Re-examination of the morphological and molecular features of Amanita clarisquamosa and Amanita avellaneosquamosa based on specimens collected in Hokkaido

Amanita clarisquamosa and A. avellaneosquamosa, both of which belong to the section Amidella, were described in 1933 in Nopporo, Hokkaido, Japan. Owing to large intraspecific variation and high interspecific resemblance in morphology, species delimitation and identification of section Amidella members is difficult. This also applies to the two focal species. Furthermore, the minimality of the original descriptions of A. clarisquamosa and A. avellaneosquamosa exacerbates this problem. For reliable identification, detailed morphological and molecular information of reliably identified specimens, hopefully type specimens is required. However, further morphological and molecular information cannot be obtained from the degraded type specimens. In this study, new specimens that showed morphological and molecular matches with A. clarisquamosa and A. avellaneosquamosa were obtained from Nopporo and the surrounding areas of Hokkaido. Detailed morphology and barcoding region sequences of these specimens were recorded. Importantly, the newly collected specimens showed morphological and molecular mismatches with previously reported A. clarisquamosa or A. avellaneosquamosa specimens. This indicated that specimens previously identified as these two species might have included misidentifications. Overall, the study results suggest a need for reconfirmation of species within the section Amidella.