50. Lasianthus nghiasonii V.S.Dang & Naiki (2021: 34) — Fig. 77 (plate), Fig. 78 (map)

Type: — VIETNAM. Lam Dong Province, Bidoup Nui Ba National Park, 1464 m elev., 26 February 2016, Tagane S., Dang V.S., Nguyen V.N., Wai J. V 4450 (holotype VNM! [VNM00042919]; isotype FU!, VNM! [VNM00042920, VNM00042921], the herbarium of Iriomote Station (Japan)).

Specimens examined: — VIETNAM. Central: Lam Dong Province, Bidoup Nui Ba National Park, 1464 m elev., 12°10’17.02’’N, 108°41’50.01’’E, in lower montane evergreen forest, 26 February 2016, Tagane S., Dang V.S., Nguyen V.N., Wai J. V 4450 (FU, VNM, the herbarium of Iriomote Station (Japan)); in the same location, 1533 m elev., 12°10’34.07’’N, 108°41’08.04’’E, in lower montane evergreen forest, 21 February 2016, Tagane S., Nagamasu H., Naiki A., Dang V.S., Nguyen V.N., Hoang T.B., Wai J. V 3987 (FU, VNM, the herbarium of Iriomote Station (Japan)); in the same location, 1438 m elev., 12˚10’23.01”N, 108˚41’52.20’’E, 26 November 2017, in moist evergreen forest, Naiki A. & Dang V.S. 10101, 10102, 10103 (VNM, the herbarium of Iriomote Station (Japan)). Khanh Hoa Province, Hon Ba Nature Reserve, 1521 m elev., 12°07’01.82’’N, 108°56’43.63’’E, in evergreen forests, 25 November 2014, Toyama H., Tagane S., Dang V.S., Nagamasu H., Naiki A., Tran H., Yang C.J. with Hieu H.N.P. V2167 (FU, VNM, the herbarium of Iriomote Station (Japan)); in the same location, 1502 m elev., 12°07’08.12’’N, 108°56’30.03’’E, in evergreen forests, 15 June 2019, Dang V.S., Dang 348 (VNM).

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

Habitat & Ecology: —Moist evergreen forest at around 1400–1600 m elev.

Phenology: —Flowering and fruiting from February to November.

Vernacular name: —Xú hưƠng hoàng nghĩa sƠn.

Notes: — Lasianthus nghiasonii is similar to L. inodorus Blume (1826: 998) in the shape of leaves, number of secondary veins, and inflorescence type, but differs from the latter in having longer petioles (10–15 mm long vs. 6–10 mm long), bracts 1–2 mm long (vs. 3–6 mm long) and larger calyx tubes (3–4 mm long vs. 2 mm long) and fruit color when ripe.