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 42. Lasianthus lancifolius Hook.f. (1880: 187) — Fig. 68 (plate), Fig. 67 (map) Type: — INDIA . Khasia, Hooker & Thomson 12 ( lectotype K! [K000031624], designated by Deb 1991 ) . Specimens examined: — VIETNAM . Northern: Ha Noi City , Ba Vi National Park , 1267 m elev., 17 November 2018 , Dang V.S. & Naiki A. , Dang 272 ( VNM , the herbarium of Iriomote Station (Japan)); in the same location, 1210 m elev., 17 November 2018 , Dang V.S. & Naiki A. , Dang 272a ( VNM , the herbarium of Iriomote Station ( Japan )) . Distribution: —Widespread in tropical and subtropical regions in Asia ( Bangladesh , Bhutan , China , India , Thailand ). In Vietnam , Lasianthus lancifolius occurs in Ha Noi , Phu Tho , and Vinh Phuc . Habitat & Ecology: —Growing under the shade of secondary forest at 1000–1300 m elev. This species is found in the forest where dominated by species Lasianthus thuyanae V.S. Dang & Naiki (2020: 49) , L. tamdaoensis V.S. Dang & Naiki (2020: 51) , L. fordii Hance (1885: 324) , Phyllanthus sp. , Melastoma sp. , Magnolia cavaleriei (Finet & Gagnep.) Figlar (2000: 21) , Asarum maximum Hemsl. (1890: 422) , Quercus myrsinifolia Blume (1851: 305) , Castanopsis fissa Rehder&E.H.Wilson(1916:203) , Cinnamomum balansae Lecomte(1913:75) , Magnolia fordiana Hu(1924:228) , Madhuca pasquieri H.J.Lam (1925: 182), Markhamia stipulata Seem. (1863: 226) , Eberhardtia tonkinensis Lecomte (1920: 346) . Phenology: —Flowering and fruiting from September to December. Vernacular name: —Xú hưƠng lá ngọn giáo. Notes: — Lasianthus lancifolius was described in 1880 by Hooker. It is characterized by having lanceolate to elliptic-lanceolate leaves, secondary veins 8–9 on each side of midrib, corolla puberulous outside and pubescent inside, lobes 5, and fruits globose, 3–5 mm diam. In Vietnam , we collected this species on the way to the highest peak in the montane natural forest of Ba Vi National Park at 1210 and 1267 m elev.