From Land to Sea: An Assessment of Global Fungal Diversity and Description

Abstract

It has become increasingly important to assess global biodiversity given the magnitude of threats facing ecosystems today. While it is widely recognised that two-thirds of life on Earth have been described, Fungi have remained an outlier. This study sought to explore the current state of fungal taxonomy and contribute to global biodiversity assessment by investigating global trends occurring across ecological and taxonomic subgroups within the Kingdom while calculating predictions of global diversity based on species description rates. The research focused on three aspects: description rates, taxonomic effort and delimitation techniques. Data on rates of species description and numbers of authors describing new species were obtained from IndexFungorum [indexfungorum.org], while data regarding characters applied in describing (delimiting) species new to science and data concerning institutional collaboration were obtained from the literature. A list of all type specimens with recorded genomic DNA data was obtained from the National Centre for Biotechnology Information. Data analyses were performed using SPSS, MS Excel and R. A nonhomogeneous renewal process model was applied to description data to calculate global species richness with 95% confidence limits. Kingdom Fungi has experienced a great acceleration in description rates within the last decade. Currently consisting of 144 035 species, an additional 68 750 species are predicted to be described this century. Mushroom-forming, lichenized and plant-associated fungi are predicted to experience the greatest degree of discovery. The number of authors involved in describing fungi is increasing, as is global effort. Increased description rates are better explained by the increase in effort than the increased use of molecular techniques, which were used in conjunction with morphological character descriptions. Less than 10% of currently accepted fungal species have associated genomic data, making it unfeasible to use a fully molecular approach to define species as new to science. A continued integrated approach is recommended, and future efforts should focus on sequencing type specimens of already established species to better understand the diversity being found within environmental samples. Efforts in fungal taxonomy are improving, but significant additional work must still be done in order to describe this highly diverse Kingdom.