Myrtaceae, a cache of fungal biodiversity

Twenty-six species of microfungi are treated, the majority of which are associated with leaf spots of Corymbia, Eucalyptus and Syzygium spp. (Myrtaceae). The treated species include three new genera, Bagadiella, Foliocryphia and Pseudoramichloridium, 20 new species and one new combination. Novelties on Eucalyptus include: Antennariella placitae, Bagadiella lunata, Cladoriella rubrigena, C. paleospora, Cyphellophora eucalypti, Elsinoë eucalypticola, Foliocryphia eucalypti, Leptoxyphium madagascariense, Neofabraea eucalypti, Polyscytalum algarvense, Quambalaria simpsonii, Selenophoma australiensis, Sphaceloma tectificae, Strelitziana australiensis and Zeloasperisporium eucalyptorum. Stylaspergillus synanamorphs are reported for two species of Parasympodiella, P. eucalypti sp. nov. and P. elongata, while Blastacervulus eucalypti, Minimedusa obcoronata and Sydowia eucalypti are described from culture. Furthermore, Penidiella corymbia and Pseudoramichloridium henryi are newly described on Corymbia, Pseudocercospora palleobrunnea on Syzygium and Rachicladosporium americanum on leaf litter. To facilitate species identification, as well as determine phylogenetic relationships, DNA sequence data were generated from the internal transcribed spacers (ITS1, 5.8S nrDNA, ITS2) and the 28S nrDNA (LSU) regions of all taxa studie

Host specificity and speciation of Mycosphaerella and Teratosphaeria species associated with leaf spots of Proteaceae

Species of Mycosphaerella and Teratosphaeria represent important foliicolous pathogens of Proteaceae. Presently approximately 40 members of these genera (incl. anamorphs) have been recorded from Proteaceae, though the majority are not known from culture, and have never been subjected to DNA sequence analysis. During the course of this study, epitypes were designated for several important species, namely Batcheloromyces leucadendri, B. proteae, Catenulostroma macowanii, Mycosphaerella marksii, Teratosphaeria bellula, T. jonkershoekensis, T. parva, and T. proteae-arboreae. Several species were also newly described, namely Batcheloromyces sedgefieldii, Catenulostroma wingfieldii, Dissoconium proteae, Teratosphaeria persoonii, T. knoxdavesii, and T. marasasii. Although accepted as being highly host specific, some species were shown to have wider host ranges, such as M. communis (Eucalyptus, Protea), M. konae (Leucospermum, Eucalyptus), M. marksii (Eucalyptus, Leucadendron), T. associata (Eucalyptus, Protea), and T. parva (Eucalyptus, Protea), which in most cases were found to co-occur with other species of Mycosphaerella or Teratosphaeria on Proteaceae. Furthermore, earlier records of T. jonkershoekensis on Proteaceae in Australia were shown to be representative of two recently described species, T. associata and T. maxii. A phenomenon of underdeveloped, or micro-ascospores was also newly observed in asci of T. maculiformis and T. proteae-arboreae. The exact purpose of asci with two distinct types of ascospores remains to be clarified, as both types were observed to germinate on agar

Co-occurring species of Teratosphaeria on Eucalyptus

A common leaf spot disease occurring on Eucalyptus cladocalyx and E. lehmannii in the Western Cape Province of South Africa is known from literature to be caused by the fungus Coniothyrium ovatum, which is a pathogen native to several eucalypts in Australia. Recent collections have shown that Australian material identified as C. ovatum is morphologically and phylogenetically distinct from the South African specimens, and that all these taxa would be better accommodated in the genus Teratosphaeria. South African specimens previously identified as C. ovatum were found to represent two species that co-occur in the same leaves and even spots and are described here as T. juvenalis and T. verrucosa. Furthermore, a fresh collection of T. ovata from E. phoenicea in Australia, is distinguished morphologically and phylogenetically from similar, newly described taxa such as T. veloci on E. miniata, and Readeriella dimorpha, which is also placed in Teratosphaeria. Although these leaf pathogens appear to be of minor economic importance, they are morphologically similar to two serious eucalypt canker pathogens, namely T. gauchensis and T. zuluensis, which predominantly cause stem cankers, but could also be found occurring in leaf spots on their own, or in association with some of the other species treated here. Further research is, therefore, required to develop molecular detection techniques for these taxa to enable researchers to rapidly distinguish the minor pathogens from the more serious quarantine pathogens that co-occur on leaves

