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 59. Lasianthus sapaensis V.S. Dang & Naiki (2019: 39) — Fig. 88 (plate), Fig. 89 (map) Type: — VIETNAM . Lao Cai Province , Sa Pa District , Hoang Lien National Park , on the way to Fansipan peak from Ton station , 1906 m elev., 11 November 2018 , Dang V.S. & Naiki A. , Dang 230 ( holotype VNM ! [ VNM00042932 ]; isotypes HN !, VNM ! [ VNM00042933 , VNM00042934 ], the herbarium of Iriomote Station , (Japan)) . FIGURE 88. Lasianthus sapaensis V.S.Dang & Naiki (from Dang 230 , VNM and the herbarium of Iriomote Station (Japan)): A. Branch, B. Close-up of young branch and leaves, C. Stipules, D. Abaxial leaf surfaces, E–F. Inflorescence showing side view calyx, G. Mature fruit, H. Seeds. FIGURE 89. Distribution maps of Lasianthus sapaensis , L. saprosmoides , L. saxorum and L. schmidtii . Specimens examined: — VIETNAM . Northern: Lao Cai Province , Hoang Lien National Park , 1906 m elev., 11 November 2018 , Dang V.S & Naiki A. , Dang 230a ( VNM , the herbarium of Iriomote Station ( Japan )) . Distribution: —Endemic to Vietnam (currently known only from Hoang Lien National Park of Lao Cai Province ). Habitat & Ecology: —Growing along roadside, streams, and edges of the secondary forest at an elevation around 1900–2100 m . Phenology: —Flowering and fruiting from August to November. Vernacular name: —Xú hưƠng sapa. Notes: — Lasianthus sapaensis was described from a Vietnamese specimen ( Dang 230 ) by Dang & Naiki (2019) . It can easily be recognized from other species of Lasianthus in having densely appressed pubescent to sericious on branches, ovate or ovate-oblong to oblong-lanceolate leaves, secondary veins 6–7 on each side of midrib, peduncles 3–7 mm long, flower white, and fruits globose, ovoid-globose to depressed globose, blue when ripe. Lasianthus sapaensis is similar to L. micranthus Hook.f. (1880: 190) but differs from the latter in having densely appressed pubescent to sericious on branches (vs. sparsely puberulent to glabrous), petioles 4–7 mm long (vs. 4–9 mm long), calyx tube 2–3 mm long (vs. 1 mm long) and calyx lobes 1.5–2 mm long (vs. 1–1.5 mm long), corolla tube 7–8 mm long (vs. 3–6 mm long) and corolla lobes 3–4 mm long (vs. 2–2.5 mm long). It is also similar to L. biermannii subsp. crassipedunculatus C.Y.Wu & H.Zhu (1994: 75) which is endemic to China , but differs from the latter in having shorter stipules ( 1.5–2 mm vs. 3–5 mm long), peduncles 3–7 mm long (vs. 10–20 mm long), bracts inconspicuous (vs. 6–10 mm long) and smaller calyx lobes ( 1.5–2 mm long vs. 5 mm long).