2023 年 49 巻 3 号 p. 105-114
Arisaema suwoense Nakai was first described in 1929 from Yamaguchi Prefecture, Japan. Recently, A. izuense Nakai, which was described from Shizuoka Prefecture, has been incorporated into A. suwoense. Due to the limited number of specimens and absence of known wild populations of A. suwoense, the taxonomic study of these species has been challenging. In this study, we compared the morphology of A. suwoense, which was rediscovered in Yamaguchi Prefecture, with that of A. izuense by morphometric measurements of 20 morphological traits. We found that the two species are distinguished by inflorescence color, leaflet number of the first leaf, rachis length, terminal leaflet length and width, spathe blade length, spathe tube circumference, spathe tube auricle width, and spadix appendage diameter. These findings suggest that A. suwoense and A. izuense should be treated as distinct species. Given that the only wild population of A. suwoense is under threat of imminent habitat loss, urgent conservation measures are required.
