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 36. Lasianthus khanhhoaensis V.S.Dang & Naiki (2021: 18) — Fig. 60 (plate), Fig. 57 (map) Type: — VIETNAM . Khanh Hoa Province , Hon Ba Nature Reserve , 617 m elev., 22 November 2014 , Toyama H. , Tagane S. , Dang V.S. , Nagamasu H. , Naiki A. , Tran H. , Yang C.J. with Cuong N.Q. , Hieu H.N.P. V1967 ( holotype VNM ! [ VNM00042901 ]; isotypes FU !, VNM ! [ VNM00042902 , VNM00042903 ], the herbarium of Iriomote Station (Japan)) . Specimens examined: — VIETNAM . Central: Khanh Hoa Province , Hon Ba Nature Reserve , 617 m elevation, 12°06’39.77’’N , 108°58’59.23’’E ,in evergreen forests, 22 November 2014 , Toyama H. , Tagane S. , Dang V.S. , Nagamasu H. , Naiki A. , Tran H. , Yang C.J. with Cuong N.Q. , Hieu H.N.P. V1967 ( FU , VNM , the herbarium of Iriomote Station (Japan)); in the same location, 617 m elev., 12°06’39.07’’N , 108°58’59.23’’E , in evergreen forests, 21 February 2014 , Toyama H. , Dang V.S. , Tagane S. , Fuse K. , Yahara T. , Nagamasu H. , Tran H. with Ngoc N.V. , Cuong N.Q. , Thach N.D. , Hieu H.N.P. V 1187 ( FU , VNM , the herbarium of Iriomote Station ( Japan )) . Distribution: —Endemic to Vietnam (known only from the Hon Ba Nature Reserve, Khanh Hoa Province ). Habitat & Ecology: —In hill evergreen forest at 600–700 m elev. Phenology: —Flowering and fruiting from February to November. Vernacular name: —Xú hưƠng khánh hòa. Notes: — Lasianthus khanhhoaensis is similar to L. stephanocalycinus Naiki, Tagane & Yahara (2015: 173) which was recently discovered in Bokor National Park, Cambodia , in the shape of leaves, inflorescences, and fruit color, but differs from the latter in having larger leaves (12–14 × 2.5–3.5 cm vs. 8–9.5 × 3–3.5 cm ), shorter stipules ( 1–2 mm long vs. 2–3 mm long) and smaller calyx lobes ( 1.5–2.5 mm long vs. 2.5–3 mm long). It is also similar to L. bachmaensis V.S.Dang & Naiki which was described from Bach Ma National Park, Central Vietnam , but differs from the latter in having plants covered by densely villous (vs. sparsely pubescent or subglabrous), larger leaves (12–14 × 2.5–3.5 cm vs. 10–12 × 2–2.5 cm ) and smaller calyx tubes ( 1.5–2 mm long vs. 1–1.5 mm long).