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 9.2. Lasianthus candidus subsp. hoanglienensis V.S.Dang, Naiki & Yahara (2021: 54) — Fig. 26 (plate), Fig. 25 (map) Type : — VIETNAM . Lao Cai Province , Hoang Lien National Park , 1288 m elev., 05 May 2016 , Naiki A. , Toyama H. , Tagane S. , Yahara T., Nagamasu H., Nguyen V.N. , Hoang T.B. , Hoang T.S. V 5328 ( holotype VNM ! [ VNM00042877 ]; isotypes FU !, the herbarium of Iriomote Station ( Japan )). Specimens examined: — VIETNAM . Northern: Lao Cai Province , Hoang Lien National Park , 1288 m elevation, 12˚19’47.05”N, 103˚49’18.00’’E, in secondary hill evergreen forest, 05 May 2016 , Naiki A. , Toyama H. , Tagane S. , Yahara T. , Nagamasu H. , Nguyen V.N. , Hoang T.B. , Hoang T.S. V 5328 ( FU , VNM ) . Distribution: —Endemic to Vietnam (known only from the Hoang Lien National Park, Lao Cai Province ). Habitat & Ecology: —In the hills of the secondary forests at 1200–1300 m elev. Phenology: —Flowering and fruiting from May to September. Vernacular name: —Xú hưƠng hoàng liên. Notes: — Lasianthus candidus subsp. hoanglienensis is similar to L. candidus subsp. candidus which was described from Vu Quang National Park in Ha Tinh Province as having densely appressed pubescent on branches and inflorescences, but differs from the latter in having blade elliptic to elliptic-lanceolate (vs. lanceolate to oblonglanceolate), shorter petioles ( 4–6 mm long vs. 8–10 mm long), smaller stipules ( 1–1.5 mm long vs. 1.5–2 mm long), and smaller calyx lobes ( 0.5–1 mm long vs. 1–1.5 mm long).