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 10. Lasianthus capitatus Blume (1826: 996) subsp. vietnamensis H. Zhu (2000: 397) — Fig. 27 (plate), Fig. 25 (map) Type : — VIETNAM . Kon Tum Province , Ngoc Linh Nature Reserve , 1700–1800 m elev., 4 April 1995 , Averyanov L. , Nguyen T.B ., Nguyen Q.B., Budantzev A., Budantzev L., Nguyen T.H., Duong D.H., Phan K.L., Nguyen X.T., Yakovlev G. VH1129 ( holotype AAU !; isotype HN!). Specimens examined: — VIETNAM . Central: Kon Tum Province , Ngoc Linh Nature Reserve , 1365 m elev., 14 February 2017 , Tagane S. , Nagamasu H. , Nguyen V.N. , Hoang T.B. , Hoang T.S. , Yang C.J. , Kawakubo A. V 6638 ( DLU , FU , VNM , the herbarium of Iriomote Station ( Japan )); in the same location, 1700–1800 m elev., 4 April 1995 , Averyanov L. , Nguyen T.B. , Nguyen Q.B. , Budantzev A. , Budantzev L. , Duong D.H. , Phan K.L. , Nguyen X.T. , Yakovlev G. VH772 ( AAU , HN ) . Distribution: —Endemic to Vietnam (currently known only from Ngoc Linh Nature Reserve in Kon Tum Province ). Habitat & Ecology: — Growing in the evergreen dry primary forest on the northwest slope of Ngoc Linh mountain system in Kon Tum Province at 1200–1800 m elev . Phenology: —Flowering and fruiting from November to June of the next year. Vernacular name: —Xú hưƠng hoa hỢp. Notes: — Lasianthus capitatus subsp. vietnamensis was first reported as new for the flora of Vietnam by Zhu (2000) . It can easily be identified in the field in having ovate to ovate-lanceolate leaves, peduncles 1–3.5 cm long, flowers white, and fruits ellipsoid, blue when ripe. This subspecies is different from other subspecies of Lasianthus capitatus by having ovate to ovate-lanceolate with apex caudate, petioles 3–5 mm long, midrib and secondary veins inconspicuous, and the histute corolla.