What is "pachyphloeus"

Pachyphloeus is a genus of Ascomycete fungi (Pezizales, Pezizaceae) that forms hypogeous fruit bodies, aka truffles. Pachyphloeus citrinus is known as the "berry truffle" and Pachyphloeus austro-oregonensis is known as the "southern Oregon berry truffle". The genus Pachyphloeus forms ectomycorrhizal mutualisms with tree roots, usually oaks. Truffles require animals to dig them up and eat them, in order to disperse their spores.