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 21. Lasianthus fansipanensis V.S. Dang & Naiki (2019: 34) — Fig. 41 (plate), Fig. 42 (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 233 ( holotype VNM ! [ VNM00042888 ]; isotypes HN !, VNM ! [ VNM00042889 , VNM00042890 ], the herbarium of Iriomote Station , (Japan)) . FIGURE 41. Lasianthus fansipanensis V.S.Dang & Naiki (from Dang 233 , 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 flower buds, G–H. Mature fruits, I. Seeds. FIGURE 42. Distribution maps of Lasianthus fansipanensis , L. foetidissimus , L. fordii and L. formosensis . Specimens examined: — VIETNAM . Northern: 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 233a ( VNM , the herbarium of Iriomote Station (Japan)); in the same location, 1850 m elev., 29 April 2016 , Naiki A. , Yahara T. , Toyama H., Tagane S. , Nagamasu H. , Nguyen V.N. , Hoang T.B. , Hoang T.S. V 4782 & V4804 ( FU , 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 under the shade of the primary and secondary forests, at 1900–2100 m elev. Phenology: —Flowering and fruiting from July to December. Vernacular name: —Xú hưƠng fansipan. Notes: — Lasianthus fansipanensis was described from a Vietnamese specimen ( Dang 233 ) by Dang & Naiki (2019) . It is easily recognizable in the field in having lanceolate to oblong-lanceolate leaves, tip pointed 10–15 mm long, oblique or obtuse leaf base, peduncles 2–5 mm long, flowers pinkish white to white, and fruits ellipsoid, blue when ripe. This species is closely related to L. foetidissimus A.Chev. ex Pit. (1924: 395) which is endemic to Vietnam , but differs in its oblique to obtuse leaf base (vs. acute or slightly rounded), blue fruits (vs. yellowish orange), and fruits with 4 pyrenes (vs. 5 pyrenes).