A new species of Diderma from Bidoup Nui Ba National Park (southern Vietnam)

A new species of Diderma, described herein as D. dalatense, was found in ground leaf litter in mixed montane tropical forests (Bidoup Nui Ba National Park) of southern Vietnam. This species was discovered during intensive studies on the distribution and ecology of fungi and myxomycetes in tropical forests of Vietnam in the context of a long-term project Ecolan 1.2. The morphology of representative specimens was examined by light and scanning electron microscopy, and micrographs of relevant details are provided. D. dalatense has unique combination of morphological characters of the sporocarps among species of Diderma including very small (0.2–0.4 mm in diam.) dark-yellow, globose to subglobose sessile sporocarps, large conical or subglobose yellow columella, smooth peridium with three layers resembling that of Leocarpus and irregularly warted spores. In addition to the morphological description, partial sequences of three genetic markers of this new species (SSU, EF1A, COI) were obtained and submitted to GenBank. The stability of the taxonomic characters of the species was confirmed by several collections obtained in different localities of the National Park.