Molecular reassessment of diaporthalean fungi associated with strawberry, including the leaf blight fungus, Paraphomopsis obscurans gen. et comb. nov. (Melanconiellaceae)

Phytopathogenic fungi in the order Diaporthales (Sordariomycetes) cause diseases on numerous economically important crops worldwide. In this study, we reassessed the diaporthalean species associated with prominent diseases of strawberry, namely leaf blight, leaf blotch, root rot and petiole blight, based on molecular data and morphological characters using fresh and herbarium collections. Combined analyses of four nuclear loci, 28S ribosomal DNA/large subunit rDNA (LSU), ribosomal internal transcribed spacers 1 and 2 with 5.8S ribosomal DNA (ITS), partial sequences of second largest subunit of RNA polymerase II (RPB2) and translation elongation factor 1-α (TEF1), were used to reconstruct a phylogeny for these pathogens. Results confirmed that the leaf blight pathogen formerly known as Phomopsis obscurans belongs in the family Melanconiellaceae and not with Diaporthe (syn. Phomopsis) or any other known genus in the order. A new genus Paraphomopsis is introduced herein with a new combination, Paraphomopsis obscurans, to accommodate the leaf blight fungus. Gnomoniopsis fragariae comb. nov. (Gnomoniaceae), is introduced to accommodate Gnomoniopsis fructicola, the cause of leaf blotch of strawberry. Both of the fungi causing leaf blight and leaf blotch were epitypified. Fresh collections and new molecular data were incorporated for Paragnomonia fragariae (Sydowiellaceae), which causes petiole blight and root rot of strawberry and is distinct from the above taxa. An updated multilocus phylogeny for the Diaporthales is provided with representatives of currently known families.

Melanospora (Sordariomycetes, Ascomycota) and its relatives

The order Melanosporales comprises a large group of ascomycetes, most of them mycoparasites, characterized by the production of usually ostiolate, translucent ascomata, unitunicate asci, and unicellular, pigmented ascospores with germ pores or germ slits. The most studied taxa are Melanospora and Sphaerodes, but the boundaries with other morphologically closely related genera are not well resolved. In this study, the taxonomy of Melanospora and related taxa have been re-evaluated based on the analysis of nuclear rDNA, actin and elongation factor genes sequences of fresh isolates and numerous type and reference strains. The genus Melanospora has been restricted to species with ostiolate ascoma whose neck is composed of intermixed hyphae, and with a phialidic asexual morph. Microthecium has been re-established for species of Melanospora and Sphaerodes without a typical ascomatal neck or, if present, being short and composed of angular cells similar to those of the ascomatal wall, and usually producing bulbils. Three new genera have been proposed: Dactylidispora, possessing ascospores with a raised rim surrounding both terminal germ pores; Echinusitheca, with densely setose, dark ascomata; and Pseudomicrothecium, characterized by ascospores with indistinct germ pores. Dichotomous keys to identify the accepted genera of the Melanosporales, and keys to discriminate among the species of Melanospora and Microthecium, as well as a brief description of the accepted species of both genera, are also provided.

Recommendations for competing sexual-asexually typified generic names in Sordariomycetes (except Diaporthales, Hypocreales, and Magnaporthales)

With the advance to one scientific name for each fungal species, the generic names in the class Sordariomycetes typified by sexual and asexual morphs are evaluated based on their type species to determine if they compete with each other for use or protection. Recommendations are made for which of the competing generic names should be used based on criteria such as priority, number of potential names changes, and frequency of use. Some recommendations for well-known genera include Arthrinium over Apiospora, Colletotrichum over Glomerella, Menispora over Zignoëlla, Microdochium over Monographella, Nigrospora over Khuskia, and Plectosphaerella over Plectosporium. All competing generic names are listed in a table of recommended names along with the required action. If priority is not accorded to sexually typified generic names after 2017, only four names would require formal protection: Chaetosphaerella over Oedemium, Diatrype over Libertella, Microdochium over Monographella, and Phaeoacremonium over Romellia and Togninia. Concerning species in the recommended genera, one replacement name (Xylaria benjaminii nom. nov.) is introduced, and the following new combinations are made: Arthrinium sinense, Chloridium caesium, C. chloroconium, C. gonytrichii, Corollospora marina, C. parvula, C. ramulosa, Juncigena fruticosae, Melanospora simplex, Seimatosporium massarina, Sporoschisma daemonoropis, S. taitense, Torpedospora mangrovei, Xylaria penicilliopsis, and X. termiticola combs. nov.

