New North American truffles (Tuber spp.) and their ectomycorrhizal associations.

Recent surveys of belowground fungal biodiversity in México and USA have revealed many undescribed truffle species, including many in the genus Tuber. Here we describe seven new species: Tuber beyerlei, T. castilloi, T. guevarai, T. lauryi, T. mexiusanum, T. miquihuanense and T. walkeri. Phylogenetic analyses place these species within the Maculatum group, an understudied clade of small truffles with little apparent economic value. These species are among the more taxonomically challenge-ing in the genus. We collected Tuber castilloi, T. mexiusanum and T. guevarai as fruit bodies and ectomycorrhizae on Quercus spp. in forests of eastern México. Tuber mexiusanum has a particularly broad geographic range, being collected in eastern USA under Populus deltoides and in Minnesota and Iowa in mixed hardwood forests. T. walkeri is described from the upper midwestern USA, and T. lauryi and T. beyerlei occur in the western USA.