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 54. Lasianthus oblongilobus H.Zhu (2002: 400) — Fig. 82 (plate), Fig. 78 (map) Type: — VIETNAM . Khanh Hoa Province , Khanh Son District , 1500–1600 m elev., 22 April 1997 , Averyanov L. , Nguyen Q.B. , Nguyen T.H. VH 4153 ( holotype AAU !) . Specimens examined: — VIETNAM . Central: Lam Dong Province , Bidoup National Park , 1655 m elev., 19 November 2014 , Toyama H. , Tagane S. , Dang V.S. , Nagamasu H. , Naiki A. , Tran H. , Yang C.J. V1923 ( FU , VNM ) ; in the same location, 1658 m elev., 26 November 2017 , Dang V.S. & Naiki A. N10109 ( VNM , the herbarium of Iriomote Station ( Japan )) ; Khanh Hoa Province , Hon Ba Nature Reserve , 30 km west of Nha Trang City , 1518 m elev., 24 July 2018 , Dang V.S. & Hoang N.T.B.N. , Dang 194 ( VNM ) . Distribution: —Endemic to Vietnam (currently known as Khanh Son District and Hon Ba Nature Reserve of Khanh Hoa Province and Biduoup Nui Ba National Park of Lam Dong Province ). Habitat & Ecology: —Growing under the canopy of an evergreen forest or the edge of a montane forest at 1200– 1700 m elev. Phenology: —Flowering and fruiting from July to December. Vernacular name: —Xú hưƠng đài thuôn. Notes: — Lasianthus oblongilobus was described as new from a Vietnamese specimen by Zhu (2002). This is characterized by having elliptic-lanceolate leaves, secondary veins 5–6 on each side of midrib, calyx lobes oblong and 1.5–2 mm long. Additional fruit morphology for L. oblongilobus : fruits globose, 4–5 mm diam., smooth, glabrous, crowned by calyx lobes, yellowish-orange when ripe; pyrenes 4. Seed ovoid, 2–3 mm long, irregular sulcate on the abaxial face, blackish brown when dry.