A revision of the genus Lasianthus Jack (Rubiaceae) from Vietnam Dang, Van-Son Naiki, Akiyo Phytotaxa 2023 2023-01-26 581 1 1921 1935 3SCNS H. Zhu (2002: 397) H. Zhu 397 2002 [178,668,1418,1445] Magnoliopsida Rubiaceae Lasianthus Plantae Gentianales 95 Tracheophyta species longissimus   Type:—  VIETNAM. Ha Giang Province, Yen Minh District,  1100–1200 melev.,  3 March 1999,  Phan K.L., Pham H.H., Averyanov L.CBL2055( holotype AAU!).   Specimensexamined:—  VIETNAM. Central: Khanh Hoa Province, Hon Ba Nature Reserve, 30 kmwest of Nha Trang City,  1210 melev.,  21 April 2018,  Dang V.S.& Hoang N.T.B.N., Dang186( VNM).   Distribution:—Endemic to Vietnam(currently known as Hon Ba Nature Reserve of Khanh Hoa Provinceand Yen Minh District of Ha Giang Province).  Habitat & Ecology:—Growing under the canopy of evergreen forest at around 1000–1300 melev.  Phenology:—Flowering from March to July.  Vernacular name:—Xú hưƠng lá dài.  Notes:—  Lasianthus longissimuswas described as new from a Vietnamese specimen by Zhu (2002). This species is characterized by having lanceolate and apex long caudate leaves, secondary veins 5–6 on each side of midrib, calyx lobes 5, and subspathulate to obovate. This species is similar to  L. lancifoliusHook.f. (1880: 187)which was distributed in Bangladesh, Bhutan, China, India, Thailandto Vietnam, but differs in having fewer secondary veins (5–6 on each side of midrib vs. 9 on each side of midrib) and calyx lobes longer than the tube (vs. shorter). It is also similar to  L. japonicusMiq. (1867: 110)in the shape of leaf blades and axillary inflorescences but distinguished by its petioles 5–7 mmlong (vs. 8–10 mmlong), calyx lobes 5 (vs. 4), and calyx lobes longer than the tube (vs. shorter). 1999-03-03 AAU Phan K. L. & Pham H. H. & Averyanov L. Vietnam 1150 Yen Minh District 95 1 Ha Giang holotype 2018-04-21 VNM Dang V. S. & Hoang N. T. B. N. & Dang Vietnam 1210 Nha Trang City Hon Ba Nature Reserve 95 1 Khanh Hoa