A revision of the genus Lasianthus Jack (Rubiaceae) from Vietnam Author Dang, Van-Son 0000-0001-8681-4141 Iriomote Station, Tropical Biosphere Research Center, University of the Ryukyus, 870 Uehara, Taketomi-cho, Yaeyama-gun, Okinawa, 907 - 1541 Japan. & Institute of Tropical Biology, Vietnam Academy of Science and Technology, 85 Tran Quoc Toan Street, District 3, Ho Chi Minh City, Vietnam. & Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Ha Noi, Vietnam. & dvsonitb @ gmail. com; https: // orcid. org / 0000 - 0001 - 8681 - 4141 dvsonitb@gmail.com Author Naiki, Akiyo 0000-0002-3235-2823 Iriomote Station, Tropical Biosphere Research Center, University of the Ryukyus, 870 Uehara, Taketomi-cho, Yaeyama-gun, Okinawa, 907 - 1541 Japan. & Iriomote Station, Tropical Biosphere Research Center, University of the Ryukyus, 870 Uehara, Taketomi-cho, Yaeyama-gun, Okinawa, 907 - 1541 Japan. & naiki @ lab. u-ryukyu. ac. jp; https: // orcid. org / 0000 - 0002 - 3235 - 2823 * Author for correspondence naiki@lab.u-ryukyu.ac.jp text Phytotaxa 2023 2023-01-26 581 1 1921 1935 http://dx.doi.org/10.1094/PDIS-04-22-0755-PDN journal article 10.11646/phytotaxa.581.1.1 1179-3163 7571550 5. Lasianthus biflorus (Blume) M.Gangop. & Chakrab. (1992: 338) — Fig. 19 (plate), Fig. 20 (map) Type: — INDONESIA . Java , Blume s.n. ( lectotype L! [L0000722], designated by Zhu 2002) . Litosanthes biflora Blume (1823: 22) . Type :— INDONESIA . Java , Blume s.n. ( lectotype L! [L0000722], designated by Zhu 2002). Lasianthus gracilis King & Gamble (1904: 132) . Type :— MALAYSIA . Perak , Tea Gardens , Ridley 2904 ( lectotype SING! [ SING0059255 ], designated by Wong 1988 ). Specimens examined: — VIETNAM . Central: Gia Lai Province , Mang Yang District , 1000–1200 m elev., 15 August 1930 , Poilane 18003 (P); Kon Tum Province , Ngoc Linh Nature Reserve , 1141 m elev., 10 February 2017 , Tagane S. , Nagamasu H. , Nguyen V.N. , Hoang T.B. , Hoang T.S. , Yang C.J. , Kawakubo A. V 6099 ( DLU , FU , the herbarium of Iriomote Station ( Japan )); Gia Lai Province , Kon Chu Rang Nature Reserve , 920 m elev., 19 August 2019 , Oguri E. , Tagane S. , Sugai K. , Suyama Y. & Bui H.Q. V10401 ( HN , VNM ) ; in the same location, 1050 m elev., 21 April 2021 , Dang V.S. & Truong B.V. , Dang 459 ( VNM ) . FIGURE 18. Lasianthus bidoupensis V.S.Dang & Naiki (from Dang 250 , VNM and the herbarium of Iriomote Station (Japan)): A. Branch with flower buds, B. Stipules, C. Abaxial leaf surfaces, D–F. Inflorescence showing lateral view bracts and flowers, G. Young fruit, H. Mature fruits, I. Cross section of fruit with 5 pyrenes. Distribution: —Widespread in tropical and subtropical regions in Asia ( Cambodia , China , Indonesia , Malaysia , Philippines , Thailand ). In Vietnam , Lasianthus biflorus occurs in Gia Lai and Kon Tum . Habitat & Ecology: —Growing in lower montane evergreen forest and at the edge of the evergreen forest at 700– 1200 m elev. The forest habitats are dominated by species of Rubiaceae , Fagaceae , Lauraceae , Myrtaceae , Clusiaceae , and Fabaceae . FIGURE 19. Lasianthus biflorus (Blume) M.Gangop. & Chakrab. (from Dang 459 , VNM): A. Branch with flower buds, B. Close-up of young branch and leaves, C. Stipules, D. Abaxial leaf surfaces, E. Inflorescences, F. Flower bud, G. Young fruit, H–I. Mature fruits. Phenology: —Flowering and fruiting from August to December. Vernacular name: —Xú hưƠng lá nhỏ. Notes: — Lasianthus biflorus was first recorded for the flora of Vietnam by Zhu & Taylor (2011) . Currently, this species is known from Ngoc Linh Nature Reserve of Kon Tum Province and Kon Chu Rang Nature Reserve of Gia Lai Province , Southern Vietnam . It is easily recognizable in the field in having the small size of leaves and flowers, inflorescences with peduncles up to 2 cm long, and black fruit when ripe.