Abstract
Declaring a species of mushroom extinct is tricky. Surprising findings of fruiting bodies of species that have not been found in a certain area for several decades show that it is not at all easy to determine when we can label any of the species as such.
For this reason, official red list documents do not talk about extinct species of mushrooms, but use the label not known. The situation with macromycetes (fungi with large fruiting bodies) is discussed in a separate article (on pages 232-234), in this post we will look at microscopic fungi, for which the situation is even more complicated.
These fungi grow most of their lives hidden in the substrate, and when they form fruiting bodies or other structures with spores, they are microscopic - smaller than 2 mm - i.e. difficult to find (some only by an experienced mycologist with a field magnifier) and can only be determined by morphological features under a microscope , possibly in combination with molecular data. Of course, they also have their demands on the climatic (or rather microclimatic) conditions of the environment and the sources of nutrients in the substrate, they compete (compete) with other organisms, and therefore they can completely disappear from the given environment during major changes.
However, we have far fewer observational records of them than of macromycetes, so we can talk about their extinction more generally.