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Species of the ascomycete genus Mycosphaerellaare regarded as some of the most destructive leaf pathogens of a large number of economically important crop plants. Amongst these, approximately 60 Mycosphaerellaspp. have been identified from various Eucalyptusspp. where they cause leaf diseases collectively known as Mycosphaerella Leaf Disease (MLD). Species concepts for this group of fungi remain confused, and hence their species identification is notoriously difficult. Thus, the introduction of DNA sequence comparisons has become the definitive characteristic used to distinguish species of Mycosphaerella. Sequences of the Internal Transcribed Spacer (ITS) region of the ribosomal RNA operon have most commonly been used to consider species boundaries in Mycosphaerella. However, sequences for this gene region do not always provide sufficient resolution for cryptic taxa. The aim of this study was, therefore, to use DNA sequences for three loci, ITS, Elongation factor 1-alpha (EF-1α) and Actin (ACT) to reconsider species boundaries for Mycosphaerellaspp. from Eucalyptus. A further aim was to study the anamorph concepts and resolve the deeper nodes of Mycosphaerella, for which part of the Large Subunit (LSU) of the nuclear rRNA operon was sequenced. The ITS and EF-1α gene regions were found to be useful, but the ACT gene region did not provide species-level resolution in Mycosphaerella. A phylogeny of the combined DNA datasets showed that species of Mycosphaerellafrom Eucalyptuscluster in two distinct groups, which might ultimately represent discrete genera.

Ophiostomarepresents a genus of fungi that are mostly arthropod-dispersed and have a wide global distribution. The best known of these fungi are carried by scolytine bark beetles that infest trees, but an interesting guild of Ophiostomaspp. occurs in the infructescences of Proteaspp. native to South Africa. Phylogenetic relationships between Ophiostomaspp. from Proteainfructescences were studied using DNA sequence data from the β-tubulin, 5.8S ITS (including the flanking internal transcribed spacers 1 and 2) and the large subunit DNA regions. Two new species, O. phasmasp. nov. and O. palmiculminatumsp. nov. are described and compared with other Ophiostomaspp. occurring in the same niche. Results of this study have raised the number of Ophiostomaspecies from the infructescences of serotinous Proteaspp. in South Africa to five. Molecular data also suggest that adaptation to the Proteainfructescence niche by Ophiostomaspp. has occurred independently more than once.

Eight pestalotioid fungi were isolated from the Restionaceaegrowing in the Cape Floral Kingdom of South Africa. Sarcostroma restionis, Truncatella megaspora, T. restionacearumand T. spadiceaare newly described. New records include Pestalotiopsis matildae, Sarcostroma lomatiae, Truncatella betulaeand T. hartigii. To resolve generic affiliations, phylogenetic analyses were performed on ITS (ITS1, 5.8S, ITS2) and part of 28S rDNA. DNA data support the original generic concept of Truncatella, which encompasses Pestalotiopsisspecies having 3-septate conidia. The genus Sarcostromais retained as separate from Seimatosporium.

Colletogloeopsis zuluensis, previously known as Coniothyrium zuluense, causes a serious stem canker disease on Eucalyptusspp. grown as non-natives in many tropical and sub-tropical countries. This stem canker disease was first reported from South Africa and it has subsequently been found on various species and hybrids of Eucalyptusin other African countries as well as in countries of South America and South-East Asia. In previous studies, phylogenetic analyses based on DNA sequence data of the ITS region suggested that all material of C. zuluensiswas monophyletic. However, the occurrence of the fungus in a greater number of countries, and analyses of DNA sequences with additional isolates has challenged the notion that a single species is involved with Coniothyrium canker. The aim of this study was to consider the phylogenetic relationships amongst C. zuluensisisolates from all available locations and to support these analyses with phenotypic and morphological comparisons. Individual and combined phylogenies were constructed using DNA sequences from the ITS region, exons 3 through 6 of the β-tubulin gene, the intron of the translation elongation factor 1-α gene, and a partial sequence of the mitochondrial ATPase 6 gene. Both phylogenetic data and morphological characteristics showed clearly that isolates of C. zuluensisrepresent at least two taxa. One of these is C. zuluensisas it was originally described from South Africa, and we provide an epitype for it. The second species occurs in Argentina and Uruguay, and is newly described as C. gauchensis.Both fungi are serious pathogens resulting in identical symptoms. Recognising them as different species has important quarantine consequences.

