Lasianthus elevatineurus H.Zhu (2002: 395)

Dang, Van-Son & Naiki, Akiyo, 2023, A revision of the genus Lasianthus Jack (Rubiaceae) from Vietnam, Phytotaxa 581 (1), pp. 1921-1935 : 1921-1935

20. Lasianthus elevatineurus H.Zhu (2002: 395) — Fig. 40 (plate), Fig. 37 (map)

Type: — VIETNAM. Lam Dong Province, Lac Duong District , 2100–2200 m elev., 22 March 1997, Averyanov L., Nguyen Q.B., Phan K.L. VH 3045 (holotype AAU!) .

Specimens examined: — VIETNAM. Central: Dak Nong Province, Gia Nghia District, 810 m elev., 9 May 2019, Dang V.S. & Hoang N.S., Dang 307 ( VNM); in the same location, Ta Dung National Park , 680 m elev., 11 June 2019, Dang V.S. & Hoang N.S., Dang 309 ( VNM) .

Distribution: —Endemic to Vietnam (currently known as Gia Nghia District and Ta Nung National Park of Dak Nong Province, and Lac Duong District and Bidoup Nui Ba National Park of Lam Dong Province).

Habitat & Ecology: —Growing in primary and secondary montane forests, edge of evergreen forest with open shaded area, at 600–2200 m elev.

Phenology: —Flowering and fruiting from December to July of the next year.

Vernacular name: —Xú hưƠng gân lồi.

Notes: — Lasianthus elevatineurus was reported as new to Vietnam by Zhu (2002). This species is characterized by having an elliptic-lanceolate leaf blade, secondary veins 7–9 on each side of midrib, bracts linear, hirsute, calyx obconical, and fruits globose, white when ripe.

This species is morphologically similar to L. lucidus Blume (1826: 997) based on its shape of stipules and calyx but differs from the latter in having 7–9 (vs. 3–6) secondary veins on each side of midrib and white (vs. blue) fruits when ripe.

Figures

FIGURE 37. Distribution maps of Lasianthus dalatensis, L. dienkhanhensis, L. eberhartii and L. elevatineurus.

FIGURE 40. Lasianthus elevatineurus H.Zhu (from Dang 307, VNM): A. Habit, B. Branch with fruits, C. Stipules and young fruit, D. Abaxial leaf surfaces, E–F. Inflorescence showing side view calyx and young fruits, G–I. Young and mature fruits.