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 18. Lasianthus dienkhanhensis V.S.Dang & Naiki (1921: 40) — Fig. 38 (plate), Fig. 37 (map) Type. VIETNAM . Khanh Hoa Province , Hon Ba Nature Reserve , 919 m elev., 21 February 2014 , Toyama H. , Dang V.S. , Tagane S. , Fuse K. , Yahara T. , Nagamasu H. , Tran H. with Ngoc N.V. , Cuong N.Q. , Thach N.D. , Hieu H.N.P. V 859 ( holotype VNM ! [ VNM00042885 ]; isotypes FU !, VNM ! [ VNM00042886 , VNM00042887 ], the herbarium of Iriomote Station (Japan)) . FIGURE 38. Lasianthus dienkhanhensis V.S.Dang & Naiki (from V859 , VNM): A. Branch with flower buds, B. Stipules, C. Abaxial leaf surfaces, D–F. Inflorescence showing lateral view buds and flower, G. Young fruits, H. Mature fruit, I. Seeds. Specimens examined: — VIETNAM . Central: Khanh Hoa Province , Hon Ba Nature Reserve , 919 m elev., 12°06’46.88’’N , 108°58’14.43’’E , in evergreen forests, 21 February 2014 , Toyama H. , Dang V.S. , Tagane S. , Fuse K. , Yahara T. , Nagamasu H. , Tran H. with Ngoc N.V. , Cuong N.Q. , Thach N.D. , Hieu H.N.P. V 859 ( FU , VNM , the herbarium of Iriomote Station (Japan)); in the same location, 919 m elev., 12°06’46.88’’N , 108°58’14.43’’E , in evergreen forests, 19 July 2014 , Tagane S. , Kanemitsu H. , Dang V.S. , Tran H. with Hanh N. , Loi X.N. , Thach N.D. , Dinh N. , Hieu P.N.H. V 1709, V1710 ( FU , VNM , the herbarium of Iriomote Station ( Japan )) . Distribution: —Endemic to Vietnam (known from the Hon Ba Nature Reserve, Khanh Hoa Province ). Habitat & Ecology: —In shaded places of the primary and secondary forests at 900–1000 m elev. Phenology: —Flowering and fruiting specimens from February to July. Vernacular name: —Xú hưƠng diên khánh. Notes: — Lasianthus dienkhanhensis is similar to L. chevalieri Pit. (1924: 384) based on leaf shape and fruit color, but differs from the latter in having shorter petioles ( 8–10 mm long vs. 10–15 mm long), larger stipules ( 4–5 mm long vs. ca. 3 mm long), bracts 8–14 mm long (vs. inconspicuous) and smaller calyx ( 2–3 mm long vs. 3–6 mm long for tubes, 8–9 mm long vs. 9–14 mm long for lobes).