Generic boundaries in the Ophiostomatales reconsidered and revised.

The Ophiostomatales was erected in 1980. Since that time, several of the genera have been redefined and others have been described. There are currently 14 accepted genera in the Order. They include species that are the causal agents of plant and human diseases and common associates of insects such as bark beetles. Well known examples include the Dutch elm disease fungi and the causal agents of sporotrichosis in humans and animals. The taxonomy of the Ophiostomatales was confused for many years, mainly due to the convergent evolution of morphological characters used to delimit unrelated fungal taxa. The emergence of DNA-based methods has resolved much of this confusion. However, the delineation of some genera and the placement of various species and smaller lineages remains inconclusive. In this study we reconsidered the generic boundaries within the Ophiostomatales. A phylogenomic framework constructed from genome-wide sequence data for 31 species representing the major genera in the Order was used as a guide to delineate genera. This framework also informed our choice of the best markers from the currently most commonly used gene regions for taxonomic studies of these fungi. DNA was amplified and sequenced for more than 200 species, representing all lineages in the Order. We constructed phylogenetic trees based on the different gene regions and assembled a concatenated data set utilising a suite of phylogenetic analyses. The results supported and confirmed the delineation of nine of the 14 currently accepted genera, i.e. Aureovirgo, Ceratocystiopsis, Esteya, Fragosphaeria, Graphilbum, Hawksworthiomyces, Ophiostoma, Raffaelea and Sporothrix. The two most recently described genera, Chrysosphaeria and Intubia, were not included in the multi-locus analyses. This was due to their high sequence divergence, which was shown to result in ambiguous taxonomic placement, even though the results of phylogenomic analysis supported their inclusion in the Ophiostomatales. In addition to the currently accepted genera in the Ophiostomatales, well-supported lineages emerged that were distinct from those genera. These are described as novel genera. Two lineages included the type species of Grosmannia and Dryadomyces and these genera are thus reinstated and their circumscriptions redefined. The descriptions of all genera in the Ophiostomatales were standardised and refined where this was required and 39 new combinations have been provided for species in the newly emerging genera and one new combination has been provided for Sporothrix. The placement of Afroraffaelea could not be confirmed using the available data and the genus has been treated as incertae sedis in the Ophiostomatales. Paleoambrosia was not included in this study, due to the absence of living material available for this monotypic fossil genus. Overall, this study has provided the most comprehensive and robust phylogenies currently possible for the Ophiostomatales. It has also clarified several unresolved One Fungus-One Name nomenclatural issues relevant to the Order. Taxonomic novelties: New genera: Harringtonia