Truffle-like Russulaceae

Whereas most Russulaceae mushrooms (Russula, Lactarius and Lactifluus species) form regular mushrooms, others show an aberrant morphology. Rather, they form enclosed fruitbodies, which can be either with or without a stipe. These species are called truffle-like or sequestrate. Some grow completely hypogeous, others are partially or fully epigeous.

They are easily recognized by their enclosed shape, compressed and contorted white to cream-colored gills, and typically ornamented, amyloid spores. In case of milkcap-truffles, the fruiting bodies release a milky substance when cut.

Almost 30 species of these truffle-like milkcaps or russulas have been described in Europe, but their distribution is poorly known due to their hidden lifestyle. They are possibly very rare, but more knowledge is needed to assess their ecology and Red List status.

Part of the “Truffulales” Project is to investigate the genomes of these species, to understand how this morphology has arisen several times in the evolutionary history of this family. To do so, we need fresh fruiting bodies of any truffle-like Russula or Lactarius species. A special focus is on clades were species show both co-occurring regular and truffle-like morphologies, such as Russula messapica and Russula meridionalis. The latter species is always sequestrate, whereas the former forms both regular (var. messapica) and truffle-like morphologies (var. messapicoides). Moreover, we will also focus on the species Russula vinaceodora and Russula ammophila/amoenolens, which also show a variable degree of truffle-likeness.

The wishlist species occur mostly in Italy and Spain, where Russula meridionalis occurs under Quercus rotundifolia, and Russula messapica can be found under Quercus coccifera and Q. ilex, from Spring to Autumn. They both show a yellow-ochre pileus, that reacts red in contact with KOH in R. messapica. R.vinaceodora and R. ammophila/amoenolens have a more coastal distribution, where they occur with Pinus on sandy soils. Figures and more detailed descriptions of these species are in our booklet.

Vidal, J. M., Alvarado, P., Loizides, M., Konstantinidis, G., Chachuła, P., Mleczko, P., Moreno, G., Vizzini, A., Krakhmalnyi, M., Paz, A., Cabero, J., Kaounas, V., Slavova, M., Moreno-Arroyo, B., & Llistosella, J. (2019). A phylogenetic and taxonomic revision of sequestrate Russulaceae in Mediterranean and temperate Europe. Persoonia, 42, 127–185.

Keys to the fungi of temperate Europe (Læssøe, T., Petersen, J.H., Frøslev, T.G. & Heilmann-Clausen, J.) –  Truffles: http://www.mycokey.com/keys/FTE-truffles.pdf