Lasianthus dakgleiensis V.S.Dang, Naiki & Tagane (1921: 36)

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

16. Lasianthus dakgleiensis V.S.Dang, Naiki & Tagane (1921: 36) — Fig. 35 (plate), Fig. 32 (map)

Type: — VIETNAM. Kon Tum Province, Ngoc Linh Nature Reserve , 1376 m elev., 13 February 2017, Tagane S., Nagamasu H., Nguyen V.N., Hoang T.B., Hoang T.S., Yang C.J., Kawakubo A. V 6528 (holotype VNM! [ VNM00042884 ]; isotypes DLU!, FU!, the herbarium of Iriomote Station ( Japan)) .

Specimens examined: — VIETNAM. Central : Kon Tum Province, Ngoc Linh Nature Reserve, 1376 m elev., 15˚10’07.04”N, 107˚45’43.04’’E, 13 February 2017, Tagane S., Nagamasu H., Nguyen V.N., Hoang T.B., Hoang T.S., Yang C.J., Kawakubo A. V6528 ( DLU, FU, VNM); in the same location, 1141 m elev., 15˚32’32.04”N, 107˚43’54.09’’E, 10 February 2017, Tagane S., Nagamasu H., Nguyen V.N., Hoang T.B., Hoang T.S., Yang C.J., Kawakubo A. V 6067 ( 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 the lower montane evergreen forest at 1000–1400 m elev.

Phenology: —Flowering and fruiting from February to July.

Vernacular name: —Xú hưƠng đắk glei.

Notes: — Lasianthus dakgleiensis is similar to L. congesticymus H. Zhu (2000: 124) which is distributed in Thailand and Malaysia, but differs from the latter in having smaller leaves (7–11 × 2–3.5 cm vs. 12–19 × 3.5–6.5 cm), fewer secondary veins (4–5 on each side of midrib vs. 6–7 on each side of midrib), shorter petioles (4–5 mm long vs. 8–10 mm long), bracts 1 mm long (vs. absent), larger calyx lobes (2.5–3 mm long vs. 1 mm long) and fruits with 5 (vs. 4) pyrenes.

Figures

FIGURE 32. Distribution maps of Lasianthus chinensis, L. chrysoneurus, L. curtisii and L. dakglaiensis.

FIGURE 35. Lasianthus dakglaiensis V.S.Dang, Naiki & Tagane (from V6528, VNM): A. Branch with fruits, B. Close-up of young branch and leaves, C. Stipules, D.Abaxial leaf surfaces, E–G. Inflorescence showing side view calyxes and flowers, H–I. Fruits, J. Seeds (A, D, E–I: photos by Shuichiro Tagane).