Novel species of Mycosphaerellaceae and Teratosphaeriaceae

Recent phylogenetic studies based on multi-gene data have provided compelling evidence that the Mycosphaerellaceae and Teratosphaeriaceae represent numerous genera, many of which can be distinguished based on their anamorph morphology. The present study represents the second contribution in a series describing several novel species in different capnodealean genera defined in a previous study. Novelties on Eucalyptus from Australia include: Penidiella pseudotasmaniensis, P. tenuiramis, Phaeothecoidea intermedia, P. minutispora, Pseudocercospora tereticornis, Readeriella angustia, R. eucalyptigena, R. menaiensis, R. pseudocallista, R. tasmanica, Teratosphaeria alboconidia, T. complicata, T. majorizuluensis, T. miniata, T. profusa, Zasmidium aerohyalinosporum and Z. nabiacense, while Teratosphaeria xenocryptica is described on Eucalyptus from Chile. Novelties on other hosts include Phaeophleospora eugeniicola on Eugenia from Brazil, and Zasmidium nocoxi on twig litter from the USA

Re-evaluation of Cryptosporiopsis eucalypti and Cryptosporiopsis-like species occurring on Eucalyptus

Cryptosporiopsis eucalypti is a common follicolous pathogen of Eucalyptus species in tropical and temperate regions where these trees are grown in plantations. The taxonomy of C. eucalypti is confused by the fact that it is phylogenetically unrelated to the type species of Cryptosporiopsis (Cryptosporiopsis nigra = C. scutellata, Helotiales). The aim of this study was to resolve the taxonomic position of C. eucalypti based on morphology and phylogenetic inference. Thirty-two Eucalyptus leaf samples with symptoms typical of C. eucalypti infection were collected from 10 tropical and temperate countries across four continents. Cultures were established from single conidia, as well as from ascospores of a previously unreported teleomorph state. DNA sequences were obtained for the 28 S nrDNA, the internal transcribed spacers of the nrDNA operon, and beta-tubulin regions to determine generic and species-level relationships. DNA-sequence analysis showed that conidial and ascospore isolates of C. eucalypti have low intraspecific variation, although two collections from Australia and one from Uruguay represented two novel taxa. Based on the newly collected teleomorph stage, as well as the phylogenetic data, C. eucalypti is shown to represent a new genus closely related to Plagiostoma (Gnomoniaceae, Diaporthales) for which the names Pseudoplagiostoma gen. nov. and Pseudoplagiostomaceae fam. nov. (Diaporthales) are introduced. Two new species of Cryptosporiopsis (Dermateaceae, Helotiales) on Eucalyptus from Australia and California (USA) are also described

Phylogeny and taxonomy of obscure genera of microfungi

The recently generated molecular phylogeny for the kingdom Fungi, on which a new classification scheme is based, still suffers from an under representation of numerous apparently asexual genera of microfungi. In an attempt to populate the Fungal Tree of Life, fresh samples of 10 obscure genera of hyphomycetes were collected. These fungi were subsequently established in culture, and subjected to DNA sequence analysis of the ITS and LSU nrRNA genes to resolve species and generic questions related to these obscure genera. Brycekendrickomyces (Herpotrichiellaceae) is introduced as a new genus similar to, but distinct from Haplographium and Lauriomyces. Chalastospora is shown to be a genus in the Pleosporales, with two new species, C. ellipsoidea and C. obclavata, to which Alternaria malorum is added as an additional taxon under its oldest epithet, C. gossypii. Cyphellophora eugeniae is newly described in Cyphellophora (Herpotrichiellaceae), and distinguished from other taxa in the genus. Dictyosporium is placed in the Pleosporales, with one new species, D. streliziae. The genus Edenia, which was recently introduced for a sterile endophytic fungus isolated in Mexico, is shown to be a hyphomycete (Pleosporales) forming a pyronellea-like synanamorph in culture. Thedgonia is shown not to represent an anamorph of Mycosphaerella, but to belong to the Helotiales. Trochophora, however, clustered basal to the Pseudocercospora complex in the Mycosphaerellaceae, as did Verrucisporota. Vonarxia, a rather forgotten genus of hyphomycetes, is shown to belong to the Herpotrichiellaceae and Xenostigmina is confirmed as synanamorph of Mycopappus, and is shown to be allied to Seifertia in the Pleosporales. Dichotomous keys are provided for species in the various genera treated. Furthermore, several families are shown to be polyphyletic within some orders, especially in the Capnodiales, Chaetothyriales and Pleosporales

Unravelling Mycosphaerella: do you believe in genera?

