Lasianthus ngoclinhensis V.S.Dang, Naiki & Yahara (2021: 22)

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

51. Lasianthus ngoclinhensis V.S.Dang, Naiki & Yahara (2021: 22) — Fig. 79 (plate), Fig. 78 (map)

Type: — VIETNAM. Kon Tum Province, Ngoc Linh Nature Reserve , 1067 m elev., 11 February 2017, Tagane S., Nagamasu H., Nguyen V.N., Hoang T.B., Hoang T.S., Yang C.J., Kawakubo A. V 6124 (holotype VNM! [ VNM00042922 ]; isotypes DLU!, FU!, the herbarium of Iriomote Station ( Japan)) .

Specimens examined: — VIETNAM. Central: Kon Tum Province, Ngoc Linh Nature Reserve , 1067 m elev., 15˚10’05.07”N, 107˚45’23.06’’E, 11 February 2017, Tagane S., Nagamasu H., Nguyen V.N., Hoang T.B., Hoang T.S., Yang C.J., Kawakubo A. V 6124 ( DLU, FU, VNM, the herbarium of Iriomote Station ( Japan)) .

Distribution: —Endemic to Vietnam (known only from the Ngoc Linh Nature Reserve, Kon Tum Province).

Habitat & Ecology: —Moist evergreen forest, in shaded places at 1000–1300 m elev.

Phenology: —Flowering and fruiting from April to July.

Vernacular name: —Xú hưƠng ngọc linh.

Notes: — Lasianthus ngoclinhensis is similar to L. chevalieri Pit. (1924: 384) in the shape of leaves, inflorescence type, and orange fruits, but differs from the latter in having smaller leaves (7–10 × 2–3 cm vs. 11–16 × 3.5–5.5 cm), fewer secondary veins (8–9 on each side of midrib vs. 11 on each side of midrib), longer petioles (3–5 mm long vs. 1–1.5 mm long) and smaller calyx (1–2 mm long vs. 3–6 mm long for tubes, 3–4 mm long vs. 9–14 mm long for lobes).

It is also related to L. capitatus Blume (1827: 996) which is distributed in Malaysia and Indonesia, but differs from the latter by having smaller leaves (7–10 × 2–3 cm vs. 10–15 × 3–3.5 cm), more secondary veins (8–9 on each side of midrib vs. 7–8 on each side of midrib), shorter petioles (3–5 mm long vs. 5–8 mm long), calyx lobes 5 (vs. 6) and fruits with 5 (vs. 6) pyrenes.

Figures

FIGURE 78. Distribution maps of Lasianthus nghiasonii, L. nhatrangensis, L. ngoclinhensis, L. nuichuaensis and L. oblongilobus.

FIGURE 79. Lasianthus ngoclinhensis V.S.Dang, Naiki & Yahara (from V6124, VNM): A. Branch with fruit, B. Close-up of expanding young leaves, C. Stipules, D. Abaxial leaf surfaces, E. Calyx, F–H. Fruits, I. Seeds (A, G–H: photos by Shuichiro Tagane).