Morphology and phylogeny of Diderma aurantiacum (Myxomycetes) — a new species for Russia from the Far East

Two specimens of a rare species Diderma aurantiacum collected in the Sikhote-Alin Nature Reserve and the territory of the Land of the Leopard National Park (Primorye Territory, Russian Federation) were found during revision of the myxomycete collection of the Mycological herbarium of the Komarov Botanical Institute (LE). These specimens are the first records of this species outside the Japanese islands. Diderma aurantiacum is characterized by a thick cartilaginous peridium of dull orange color that breaks into petal-like fragments during dehiscence, a small hemispherical columella, weakly branched dark capillitial threads with pale tips, and warted spores with darker warts arranged in small groups. The color photographs of sporocarp structures and SEM images of spores and capillitium are published for the first time. The partial nucleotide sequences of nrSSU (18S rDNA) and EF1α genes of specimens from the Russian Far East differed clearly from these of other Diderma species.