Cornuvesica: A little known mycophilic genus with a unique biology and unexpected new species

Little is known about the biology of the monotypic genus Cornuvesica (Microascales), apart from that isolates are notoriously difficult to culture on artificial media. A recent collection of material resembling this genus from freshly made wounds on Gmelina arborea in Indonesia, provided an opportunity to reconsider all available material of Cornuvesica falcata, type species of the genus. In addition to morphological comparisons, multigene phylogenetic analyses were made using sequences of the SSU, ITS, LSU and TEF-1α genes. Our results showed that the holotype of Cor. falcata from pine in Canada differed from all other material previously considered to represent this species and also from the new Indonesian collections. The collections considered represented three additional species that we describe here as new. Three New Zealand isolates and an isolate from UK were respectively described as Cor. acuminata and Cor. crypta, while the Indonesian isolates were described as Cor. magnispora. Phylogenies based on the SSU and LSU data sets showed that Cornuvesica spp. do not belong in the Ceratocystidaceae as previously suggested, but represent a distinct lineage in the Microascales that has yet to be named. Results showed that culture filtrates from other fungi or ferric chloride markedly stimulated the growth of Cor. magnispora.

A higher-level phylogenetic classification of the Fungi

A comprehensive phylogenetic classification of the kingdom Fungi is proposed, with reference to recent molecular phylogenetic analyses, and with input from diverse members of the fungal taxonomic community. The classification includes 195 taxa, down to the level of order, of which 16 are described or validated here: Dikarya subkingdom nov.; Chytridiomycota, Neocallimastigomycota phyla nov.; Monoblepharidomycetes, Neocallimastigomycetes class. nov.; Eurotiomycetidae, Lecanoromycetidae, Mycocaliciomycetidae subclass. nov.; Acarosporales, Corticiales, Baeomycetales, Candelariales, Gloeophyllales, Melanosporales, Trechisporales, Umbilicariales ords. nov. The clade containing Ascomycota and Basidiomycota is classified as subkingdom Dikarya, reflecting the putative synapomorphy of dikaryotic hyphae. The most dramatic shifts in the classification relative to previous works concern the groups that have traditionally been included in the Chytridiomycota and Zygomycota. The Chytridiomycota is retained in a restricted sense, with Blastocladiomycota and Neocallimastigomycota representing segregate phyla of flagellated Fungi. Taxa traditionally placed in Zygomycota are distributed among Glomeromycota and several subphyla incertae sedis, including Mucoromycotina, Entomophthoromycotina, Kickxellomycotina, and Zoopagomycotina. Microsporidia are included in the Fungi, but no further subdivision of the group is proposed. Several genera of 'basal' Fungi of uncertain position are not placed in any higher taxa, including Basidiobolus, Caulochytrium, Olpidium, and Rozella.

Unusual compact rDNA gene arrangements within some members of the Ascomycota: evidence for molecular co-evolution between ITS1 and ITS2

The internal transcribed spacers of the ribosomal DNA tandem repeat were examined in members of the ascomycetous genus Sphaeronaemella. Species of Sphaeronaemella and its mitotic counterpart Gabarnaudia, have a compact rDNA gene arrangement due to unusually short internal transcribed spacer (ITS) regions. Examination of these regions from phylogenetically related taxa, Cornuvesica, Gondwanamyces, and Ceratocystis, showed that their ITS1 and ITS2 regions could be folded into central hairpin-like structures with the size reduction in species of Sphaeronaemella being due to length reduction of the main-hairpin and the loss of smaller hairpin-like structures that emanate from the main hairpin. A databank compilation, combined with newly obtained sequences, provided an ITS data set that includes sequences of 600 species belonging to the Ascomycota. Correlation analysis revealed that the sizes of ITS1 and ITS2 show a strong positive correlation, suggesting that the 2 rDNA regions have co-evolved. This supports biochemical evidence indicating that the ITS1 and ITS2 segments interact to facilitate the maturation of the rRNA precursor.