Should describing a new species be science or data release? Rethinking introductions in fungal taxonomy

The Kingdom Fungi is estimated to contain several million species and accounts for a large portion of global biodiversity. However, only a small proportion of these fungal species are currently known to science. Ongoing habitat destruction and the resulting loss of diversity due to human activities have created a pressing need to document fungal communities and describe new fungal species. In this study, we analysed publications describing new species from 2020 through 2024 in the basidiomycete genera Amanita, Cortinarius, and Russula, and the ascomycete genera Aspergillus, Fusarium, and Pestalotiopsis. These genera, each containing hundreds or even thousands of known species, rank among the most species-rich groups globally. Our analyses show that in these genera, approximately 60% of 591 new species described in basidiomycetes and 58% of 322 new species of ascomycetes were published in taxonomic papers dealing with a few species in closely related groups (single lineage), but there has been an increasing trend to publish new species in publications containing multiple unrelated new species (cumulative and online release publications). In single lineage publications describing new species, the introduction section often provides only a general description of the genus, omitting important background information for the new or closely related species often mentioning the name of the newly described species to indicate the intent to describe it. However, the formal description and naming should only appear in the taxonomy section as a result of the study. Based on our estimates of the completeness and quality of introductions in single lineage publications, only 25% received scores above 50 points out of a potential 100 points, which is half the expected information needed to assess new species hypotheses. The majority of new species hypotheses are likely based on molecular sequence data, neglecting morphological or ecological components. Due to incomplete background information and poorly articulated aims, many publications resemble data releases rather than hypothesis-driven scientific studies. Based on a thorough review of publications and the authors' combined experience, we provide recommendations to improve the quality of introductions when describing new species. We outline the importance of complete background information for new species descriptions that link available data with individual study aims. Well-formulated, hypothesis-driven research enhances publication quality, improves clarity for readers, and increases the likelihood of acceptance, while also helping to avoid taxonomic ambiguities and redundant manuscript structure. For studies focused on a single lineage that includes more than five species, we recommend emphasizing lower-rank infrageneric groups (e.g., subgenera, sections, or subsections) in the introduction rather than providing detailed descriptions of individual species. Cumulative and online release publications are efficient tools for documenting and exploring fungal diversity. However, they have limitations, and their long-term contribution to understanding species boundaries will depend on the quality of the data presented and how well they are integrated with more comprehensive, traditional taxonomic studies.