FLORA OF VIETNAM
Begoniaceae
Begonia semilunata Aver., sp. nov.

Ha Giang Prov., Quan Ba Distr., Can Ty Commune, Sin Suoi Ho Village, around point 23.09566°N 105.02142°E. Very steep mountain slopes composed of solid highly eroded karstic limestone at elevation 800–1000 m a.s.l. Remnants of primary evergreen broad-leaved and coniferous (with Calocedrus rupestris and Xanthocyparis vietnamensis) humid forest. Terrestrial and lithophytic rhizomatous herb in shady place among rocks. Leaves dark green above, light pale green below, petioles dull dirty purple. Flowers white with light pink tint. Locally very common. 11 October 2019, L. Averyanov, Nguyen Sinh Khang, T. Maisak, VR 1549 (holotype – LE01067022, isotype – HN, LE01070149 – photo). From similar species B. howii Merr. & Chun, B. psilophylla Irmsch. and B. subhowii S.H.Huang new species differs in rather rigid, narrowly half elliptic leaves (vs. leaves soft, herbaceous, oblique ovate to broadly ovate) and subequal wings on capsule (vs. abaxial wing much longer thal lateral wings), staminate subsimilar in all mentioned species, pistillate flowers unknown.