59. Lasianthus sapaensis V.S. Dang & Naiki (2019: 39) — Fig. 88 (plate), Fig. 89 (map) Type: — VIETNAM. Lao Cai Province, Sa Pa District, Hoang Lien National Park, on the way to Fansipan peak from Ton station, 1906 m elev., 11 November 2018, Dang V.S. & Naiki A., Dang 230 (holotype VNM! [VNM00042932]; isotypes HN!, VNM! [VNM00042933, VNM00042934], the herbarium of Iriomote Station, (Japan)). Specimens examined: — VIETNAM. Northern: Lao Cai Province, Hoang Lien National Park, 1906 m elev., 11 November 2018, Dang V.S & Naiki A., Dang 230a (VNM, the herbarium of Iriomote Station (Japan)). Distribution: —Endemic to Vietnam (currently known only from Hoang Lien National Park of Lao Cai Province). Habitat & Ecology: —Growing along roadside, streams, and edges of the secondary forest at an elevation around 1900–2100 m. Phenology: —Flowering and fruiting from August to November. Vernacular name: —Xú hưƠng sapa. Notes: — Lasianthus sapaensis was described from a Vietnamese specimen (Dang 230) by Dang & Naiki (2019). It can easily be recognized from other species of Lasianthus in having densely appressed pubescent to sericious on branches, ovate or ovate-oblong to oblong-lanceolate leaves, secondary veins 6–7 on each side of midrib, peduncles 3–7 mm long, flower white, and fruits globose, ovoid-globose to depressed globose, blue when ripe. Lasianthus sapaensis is similar to L. micranthus Hook.f. (1880: 190) but differs from the latter in having densely appressed pubescent to sericious on branches (vs. sparsely puberulent to glabrous), petioles 4–7 mm long (vs. 4–9 mm long), calyx tube 2–3 mm long (vs. 1 mm long) and calyx lobes 1.5–2 mm long (vs. 1–1.5 mm long), corolla tube 7–8 mm long (vs. 3–6 mm long) and corolla lobes 3–4 mm long (vs. 2–2.5 mm long). It is also similar to L. biermannii subsp. crassipedunculatus C.Y.Wu & H.Zhu (1994: 75) which is endemic to China, but differs from the latter in having shorter stipules (1.5–2 mm vs. 3–5 mm long), peduncles 3–7 mm long (vs. 10–20 mm long), bracts inconspicuous (vs. 6–10 mm long) and smaller calyx lobes (1.5–2 mm long vs. 5 mm long).

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/7571550