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 65. Lasianthus stephanocalycinus Naiki, Tagane & Yahara (2015: 173) — Fig. 96 (plate), Fig. 94 (map) Type : — CAMBODIA . Kampot Province , Bokor National Park , 903 m elev., 13 May 2012 , Toyama H. , Tagane S. , Mishima T. , Tagawa K ., Zhang M., Chhang P., Iwanaga F., Nagamasu H. & Yahara T. 3100 ( holotype KYO !; isotypes Cam !, K!, P!) . FIGURE 96. Lasianthus stephanocalycinus Naiki, Tagane & Yahara (A–D & G–H from N10123 and E–F from Dang 196 , VNM and the herbarium of Iriomote Station (Japan)): A. Branch with fruits, B. Close-up of expanding young leaves, C. Stipules, D. Abaxial leaf surfaces, E–F. Inflorescence showing side view calyx and flower buds, G–H. Young fruits. Specimens examined: — VIETNAM . Central: Khanh Hoa Province , Hon Ba Nature Reserve , 400 m elev., 12 July 2014 , Tagane S. , Kanemitsu H. , Dang V.S. , Tran H. with Loi X.N. , Thach N.D. , Hieu P.N.H. V1618 ( FU , VNM ); in the same location, 919 m elev., 13 July 2014 , Tagane S. , Kanemitsu H. , Dang V.S. , Tran H. with Ngoc N.V. , Cuong N.Q. , Thi D.N. , Hieu P.N.H. V 1711 ( FU , VNM ); in the same location, 907 m elev., 28 November 2017 , Dang V.S. & Naiki A . N10123 ( VNM , the herbarium of Iriomote Station ( Japan )); in the same location, 920 m elev., 27 July 2018 , Dang V.S. & Hoang N.T.B.N. , Dang 196 ( VNM ) . Distribution: —Indochina region ( Cambodia ). In Vietnam , Lasianthus stephanocalycinus occurs in Khanh Hoa and Kien Giang . Habitat & Ecology: —Growing in the shade of primary forest or along the stream of the evergreen montane forest at 300–1000 m elev.The forest habitats are dominated by species of Fagaceae , Rubiaceae , Apocynaceae , Euphorbiaceae , Fabaceae , Symplocaceae , Clusiaceae , Myrtaceae , Acanthaceae , Celastraceae , Moraceae , Phyllanthaceae and Polygonaceae . Phenology: —Flowering and fruiting from May to November. Vernacular name: —Xú hưƠng mịn, Xú hưƠng đài vòng. Notes: — Lasianthus stephanocalycinus was described as new based on the specimens which were collected from Bokor National Park of Cambodia and Hon Ba Nature Reserve of Vietnam by Naiki et al. (2015) . This species can easily be recognized in the field in having elliptic leaves, secondary veins 4–9 on each side of midrib, flowers congested, white, and fruits globose, crowned by calyx lobes, and orange when ripe.