Tuber purpureum sp. nov. (Tuberaceae, Pezizomycetes) From China and Deeper Insights of Understudied Tuber Species within the Excavatum Group

The Excavatum Group of Tuber is relatively poorly studied worldwide. Through extensive exploration and research on truffles, we identified a new excavated truffle species, Tuber purpureum, based on morphological and molecular analyses (ITS-nrLSU concatenated dataset). The main characteristics of this species include yellow-brown ascomata that are covered with distinctly verrucose warts on the surface. The gleba is solid and purple when mature, with a marbled pattern of white veins. The asci are subglobose, ellipsoid, or irregular, sessile or with short stalks, and contain 1–6 spores. Here, we conducted thorough studies on species of the Excavatum group and supplemented key morphological characteristics of the known species T. neoexcavatum and T. magnameshanum of this group. Furthermore, we integrated global data to comprehensively analyze the morphological, molecular, ecological, and geographical distribution characteristics of the Excavatum group species. Our observations highlight the significantly underestimated diversity of the Excavatum group worldwide, greatly clarifying the resource potential and geographical distribution characteristics of this group, and further documenting the need for additional systematic focus on the group.