Z.W. de Beer & M. Procter, Heinzbutinia Z.W. de Beer & M. Procter, Jamesreidia Z.W. de Beer & M. Procter, Masuyamyces Z.W. de Beer & M. Procter. New species: Masuyamyces massonianae M. Procter & Z.W. de Beer. New combinations: Dryadomyces montetyi (M. Morelet) M. Procter & Z.W. de Beer, Dryadomyces quercivorus (Kubono & Shin. Ito) M. Procter & Z.W. de Beer, Dryadomyces quercus-mongolicae (K.H. Kim et al.) M. Procter & Z.W. de Beer, Dryadomyces sulphureus (L.R. Batra) M. Procter & Z.W. de Beer, Graphilbum pusillum (Masuya) M. Procter & Z.W. de Beer, Grosmannia abieticolens (K. Jacobs & M.J. Wingf.) M. Procter & Z.W. de Beer, Grosmannia altior (Paciura et al.) M. Procter & Z.W. de Beer, Grosmannia betulae (Jankowiak et al.) M. Procter & Z.W. de Beer, Grosmannia curviconidia (Paciura et al.) M. Procter & Z.W. de Beer, Grosmannia euphyes (K. Jacobs & M.J. Wingf.) M. Procter & Z.W. de Beer, Grosmannia fenglinhensis (R. Chang et al.) M. Procter & Z.W. de Beer, Grosmannia gestamen (de Errasti & Z.W. de Beer) M. Procter & Z.W. de Beer, Grosmannia innermongolica (X.W. Liu et al.) M. Procter & Z.W. de Beer, Grosmannia pistaciae (Paciura et al.) M. Procter & Z.W. de Beer, Grosmannia pruni (Masuya & M.J. Wingf.) M. Procter & Z.W. de Beer, Grosmannia taigensis (Linnak. et al.) M. Procter & Z.W. de Beer, Grosmannia trypodendri (Jankowiak et al.) M. Procter & Z.W. de Beer, Harringtonia aguacate (D.R. Simmons et al.) M. Procter & Z.W. de Beer, Harringtonia brunnea (L.R. Batra) M. Procter & Z.W. de Beer, Harringtonia lauricola (T.C. Harr. et al.) Z.W. de Beer & M. Procter, Heinzbutinia grandicarpa (Kowalski & Butin) Z.W. de Beer & M. Procter, Heinzbutinia microspora (Arx) M. Procter & Z.W. de Beer, Heinzbutinia solheimii (B. Strzalka & Jankowiak) Z.W. de Beer & M. Procter, Jamesreidia coronata (Olchow. & J. Reid) M. Procter & Z.W. de Beer, Jamesreidia nigricarpa (R.W. Davidson) M. Procter & Z.W. de Beer, Jamesreidia rostrocoronata (R.W. Davidson & Eslyn) M. Procter & Z.W. de Beer, Jamesreidia tenella (R.W. Davidson) Z.W. de Beer & M. Procter, Leptographium cainii (Olchow. & J. Reid) M. Procter & Z.W. de Beer, Leptographium europioides (E.F. Wright & Cain) M. Procter & Z.W. de Beer, Leptographium galeiforme (B.K. Bakshi) M. Procter & Z.W. de Beer, Leptographium pseudoeurophioides (Olchow. & J. Reid) M. Procter & Z.W. de Beer, Leptographium radiaticola (J.J. Kim et al.) M. Procter & Z.W. de Beer, Masuyamyces acarorum (R. Chang & Z.W. de Beer) M. Procter & Z.W. de Beer, Masuyamyces ambrosius (B.K. Bakshi) M. Procter & Z.W. de Beer, Masuyamyces botuliformis (Masuya) Z.W. de Beer & M. Procter, Masuyamyces jilinensis (R. Chang et al.) M. Procter & Z.W. de Beer, Masuyamyces lotiformis (Z. Wang & Q. Lu) M. Procter & Z.W. de Beer, Masuyamyces pallidulus (Linnak. et al.) M. Procter & Z.W. de Beer, Masuyamyces saponiodorus (Linnak. et al.) M. Procter & Z.W. de Beer, Sporothrix longicollis (Massee & E.S. Salmon) M. Procter & Z.W. de Beer. Citation: de Beer W, Procter M, Wingfield MJ, Marincowitz S, Duong TA (2022). Generic boundaries in the Ophiostomatales reconsidered and revised. Studies in Mycology 101: 57-120. doi: 10.3114/sim.2022.101.02.

