The term riffs off a similar problem in astronomy, in which researchers sometimes struggle to characterize “dark matter” that defies standard scientific rules. Similarly, the mycologists write, their field’s naming rules don’t account for fungi discovered with DNA sequencing instead of being observed visually or grown in the lab.

DNA discovery has shaken up the world of mycology, revealing signatures of thousands of distinct fungi in soil, water and elsewhere. But although DNA discovery has far outpaced other methods of identifying new fungal species, the researchers argue, processes for naming these new species have lagged.

Scientific naming of algae, fungi and plants is governed by the International Code of Nomenclature, a set of rules established by a world body of scientists that doesn’t allow fungi to be identified solely by their DNA.

That leaves researchers in the dark, despite signs these newfound fungi are a vital part of the natural world.

“We’re talking about tens of large groups of fungi — and thousands upon thousands of species, some of which seem to be so common that we have yet to find a soil sample from which they’re absent,” Martin Ryberg, a biology researcher at Uppsala University in Sweden and a co-author of the study, said in a news release. Dark fungi could dominate the fungal kingdom, he added.

So far, mycologists haven’t settled the debate. In the paper, the researchers propose a way forward with a list of possible criteria for recognizing dark fungi.

“These fungi deserve and need formal names, and it is our firm belief and opinion that this is achievable,” they write.

Will their colleagues agree? That remains to be seen. Meanwhile, researchers will continue to use DNA to pinpoint new types of fungi and look to upcoming gatherings, such as the 2024 International Mycological Congress in the Netherlands, for possible resolution on their unnamed discoveries.