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 26. Lasianthus giganteus Naiki (2015: 165) — Fig. 48 (plate), Fig. 47 (map) Type: — CAMBODIA . Kampot Province , Bokor National Park , 960 m elev., 17 October 2012 , Tagane S. , Fuse K. , Choeun H.N. 4279 ( holotype KYO !; isotypes Cam!, K!) . Specimens examined: — VIETNAM . Central: Thua Thien Hue Province , Bach Ma National Park , 30 August 1941 , J. E. Vidal 1052A (P); in the same location, 1285 m elev., 25 May 2015 , Yahara T. , Tagane S. , Toyama H., Nguyen N. , Nguyen C. , Okabe N. V2722 & V2975 ( DLU , FU , KYO , the herbarium of Iriomote Station (Japan)); in the same location, 1193 m elev., 26 July 2019 , Dang V.S. & Naiki A. , Dang 408 ( VNM , the herbarium of Iriomote Station ( Japan )); Da Nang City , Ba Na Nui Chua Nature Reserve , 1489 m elev., 27 July 2019 , Dang V.S. & Naiki A. , Dang 422 ( VNM , the herbarium of Iriomote Station (Japan)); in the same location, 1489 m elev., February 2017 , Tagane S. , Nagamasu H. , Nguyen V.N. , Hoang T.B. , Hoang T.S. , Yang C.J. , Kawakubo A. V 6948 ( DLU , FU , the herbarium of Iriomote Station ( Japan )) . Distribution: —Indochina region ( Cambodia ). In Vietnam , Lasianthus giganteus occurs in Da Nang and Thua Thien Hue. Habitat & Ecology: —Growing under shade secondary forest or on the edge of submontane evergreen forests, at 1000–1500 m elev. Phenology: —Flowering and fruiting from May to November. Vernacular name: —Xú hưƠng đại. Notes: — Lasianthus giganteus was described as new for the flora of Cambodia based on the specimen Tagane et al. 4279 ( KYO , K) which was collected from Bokor National Park of Kampot Province . This species is easily identified in the field in having elliptic to lanceolate leaves, oblique leaf base, secondary veins 16–17 on each side of midrib, bracts 15–18 mm long, and bracteoles narrowly lanceolate to linear, 5–18 mm long, and fruits conical, blue when ripe .