Molecular phylogeny and taxonomy of the complex (Hydrangeaceae) in western Japan, including a new subspecies of from Yakushima.

According to the contemporary classification of native to Japan, is a polymorphic species including six varieties. We discovered a plant identified as , but morphologically distinct from previously known varieties, in Yakushima island where approximately 50 endemic species are known. To determine the relationship of this plant with previously known varieties, we examined morphology and constructed a highly resolved phylogeny of and its relatives using three chloroplast genomic regions, L, L intron, A-H, and two nuclear genomic regions, ITS1 and ITS2, and Multiplex ISSR genotyping by sequencing (MIG-seq). Based on these morphological and phylogenetic observations, we describe Hydrangeaacuminatasubsp.yakushimensis as a newly discovered lineage in Yakushima, Japan and propose and Hydrangeaacuminatasubsp.australis which were previously treated as varieties of .