Two new species of Leptographium associated with Tomicus spp. infesting Pinus spp. in Southwestern China.

Leptographium panxianense and L. puerense are proposed as new taxa based on sequence data and morphological characters. The phylogenetic analyses based on ITS2-partial LSU rDNA region, ß-tubulin and elongation factor 1-α genes showed that L. panxianense and L. puerense formed well-supported clades and were closely related to L. yunnanense, L. wushanense and L. conjunctum, and then nested within the L. lundbergii complex. The two species differ in their conidial size and shape. The conidia of L. panxianense are larger than those of L. puerense while the conidial shape of L. puerense is more ovovoid. The optimal growth temperature of both L. panxianense and L. puerense is at 20 °C, which is different from those of L. yunnanense, L. wushanense and L. conjunctum. Comparison of sequence data and morphological characters confirmed the placement of the two undescribed taxa in the genus of Leptographium.

Novel ophiostomatalean fungi from galleries of Cyrtogenius africus (Scolytinae) infesting dying Euphorbia ingens.

Euphorbia ingens trees have been dying in large numbers in the Limpopo Province of South Africa for approximately 15 years. The ambrosia beetle Cyrtogenius africus is often found infesting diseased and dying trees. The aim of this study was to identify the ophiostomatoid fungi occurring in the galleries of C. africus. Logs infested with this beetle were collected from the KwaZulu-Natal, Limpopo, Mpumalanga, and North West Provinces of South Africa. Fungi belonging to the Ophiostomatales were identified based on morphology and comparison of sequence data for the ß-tubulin, ITS1-5.8S-ITS2 and LSU gene regions. A novel species of Ophiostoma and a novel genus in the Ophiostomatales were identified. Inoculation studies with these fungi produced lesions in the branches of healthy E. ingens trees.

Four New Species of Harringtonia: Unravelling the Laurel Wilt Fungal Genus.

Symbiosis between beetles and fungi arose multiple times during the evolution of both organisms. Some of the most biologically diverse and economically important are mutualisms in which the beetles cultivate and feed on fungi. Among these are bark beetles and Harringtonia, a fungal genus that produces Raffaelea-like asexual morph and hosts the causal agent of laurel wilt, H. lauricola (formerly Raffaelea lauricola). In this study, we propose four new species of Harringtonia associated with beetles from Belize and Florida (USA). We hope to contribute towards a more robust and inclusive phylogenetic framework for future studies on these beetle-fungi relationships and their potential impact in crops and forests worldwide.

Phylogenetic and phylogenomic analyses reveal two new genera and three new species of ophiostomatalean fungi from termite fungus combs.

The Ophiostomatales (Ascomycota) accommodates more than 300 species characterized by similar morphological adaptations to arthropod dispersal. Most species in this order are wood-inhabiting fungi associated with bark or ambrosia beetles. However, a smaller group of species occur in other niches such as in soil and Protea infructescences. Recent surveys of Termitomyces fungus gardens (fungus combs) of fungus-growing termites led to the discovery of characteristic ophiostomatalean-like fruiting structures. In this study, these ophiostomatalean-like fungi were identified using morphological characteristics, conventional molecular markers, and whole genome sequencing. In addition, the influence of the extracts derived from various parts of Termitomyces combs on the growth of these fungi in culture was considered. Based on phylogenomic analyses, two new genera (Intubia and Chrysosphaeria) were introduced to accommodate these ophiostomatalean species. Phylogenetic analyses revealed that the isolates resided in three well-supported lineages, and these were described as three new species (Intubia macrotermitinarum, I. oerlemansii, and Chrysosphaeria jan-nelii). Culture-based studies showed that these species do not depend on the Termitomyces comb material for growth.

Genome-Wide Analysis of Secondary Metabolite Gene Clusters in Ophiostoma ulmi and Ophiostoma novo-ulmi Reveals a Fujikurin-Like Gene Cluster with a Putative Role in Infection.

The emergence of new microbial pathogens can result in destructive outbreaks, since their hosts have limited resistance and pathogens may be excessively aggressive. Described as the major ecological incident of the twentieth century, Dutch elm disease, caused by ascomycete fungi from the Ophiostoma genus, has caused a significant decline in elm tree populations (Ulmus sp.) in North America and Europe. Genome sequencing of the two main causative agents of Dutch elm disease (Ophiostoma ulmi and Ophiostoma novo-ulmi), along with closely related species with different lifestyles, allows for unique comparisons to be made to identify how pathogens and virulence determinants have emerged. Among several established virulence determinants, secondary metabolites (SMs) have been suggested to play significant roles during phytopathogen infection. Interestingly, the secondary metabolism of Dutch elm pathogens remains almost unexplored, and little is known about how SM biosynthetic genes are organized in these species. To better understand the metabolic potential of O. ulmi and O. novo-ulmi, we performed a deep survey and description of SM biosynthetic gene clusters (BGCs) in these species and assessed their conservation among eight species from the Ophiostomataceae family. Among 19 identified BGCs, a fujikurin-like gene cluster (OpPKS8) was unique to Dutch elm pathogens. Phylogenetic analysis revealed that orthologs for this gene cluster are widespread among phytopathogens and plant-associated fungi, suggesting that OpPKS8 may have been horizontally acquired by the Ophiostoma genus. Moreover, the detailed identification of several BGCs paves the way for future in-depth research and supports the potential impact of secondary metabolism on Ophiostoma genus' lifestyle.