Morphological and molecular evidence reveals three new species of Lithocarpus (Fagaceae) from Bidoup-Nui Ba National Park, Vietnam Author Ngoc, Nguyen Van https://orcid.org/0000-0002-1518-9470 Faculty of Biology, Dalat University, 01 - Phu Dong Thien Vuong, Dalat, Vietnam mr.ngocnv@gmail.com Author Binh, Hoang Thi https://orcid.org/0000-0002-0829-2955 Faculty of Biology, Dalat University, 01 - Phu Dong Thien Vuong, Dalat, Vietnam Author Nagahama, Ai Faculty of Science, Kyushu University, 744 Motooka, Fukuoka, 819 - 0395, Japan Author Tagane, Shuichiro The Kagoshima University Museum, Kagoshima University, 1 - 21 - 30 Korimoto, Kagoshima, 890 - 0065, Japan Author Toyama, Hironori Biodiversity Division, National Institute for Environmental Studies, Tsukuba, Ibaraki, 305 - 8506, Japan Author Matsuo, Ayumi Kawatabi Field Science Center, Graduate School of Agricultural Science, Tohoku University, 232 - 3 Yomogida, Naruko-onsen, Osaki, Miyagi 989 - 6711, Japan Author Suyama, Yoshihisa Kawatabi Field Science Center, Graduate School of Agricultural Science, Tohoku University, 232 - 3 Yomogida, Naruko-onsen, Osaki, Miyagi 989 - 6711, Japan Author Yahara, Tetsukazu https://orcid.org/0000-0001-5105-7152 Faculty of Science, Kyushu University, 744 Motooka, Fukuoka, 819 - 0395, Japan & Kyushu Open University, 744 Motooka, Fukuoka, 819 - 0395, Japan text PhytoKeys 2021 2021-12-06 186 73 92 http://dx.doi.org/10.3897/phytokeys.186.69878 journal article http://dx.doi.org/10.3897/phytokeys.186.69878 1314-2003-186-73 A4FD5ADA118558C9BEEDEF285BD8B25B Lithocarpus bidoupensis Ngoc & Tagane sp. nov. Fig. 3 Type . Vietnam . Lam Dong Province : Bidoup-Nui Ba National Park , in hill evergreen forest dominated by the species of Fagaceae , 1698 m elev., 12°09'52.95"N , 108°32'00.38"E , 24 February 2016 , S. Tagane , H. Toyama , H. Nagamasu , A. Naiki , V.S. Dang , N.V. Ngoc , J. Wai V4320 [fr.] ( holotype DLU!, isotypes FU!, HN!, KYO!, VNM!) . Diagnosis. Lithocarpus bidoupensis is most similar to L. blaoensis but differs in its shorter leaf blades, petioles and infructescences, and bigger cupules and nuts. The new species is also similar to L. licentii but distinguished from L. licentii by its shorter petioles, fewer secondary veins (10-12 pairs in L. bidoupensis vs. 12-15 pairs in L. licentii ), much shorter infructescences, clustered cupules (vs. solitary), cupule covering less than 1/3 of the nut (vs. 1/2-2/3 of the nut), and concave basal scar of the nut (vs. convex) (Table 2 ). Figure 3. Lithocarpus bidoupensis Ngoc & Tagane A leafy twig B abaxial leaf surface C holotype ( Tagane et al. V4320 , DLU) D mature fruit E cupule F mature nut G section of mature nut. Description. Evergreen tree, up to 27 m tall. Branches yellowish green when young, turning greyish brown when old, glabrous, sparsely lenticellate. Terminal and lateral buds ovoid, up to 7 mm long. Leaves alternate; petiole 0.3-0.4 cm long, glabrous; blade elliptic to oblong-elliptic, obovate-elliptic, 6-11.6 x 2.8-5.3 cm, coriaceous, glabrous, glossy green on both surfaces, apex acuminate or attenuate, acumen up to 0.9 cm long, base cuneate, rarely obtuse, margin completely entire, midrib prominent on both surfaces, secondary veins 10-12 pairs, prominent abaxially, at an angle of 55-70° from the midrib, tertiary veins scalariform-reticulate, visible abaxially. Inflorescences not seen. Infructescences a woody spike, 8.4-11.5 cm long. Cupules sessile, usually in cluster of 3, fused at the base each other, depressed obconical or saucer-shaped, 0.71-1.40 cm high, 2.13-2.80 cm in diam., enclosing 1/4-1/3 of the nut, pubescent with short grayish indumentum outside; wall woody, ca. 2 mm thick, with brown triangular scales outside, the scales up to 4 x 4 mm, imbricate, arranged in 3 or 4 interrupted concentric rings. Nut broadly ovoid-conical to depressed ovoid-globose, 1.5-1.6 cm high, 2.1-2.3 cm in diam., glabrous, brown to blackish brown; basal scar slightly concave, 1.4-1.9 cm in diam. Phenology. Unknown. Fallen fruits were collected in February. Distribution. Vietnam (Khanh Hoa and Lam Dong provinces) (Fig. 1 ). Etymology. The specific epithet is derived from the type locality, Bidoup-Nui Ba National Park, Lam Dong Province, Vietnam. Vernacular name. De đa Bidoup Additional specimens examined. Vietnam . Lam Dong Province : Bidoup-Nui Ba National Park; 1602 m elev., 12°09'27.6"N , 108°32'06.6"E , 24 Mar. 2018 , T. Yahara , H. Nagamasu , H. Toyama , M. Zhang , A. Nagahama , N.V. Ngoc , K. Tsuchiya V7850 [ster.] (DLU!, FU!); ibid., 1656 m elev., 12°09'36.61"N , 108°32'11.16"E , 24 Mar. 2018 , T. Yahara, S. Tagane, M. Zhang, A. Nagahama, K. Tsuchiya, N.V. Ngoc, H.T. Binh, T.Q. Cuong V8190 , V8417 [ster.] (DLU!, FU!); ibid., 1669 m elev., 12°09'36.65"N , 108°32'11.18"E , 29 Apr. 2019 , N.V. Ngoc , H.T. Binh , N.V. Duy , T.T. Nhung NAF122 [ster.] (DLU!); ibid., 1669 m elev., 12°09'36.62"N , 108°32'11.25"E , 29 Apr. 2019 , N.V. Ngoc, H.T. Binh, N.V. Duy, T.T. Nhung NAF185 [ster.] (DLU!). Khanh Hoa Province : Son Thai Commune, Khanh Vinh District, in evergreen; 1430 m elev., 12°10'42.09"N , 108°43'32.59"E , 23 Apr. 2019 , T. Yahara , S. Tagane , A. Nagahama , N. Komada , V.N. Ngoc , H.V. Thanh V9940 [ster.] (DLU!, FU!). Conservation status. Critically Endangered (CR). From our intensive field survey in Bidoup-Nui Ba Naitonal Park and its vicinities from 2015 to present ( Tagane et al. 2017 & 2020, Binh et al 2018b ), Lithocarpus bidoupensis was found only in a narrow area within the protected areas of Bidoup-Nui Ba National Park, and its adjascent area of Son Thai Commune at the elevation range between 1400 and 1669 m. In the area, we observed fewer than 50 mature individuals. Based on criterion D of the IUCN Red List criteria ( IUCN 2012 ), this species is qualified as CR.