In contrast, the gelatinized fruiting bodies of Hohenbuehelia and Resupinatus are independently derived.
Phylogenetic analyses based on partial sequences from nuclear 25S rDNA indicate a monophyletic Pleurotaceae, consisting of the monophyletic genera Pleurotus and Hohenbuehelia, within the polyphyletic pleurotoid-lentinoid fungi. The attack and consumption of nematodes (nematophagy) supports the monophyly of this family. Other pleurotoid-lentinoid fungi that have been studied are not nematophagous and, in phylogenetic analyses, occur within the euagaric, polyporoid and russuloid clades. The pleurotoid agarics Lampteromyces, Lentinula, Nothopanus, and Omphalotus form a clade together with Gymnopus dryophilus. A clade that corresponds to the Tricholomataceae includes the pleurotoid agarics Conchomyces, Hypsizygus, Phyllotopsis, and Resupinatus. Faerberia, Heliocybe, Lentinus, Neolentinus, and Panus are gilled polypores, and all deserve recognition at the generic level. The brown-rotters Heliocybe and Neolentinus form a distinct clade within the polypores together with the brown-rotting polypore, Gloeophyllum. The Pleurotaceae belong in the Agaricales, are not closely related to or synonymous with the Polyporaceae, and should be restricted to the genera Pleurotus and Hohenbuehelia. An isolate of Hohenbuehelia from Alberta, Canada produces adhesive knobs typical of Hohenbuehelia and its anamorph Nematoctonus, and also nonadhesive nematotoxic droplets characteristic of Pleurotus. This combination is unique within Hohenbuehelia and Pleurotus. Phylogenetic analyses place this species at the base of the genus Hohenbuehelia, indicating that nematotoxic droplets were probably present in the common ancestor of Pleurotus and Hohenbuehelia. In contrast, the gelatinized fruiting bodies of Hohenbuehelia and Resupinatus are independently derived. The tribe Resupinateae (Tricholomataceae) should be restricted to Resupinatus (including Asterotus) and cyphelloid allies such as Stigmatolemma.