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 58. Lasianthus rhinocerotis Blume (1826: 996) subsp. pedunculatus (Pit.) H.Zhu (1998: 154) — Fig. 87 (plate), Fig. 84 (map) Type: — VIETNAM . Lang Son Province , Cao Loc District , Dong Dang Commune , 10 February 1886 , Balansa 638 ( holotype P! [P02285237]; isotype L!, P!) . Lasianthus koi Merr. & Chun (1934: 47) . Type:— CHINA . Hainan , 29 April 1932 , S.P. Ko 52243 ( holotype IBSC !; isotype K!, US !) . Lasianthus rhinocerotis var. pedunculatus Pit. (1924: 395) . Type :— VIETNAM . Lang Son Province , Cao Loc District , Dong Dang Commune , 10 February 1886 , Balansa 638 ( holotype P! [P02285237]; isotype L!, P!). Specimens examined: — VIETNAM . Central: Ha Tinh Province , Vu Quang National Park , 860 m elev., 26 July 2015 , Yahara T. , Toyama H. , Tagane S. , Nguyen N. , Yang C.J. , Nguyen H. V 3755 & V3805 ( DLU , FU , VNM , the herbarium of Iriomote Station ( Japan )); in the same location, 546 m elev., Yahara T. , Toyama H. , Tagane S. , Nguyen N. , Yang C.J. , Nguyen H. V 3585 ( DLU , FU , the herbarium of Iriomote Station ( Japan )) . Distribution: —Tropical and subtropical regions in Asia ( China ). In Vietnam , Lasianthus rhinocerotis subsp. pedunculatus occurs in Ha Tinh and Lang Son . Habitat & Ecology: —Growing in a hill of the evergreen montane forest at 500–900 m elev. The forest habitats are dominated by species of Fabaceae , Symplocaceae , Euphorbiaceae , Fagaceae , Rubiaceae , Annonaceae , Apocynaceae , Clusiaceae , and Anacardiaceae . Phenology: —Flowering and fruiting from February to July. Vernacular name: —Xú hưƠng có cọng. Notes: — Lasianthus rhinocerotis var. pedunculatus was reported as subspecies of Vietnam by Zhu (1998). This subspecies is easily identified in the field in having oblong-lanceolate or lanceolate leaves, secondary veins 9–10 on each side of midrib, peduncles 2–4 mm long, densely villous, and fruits subglobose or obovate, blue when ripe.