Asexually reproducing fungi play a significant role in essential processes in managed and wild ecosystems such as nutrients cycling and multitrophic interactions. A large number of such taxa are among the most notorious plant and animal pathogens. In addition, they have a key role in food production, biotechnology and medicine. Taxa without or rare sexual reproduction are distinguished based on their sporulating structures and conidiomata in traditional morphology-based taxonomy. The number, variation and diversity of asexually reproducing taxa are insufficiently known, even though fungi capable of asexual reproduction may provide an untapped, rich biological resource for future exploitation. Currently, ca. 30,000 asexual species belonging to ca. 3800 genera have been reported (including 1388 coelomycetous and 2265 hyphomycetous genera). Recent reports (2017–2020) reiterate that the number of asexually producing fungi is higher than the number of frequently sexually-reproducing fungi. With the advent of molecular tools and the abandonment of the dual nomenclature system for pleomorphic fungi, priority criteria were established and revisited in the latest outline of fungi and fungus-like taxa. However, species numbers and taxonomic boundaries of pleomorphic taxa and their synanamorphs or synasexual morphs have yet to be addressed. The number of species of speciose genera (e.g. Alternaria, Aspergillus, Cercospora, Fusarium, Phoma and Pseudocercospora), cryptic species, species of pleomorphic genera, less studied life modes (such as lichenicolous taxa, taxa from extreme environments) and species from biodiversity-rich areas still need evaluation to achieve more reliable estimates of their diversity. This paper discusses the current knowledge on the matter, with diversity estimates, and potential obstacles in several chapters on (1) speciose genera; (2) pleomorphic genera; (3) cryptic species; (4) well-studied but insufficiently resolved taxa, e.g. leaf inhabiting species, marine fungi, (5) less studied life modes, e.g. lichenicolous, rock-inhabiting fungi, insect-associated and yeast-forming taxa and (6) species from biodiversity-rich areas.

Guizhou and Yunnan Provinces (Yungui Plateau) in Southwestern China are well known as biodiversity hotspots. We introduce two new species in this study viz., Mucispora hydei (in Fuscosporellaceae, Fuscosporellales, Sordariomycetes) and Tolypocladium cucullae (Ophiocordycipitaceae, Hypocreales, Sordariomycetes) and six new records based on morpho-molecular analyses. Full descriptions, color photographs and phylogenetic trees to indicate the placements of new species are provided.

Fungi play many roles in different ecosystems. The precise identification of fungi is important in different aspects. Historically, they were identified based on morphological characteristics, but technological advancements such as polymerase chain reaction (PCR) and DNA sequencing now enable more accurate identification and taxonomy, and higher-level classifications. However, some species, referred to as “dark taxa”, lack distinct physical features that makes their identification challenging. High-throughput sequencing and metagenomics of environmental samples provide a solution to identifying new lineages of fungi. This paper discusses different approaches to taxonomy, including PCR amplification and sequencing of rDNA, multi-loci phylogenetic analyses, and the importance of various omics (large-scale molecular) techniques for understanding fungal applications. The use of proteomics, transcriptomics, metatranscriptomics, metabolomics, and interactomics provides a comprehensive understanding of fungi. These advanced technologies are critical for expanding the knowledge of the Kingdom of Fungi, including its impact on food safety and security, edible mushrooms foodomics, fungal secondary metabolites, mycotoxin-producing fungi, and biomedical and therapeutic applications, including antifungal drugs and drug resistance, and fungal omics data for novel drug development. The paper also highlights the importance of exploring fungi from extreme environments and understudied areas to identify novel lineages in the fungal dark taxa.

This study documents the morphology and phylogeny of micro-fungi collected from various medicinal plants in southern China and northern Thailand. Based on morphological characteristics and phylogenetic analyses, 99 species were identified, classified within one phylum (Ascomycota), spanning three classes (Dothideomycetes, Leotiomycetes and Sordariomycetes), 16 orders, 36 families and 67 genera. We introduce one new order, Oncopodiellales, two new families, Catenuliconidiaceae and Oncopodiellaceae, one new genus, Biascospora, and 48 new species: Achroiostachys brunnea, A. catenata, Amphisphaeria hibiscicola, Apiculospora thailandensis, Arecophila maolanensis, A. yunnanensis, Barriopsis caryotae, Biascospora chishuiensis, Conioscypha synnemata, Diaporthe ervatamiae, D. kunmingensis, D. tuchungicola, Dictyocheirospora xishuiensis, Diplocladiella hainanensis, Distoseptispora gelatinosa, D. olivaceoviridis, Gregatothecium diflugossae, Helicosporium multiseptatum, Helminthosporium thailandicum, Kalmusia tetrastigmae, Keissleriella yunnanensis, Lasiodiplodia houttuyniae, L. liliacearum, Leptospora houttuyniae, Lophiotrema asexuale, L. guizhouense, Melanopsamma tongrenensis, Memnoniella chiangmaiensis, Murichromolaenicola dendrobii, Heleiosa brunnea, Neohelicascus guizhouensis, Neohelicomyces sexualis, Neohendersonia tongrenensis, Neomassaria fibraureae, Neoscytalidium dendrobii, Parabahusutrabeeja hyalina, Paramyrothecium xishuiense, Phaeosphaeria boehmeriae, P. guiyangensis, Phaeosphaeriopsis oblongispora, Psiloglonium bambusicola, P. brunneum, P. guizhouense, Roussoella panzhouensis, Seriascoma guizhouense, Striaticonidium olivaceobrunneum, Vamsapriya chiangraiensis and Virgatospora thailandica, with illustrations, discussions of their taxonomic placement, and comparisons with morphologically similar taxa. Twelve new combinations are introduced: Conioscypha chiangmaiensis (≡ Vanakripa chiangmaiensis), C. minutiellipsoidea (≡ Vanakripa minutiellipsoidea), Conioscypha obovoidea (≡ Vanakripa obovoidea), Heleiosa guizhouensis (≡ Neoheleiosa guizhouensis), H. lincangensis (≡ Neoheleiosa lincangensis), Keissleriella acaciae (≡ Pleurophoma acaciae), K. italicum (≡ Pleurophoma italica), K. ossicula (≡ Pleurophoma ossicola), K. pleurospora (≡ Phoma pleurospora), Phaeosphaeria brachylaenae (≡ Didymocyrtis brachylaenae), P. pini (≡ Didymocyrtis pini) and P. septata (≡ Didymocyrtis septata). Additionally, we report 34 new host records from medicinal plants and seven new geographical records for China and Thailand. We also resolved inter-generic synonymy for two species. A reference specimen is designated for Diplocladiella taurina. Detailed descriptions and illustrations of all these taxa are provided.

Culture techniques are vital in both traditional and modern fungal taxonomy. Establishing sexual–asexual links and synanamorphs, extracting DNA and secondary metabolites are mainly based on cultures. However, it is widely accepted that a large number of species are not sporulating in nature while others cannot be cultured. Recent ecological studies based on culture-independent methods revealed these unculturable taxa, i.e., dark taxa. Recent fungal diversity estimation studies suggested that environmental sequencing plays a vital role in discovering missing species. However, Sanger sequencing is still the main approach in determining DNA sequences in culturable species. In this paper, we summarize culture-based and culture-independent methods in the study of ascomycetous taxa. High-throughput sequencing of leaf endophytes, leaf litter fungi and fungi in aquatic environments is important to determine dark taxa. Nevertheless, currently, naming dark taxa is not recognized by the ICN, thus provisional naming of them is essential as suggested by several studies.