Revisiting the taxonomy of the genus Diplocentrum (Orchidaceae) with the proposal for reinstatement of D. longifolium

Morphotaxonomical studies have been conducted on the orchid genus Diplocentrum (Orchidaceae; Tribe: Vandeae; SubTribe: Aeridinae) endemic to peninsular India. A critical examination of type specimens and other materials of the genus, along with the specimens collected from Idukki and Wayanad districts of Kerala and Shevaroy Hills of Tamil Nadu, showed that Diplocentrum longifolium should be considered as a valid species. Thus, we therefore reinstate the independent status of D. longifolium. Furthermore, a lectotype is designated for D. congestum. To facilitate its identification in the field, we provide colour photographs, taxonomical keys, and notes on the distribution of the three species of the genus.