In a survey for Cryphonectriaand Chrysoporthespecies on Myrtalesin South Africa, a fungus resembling the stem canker pathogen Chrysoporthe austroafricanawas collected from native Syzygium cordatumnear Tzaneen (Limpopo Province), Heteropyxis canescensnear Lydenburg (Mpumalanga Province) and exotic Tibouchina granulosain Durban (KwaZulu-Natal Province). The fungus was associated with dying branches and stems on S. cordatum, H. canescensand T. granulosa. However, morphological differences were detected between the unknown fungus from these three hosts and known species of Chrysoporthe. The aim of this study was to characterise the fungus using DNA sequence comparisons and morphological features. Pathogenicity tests were also conducted to assess its virulence on Eucalyptus(ZG 14 clones), H. natalensisand T. granulosa. Plants of H. canescenswere not available for inoculation. Results showed distinct morphological differences between the unknown fungus and Chrysoporthespp. Phylogenetic analysis showed that isolates reside in a clade separate from Chrysoportheand other related genera. Celoporthe dispersagen. et sp. nov. is, therefore, described to accommodate this fungus. Pathogenicity tests showed that C. dispersais not pathogenic to H. natalensis, but that it is a potential pathogen of Eucalyptusand Tibouchinaspp.

Bark beetles (Coleoptera: Scolytinae) are well-recognized vectors of Ophiostomaspecies. Three non-native bark beetle species infest various Pinusspecies in South Africa, and they are known to carry at least 12 different species of ophiostomatoid fungi. Some of these fungi have not been identified to species level. The aim of this study was to determine or confirm the identities of Ophiostomaspecies associated with bark beetles in South Africa using comparisons of DNA sequence data. Identities of Ophiostoma ips, O. floccosum, O. pluriannulatum, O. quercusand O. stenoceraswere confirmed. Ophiostoma abietinum, O. piliferumand Pesotum fragransare recognised for the first time and the new species, O. auroraesp. nov., is described from pine-infesting bark beetles in South Africa.

The genus Quambalariaconsists of plant-pathogenic fungi causing disease on leaves and shoots of species of Eucalyptusand its close relative, Corymbia. The phylogenetic relationship of Quambalariaspp., previously classified in genera such as Sporothrixand Ramularia, has never been addressed. It has, however, been suggested that they belong to the basidiomycete orders Exobasidialesor Ustilaginales. The aim of this study was thus to consider the ordinal relationships of Q. eucalyptiand Q. piterekausing ribosomal LSU sequences. Sequence data from the ITS nrDNA were used to determine the phylogenetic relationship of the two Quambalariaspecies together with Fugomyces(= Cerinosterus) cyanescens.In addition to sequence data, the ultrastructure of the septal pores of the species in question was compared. From the LSU sequence data it was concluded that Quambalariaspp. and F. cyanescensform a monophyletic clade in the Microstromatales,an order of the Ustilaginomycetes. Sequences from the ITS region confirmed that Q. piterekaand Q. eucalyptiare distinct species. The ex-type isolate of F. cyanescens, together with another isolate from Eucalyptusin Australia, constitute a third species of Quambalaria, Q. cyanescens(de Hoog & G.A. de Vries) Z.W. de Beer, Begerow & R. Bauer comb. nov. Transmission electron-microscopic studies of the septal pores confirm that all three Quambalariaspp. have dolipores with swollen lips, which differ from other members of the Microstromatales(i.e. the Microstromataceaeand Volvocisporiaceae) that have simple pores with more or less rounded pore lips. Based on their unique ultrastructural features and the monophyly of the three Quambalariaspp. in the Microstromatales, a new family, QuambalariaceaeZ.W. de Beer, Begerow & R. Bauer fam. nov., is described.

