Abstract
Ganoderma is a cosmopolitan genus of mushrooms, which can cause root and butt rot diseases on many tree species. Members of this genus are particularly diverse in tropical regions. Some Ganoderma spp. are medicinally active and therefore are used to treat human diseases or as a dietary supplement. In this study, three Ganoderma strains were collected in tropical southern Thailand. Phylogenetic analyses of combined ITS, LSU, TEF1α and RPB2 sequence data indicated that the three strains grouped in a distinct lineage within laccate Ganoderma. One strain was collected from Surat Thani Province clustered in the G. casuarinicola clade with high statistical support (MLBS = 100% / MPBS = 98% / PP = 0.96), while the other two strains of Ganoderma, collected from Nakhon Si Thammarat Province, formed a distinct well-supported clade (MLBS = 100% / MPBS = 100% / PP = 1.00) and are described here as a new species. Ganoderma casuarinicola is reported here as a new record to Thailand. Morphological differences of the two taxa and their closely related taxa are discussed. Colour photographs of macro and micro morphological characteristics and a phylogenetic tree to show the placement of the new record and new species are provided.