The numbers of fungi: contributions from traditional taxonomic studies and challenges of metabarcoding

<jats:title>Abstract</jats:title><jats:p>The global diversity of fungi has been estimated using several different approaches. There is somewhere between 2–11 million estimated species, but the number of formally described taxa is around 150,000, a tiny fraction of the total. In this paper, we examine 12 ascomycete genera as case studies to establish trends in fungal species descriptions, and introduce new species in each genus. To highlight the importance of traditional morpho-molecular methods in publishing new species, we introduce novel taxa in 12 genera that are considered to have low species discovery. We discuss whether the species are likely to be rare or due to a lack of extensive sampling and classification. The genera are <jats:italic>Apiospora</jats:italic>, <jats:italic>Bambusicola</jats:italic>, <jats:italic>Beltrania</jats:italic>, <jats:italic>Capronia</jats:italic>, <jats:italic>Distoseptispora</jats:italic>, <jats:italic>Endocalyx</jats:italic>, <jats:italic>Neocatenulostroma</jats:italic>, <jats:italic>Neodeightonia</jats:italic>, <jats:italic>Paraconiothyrium</jats:italic>, <jats:italic>Peroneutypa</jats:italic>, <jats:italic>Phaeoacremonium</jats:italic> and <jats:italic>Vanakripa</jats:italic>. We discuss host-specificity in selected genera and compare the number of species epithets in each genus with the number of ITS (barcode) sequences deposited in GenBank and UNITE. We furthermore discuss the relationship between the divergence times of these genera with those of their hosts. We hypothesize whether there might be more species in these genera and discuss hosts and habitats that should be investigated for novel species discovery.</jats:p>