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Human-associated introduction of pathogens and consequent invasions is very evident in areas where no related organisms existed before. In areas where related but distinct populations or closely related cryptic species already exist, the invasion process is much harder to unravel. In this study, the population structure of the Eucalyptus leaf pathogen Teratosphaeria nubilosa was studied within its native range in Australia, including both commercial plantations and native forests. A collection of 521 isolates from across its distribution was characterized using eight microsatellite loci, resulting in 112 multilocus haplotypes (MLHs). Multivariate and Bayesian analyses of the population conducted in structure revealed three genetically isolated groups (A, B and C), with no evidence for recombination or hybridization among groups, even when they co-occur in the same plantation. DNA sequence data of the ITS (n = 32), β-tubulin (n = 32) and 27 anonymous loci (n = 16) were consistent with microsatellite data in suggesting that T. nubilosa should be considered as a species complex. Patterns of genetic diversity provided evidence of biological invasions by the pathogen within Australia in the states of Western Australia and New South Wales and helped unravel the pattern of invasion beyond Australia into New Zealand, Brazil and Uruguay. No significant genetic differences in pathogen populations collected in native forests and commercial plantations were observed. This emphasizes the importance of sanitation in the acquisition of nursery stock for the establishment of commercial plantations., (© 2012 Blackwell Publishing Ltd.)

The genus Ceratocystis includes important fungal pathogens of trees, including Eucalyptus spp. Ironically, very little is known regarding the diversity or biology of Ceratocystis species on Eucalyptus species in Australia, where most of these trees are native. The aim of this study was to survey for Ceratocystis spp., and their possible insect associates, on eucalypts in Australia and thus to establish a foundation of knowledge regarding these fungi on the continent. Collections were made in three states of Australia from wounds on trees, as well as from nitidulid beetles associated with these wounds. Ceratocystis spp. were identified based on morphology and multigene sequence comparisons. Of the 54 isolates obtained, two previously unknown species of Ceratocystis were found and these are described here as Ceratocystis corymbiicola sp. nov. and Ceratocystis tyalla sp. nov. Furthermore, the distribution of Ceratocystis pirilliformis is expanded to include Eucalyptus spp. in Tasmania.

Background: Teratosphaeria nubilosa is a serious leaf pathogen of several Eucalyptus spp. This review considers the taxonomic history, epidemiology, host associations and molecular biology of T. nubilosa., Taxonomy: Kingdom Fungi; Phylum Ascomycota; Class Dothideomycetes; Order Capnodiales; Family Teratosphaeriaceae; genus Teratosphaeria; species nubilosa., Identification: Pseudothecia hypophyllous, less so amphigenous, ascomata black, globose becoming erumpent, asci aparaphysate, fasciculate, bitunicate, obovoid to ellipsoid, straight or incurved, eight-spored, ascospores hyaline, non-guttulate, thin walled, straight to slightly curved, obovoid with obtuse ends, medially one-septate, slightly constricted at the median septum, tapering to both ends, ascospore germination type F, germinating from both ends, germ tubes growing parallel to the long axis of the spore with distortion of the primary ascospore cell., Host Range: Teratosphaeria nubilosa is a primary pathogen of several Eucalyptus spp., including E. botryoides, E. bicostata, E. bridgesiana, E. cypellocarpa, E. dunnii, E. globulus ssp. bicostata, E. globulus ssp. globulus, E. globulus ssp. maidenii, E. globulus ssp. pseudoglobulus, E. grandis, E. gunnii, E. nitens, E. pilularis, E. quadrangulata, E. viminalis, E. grandis x E. resinifera and E. urophylla x E. globulus., Disease Symptoms: Leaf spots predominantly occur on juvenile Eucalyptus foliage; however, T. nubilosa has also recently been found on mature Eucalyptus foliage. Leaf spots are amphigenous, varying in size from small spots that are round to irregular. Lesions enlarge and coalesce to form larger blotches over the leaf surface. Initial lesions appear as pale-green spots surrounded by purple margins and, once mature, are generally yellow to pale brown with dark-brown raised borders., Useful Websites: Mycobank, http://www.mycobank.org; Mycosphaerella identification website, http://www.cbs.knaw.nl/mycosphaerella/BioloMICS.aspx.

Species of Phaeophleospora are anamorphs of Mycosphaerella and they include some of the most serious foliar pathogens of Eucalyptus spp. grown in plantations worldwide. Pathogens assigned to this genus and occurring on Eucalyptus spp. were previously treated in Kirramyces and they are also phylogenetically closely related to other anamorphs of Mycosphaerella residing in the genus Colletogloeopsis. The primary aim of this study was to consider the appropriate taxonomic placement of these species. To achieve this goal, morphological characteristics and DNA sequence data from the ITS and translation EF1-alpha gene regions were used to compare the type species P. eugeniae, Phaeophleospora spp. and Colletogloeopsis spp. occurring on eucalypts, using ex-type cultures and herbarium specimens. Phylogenetic data and morphological comparisons supported the separation of P. eugeniae from Phaeophleospora species occurring on eucalypts. The name Phaeophleospora is retained for P. eugeniae and the name Kirramyces is resurrected for the species occurring on eucalypts (genera Eucalyptus, Corymbia, and Angophora). Sequence data from the type specimens of two previously described species of Kirramyces, K. lilianiae and K. delegatensis, show they reside in a clade with other Kirramyces spp. Morphological and DNA sequence comparisons also showed that there is considerable overlap between species of Phaeophleospora and Colletogloeopsis from eucalypts. Based on these findings, Colletogloeopsis is reduced to synonymy with the older Kirramyces and the description of Kirramyces is emended to include species with aseptate, as well as multiseptate, conidia produced in acervuli or pycnidia. Two new species of Kirramyces, K. angophorae and K. corymbiae, are also described.