Lasianthus lamdongensis V.S.Dang, Naiki

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

41. Lasianthus lamdongensis V.S.Dang, Naiki & Toyama (2021: 48)— Fig. 66 (plate), Fig. 67 (map)

Type: — VIETNAM. Lam Dong Province, Bidoup Nui Ba National Park , 1698 m elev., 24 February 2016, Tagane S., Nagamasu H., Naiki A., Dang V.S., Nguyen V.N., Wai J. V 4312 (holotype VNM![ VNM00042913 ]; isotypes FU!, VNM! [ VNM00042914 , VNM00042915 ], the herbarium of Iriomote Station ( Japan)) .

Specimens examined: — VIETNAM. Central: Lam Dong Province, Bidoup Nui Ba National Park , 1698 m elev., 12°09’52.95’’N, 108°32’00.38’’E, in hill evergreen forests, 24 February 2016, Tagane S., Nagamasu H., Naiki A., Dang V.S., Nguyen V.N., Wai J. V 4312 ( FU, VNM, the herbarium of Iriomote Station ( Japan)) .

Distribution: —Endemic to Vietnam (known only from the Bidoup Nui Ba National Park, Lam Dong Province).

Habitat & Ecology: —In hill evergreen forests at 1400–1700 m elev.

Phenology: —Flowering and fruiting from February to July.

Vernacular name: —Xú hưƠng lâm đồng.

Notes: — Lasianthus lamdongensis is similar to L. capitatus Blume (1827: 996) in the shape of leaves, linear bracts, and relatively small flowers, but differs from the latter in having smaller leaves (7–9 × 1.5–2.5 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 (4–5 mm long vs. 5–8 mm long), smaller bracts (4–5 mm long vs. 5–10 mm long) and larger calyx tubes (2–3 mm long vs. 1–2 mm long).

It is also similar to L. camlamensis V.S.Dang & Naiki which was described from Hon Ba Nature Reserve in Khanh Hoa Province, but differs from the latter in having smaller leaves (7–9 × 1.5–2.5 cm vs. 9–12 × 2–4 cm), more secondary veins (8–9 on each side of midrib vs. 7–8 on each side of midrib), shorter petioles (4–5 mm long vs. 5–8 mm long), bracts 4–5 mm long (vs. inconspicuous), white (vs. orange) when ripe, and fruits with 6 (vs. 4) pyrenes.

Figures

FIGURE 66. Lasianthus lamdongensis V.S.Dang, Naiki & Toyama (from V4312, VNM): A. Branch with fruits, B. Close-up of expanding young leaves, C. Stipules, D. Abaxial leaf surfaces, E. Calyx, F–H. Fruits, I. Seeds (A, D, F, H: photos by Shuichiro Tagane).

FIGURE 67. Distribution maps of Lasianthus lamdongensis, L. lancifolius, L. larsenii, L. latifolius and L. lecomtei.