Abstract
We evaluated the inclusion of a cryptic species in a Japanese Amanita caesareoides population. We sampled A. caesareoides specimens under various vegetation and climate conditions, and then conducted phylogenetic analyses on sequences from seven loci. The A. caesareoides specimens showed two distinct groups, except when the ITS phylogeny was considered. These two phylogroups showed different distributions: subalpine-cool temperate and temperate-subtropical areas. Although these two phylogroups overlapped in terms of basidiospore size, the latter tended to exhibit smaller basidiospores. In addition, only the former showed mycelial growth on nutrient agar. Based on these phylo-morpho-ecophysiological characteristics, we separated the specimens labeled with the name A. caesareoides into two species. As the lectotype of A. caesareoides showed similarity to the former by DNA analysis, the latter was described as a new species, namely A. satotamagotake. Based on the geographic patterns of the two species, A. satotamagotake may have invaded the natural habit of A. caesareoides because of global warming.