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 14. Lasianthus chrysoneurus (Korth.) Miq. (1857: 322) — Fig. 33 (plate), Fig. 32 (map) Type: — INDONESIA . Java , Jawa Barat , 1917, Backer 22515 ( neotype L! [L0306249], designated by Zhu 2002) . Mephitidia chrysoneura Korth. (1851: 222) . Type :— INDONESIA . Java , Jawa Barat , 1917, Backer 22515 ( neotype L! [L0306249], designated by Zhu 2002). Lasianthus kurzii Hook.f. (1880: 183) . Type :— MYANMAR . Chopedang , 1827, Wall. Cat. 8310 ( holotype K! [K000031671]. Lasianthus hoaensis Pierre ex Pit. (1924: 383) . Type :— VIETNAM . Dong Nai Province , Bien Hoa , Pierre 1316 ( syntype P!; isosyntypes BM!, E!, K!). Lasianthus hoaensis var. microphyllus Pit. (1924: 383) . Type :— CAMBODIA . Mont. de l’Lephant , 6 August 1919 , Poilane s.n. ( lectotype P! [P02285244], designated by Napiroon et al. 2020 ). Specimens examined: — VIETNAM . Central: Dak Nong Province , Gia Nghia District , 810 m elev., 9 May 2019 , Dang V.S. & Hoang N.S. , Dang 301 ( VNM ) ; in the same location, Ta Dung National Park , 680 m elev., 11 June 2019 , Dang V.S. & Hoang N.S. , Dang 310 ( VNM ) ; Gia Lai Province , Kon Ka Kinh National Park , 887 m elev., August 2019 , Oguri E. , Tagane S. , Sugai K. , Suyama Y. & Bui H.Q. V10916 & V10994 ( HN , KAG , MAK , VNM ) . Southern: Dong Nai Province , Xuan Loc District , Nui Chua Chan , 20 August 1931 , Poilane 19336 ( VNM ) ; in the same location, 750 m elev., 24 August 1931 , Poilane 18381 ( VNM ) . Distribution: —Widespread in tropical and subtropical regions in Asia ( Cambodia , China , India , Indonesia , Laos , Myanmar , Papua New Guinea , Thailand ). In Vietnam , Lasianthus chrysoneurus occurs in Dak Nong , Dong Nai , Gia Lai , and Lam Dong . Habitat & Ecology: —Growing in primary and secondary montane forests or open areas at 600–1000 m elev. Phenology: —Flowering and fruiting from May to October. Vernacular name: —Xú hưƠng biên hòa. Notes: — Lasianthus chrysoneurus was clarified in the revisions by Zhu & Taylor (2011) , Zhu et al. (2012) , and Napiroon et al. (2020) . This species is easily recognizable in the field in having appressed pubescent branches, stipules up to 8 mm long, bracts 5 mm long, and fruits subglobose, white when ripe.