Viola umphangensis (Violaceae), a new species from Thailand

Viola umphangensis S. Nansai, Srisanga & Suwanph., a new species from Thailand, is described and illustrated. Morphological, anatomical and palynological characters of V. umphangensis are compared with a similar species, V. betonicifolia Sm.. An amended key to the Viola species in the Flora of Thailand account is provided.
Methods
Fresh and dried materials were examined from field collections and herbarium specimens and measurements of vegetative and reproductive parts were taken using a dissecting microscope. Voucher specimens were prepared and deposited at BK, BKF and QBG (Table 1). Permanent cross-section slides of rhizomes, petioles and leaves were prepared using a paraffin method (Johansen 1940, Kermanee 2008). The permanent slides of the epidermis were prepared using a peeling method (Thammathaworn 1995). All permanent slides were observed under a light microscope (LM) (Zeiss-Axioskop 2) and stored at the Palynology Special Research Unit, Department of Botany, Faculty of Science, Kasetsart University, Bangkok, Thailand. The pollen grains were obtained using a modified acetolysis technique (Erdtman 1960). The pollen slides were investigated under a LM (Zeiss-primo star) and a scanning electron microscope (SEM) (FEI-Quanta 450) at the Scientific Equipment Center, Faculty of Science, Kasetsart University, Bangkok, Thailand.