Lasianthus thuyanae V.S. Dang & Naiki (2020: 49)

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

68. Lasianthus thuyanae V.S. Dang & Naiki (2020: 49) — Fig. 100 (plate), Fig. 99 (map)

Type: — VIETNAM. Ha Noi City, Ba Vi National Park , 50 km west of Ha Noi city center, 1267 m elev., 17 November 2018, Dang V.S. & Naiki A., Dang 277 (holotype VNM! [ VNM00042943 ]; isotypes HN!, KYO!, VNM! [ VNM00042944 ], VNMN!) .

Specimens examined: — VIETNAM. Northern: Ha Noi City, Ba Vi National Park, 1267 m elev., 17 November 2018, in evergreen forest, Dang V.S. & Naiki A., Dang 277a ( VNM, the herbarium of Iriomote Station (Japan )) .

Distribution: —Endemic to Vietnam (currently known only from Ba Vi National Park of Ha Noi City).

Habitat & Ecology: —Growing under the canopy of the evergreen forest at 1000–1250 m elev. The forest habitats where collected Lasianthus thuyanae dominated by species of Lauraceae , Fagaceae , Fabaceae , and Rubiaceae .

Phenology: —Flowering and fruiting from July to December.

Vernacular name: —Xú hưƠng thúy an. Notes: — Lasianthus thuyanae was described as new from a Vietnamese specimen (Dang 277) by Dang & Naiki (2020). It is characterized by having densely brown tomentose on branches, secondary veins 5–6 on each side of midrib, flowers sessile, calyx dark purple and corolla white, and fruits ovoid or globose, blue when ripe.

This species is similar to L. curtisii King & Gamble (1904: 128) in the shape of the leaves, the number of secondary veins, and fruit color, but differs from the latter in having brown tomentose hairs on branches and petioles (vs. villose), stipules 1.7–2 mm long (vs. 1–1.5 mm long), corolla tubes 11–15 mm long (vs. 7–8 mm long), and calyx dark purple (vs. greenish white).

Figures

FIGURE 99. Distribution maps of Lasianthus thuathienhuensis, L. thuyanae, L. trichophlebus and L. verticillatus.

FIGURE 100. Lasianthus thuyanae V.S.Dang & Naiki (from Dang 277, VNM and the herbarium of Iriomote Station (Japan)): A. Branch, B. Close-up of expanding young leaves, C. Stipules, D. Abaxial leaf surfaces, E–H. Inflorescence showing lateral view buds flowers, I. Young fruit, J. Mature fruit, K. Seeds.