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 41. Lasianthus lamdongensis V.S.Dang, Naiki & Toyama (2021: 48)— Fig. 66 (plate), Fig. 67 (map) Type: — VIETNAM . Lam Dong Province , Bidoup Nui Ba National Park , 1698 m elev., 24 February 2016 , Tagane S. , Nagamasu H. , Naiki A. , Dang V.S. , Nguyen V.N. , Wai J. V 4312 ( holotype VNM ![ VNM00042913 ]; isotypes FU !, VNM ! [ VNM00042914 , VNM00042915 ], the herbarium of Iriomote Station ( Japan )) . FIGURE 66. Lasianthus lamdongensis V.S.Dang, Naiki & Toyama (from V4312 , VNM): A. Branch with fruits, B. Close-up of expanding young leaves, C. Stipules, D. Abaxial leaf surfaces, E. Calyx, F–H. Fruits, I. Seeds ( A , D , F , H : photos by Shuichiro Tagane). FIGURE 67. Distribution maps of Lasianthus lamdongensis , L. lancifolius , L. larsenii , L. latifolius and L. lecomtei . Specimens examined: — VIETNAM . Central: Lam Dong Province , Bidoup Nui Ba National Park , 1698 m elev., 12°09’52.95’’N , 108°32’00.38’’E , in hill evergreen forests, 24 February 2016 , Tagane S. , Nagamasu H. , Naiki A. , Dang V.S. , Nguyen V.N. , Wai J. V 4312 ( FU , VNM , the herbarium of Iriomote Station ( Japan )) . Distribution: —Endemic to Vietnam (known only from the Bidoup Nui Ba National Park, Lam Dong Province ). Habitat & Ecology: —In hill evergreen forests at 1400–1700 m elev. Phenology: —Flowering and fruiting from February to July. Vernacular name: —Xú hưƠng lâm đồng. Notes: — Lasianthus lamdongensis is similar to L. capitatus Blume (1827: 996) in the shape of leaves, linear bracts, and relatively small flowers, but differs from the latter in having smaller leaves (7–9 × 1.5–2.5 cm vs. 10–15 × 3–3.5 cm ), more secondary veins (8–9 on each side of midrib vs. 7–8 on each side of midrib), shorter petioles ( 4–5 mm long vs. 5–8 mm long), smaller bracts ( 4–5 mm long vs. 5–10 mm long) and larger calyx tubes ( 2–3 mm long vs. 1–2 mm long). It is also similar to L. camlamensis V.S.Dang & Naiki which was described from Hon Ba Nature Reserve in Khanh Hoa Province , but differs from the latter in having smaller leaves (7–9 × 1.5–2.5 cm vs. 9–12 × 2–4 cm ), more secondary veins (8–9 on each side of midrib vs. 7–8 on each side of midrib), shorter petioles ( 4–5 mm long vs. 5–8 mm long), bracts 4–5 mm long (vs. inconspicuous), white (vs. orange) when ripe, and fruits with 6 (vs. 4) pyrenes.