Asarum yaeyamense Hatusima (Aristolochiaceae) newly found in northern Taiwan

Asarum yaeyamense Hatusima, a member of the section Heterotropa, was formerly reported as an endemic species distributed on Iriomote Island, southern Ryukyus of Japan. During our botanical surveys, this species was newly found in northern Taiwan, representing a new record to the flora of Taiwan. The species is closely related to A. hypogynum Hayata in central Taiwan and A. fudsinoi T. Ito on Amami Island, the northern Ryukyus. However, it can be distinguished from the former by a smaller flower and less-raised rugosity at the base of the calyx-lobes, and from the latter by the greenish-purple flower. In addition to a taxonomic description, line drawings, and color photos, the chromosome number (2n=24) and pollen morphology of the Taiwanese materials are also provided. Moreover, the relationship of this species with its close allies in Taiwan and the Ryukyus is discussed.