abstract
The Pleurotus eryngii species-complex comprises choice edible mushrooms growing on
roots and lower stem residues of Apiaceae (umbellifers) plants. Material deriving from extensive
sampling was studied by mating compatibility, morphological and ecological criteria,
and through analysis of ITS1-5.8S-ITS2 and IGS1 rRNA sequences. Results revealed that
P. eryngii sensu stricto forms a diverse and widely distributed aggregate composed of varieties
elaeoselini, eryngii, ferulae, thapsiae, and tingitanus. Pleurotus eryngii subsp. tuoliensis comb.
nov. is a phylogenetically sister group to the former growing only on various Ferula species
in Asia. The existence of Pleurotus nebrodensis outside of Sicily (i.e., in Greece) is reported for
the first time on the basis of molecular data, while P. nebrodensis subsp. fossulatus comb.
nov. is a related Asiatic taxon associated with the same plant (Prangos ferulacea). Last, Pleurotus
ferulaginis sp. nov. grows on Ferulago campestris in northeast Italy, Slovenia and Hungary;
it occupies a distinct phylogenetic position accompanied with significant differences
in spore size and mating incompatibility versus other Pleurotus populations. Coevolution
with umbellifers and host/substrate specificity seem to play key roles in speciation processes
within this fungal group. An identification key to the nine Pleurotus taxa growing
in association with Apiaceae plants is provided.