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.

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.

Dataset content overview

Figure 1. Distribution of Viola umphangensis S. Nansai, Srisanga & Suwanph. in Thailand, designed by a star.

Figure 2. Viola umphangensis S. Nansai, Srisanga & Suwanph. (A) habit, (B) stipules, (C) flower bud, (D) flower, (E) stamen, (F) stigma, (G) fruit, (H) seeds. Photos by S. Nansai (S. Nansai 10 (BK, BKF & QBG)).

Figure 3. Viola umphangensis S. Nansai, Srisanga & Suwanph. (A) habit, (B) leaf margin, (C–D) flower, (E) stamen, (F) pistil, (G) fruit, (H) seeds. Drawing by S. Nansai. (S. Nansai 10 (BK, BKF & QBG)).

Figure 4. Seed morphology from LM and SEM. (A–C) Viola umphangensis S. Nansai, Srisanga & Suwanph. (A) conspicuous raphe, (B) size, (C) areolate and smooth surface. All from S. Nansai 10 (BK, BKF & QBG). (D–F) V. betonicifolia Sm. (D) inconspicuous raphe, (E) size, (F) striate surface. All from S. Nansai 7 (BK, BKF & QBG).

Figure 5. Anatomical characters. (A–D) Viola umphangensis S. Nansai, Srisanga & Suwanph. (A) rhizome, (B) petiole, (C) upper epidermis, (D) lower epidermis. All from S. Nansai 20 (BK, BKF & QBG). (E–H) V. betonicifolia Sm. (E) rhizome, (F) petiole, (G) upper epidermis, (H) lower epidermis. All from S. Nansai 32 (BK, BKF & QBG). Abbreviation: cb = cortical bundle.

Figure 6. Pollen morphology from LM. (A–C) Viola umphangensis S. Nansai, Srisanga & Suwanph. (A) polar view, (B) equatorial view, (C) colporate. All from S. Nansai 10 (BK, BKF & QBG). (D–F) V. betonicifolia Sm. (D) polar view, (E) equatorial view, (F) colporate. All from S. Nansai 7 (BK, BKF & QBG).

Figure 7. Pollen morphology from SEM. (A–C) Viola umphangensis S. Nansai, Srisanga & Suwanph. (A) polar view, (B) equatorial view, (C) granulate. All from S. Nansai 10 (BK, BKF & QBG). (D–F) V. betonicifolia Sm. (D) polar view, (E) equatorial view, (F) granulate fossula. All from S. Nansai 7 (BK, BKF & QBG).