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

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