Tuber petrophilum, a new truffle species from Serbia

Tuber petrophilum sp. nov., within the Tuber melanosporum lineage, is described from Mount Tara (western Serbia) based on morphological and ITS molecular data. It is recognizable by its minute ascomata that produce ovoid to ellipsoid to subfusiform spores bearing aculeate ornamentation. Among black truffles, the new species is distinguished by its irregularly roundish to subglobose ascomata not exceeding 1.6 cm in diameter, with a basal depression or cavity and peridium surface which appears as a thin semi-transparent layer while fresh. The species forms a monophyletic well-supported clade in Maximum Likelihood ITS phylogeny, closely related to Tuber brumale aggr. The distinctive feature of the new species lies in its specific and unique microhabitat, limited to humus-rich substrata accumulated as soil pockets in limestone rocks, commonly 20–100 cm above the continuous forest soil terraces. The species description is supplemented with macro- and micro-photographs, and a key to the species of the T. melanosporum lineage.