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 16. Lasianthus dakgleiensis V.S.Dang, Naiki & Tagane (1921: 36) — Fig. 35 (plate), Fig. 32 (map) Type: — VIETNAM . Kon Tum Province , Ngoc Linh Nature Reserve , 1376 m elev., 13 February 2017 , Tagane S. , Nagamasu H. , Nguyen V.N. , Hoang T.B. , Hoang T.S. , Yang C.J. , Kawakubo A. V 6528 ( holotype VNM ! [ VNM00042884 ]; isotypes DLU !, FU !, the herbarium of Iriomote Station ( Japan )) . Specimens examined: — VIETNAM . Central : Kon Tum Province , Ngoc Linh Nature Reserve , 1376 m elev., 15˚10’07.04”N, 107˚45’43.04’’E, 13 February 2017 , Tagane S., Nagamasu H., Nguyen V.N. , Hoang T.B., Hoang T.S., Yang C.J., Kawakubo A. V6528 ( DLU , FU , VNM ); in the same location, 1141 m elev., 15˚32’32.04”N, 107˚43’54.09’’E, 10 February 2017 , Tagane S. , Nagamasu H. , Nguyen V.N. , Hoang T.B. , Hoang T.S. , Yang C.J. , Kawakubo A. V 6067 ( DLU , FU , the herbarium of Iriomote Station ( Japan )) . Distribution: —Endemic to Vietnam (known only from the Ngoc Linh Nature Reserve, Kon Tum Province ). Habitat & Ecology: —In the lower montane evergreen forest at 1000–1400 m elev. Phenology: —Flowering and fruiting from February to July. Vernacular name: —Xú hưƠng đắk glei. Notes: — Lasianthus dakgleiensis is similar to L. congesticymus H. Zhu (2000: 124) which is distributed in Thailand and Malaysia , but differs from the latter in having smaller leaves (7–11 × 2–3.5 cm vs. 12–19 × 3.5–6.5 cm ), fewer secondary veins (4–5 on each side of midrib vs. 6–7 on each side of midrib), shorter petioles ( 4–5 mm long vs. 8–10 mm long), bracts 1 mm long (vs. absent), larger calyx lobes ( 2.5–3 mm long vs. 1 mm long) and fruits with 5 (vs. 4) pyrenes.