Abstract
Data about the occurrence of basidiomata forming hypogeous sequestrate fungi in Brazil are limited, and studies on this group are needed. During studies of hypogeous sequestrate fungi in Rio Grande do Sul State, Brazil, an unexpected new species of Lactarius was sampled from soils of an exotic Pinus plantation and described based on molecular and morphological data. This new species is recognized by the reddish yellow to dark brown, hypogeous basidiomes with a persistent peridium, white unchanging latex, globose to broadly ellipsoid basidiospores that are ornamented with a complete and dense reticulum and the peridiopellis composed by a cutis of repent firmly woven hyphae.