Tricholomopsis badinensis sp. nov. and T. sulphureoides—two rare fungi of European old-growth forests

Abstract

Interesting Tricholomopsis collections from old-growth forests in Slovakia and Poland were studied morphologically and molecularly using the ITS-LSU rDNA regions. Phylogenetic analysis of sequence data for all hitherto sequenced Tricholomopsis species revealed a geographic pattern. Species distributed primarily in the Holarctic are separated from those occurring in the Southern Hemisphere. Tricholomopsis decora is a species complex within which T. badinensis, a newly discovered European species, is described based on collections from fallen trunks of silver fir (Abies alba) in the Badinsky prales virgin forest in Slovakia. The species forms a well-supported clade in the phylogenetic tree. Morphologically, it is distinguished by medium-sized basidiomata, a brightly yellow to olive-yellow pileus with a tomentose, finely scaly to fibrillose covering which has an orange-yellow, yellow-brown to olive-brown color, scales adpressed for a long time and mostly ellipsoid basidiospores measuring 7–9(9.5) × (4)4.5–6 μm. Rich collections of T. sulphureoides from the Bialowieza virgin forest in Poland are described, and the distribution and ecology of the species is summarized. The great biological value of the two aforementioned localities and the Dobrocský prales virgin forest in Slovakia, a formerly published locality of T. sulphureoides (as T. osiliensis), is documented by a rich list of fungi considered old-growth forest indicators. A preliminary key for the identification of European Tricholomopsis species lacking red or violet coloration is proposed.