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 66. Lasianthus tamdaoensis V.S. Dang (2020: 51) — Fig. 97 (plate), Fig. 94 (map) Type: — VIETNAM . Vinh Phuc Province , Tam Dao National Park , 75 km north of Ha Noi City , 1124 m elev., 13 November 2018 , Dang V.S. & Naiki A. , Dang 242 ( holotype VNM ! [ VNM00042938 ]; isotypes HN !, KYO !, VNM ! [ VNM00042939 ], VNMN!) . Specimens examined: — VIETNAM . Northern: Vinh Phuc Province , Tam Dao National Park , 75 km north of Ha Noi City , 1124 m elev., 13 November 2018 , Dang V.S. & Naiki A. , Dang 243 ( VNM , the herbarium of Iriomote Station (Japan)); Ha Noi City, Ba Vi National Park , 50 km west of Ha Noi city center, 1267 m elev., 17 November 2018 , Dang V.S. & Naiki A. , Dang 271 ( VNM , the herbarium of Iriomote Station ( Japan )) . Distribution: —Endemic to Vietnam (currently known as Tam Dao National Park of Vinh Phuc Province and Ba Vi National Park of Ha Noi City). Habitat & Ecology: —Growing under the shade of evergreen forest or the edge of the evergreen montane forest at 1000–1300 m elev. Phenology: —Flowering and fruiting from June to December. Vernacular name: —Xú hưƠng tam đảo. Notes: — Lasianthus tamdaoensis was described as new from a Vietnamese specimen ( Dang 242 ) by Dang & Naiki (2020) . This species is easily identified in the field in having densely appressed pubescent to strigose on branches, ovate to ovate-oblong leaves, secondary veins 5–6 on each side of midrib, flowers white, and fruits ovoid or globose, blue when ripe.