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 70. Lasianthus verticillatus (Lour.) Merr. (1935: 372) — Fig. 102 (plate), Fig. 99 (map) Type: — VIETNAM . G. Dausus 48 ( holotype BM!) . Dasus verticillatus Lour. (1790: 141) . Type: — VIETNAM . G. Dausus 48 ( holotype BM!). Lasianthus andamanicus Hook.f. (1880: 189) . Type :— MYANMAR . Amherst , Tenasserim , Wall. Cat. 8309 ( holotype K! [K000031676]). Lasianthus tamirensis Pierre ex Pit. (1924: 390) . Type :— CAMBODIA . Samrong-tong , Mt Tamire , May 1870 , Pierre 587 ( holotype P! [P02285234]; isotype K! [K000777002]). Lasianthus wrayi King & Gamble (1904: 119) . Type :— MALAYSIA . Perak , Wray 257 ( holotype K! [K000777043]). Specimens examined: — VIETNAM . Northern: Ninh Binh Province , Cuc Phuong National Park , 365 m elev., 18 November 2018 , Dang V.S. & Naiki A. , Dang 284 & Dang 290 ( VNM , the herbarium of Iriomote Station ( Japan )) . Central: Khanh Hoa Province , Hon Ba Nature Reserve , 910 m elev., 25 July 2018 , Dang V.S. & Hoang N.T.B.N. , Dang 197 ( VNM ). Southern : Tay Ninh Province , Logo-Xamat National Park , 10 elev., 22 November 2020 , Dang V.S. & Hoang N.S. , Dang 435 ( VNM ) . Distribution: —Widespread in the tropical and subtropical regions in Asia ( Cambodia , China , India , Indonesia , Japan , Laos , Malaysia , Myanmar , Papua New Guinea , Philippines , Sri Lanka , Thailand ). In Vietnam , Lasianthus verticillatus occurs in Dong Nai , Ha Tinh , Khanh Hoa , Kien Giang , Kon Tum , Lam Dong , Ninh Binh , Tay Ninh , and Thua Thien Hue. Habitat & Ecology: —Growing under the shade of primary and secondary forests or in hills and the edge of the evergreen montane forests at 300–1000 m elev. Phenology: —Flowering and fruiting from November to April of the next year. Vernacular name: —Xú hưƠng luân sinh. Notes: —Two Vietnamese species, L. tamirensis Pierre ex Pit. (1924: 390) and L. wrayi King & Gamble (1904: 119) were treated as synonyms of L. verticillatus by Zhu et al. (2012) . This species is easily identified in the field in having oblong to oblong-lanceolate leaves, secondary veins 7–9 on each side of midrib, calyx cupular truncate, and fruits subglobose, smooth, black when ripe.