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).