Based on fungal material collected in the Mbalmayo Forest Reserve, Cameroon, two Russulaceae for which the specimens Could not be satisfactorily placed to any known species, are described as new to science. Lactarius dewevrei is strikingly characterised by the entire blackish to dark date brown basidiomata and winged basidiospores with broad branched ridges of Plinthogali type, and Russula caeruleoanulata is distinguished by the uniformly pastel yellow color, a blue line at the stem apex as well as the bluing of injured surfaces of the stem. DNA-based phylogenetic placement of the new species was assessed using nucleotide sequences of the partial nuclear large subunit ribosomal DNA (nucLSU rDNA). Molecular analyses Supported the placement of R. caeruleoanulata in R. delica-R. brevipes group of Russula subg. Compacta sect. Compactae, but did not afford a clear-cut placement of L. dewevrei, rather closely related to Lactarius subg. Plinthogali and also subg. Lactariopsis, while BLAST analyses showed similarity with subgs. Lactariopsis, Piperites and Russularia.

Marasmius mbalmayoensis (Basidiomycotina, Marasmiaceae) growing on decayed leaves of Canarium schweinfurthii in the Mbalmayo Forest Reserve, Cameroon, is described. The species is remarkable due to the large basidiomata with shallow orange yellow umbilicus, long central stipe accompanied by similar long rhizomorphs on thickened basal mycelium and large lacrymiform to sigmoid basidiospores. The coarsely plicate pilei with lilac, violet to dark violaceous tints, and large distant adnate lamellae are reminiscent macroscopically of the tropical African species M. bekolacongoli. The phylogenetic relationship among M. mbalmayoensis and M. bekolacongoli was assessed, extended to other species of sects. Globulares and Sicci based on DNA sequences. Phylogenetic analysis based on nuc-LSU rDNA sequence data of selected Marasmiaceae taxa confirmed the placement of M. mbalmayoensis within the Marasmius spp. and its phylogenetic separation from M. bekolacongoli. Amyloflagellula inflata, which a BLAST analysis closely related to M mbalmayoensis , clustered in the same clade with M. mbalmayoensis and M. bekolacongoli. The findings also indicated the complexity of M. bekolacongoli.

The hymenochaetoid clade is dominated by wood-decaying species previously classified in the artificial families Corticiaceae, Polyporaceae and Stereaceae. The majority of these species cause a white rot. The polypore Bridgeoporus and several corticioid species with inconspicuous basidiomata, live in association with brown-rotted wood, but their nutritional strategy is Dot known. Mycorrhizal habit is reported for Coltricia perennis but needs confirmation. A surprising element in the hymenochaetoid clade is a group of small white to brightly pigmented agarics earlier classified in Omphalina. They form a subclade together with some similarly colored stipitate stereoid and corticioid species. Several are associated with living mosses or one-celled green algae. Hyphoderma pratermissum and some related corticioid species have specialized organs for trapping and killing nematodes as a source of nitrogen. There are no unequivocal morphological synapomorphies known for the hymenochaetoid clade. However almost all species examined ultrastructurally have dolipore septa with continuous parenthesomes while perforate parenthesomes is the normal condition for other homobasidiomycete clades. The agaricoid Hymenochaetales have not been examined. Within Hymenochaetales the Hymenochaetaceae forms a distinct clade but unfortunately all morphological characters supporting Hymenochaetaceae also are found in species outside the clade. Other subclades recovered by the molecular phylogenetic analyses are less uniform, and the overall resolution within the nuclear LSU tree presented here is still unsatisfactory.