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 69. Lasianthus trichophlebus Hemsl. (1888: 388) — Fig. 101 (plate), Fig. 99 (map) Type: — CHINA . Guangdong , Luo Fu Shan , 7 August 1883 , C. Ford 113 ( holotype K! [K000763824]) . Lasianthus barbellatus Ridl. (1917: 187) . Type :— MALAYSIA . Pahang , Pulau Tiuman , Juara Bay , 22 June 1915 , Burkill 976 (isotypes K! [K000763901]). Lasianthus cupreus Pierre ex Pit. (1924: 392) . Type :— VIETNAM . Ba Ria— Vung Tau , Con Dao District , October 1876 , Harmand 6173 ( lectotypes P! [P02285252, P02285253], designated by Zhu 2001 ). Specimens examined: — VIETNAM . Central: Gia Lai Province , Kon Ka Kinh National Park , 905 m elev., August 2019 , Oguri E. , Tagane S. , Sugai K. , Suyama Y. & Bui H.Q. V10808 ( HN ) ; in the same location, K’Bang District , Son Lang Commune , Kon Chu Rang Nature Reserve , 1100 m elev., 22 April 2021 , Van-Son Dang , Ba Vuong Truong & Minh Tam Thao Ngoc Duong , Dang 454 ( VNM ) . Southern : Ba Ria—Vung Tau Province , Con Dao National Park , 50 m elev., 22 December 2018 , Dang V.S. , Dang 298 & Dang 299 ( VNM ) ; Distribution: —Widespread in the tropical and subtropical regions in Asia ( China , India , Indonesia , Malaysia , Philippines , Thailand ). In Vietnam , Lasianthus trichophlebus occurs in An Giang , Ba Ria—Vung Tau, and Gia Lai . Habitat & Ecology: —Growing under shade of evergreen forest or in hill and edge of evergreen montane forest at 50–1000 m elev. Phenology: —Flowering and fruiting from July to December. Vernacular name: —Xú hưƠng ten đồng. Notes: —This species was clarified in the revision by Zhu et al. (2012) and a Vietnamese species, L. cupreus Pierre ex Pit. (1924: 392) was treated as the synonym of L. trichophlebus . It is easily identified in the field in having sparsely strigillose or glabrous on branches, secondary veins 7–9 on each side of midrib, flowers yellowish white, and fruits subglobose, black when ripe, pyrenes 4.