Lasianthus stephanocalycinus Naiki, Tagane & Yahara (2015: 173)

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

65. Lasianthus stephanocalycinus Naiki, Tagane & Yahara (2015: 173) — Fig. 96 (plate), Fig. 94 (map) Type: — CAMBODIA. Kampot Province, Bokor National Park , 903 m elev., 13 May 2012, Toyama H., Tagane S., Mishima T., Tagawa K.,

Zhang M., Chhang P., Iwanaga F., Nagamasu H. & Yahara T. 3100 ( holotype KYO!; isotypes Cam!, K!, P!) .

Specimens examined: — VIETNAM. Central: Khanh Hoa Province, Hon Ba Nature Reserve , 400 m elev., 12 July 2014, Tagane S., Kanemitsu H., Dang V.S., Tran H. with Loi X.N., Thach N.D., Hieu P.N.H. V1618 ( FU, VNM); in the same location, 919 m elev., 13 July 2014, Tagane S., Kanemitsu H., Dang V.S., Tran H. with Ngoc N.V., Cuong N.Q., Thi D.N., Hieu P.N.H. V 1711 ( FU, VNM); in the same location, 907 m elev., 28 November 2017, Dang V.S. & Naiki A .

N10123 ( VNM, the herbarium of Iriomote Station ( Japan)); in the same location, 920 m elev., 27 July 2018, Dang V.S. & Hoang N.T.B.N., Dang 196 ( VNM) .

Distribution: —Indochina region ( Cambodia). In Vietnam, Lasianthus stephanocalycinus occurs in Khanh Hoa and Kien Giang.

Habitat & Ecology: —Growing in the shade of primary forest or along the stream of the evergreen montane forest at 300–1000 m elev.The forest habitats are dominated by species of Fagaceae , Rubiaceae , Apocynaceae , Euphorbiaceae , Fabaceae , Symplocaceae , Clusiaceae , Myrtaceae , Acanthaceae , Celastraceae , Moraceae , Phyllanthaceae and Polygonaceae .

Phenology: —Flowering and fruiting from May to November.

Vernacular name: —Xú hưƠng mịn, Xú hưƠng đài vòng.

Notes: — Lasianthus stephanocalycinus was described as new based on the specimens which were collected from Bokor National Park of Cambodia and Hon Ba Nature Reserve of Vietnam by Naiki et al. (2015). This species can easily be recognized in the field in having elliptic leaves, secondary veins 4–9 on each side of midrib, flowers congested, white, and fruits globose, crowned by calyx lobes, and orange when ripe.

Figures

FIGURE 94. Distribution maps of Lasianthus sikkimensis, L. sonlangensis, L. stephanocalycinus and L. tamdaoensis.

FIGURE 96. Lasianthus stephanocalycinus Naiki, Tagane & Yahara (A–D & G–H from N10123 and E–F from Dang 196, VNM and the herbarium of Iriomote Station (Japan)): A. Branch with fruits, B. Close-up of expanding young leaves, C. Stipules, D. Abaxial leaf surfaces, E–F. Inflorescence showing side view calyx and flower buds, G–H. Young fruits.