New species and records of Tricholoma (Agaricales: Tricholomataceae) sections Genuina and Megatricholoma from Costa Rica and United States

Species of Tricholoma sections Genuina and Megatricholoma are characterized by having pilei that are some shade of brown, and by white or yellow lamellae that also discolor some shade of brown. From Costa Rica in sect. Genuina, we describe as new T. luteopallidum, T. cacumense, and T. talamancense, and confirm the occurrence of Tricholoma stans, and from the United States describe as new Tricholoma brunneoluteum. Tricholoma roseoacerbum from sect. Megatricholoma is con-firmed for Costa Rica. Morphology as well as ITS sequences are employed to confirm the species’ identifications or circumscription of the new species.