Lasianthus chrysoneurus (Korth.) Miq. (1857: 322)

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

14. Lasianthus chrysoneurus (Korth.) Miq. (1857: 322) — Fig. 33 (plate), Fig. 32 (map)

Type: — INDONESIA. Java, Jawa Barat, 1917, Backer 22515 (neotype L! [L0306249], designated by Zhu 2002) .

Mephitidia chrysoneura Korth. (1851: 222) . Type:— INDONESIA. Java, Jawa Barat, 1917, Backer 22515 (neotype L! [L0306249], designated by Zhu 2002).

Lasianthus kurzii Hook.f. (1880: 183) . Type :— MYANMAR. Chopedang, 1827, Wall. Cat. 8310 (holotype K! [K000031671].

Lasianthus hoaensis Pierre ex Pit. (1924: 383) . Type:— VIETNAM. Dong Nai Province, Bien Hoa, Pierre 1316 (syntype P!; isosyntypes BM!, E!, K!).

Lasianthus hoaensis var. microphyllus Pit. (1924: 383) . Type :— CAMBODIA. Mont. de l’Lephant, 6 August 1919, Poilane s.n. (lectotype P! [P02285244], designated by Napiroon et al. 2020).

Specimens examined: — VIETNAM. Central: Dak Nong Province, Gia Nghia District , 810 m elev., 9 May 2019, Dang V.S. & Hoang N.S., Dang 301 ( VNM) ; in the same location, Ta Dung National Park , 680 m elev., 11 June 2019, Dang V.S. & Hoang N.S., Dang 310 ( VNM) ; Gia Lai Province, Kon Ka Kinh National Park , 887 m elev., August 2019, Oguri E., Tagane S., Sugai K., Suyama Y. & Bui H.Q. V10916 & V10994 ( HN, KAG, MAK, VNM) . Southern: Dong Nai Province, Xuan Loc District, Nui Chua Chan , 20 August 1931, Poilane 19336 ( VNM) ; in the same location, 750 m elev., 24 August 1931, Poilane 18381 ( VNM) .

Distribution: —Widespread in tropical and subtropical regions in Asia ( Cambodia, China, India, Indonesia, Laos, Myanmar, Papua New Guinea, Thailand). In Vietnam, Lasianthus chrysoneurus occurs in Dak Nong, Dong Nai, Gia Lai, and Lam Dong.

Habitat & Ecology: —Growing in primary and secondary montane forests or open areas at 600–1000 m elev.

Phenology: —Flowering and fruiting from May to October.

Vernacular name: —Xú hưƠng biên hòa.

Notes: — Lasianthus chrysoneurus was clarified in the revisions by Zhu & Taylor (2011), Zhu et al. (2012), and Napiroon et al. (2020). This species is easily recognizable in the field in having appressed pubescent branches, stipules up to 8 mm long, bracts 5 mm long, and fruits subglobose, white when ripe.

Figures

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

FIGURE 33. Lasianthus chrysoneurus (Korth.) Miq. (A–F from Dang 301 and G from V10916, VNM and HN): A. Branch with flower buds, B. Close-up of young branch and leaves, C. Stipules, D. Abaxial leaf surfaces, E–F. Inflorescence showing side view flower buds and bracts, G. Young and mature fruits (G: photos by Shuichiro Tagane).