Abstract
In the Kyushu region of Japan, a novel species, Chrysosplenium brevifilamentum (Saxifragaceae), has been identified. The species was previously confused with either C. macrostemon var. macrostemon or C. macrostemon var. viridescens owing to its morphological similarities, including yellow anthers and overall appearance. However, C. brevifilamentum can be distinguished from the varieties of C. macrostemon by the oblong leaves of the scape with a cuneate base and flowers exhibiting a pronounced disk and abbreviated stamens. Additionally, Chrysosplenium brevifilamentum usually maintains greenish hued foliage during winter; C. macrostemon usually displays brownish coloration. Comprehensive molecular phylogenetic analyses, employing sequence variations in the ITS and ETS regions of the nuclear ribosomal DNA and six chloroplast DNA regions, corroborated the distinct phylogenetic position of C. brevifilamentum within Chrysosplenium Ser. Macrostemon in Japan. Like other species of Chrysosplenium Ser. Macrostemon, C. brevifilamentum is diploid, suggesting that polyploidization is not relevant to its origin. Chrysosplenium brevifilamentum is primarily restricted to calcareous areas in central Kyushu.