Many fungal genera have been defined based on single characters considered to be informative at the generic level. In addition, many unrelated taxa have been aggregated in genera because they shared apparently similar morphological characters arising from adaptation to similar niches and convergent evolution. This problem is aptly illustrated in Mycosphaerella. In its broadest definition, this genus of mainly leaf infecting fungi incorporates more than 30 form genera that share similar phenotypic characters mostly associated with structures produced on plant tissue or in culture. DNA sequence data derived from the LSU gene in the present study distinguish several clades and families in what has hitherto been considered to represent the Mycosphaerellaceae. In some cases, these clades represent recognisable monophyletic lineages linked to well circumscribed anamorphs. This association is complicated, however, by the fact that morphologically similar form genera are scattered throughout the order (Capnodiales), and for some species more than one morph is expressed depending on cultural conditions and media employed for cultivation. The present study shows that Mycosphaerella s.s. should best be limited to taxa with Ramularia anamorphs, with other well defined clades in the Mycosphaerellaceae representing Cercospora, Cercosporella, Dothistroma, Lecanosticta, Phaeophleospora, Polythrincium, Pseudocercospora, Ramulispora, Septoria and Sonderhenia. The genus Teratosphaeria accommodates taxa with Kirramyces anamorphs, while other clades supported in the Teratosphaeriaceae include Baudoinea, Capnobotryella, Devriesia, Penidiella, Phaeothecoidea, Readeriella, Staninwardia and Stenella. The genus Schizothyrium with Zygophiala anamorphs is supported as belonging to the Schizothyriaceae, while Dissoconium and Ramichloridium appear to represent a distinct family. Several clades remain unresolved due to limited sampling. Mycosphaerella, which has hitherto been used as a term of convenience to describe ascomycetes with solitary ascomata, bitunicate asci and 1-septate ascospores, represents numerous genera and several families yet to be defined in future studies

A case for re-inventory of Australia’s plant pathogens

Australia has efficient and visible plant quarantine measures, which through various border controls and survey activities attempt to prevent the entry of unwanted pests and diseases. The ability to successfully perform this task relies heavily on determining what pathogens are present and established in Australia as well as those pathogens that are exotic and threatening. There are detailed checklists and databases of fungal plant pathogens in Australia, compiled, in part, from surveys over many years sponsored by Federal and State programmes. These checklists and databases are mostly specimen-based, which enables validation of records with reference herbarium specimens and sometimes associated cultures. Most of the identifications have been based on morphological examination. The use of molecular methods, particularly the analysis of DNA sequence data, has recently shown that several well-known and important plant pathogenic species are actually complexes of cryptic species. We provide examples of this in the important plant pathogenic genera Botryosphaeria and its anamorphs, Colletotrichum, Fusarium, Phomopsis / Diaporthe and Mycosphaerella and its anamorphs. The discovery of these cryptic species indicates that many of the fungal names in checklists need scrutiny. It is difficult, and often impossible, to extract DNA for sequence analysis from herbarium specimens in order to validate identifications that may now be considered suspect. This validation can only be done if specimens are recollected, re-isolated and subjected to DNA analysis. Where possible, herbarium specimens as well as living cultures are needed to support records. Accurate knowledge of the plant pathogens within Australia’s borders is an essential prerequisite for the effective discharge of plant quarantine activities that will prevent or delay the arrival of unwanted plant pathogens

Allelochaeta (Sporocadaceae): Pigmentation lost and gained

The appendaged coelomycete genus Seimatosporium (Sporocadaceae, Sordariomycetes) and some of its purported synonyms Allelochaeta,Diploceras and Vermisporium are re-evaluated. Based on DNA data for five loci (ITS, LSU, rpb2, tub2 and tef1), Seimatosporium is shown to be paraphyletic. The ex-type species of Allelochaeta, Discostromopsis and Vermisporium represent a distinct sister clade to which the oldest name Allelochaeta is applied. These genera were traditionally separated based on a combination of conidial pigmentation, septation, and the nature of their conidial appendages. Allelochaeta is revealed to include taxa with both branched or solitary appendages, that could be cellular or continuous, with conidia being (2–)3(–5)-septate, hyaline, or pigmented, concolourous or versicolourous. This suggests that these characters should be applied at species, and not at the generic level. Conidial pigmentation appears to have been lost or gained several times during the evolution of species within Allelochaeta. In total, 25 new species, 15 new combinations, and 10 new epitypifications are proposed

Genera of diaporthalean coelomycetes associated with leaf spots of tree hosts

Four different genera of diaporthalean coelomycetous fungi associated with leaf spots of tree hosts are morphologically treated and phylogenetically compared based on the DNA sequence data of the large subunit nuclear ribosomal DNA gene (LSU) and the internal transcribed spacers and 5.8S rRNA gene of the nrDNA operon. These include two new Australian genera, namely Auratiopycnidiella, proposed for a leaf spotting fungus occurring on Tristaniopsis laurina in New South Wales, and Disculoides, proposed for two species occurring on leaf spots of Eucalyptus leaves in Victoria. Two new species are described in Aurantiosacculus, a hitherto monotypic genus associated with leaf spots of Eucalyptus in Australia, namely A. acutatus on E. viminalis, and A. eucalyptorum on E. globulus, both occurring in Tasmania. Lastly, an epitype specimen is designated for Erythrogloeum hymenaeae, the type species of the genus Erythrogloeum, and causal agent of a prominent leaf spot disease on Hymenaea courbaril in South America. All four genera are shown to be allied to Diaporthales, although only Aurantiosacculus (Cryphonectriaceae) could be resolved to family level, the rest being incertae sedis