A Taxonomic Revision of Tribe Ocimeae Dumort. (Lamiaceae) in Continental South East Asia I. Introduction, Hyptidinae & Hanceolinae

The tribe Ocimeae is fully revised for continental South East Asia (Burma, Thailand, Laos, Cambodia and Vietnam). In all, 77 taxa including 70 species and 14 varieties are recognised under 9 genera: Hyptis Jacq., Siphocranion Kudo, Isodon (Schrad. ex Benth.) Spach, Anisochilus Wall. ex Benth., Plectranthus L'Hér., Basilicum Moench, Orthosiphon Benth., Ocimum L. and Platostoma P. Beauv. This first part of the revision includes a general introduction covering the Ocimeae in SE Asia and taxonomic accounts of the Hyptidinae (Hyptis) and Hanceolinae (Siphocranion and Isodon). Descriptions, full synonyms relevant to South East Asian Floras, maps, line drawings, information about ethnobotany, distributions, habitats, ecology, endemism and conservation, selected specimen citations and an index to accepted names and synonyms are given. In all parts, 16 new species (including 11 validated names) and 3 new varieties are described in the genera Anisochilus, Isodon, Orthosiphon, Plectranthus and Platostoma. In this part, Isodon colaniae S. Suddee & A. J. Paton is validated and Isodon meeboldii (W. W. Sm.) S. Suddee is presented as a new combination. Two floristic elements are identified here: the Indo-Burmese and Sino-Himalayan elements that enter the area from the northwest and north, and the Indo-Chinese element that enters the area from Indo-China. Most species of Platostoma, the largest Indo-Chinese element, especially section Mesona and section Ceratanthus, are concentrated along the Mekong River in the Indo-Chinese peninsula around the Bolovens-Langbian plateaus. In all, there are 33 (43%) taxa endemic to the area of study. Seventy-four taxa were assessed according to IUCN red list criteria. Fourteen taxa were assessed as threatened. Two, Plectranthus tomentifolius and Orthosiphon truncatus are believed to be extinct.