Oberonia pygmaea sp. nov. (Orchidaceae) from Thailand

In the context of an ongoing revision of the orchid genus Oberonia in Thailand, we describe and illustrate a new species under the name O. pygmaea Bunpha, H. A. Pedersen & Sridith. Vegetatively, the tiny new species is particularly similar to O. rufilabris Lindl. (widespread in mainland southeast Asia, including Thailand), whereas its floral morphology comes closest to the much larger O. costeriana J. J. Sm. from Sumatra, Java and Sulawesi. So far, O. pygmaea is only known from Pang Ung in the northern Thai province of Mae Hong Son, but we suggest that it should also be searched for in hill evergreen forest in adjoining parts of the Dawna Range, both in Thailand and Myanmar.