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 48. Lasianthus micranthus Hook.f. (1880: 190) — Fig. 75 (plate), Fig. 73 (map) Type: — INDIA . Bengal , Mishmi hills, Griffith 2930 ( holotype K!, [K000031633]) . Litosanthes micrantha (Hook.f.) Deb & M.Gangop. (1989: 220) . Lasianthus balansae (Drake) Pit. (1924: 396) ; Mephitidia balansae Drake (1924: 396) . Type :— VIETNAM . Ha Noi City , Ba Vi District , 500 m elev., November 1887 , Balansa 2652 ( lectotype K! [K000777016], designated by Napiroon et al. 2020 ). Specimens examined: — VIETNAM . Northern: Lang Son Province , Cao Loc District , Dong Dang Commune , 10 February 1886 , Balansa 659 (P); Lao Cai Province , Hoang Lien National Park , 850 m elev., 29 April 2016 , Naiki A. , Yahara T. , Toyama H. , Tagane S. , Nagamasu H. , Nguyen V.N. , Hoang T.B. , Hoang T.S. V 4640 ( DLU , FU , VNM , the herbarium of Iriomote Station ( Japan )); Vinh Phuc Province , Tam Dao National Park , 1124 m elev., 13 November 2018 , Dang V.S. & Naiki A. , Dang 238, Dang 239 & Dang 260 ( VNM , the herbarium of Iriomote Station ( Japan )); Ha Noi City, Ba Vi National Park , 1267 m elev., 17 November 2018 , Dang V.S. & Naiki A. , Dang 273 & Dang 279 ( VNM , the herbarium of Iriomote Station ( Japan )) . Distribution: —Widespread in tropical and subtropical regions in Asia ( China , India , Thailand ). In Vietnam , Lasianthus micranthus occurs in Lao Cai , Lang Son , Ha Noi , and Vinh Phuc . Habitat & Ecology: —Growing in the shade of the evergreen forest and the hill of natural forest at 800–1300 m elev. Phenology: —Flowering and fruiting from October to April of the next year. Vernacular name: —Xú hưƠng balansa. Notes: —A Vietnamese species, L. balansae (Drake) Pit. (1924: 396) was treated as the synonym of L. micranthus by Zhu and Taylor (2011) . Lasianthus micranthus is easily recognizable in the field in having sparsely puberulent to glabrous branches; ovate, ovate-oblong to oblong-lanceolate leaves, secondary veins 5–6 on each side of midrib, calyx lobes 5, and fruits globose, blue when ripe.