This study records a severe outbreak of a disease on Zizyphus mucronata(Rhamnaceae) in Greater Kruger National Park, South Africa. The causal agent of the disease was found to be Coniodictyum chevalieri, a fungus previously believed to be very rare. Detailed illustrations of the symptoms and fungus are presented in order to facilitate future studies. The known geographical distribution of Coniodictyumis presented in relation to the distribution of its host, and a short review of its systematic history is also given. This also treats an invalidly published species name in South Africa, which has confused the literature. A DNA-based phylogeny is presented for the pathogen and this reflects the unique nature of its geographical distribution and biology.

Cryphonectria havanensisis a fungus associated with Eucalyptusspecies in Cuba and Florida (U.S.A.). Until recently, there have been no living cultures of C. havanensisand it has thus not been possible to assess its taxonomic status. Isolates thought to represent this fungus have, however, emerged from surveys of Eucalyptusin Mexico and Hawaii (U.S.A.). Results of this study showed that these isolates represent C. havanensisbut reside in a genus distinct from Cryphonectria sensu stricto, which is described here as Microthia. Isolates of an unidentified fungus occurring on Myrica fayain the Azores and Madeira also grouped in Microthiaand were identical to other M. havanensisisolates. Cryphonectria coccolobae, a fungus occurring on sea grape (Coccoloba uvifera) in Bermuda and Florida, was found to be morphologically identical to Microthiaand is transferred to this genus, but as a distinct species. Surveys for M. coccolobaeon sea grape in Florida, yielded a second diaporthalean fungus from this host. This fungus is morphologically and phylogenetically distinct from M. coccolobaeand other closely related taxa and is described as Ursicollum fallaxgen. et sp. nov. Phylogenetic analyses in this study have also shown that isolates of C. eucalypti, a pathogen of Eucalyptusin South Africa and Australia, group in a clade separate from all other groups including that representing Cryphonectria sensu stricto. This difference is supported by the fact that Cryphonectria eucalyptihas ascospore septation different to that of all other Cryphonectriaspecies. A new genus, Holocryphia, is thus erected for C. eucalypti.

Species of Eucalyptusare widely planted as exotics in the tropics and Southern Hemisphere and to some extent in southern Europe, for timber and fibre production. Species of Mycosphaerellaare commonly associated with leaves and twigs of Eucalyptusand can result in defoliation, dieback, and even tree death. In the present study, numerous isolates of Mycosphaerellaspecies were collected from leaf litter, living leaves exhibiting leaf spot symptoms or severe Mycosphaerella leaf blotch symptoms. Isolates were compared based on DNA sequence data for the internal transcribed spacer region (ITS1 & ITS2) and the 5.8S gene. These data, together with characteristics of the fungal growth on three different media, morphology of the anamorph and teleomorph structures as well as ascospore germination patterns were used to describe 21 new species.

Ophiostomaspecies have diverse morphological features and are found in a large variety of ecological niches. Many different classification schemes have been applied to these fungi in the past based on teleomorph and anamorph features. More recently, studies based on DNA sequence comparisions have shown that Ophiostomaconsists of different phylogenetic groups, but the data have not been sufficient to define clear monophyletic lineages represented by practical taxonomic units. We used DNA sequence data from combined partial nuclear LSU and β-tubulin genes to consider the phylogenetic relationships of 50 Ophiostomaspecies, representing all the major morphological groups in the genus. Our data showed three well-supported, monophyletic lineages in Ophiostoma. Species with Leptographiumanamorphs grouped together and to accommodate these species the teleomorph-genus Grosmannia(type species G. penicillata), including 27 species and 24 new combinations, is re-instated. Another well-defined lineage includes species that are cycloheximide-sensitive with short perithecial necks, falcate ascospores and Hyalorhinocladiellaanamorphs. For these species, the teleomorph-genus Ceratocystiopsis(type species O. minuta), including 11 species and three new combinations, is re-instated. A third group of species with either Sporothrixor Pesotumanamorphs includes species from various ecological niches such as Proteainfructescences in South Africa. This group also includes O. piliferum, the type species of Ophiostoma,and these species are retained in that genus. Ophiostomais redefined to reflect the changes resulting from new combinations in Grosmanniaand Ceratocystiopsis. Our data have revealed additional lineages in Ophiostomalinked to morphological characters. However, these species are retained in Ophiostomauntil further data for a larger number of species can be obtained to confirm monophyly of the apparent lineages.