Three new species of Isodon (Nepetoideae, Lamiaceae) from China.

Three new species of Isodon (Lamiaceae) from China are described and illustrated, based on both morphological evidence and our recent phylogenomic studies of the genus. Isodonattenuatus, a herbaceous new species known only from the Fanjing Mountain, is shown to be sister to I.villosus, but they can be easily distinguished by leaf and inflorescence indumentum, calyx teeth shape and corolla tube morphology. Isodongongshanensis, a herbaceous new species collected from the Hengduan Mountains in southwest China, represents a distinct lineage within the genus. Isodonsukungii, a shrubby new species also endemic to the Hengduan Mountains, was previously misidentified as I.tenuifolius, but they are phylogenetically distantly related and differ in lamina size and margin, inflorescence type and corolla length and shape.