Lasianthus vietnamensis V.S.Dang, Naiki & Tagane (2021: 50)

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

71. Lasianthus vietnamensis V.S.Dang, Naiki & Tagane (2021: 50) — Fig. 103 (plate), Fig. 104 (map)

Type: — VIETNAM. Kon Tum Province, Ngoc Linh Nature Reserve , 1365 m elev., 14 February 2017, Tagane S., Nagamasu H., Nguyen V.N., Hoang T.B., Hoang T.S., Yang C.J., Kawakubo A. V 6668 (holotype VNM! [ VNM00042945 ]; isotypes DLU!, FU!, the herbarium of Iriomote Station ( Japan)) .

Specimens examined: — VIETNAM. Central: Kon Tum Province, Ngoc Linh Nature Reserve , 1365 m elev., 15˚12’24.02”N, 107˚46’10.04’’E, 14 February 2017, Tagane S., Nagamasu H., Nguyen V.N., Hoang T.B., Hoang T.S., Yang C.J., Kawakubo A. V6668 ( DLU, FU, VNM, the herbarium of Iriomote Station ( Japan)); in the same location, 1070 m elev., 15˚10’05.07”N, 107˚45’23.06’’E, 12 February 2017, Tagane S., Nagamasu H., Nguyen V.N., Hoang T.B., Hoang T.S., Yang C.J., Kawakubo A. V 6422 ( DLU, FU, the herbarium of Iriomote Station ( Japan)) .

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

Habitat & Ecology: —In primary forests at 1000–1400 m elev.

Phenology: —Flowering and fruiting from February to June.

Vernacular name: —Xú hưƠng việt.

Notes: — Lasianthus vietnamensis is similar to L. caeruleus Pit. (1924: 390) which is endemic to Vietnam in the shape of leaves and inflorescence type, but differs from the latter in having larger leaves (8–14 × 1.5–3.5 cm vs. 4.5–7 × 0.8–1.5 cm), more secondary veins (5–7 on each side of midrib vs. 4–5 on each side of midrib), longer petioles (5–10 mm long vs. 4–5 mm long), bracts 0.7–1 mm long (vs. absent) and larger calyx (2.5–3 mm long vs. tube ca. 1 mm long for tubes, 0.5–1 mm long vs. 0.5 mm long for lobes), yellowish-white (vs. blue) when ripe, and fruits with 5 (vs. 4) pyrenes.

Figures

FIGURE 103. Lasianthus vietnamensis V.S.Dang, Naiki & Tagane (from V6668, VNM): A. Branch with flower buds, B. Close-up of expanding young leaves, C. Stipules, D.Abaxial leaf surfaces, E–G. Inflorescence showing side view calyxes, H. Fruits, I. Seeds (A, D–F, H: photos by Shuichiro Tagane).

FIGURE 104. Distribution maps of Lasianthus vietnamensis, L. viridiramulis, L. vuquangensis, L. yaharae and L. yersinii.