Molecular analyses of soil and water commonly reveal large proportions of fungal taxa that cannot be assigned to any taxonomic or functional groups. Some of these so-called dark taxa have been encoded alphanumerically, while others have remained completely overlooked. Using long-read sequencing that covers much of the ribosomal RNA operon, we shed light on the phylogenetic and ecological distribution of fungal dark taxa and formally describe 30 of the most prominent phylum- to order-level lineages based on their characteristic DNA features. This increases the known large-scale fungal phylogenetic diversity by roughly one-third. Formal names will enhance taxonomic reproducibility, facilitate communication among researchers, and enable the estimation of conservation and quarantine needs for uncultivable species and higher-ranking taxa. The new species in the respective highest-level novel taxonomic groups include Pantelleria saittana (Pantelleriomycetes), Paraspizellomyces parrentiae (Paraspizellomycetales), Aquieurochytrium lacustre (Aquieurochytriomycetes), Edaphochytrium valuojaense (Edaphochytriomycetes), Tibetochytrium taylorii (Tibetochytriomycetes), Tropicochytrium toronegroense (Tropicochytriomycetes), Algovorax scenedesmi (comb. nov.) and Solivorax pantropicus (Algovoracomycetes), Aquamastix sanduskyensis (Aquamastigomycetes), Cantoromastix holarctica (Cantoromastigomycetes), Dobrisimastix vlkii (Dobrisimastigomycetes), Palomastix lacustris (Palomastigomycetes), Sedimentomastix tueriensis (Sedimentomastigomycetes), Terrincola waldropii (Terrincolales), Curlevskia holarctica (Curlevskiomycota), Mycosocceria estonica (Mycosocceriales), Maerjamyces jumpponenii (Maerjamycetes), Ruderalia cosmopolita (Ruderaliomycetes), Bryolpidium mundanum (Bryolpidiomycetes), Chthonolpidium enigmatum (Chthonolpidiomycetes), Savannolpidium raadiense (Savannolpidiomycetes), Gelotisporidium boreale (Gelotisporidiomycetes), Sumavosporidium sylvestre (Sumavosporidiomycetes), Parakickxella borikenica (Parakickxellomycetes), Aldinomyces tarquinii (Aldinomycota), Borikenia urbinae (Borikeniomycota), Mirabilomyces abrukanus (Mirabilomycota), Nematovomyces vermicola (comb. nov.) and N. soinasteënsis (Nematovomycota), Viljandia globalis (Viljandiomycota), Waitukubulimyces cliftonii (Waitukubulimycota), and Tartumyces setoi (Tartumyceta).

Soil eukaryotes, including fungi, protists, plants, and animals, are central to biosphere functioning and resilience. The Global Standardised Soil Eukaryome Dataset (GloSED) is the first dataset encompassing the entire spectrum of soil eukaryotes, covering 4,063 sampling sites in 121 countries on all continents, revealing nearly one million operational taxonomic units. All samples were collected and analysed using a standardised protocol minimizing technical biases. Long-read sequencing of full-length ITS and 18S-V9 regions provide broad taxonomic coverage and high-resolution identification supported by specialist curation of “dark taxa”. A rigorous bioinformatic processing ensures against homopolymer errors, PCR-mediated chimeras, and index switching providing high data quality. The dataset is supported by raw sequences and an open-source containerised workflow for reproducible analyses. The samples are accompanied by land-cover description and directly measured soil pH, δ ¹³ C, δ ¹⁵ N, as well as P, K, Ca, Mg, and total C and N contents. GloSED is the first database that enables ecological and biogeographic studies of entire soil eukaryotic communities from local to global scales.

Protists play important roles in food chains and symbioses in soil and aquatic environments, displaying an enormous morphological and functional diversity ^1,2 . While most commonly found protist species are well known to science, our global-scale environmental DNA survey across soil, water, and sediments reveals dozens of novel, phylum-level phylogenetic lineages that remain to be characterized for basic morphology and function. A vast majority of these undescribed taxa occur in marine water and sediments, but some are common in soil. Most of these novel taxa have distinct substrate and habitat preferences and biogeographic patterns. To accord these lineages scientific agency and enable unambiguous scientific communication, we propose formal names for 150 species to phylum-level taxa from 25 deep lineages based on eDNA and rRNA gene long-read sequence information.