Abstract
A new collection of Lentinus giganteus from Sri Lanka, where it was originally described, is used to epitypify the species after comparison with the type protologue and drawings held in Peradeniya, Sri Lanka; a full description and illustrations are provided. Additional collections were made at three sites in northern Thailand. Phylogenetic ITS-1-5.8S-ITS2 rDNA sequence analyses using maximum likelihood, maximum parsimony and Bayesian inference all support the transfer of L. giganteus to Pleurotus. Although the collections from Thailand differ slightly morphologically and phylogenetically from P. giganteus sensu stricto, these differences do not yet merit specific status. Instead, P. giganteus is maintained as one widely variable species represented by relatively large fruiting bodies. Saprobic on buried well-rotted wood in forests, P. giganteus is widely consumed in Sri Lanka and might be profitably cultivated in Thailand.