Lasianthus phamhoangii V.S.Dang & Naiki (2021: 28)

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

55. Lasianthus phamhoangii V.S.Dang & Naiki (2021: 28) — Fig. 83 (plate), Fig. 84 (map)

Type: — VIETNAM. Khanh Hoa Province, Hon Ba Nature Reserve, 617 m elev., 22 November 2014, Toyama H., Tagane S., Dang V.S., Nagamasu H., Naiki A., Tran H., Yang C.J. with Hieu H.N.P. V1962 (holotype VNM! [ VNM00042929 ]; isotypes FU!, VNM! [ VNM00042930 , VNM00042931 ], the herbarium of Iriomote Station (Japan)) .

Specimens examined: — VIETNAM. Central: Khanh Hoa Province, Hon Ba Nature Reserve, 617 m elev., 12°06’39.77’’N, 108°58’59.23’’E, in evergreen forests, 22 November 2014, Toyama H., Tagane S., Dang V.S., Nagamasu H., Naiki A., Tran H., Yang C.J. with Hieu H.N.P. V1962 ( FU, VNM, the herbarium of Iriomote Station (Japan)); in the same location, 919 m elev., 12°06’46.88’’N, 108°58’14.43’’E, in evergreen forests, 21 February 2014, Toyama H., Dang V.S., Tagane S., Fuse K., Yahara T., Nagamasu H., Tran H. with Ngoc N.V., Cuong N.Q., Thach N.D., Hieu H.N.P. V 846 ( FU, VNM, the herbarium of Iriomote Station (Japan )) .

Distribution: —Endemic to Vietnam (known only from the Hon Ba Nature Reserve, Khanh Hoa Province).

Habitat & Ecology: —Primary or secondary forests at elevations between 600–1000 m.

Phenology: —Flowering and fruiting from April to September.

Vernacular name: —Xú hưƠng phạm hoàng hộ.

Notes: — Lasianthus phamhoangii is similar to L. hirsutus (Roxb.) Merr. (1924: 382) in having rusty hirsute on branches and branchlets, the shape of leaves, inflorescences and fruit color but distinguished by its secondary veins (12–16 on each side of midrib vs. 7–10 on each side of midrib), shorter stipules (6–7.5 mm long vs. 8–10 mm long), calyx and corolla lobes 4 (vs. 5), larger calyx (2.5–3.5 mm long vs. 1 mm long for tubes and 1.5–2 mm long vs. 2.5 mm long for lobes) and corolla (12–15 mm long vs. 10–12 mm long for tubes and 3–5 mm long vs. 3 mm long for lobes) and fruits with 4 (vs. 5) pyrenes.

Figures

FIGURE 83. Lasianthus phamhoangii V.S.Dang & Naiki (from V1962, VNM): A. Branch with flowers, B. Stipules, C. Abaxial leaf surfaces, D–F. Inflorescence showing side view flowers, G–H. Fruits, I. Seeds.

FIGURE 84. Distribution maps of Lasianthus phamhoangii, L. pierrei, L. repoeuensis and L. rhinocerotis subsp. pedunculatus.