Phylogenetic and morphological evidence supports the recently described Tuber thracicum

Truffles in the genus Tuber are hypogeous fungi living in symbiosis with the roots of many trees and shrubs. Within the genus Tuber, the Melanosporum clade includes some commercial species of great economic interest that are cultivated worldwide. At least four species of the clade have been described in Europe: Tuber melanosporum, T. brumale, T. crytpobrumale and T. petrophilum. Recent phylogenetic studies have also shown the existence of cryptic species in this clade. While analysing ascomata of T. brumale from Bulgaria, we found distinctive macro and micro-morphological features in some specimens. Phylogenetic analysis conducted on the internal transcribed spacer (ITS), the large subunit (LSU) rDNA and the protein kinase C like (PKC) sequences showed that these specimens form a monophyletic, well-supported taxon within the Melanosporum clade, closely related to T. brumale complex and T. petrophilum. Morphological and molecular analyses supported the recent proposal of the new species T. thracicum.