Dark taxa are species known only from eDNA sequences. In the natural sciences, when a species is described, the name consists of two Latin words to describe the species and the genus. This allows for categorization of plants, animals, and fungi. Mycorrhizal fungi are collected (soil and root samples) in nature. Fungal eDNA (environmental DNA) is extracted from the samples and sequenced. The sequences are then put through a bioinformatic pipeline to match the sequence to a described species. Dark taxa are species which are only known from sequences.  

Approximately 155,000 of the 2–3 million fungal species on the planet have been formally described and named, with dark taxa representing the vast majority of species within the Fungal Kingdom.

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How can you protect something that hasn’t yet been named?

A 2025 paper in Current Biology found that 83% of ectomycorrhizal fungi are known only by their DNA sequences. This means they can’t be linked to named or described species, posing problems for conservation. The article states that only 155,000 of the roughly 2-3 million fungal species on the planet have been formally described. eDNA has great potential for detecting new fungal species, but species need to be named before they can be included in conservation efforts. SPUN predicts that the global diversity of EcM fungi could be ∼25,500–55,500 species.

When a species hasn’t been formally described, it is much more difficult to study and protect.

Our recent work found that hotspots of ectomycorrhizal dark taxa are concentrated in tropical and southern-hemisphere regions, including parts of Southeast Asia, South America, and Africa. Yet much of the research and funding on ectomycorrhizal fungi has been focused in the Global North.

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Closing this gap will require more field sampling, more sequencing, and more support for scientists working in these regions.

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