Tests of species concepts of the small, white, European group of Tuber spp. based on morphology and rDNA ITS sequences with special reference to Tuber rapaeodorum

Several taxonomic problems arise in the group of small, white European truffles, probably due to the over-emphasized significance of certain morphological features of ascomata. The distinction between Tuber rapaeodorum Tul. & C. Tul. and Tuber borchii Vittad. and Tuber puberulum Berk. & Broome has not been accepted in several recent studies. Furthermore, the existence of T. rapaeodorum been questioned in some recent synopses of the genus. We conducted microscopic and ITS sequence investigations of 31 herbarium specimens. Using morphological features such as peridium structure, form and size of spores and dermatocystidia and spore numbers per ascus, we could distinguish T. borchii, T. foetidum Vittad., T. maculatum Vittad., Tuber puberulum, and T. rapaeodorum. Analysis of whole ITS sequences showed sharp differences among the morphologically separated groups. Neighbour-joining and parsimony methods produced highly supported branches and confirmed the identity of these species.[PUBLICATION ABSTRACT]