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 22. Lasianthus foetidissimus A.Chev. ex Pit. (1924: 395) — Fig. 43 (plate), Fig. 42 (map) Type: — VIETNAM . Khanh Hoa Province , Hon Ba Nature Reserve , 1200–1500 m elev., 3 April 1918 , A. Chevalier 38778 ( holotype P! [P03980391]; isotype P!) . Specimens examined: — VIETNAM . Central: Khanh Hoa Province , Hon Ba Nature Reserve , 1300 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. V1778 ( FU , VNM ); in the same location, 1000 m elev., 22 July 2018 , Dang V.S. & Hoang N.T.B.N. , Dang 190 ( VNM ); in the same location, 1502 m elev., 15 June 2019 , Dang V.S. & Hoang N.T.B.N. , Dang 343 ( VNM , the herbarium of Iriomote Station (Japan)); Lam Dong Province , Lac Duong District , 1500 m elev., 15 April 1997 , L. Averyanov , N. Q. Binh , P. K. Loc , VH3979 (P); in the same location, Bidoup Nui Ba National Park , 50 km northeast of Dalat City , 1490 m elev., 19 November 2014 , Toyama H. , Tagane S. , Dang V.S. , Nagamasu H. , Naiki A. , Tran H. , Yang C.J. V1956 ( FU , VNM , the herbarium of Iriomote Station (Japan)) . Distribution: —Endemic to Vietnam (currently known as Hon Ba Nature Reserve of Khanh Hoa Province and Bidoup Nui Ba National Park of Lam Dong Province ). Habitat & Ecology: —Growing in secondary and primary forests, on the edge of the forest, at 700–1500 m elev. Phenology: —Flowering and fruiting from June to December. Vernacular name: —Xú hưƠng hôi. Notes: — Lasianthus foetidissimus is similar to L. fasipanensis V.S. Dang & Naiki (2019: 34) which was discovered at Hoang Lien National Park of northern Vietnam by Dang & Naiki (2019) , based on its pedunculate congested cymes and flower color at anthesis, but differs in its acute or slightly rounded leaf base (vs. oblique to obtuse), longer petioles ( 9–12 mm long vs. 6–10 mm long), smaller calyx ( 1.25 mm long vs. 1.5–2 mm long for tubes and 0.25 mm long vs. 0.8–1 mm long lobes), yellow to yellowish orange fruits (vs. blue) and fruits with 5 pyrenes (vs. 4 pyrenes).