Reevaluation of Japanese Amanita section Caesareae species with yellow and brown pileus with descriptions of Amanita kitamagotake and A. chatamagotake spp. nov.

Japanese species of Amanita section Caesareae, “Kitamagotake” with a uniformly yellow pileus, and “Chatamagotake” with an olive-brown pileus, formerly treated as “A. javanica” and “A. similis”, respectively, were taxonomically reevaluated. Specimens of Japanese “A. javanica” and “A. similis” are morphologically distinct from Southeast Asian A. javanica and A. similis sensu stricto, respectively. Phylogenetic analysis of the internal transcribed spacer region, the 28S large subunit regions of nuclear ribosomal RNA, and translation elongation factor 1 (tef-1) genes showed that both Japanese entities are distinct from any previously described species of the Amanita section Caesareae, including A. javanica and A. similis sensu stricto. Therefore, we have described them as new species, namely A. kitamagotake and A. chatamagotake, respectively. Interestingly, specimens of A. caesareoides, which normally exhibit a red pileus, and A. chatamagotake included yellow color variants. The original Japanese “A. javanica” specimen was not morphologically consistent with A. kitamagotake but was determined to be a yellow color variant of A. chatamagotake. These results demonstrate the importance of precise morphological observation and molecular analysis for species identification of Amanita section Caesareae with yellow or brown pilei.