptions of the micromorphological features of A. fuscipes and A. fellea are given.

Species and population structures of Pisolithus and Scleroderma identified by combined phenotypic and genomic marker analysis

Isolates of Pisolithus and Scleroderma species from different northern temperate and tropical geographical regions were subjected to analyses of pure culture morphology, colony growth rates, isozyme (allozyme) variation and ribosomal DNA (rDNA) restriction fragment length polymorphisms (RFLPs). Cultural characteristics enabled clear species separation of isolates and together with growth rates suggested geographically-linked intraspecific variability in the Pisolithus populations. Combined or method-specific hierarchical cluster analyses of allozyme polymorphisms and RFLPs of the fungal internal transcribed spacer (ITS) and intergenic spacer (IGS) sequences confirmed the Scleroderma species groupings and considerable geographical and host-linked variation in the Pisolithus population. Isolates of Pisolithus from the Philippines were genetically very homogeneous and distinct from less related isolates from Europe, Scandinavia and North America. Based on the ITS—RFLP and isozyme polymorphism data, the isolates investigated probably represent four different ‘species groupings’ which supports similar findings from recent taxonomic and genetic studies of Australian Pisolithus species.

Spread and effects of Armillaria luteobubalina sp. nov. in an Australian Eucalyptus regnans plantation

Trees up to 25 m tall died suddenly at the edges of a steadily extending patch of dead and dying trees in a fast-growing plantation of Eucalyptus regnans F. Muell. near Traralgon, Victoria. Measurements of tree height and stem diameter made during the 12 years since the plantation was established indicate that, prior to their death, trees at the margins of the extending patch grew as rapidly as unaffected neighbours. During May 1973 and May 1974, Armillaria luteobubalina Watling & Kile sp.nov. fruited prolifically on dead and infected trees. Few rhizomorphs have been found so that spread of infection seems to have been mainly by mycelial growth within root systems and at root contacts. Infection has spread from inoculum in a single stump of Acacia melanoxylon R. Br. at an average annual rate of 2.5 m. Untreated stumps of healthy 10-year-old trees felled in unaffected parts of the plantation during the fruiting season of 1973 have not become infected. In pathogenicity tests with an isolate from the cap of a fruiting body, E. regnans seedlings have suddenly wilted and died following penetration of the tap root-root collar zone and subsequent girdling of the stem. It is concluded that the deaths at Traralgon are due to primary attack by A. luteobubalina .

Ectomycorrhizal fungi of the Guinea–Congo Region

The occurrence of ectomycorrhizal fungi in West African rain forest systems is demonstrated and linked to the presence of a range of caesalpinoid legumes and to members of the genus Uapaca . The vast array of boletes, members of the Russulaceae and Amanitaceae, and chanterelles is described. The virtual absence of ectomycorrhizal Cortinariaceae is emphasised. After an overview three separate yet interlinked studies are described: a survey of ectomycorrhizal fungi throughout the region (Thoen): ectomycorrhizal fungi of a single rain forest community (Watling) and the significance and relationships of the genus Russula in the Guinea–Congo Region (Buyck). Some comparisons are made with other rain forest areas of the world.