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 56. Lasianthus pierrei Pit. (1924: 386) — Fig. 85 (plate), Fig. 84 (map) Type: — VIETNAM . Ba Ria— Vung Tau , Con Dao District , October 1876 , Harmand 6174 ( holotype P! [P03981118]; isotype P! [P03981115]) . FIGURE 85. Lasianthus pierrei Pit. (from Dang 345 , VNM and the herbarium of Iriomote Station (Japan)): A. Branch, B. Stipules, C. Abaxial leaf surfaces, D–E. Inflorescence showing side view calyx, buds and flower, F–G. Young fruits. Specimens examined: — VIETNAM . Central: Khanh Hoa Province , Hon Ba Nature Reserve , 900 m elev., 24 July 2018 , Dang V.S. & Hoang N.T.B.N. , Dang 195 ( VNM ); in the same location, 1502 m elev., 15 June 2019 , Dang V.S. & Hoang N.T.B.N. , Dang 345 ( VNM , the herbarium of Iriomote Station ( Japan )) . Distribution: —Endemic to Vietnam (currently known as Con Dao National Park in Con Dao District of Ba Ria—Vung Tau Province and Hon Ba Nature Reserve of Khanh Hoa Province ). Habitat & Ecology: —Growing under the shade of evergreen forest or on a hill of the forest at 500–1600 m elev. Phenology: —Flowering and fruiting from June to November. Vernacular name: —Xú hưƠng pierre. Notes: — Lasianthus pierrei was described in 1924 from a Vietnamese specimen ( A. Harmand 6174 ). It is characterized in the field as having yellow-brown pubescent branches, linear-lanceolate leaves, secondary veins 4–6 on each side of midrib; petioles 4–5 mm long, flowers white, calyx tube longer than the lobes, and fruits globose with 4 pyrenes. Additional fruit morphology for L. pierrei : Fruit drupaceous, globose, 5–7 mm long, 4–5 mm in diam., sparsely strigose, crowned by persistent short calyx lobes; pyrenes 4. Seeds ovoid, 3–4 mm long, sulcate on the abaxial face, brown when dry.