Lasianthus sikkimensis Hook. f. 1880

63. Lasianthus sikkimensis Hook.f. (1880: 180) — Fig. 93 (plate), Fig. 94 (map) Type: — INDIA. Sikkim, Hooker & Thomson 11 (holotype K! [K000031598]; isotypes L! [L0000706, L0000705], LE! [LE00017554]). Lasianthus tsangii Merr. ex H.L.Li (1943: 457). Type:— CHINA. Kwangsi (Guangxi), W.T.Tsang 23940 (holotype IBSC!). Lasianthus baviensis (Drake) Pit. (1924: 380). Type:— VIETNAM. Ha Noi City, Ba Vi District, 1 July 1887, Balansa 2655 (holotype P! [P04009933]; isotype K! [K000777006]). Lasianthus langkokensis (Drake) Pit. (1924: 397). Type:— VIETNAM. Ha Noi City, Ba Vi District, 1 October 1887, Balansa 2654 (holotype P!). Specimens examined: — VIETNAM. Northern: Vinh Phuc Province, Tam Dao National Park, 1124 m elev., 13 November 2018, Dang V.S. & Naiki A., Dang 237 (VNM, the herbarium of Iriomote Station (Japan)); Ha Noi City, Ba Vi National Park, 1267 m elev., 17 November 2018, Dang V.S. & Naiki A., Dang 281 (VNM, the herbarium of Iriomote Station (Japan)). Distribution: —Widespread in the tropical and subtropical regions in Asia (Bangladesh, China, India, Malaysia, Philippines, Thailand). In Vietnam, Lasianthus sikkimensis occurs in Ha Noi, Hoa Binh, and Vinh Phuc. Habitat & Ecology: —Growing in the shade of evergreen forest or the hill of evergreen montane forest at 700– 1300 m elev. Phenology: —Flowering and fruiting from July to November. Vernacular name: —Xú hưƠng ba vì, Xú hưƠng lăng cốc. Notes: — Lasianthus sikkimensis was described in 1880 by Hooker. It was clarified in the revision by Zhu et al. (2012) and two Vietnamese species, L. langkokensis (Drake) Pit. (1924: 397) and L. baviensis (Drake) Pit. (1924: 380) were treated as the synonyms of L. sikkimensis. This species is easily identified in the field by having densely brown-tomentose on branches, leaf blade ellipticlanceolate or elliptic, 10–20 cm long, bracts linear to lanceolate, 0.5–2 cm long, brown-tomentose, and fruits ellipsoid, blue when ripe.Published as part of Dang, Van-Son & Naiki, Akiyo, 2023, A revision of the genus Lasianthus Jack (Rubiaceae) from Vietnam, pp. 1921-1935 in Phytotaxa 581 (1) on pages 1921-1935, DOI: 10.11646/phytotaxa.581.1.1, http://zenodo.org/record/757155