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 13. Lasianthus chinensis Benth. (1861: 160) — Fig. 31 (plate), Fig. 32 (map) Type: — CHINA . Hong Kong , Festland bei, Champion s.n. ( lectotype K! [L000763825], designated by Zhu 2001 ) . Mephitidia chinensis Champ.ex Benth.(1852:196) . Type :— CHINA . Hong Kong , Festland bei, Champion s.n. ( lectotype K! [K000763825], designated by Zhu 2001 ). Lasianthus dinhensis Pierre ex Pit. (1924: 388) . Type :— CAMBODIA . Kampot, Poilane 283 ( syntypes P!); VIETNAM . Ba Ria-Vung Tau Province , Pierre 3257 ( syntypes P!; isosyntypes K!, BM!). Lasianthus dinhensis var. tonkinensis Pit. (1924: 388) . Type :— LAOS . Xiangkhouang , 18 November 1920 , Poilane 2327 ( lectotype P! [P03980279]; isolectotypes P! [P03980278, P03980280]; designated by Napiroon et al. 2020 ). Lasianthus dinhensis var. glabrescens Pierre ex Pit. (1924: 388) . Type :— VIETNAM . Dong Nai Province , Chua Chang mountain , March 1877 , Pierre 3258 ( holotype P!; isotype P!). FIGURE 31. Lasianthus chinensis Benth. (from Dang 188 , VNM): A. Branch, B. Stipules, C. Abaxial leaf surfaces, D–G. Inflorescence showing side view flowers and young fruits, H. Young fruits, I. Cross section of fruit with pyrenes. FIGURE 32. Distribution maps of Lasianthus chinensis , L. chrysoneurus , L. curtisii and L. dakglaiensis . Specimens examined: — VIETNAM . Northern: Lao Cai Province , Sapa District , 1500 m elev., July 1924 , Petelot 1668 (P) . Central: Khanh Hoa Province , Hon Ba Nature Reserve , 300 m elev., 20 July 2018 , Dang V.S. & Hoang N.T.B.N. , Dang 188 ( VNM ) ; in the same location, 900 m elev., 13 July 2014 , Tagane S., Kanemitsu H., Dang V.S. , Tran H. with Loi X.N. , Thach N.D. , Hieu P.N.H. V1626 & V1678 ( FU , VNM ) . Southern : Ba Ria – Vung Tau Province , Tan Thanh District , Nui Dinh , May 1869 , Pierre 3257 ( VNM ) ; Dong Nai Province , Xuan Loc District , Nui Chua Chan , March 1877 , Pierre 3258 ( VNM ) . Distribution: —Widespread in tropical and subtropical regions in Asia ( Cambodia , China , Laos , Malaysia , Philippines , Thailand ). In Vietnam , Lasianthus chinensis occurs in Ba Ria—Vung Tau, Dong Nai , Khanh Hoa , Lam Dong , Lang Son , and Lao Cai . Habitat & Ecology: —Growing under the shade of evergreen forest or on the edge of the forest at 300–900 m elev. Phenology: —Flowering and fruiting from July to November. Vernacular name: —Xú hưƠng trung quốc. Notes: —Three Vietnamese taxa, L. dinhensis Pierre ex Pit. (1924: 388) , L. dinhensis var. tonkinensis Pit. (1924: 388) and L. dinhensis var. glabrescens Pierre ex Pit. (1924: 388) were treated as the synonyms of L. chinensis by Zhu et al. (2012) . Lasianthus chinensis can easily be recognized in the field in having more than 14 cm long leaves, secondary veins 10–12 on each side of midrib, calyx elongated campanulate, 5–7 mm long, and corolla white.