Lasianthus yaharae V.S.Dang, Tagane & H.Tran (2015: 352)

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

74. Lasianthus yaharae V.S.Dang, Tagane & H.Tran (2015: 352) — Fig. 107 (plate), Fig. 104 (map)

Type: — VIETNAM. Khanh Hoa Province, Hon Ba Nature Reserve, 1521 m elev., 18 July 2014, Tagane S., Kanemitsu H., Son V.D., Tran H. with Loi X.N., Thach N.D., Dinh N. & Hieu P.N.H. V1741 (holotype VNM! [ VNM00042947 ]; isotypes FU!, KYO!, VNM! [ VNM00042948 , VNM00042949 ], Station of Hon Ba Nature Reserve ) .

Specimens examined: — VIETNAM. Central: Khanh Hoa Province, Hon Ba Nature Reserve, 30 km west of Nha Trang City, 1521 m elev., 2 November 2012, Son V.D., Tagane S., Toyama H., Fuse K., Nagamasu H., Hop T., Lam T.T. & Yahara T. VHB44 ( VNM); in the same location, 1524 m elev., 28 November 2017, Dang V.S. & Naiki A. N10114 ( VNM, the herbarium of Iriomote Station (Japan)); in the same location, 1520 m elev., 26 July 2018, Dang V.S. & Hoang N.T.B.N., Dang 198 ( VNM, the herbarium of Iriomote Station (Japan)) .

Distribution: —Endemic to Vietnam (currently known as Hon Ba Nature Reserve of Khanh Hoa Province and Bidoup Nui Ba National Park of Lam Dong Province).

Habitat & Ecology: —Growing in moist evergreen forest, dominated by members of the Fagaceae family at 1400–1600 m elev.

Phenology: —Flowering and fruiting from May to January of the next year.

Vernacular name: —Xú hưƠng yahara.

Notes: — Lasianthus yaharae was described as new from a Vietnamese specimen (V1741) by Dang et al. (2015). This species morphologically resembles L. dalatensis Wernham (1921: 138) which is endemic to Vietnam, but differs from the latter in having secondary veins 4–5 on each side of midrib (vs. 7–9 on each side of midrib), flowers pinkish at anthesis (vs. white), and calyx 2–3 mm long (vs. 1 mm long), corolla tube 5–10 mm long (vs. 4 mm long) and corolla lobes 2–4 mm long (vs. 1.5 mm long).

Figures

FIGURE 104. Distribution maps of Lasianthus vietnamensis, L. viridiramulis, L. vuquangensis, L. yaharae and L. yersinii.

FIGURE 107. Lasianthus yaharae V.S.Dang, Tagane & H.Tran (A–I from Dang 198 & J from V1741, 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–G. Inflorescence showing lateral view buds and flowers, H–I. Young fruits, J. Mature fruits.