New orchids in the flora of Vietnam VI (Orchidaceae, tribes Arethuseae, Cymbidieae, Diurideae, Epidendreae, Vandeae, and Vanilleae) Author Averyanov, Leonid V. 0000-0001-8031-2925 Komarov Botanical Institute of the Russian Academy of Sciences, Prof. Popov Str., 2, 197376 St. Petersburg, Russia. & av _ leonid @ mail. ru; https: // orcid. org / 0000 - 0001 - 8031 - 2925 av_leonid@mail.ru Author Nguyen, Van Canh 0000-0001-9578-0342 Institute of Applied Technology, Thu Dau Mot University, No. 6, Tran Van On Street, Phu Hoa Ward, Thu Dau Mot City, Binh Duong Province, Vietnam. & nguyenvancanh @ tdmu. edu. vn; https: // orcid. org / 0000 - 0001 - 9578 - 0342 nguyenvancanh@tdmu.edu.vn Author Truong, Ba Vuong 0000-0003-3452-8455 Institute of Tropical Biology Vietnam Academy of Science and Technology, 85 Tran Quoc Toan, District 3, Ho Chi Minh City, Vietnam. Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, 18, Hoang Quoc Viet Road, Cau Giay, Hanoi, Vietnam. & bavuong 2019 @ yahoo. com; https: // orcid. org / 0000 - 0003 - 3452 - 8455 bavuong2019@yahoo.com Author Nguyen, Khang Sinh Graduate University of Science and Technology, Vietnam Academy of Science and Technology. Vietnam. Author Nguyen, Cuong Huu Vietnam National University of Forestry, Xuan Mai, Chuong My, Ha Noi, Vietnam. & nguyenhuucuong. tvr @ gmail. com; https: // orcid. org / 0000 - 0003 - 2281 - 741 X nguyenhuucuong.tvr@gmail.com Author Maisak, Tatiana V. Komarov Botanical Institute of the Russian Academy of Sciences, Prof. Popov Str., 2, 197376 St. Petersburg, Russia. Author Doan, Nga Thi Saint-Petersburg State Forest-Technical University, The Institute Lane 5, 195021, St. Petersburg, Russia. & Vietnam National University of Forestry, Xuan Mai, Chuong My, Hanoi, Vietnam. Author Nguyen, Tuan Hoang Hanoi University of Pharmacy, Faculty of Pharmacognosy and Traditional Medicine, 15 Le Thanh Tong, Hoan Kiem, Hanoi, Vietnam. Laboratory of Ecology and Environmental Management, Science and Technology Advanced Institute, Van Lang University, Ho Chi Minh City, Vietnam. Author Pham, Van The Faculty of Applied Technology, School of Technology, Van Lang University, Ho Chi Minh City, Vietnam. Author Dat, Pham Thi Thanh Institute of Applied Technology, Thu Dau Mot University, No. 6, Tran Van On Street, Phu Hoa Ward, Thu Dau Mot City, Binh Duong Province, Vietnam. Author Thai, Tran Huy Author Nguyen, Van Khuong Institute of Applied Technology, Thu Dau Mot University, No. 6, Tran Van On Street, Phu Hoa Ward, Thu Dau Mot City, Binh Duong Province, Vietnam. Author Trinh, Ngoc Bon Department of Silviculture Foundation and Forest Phytodiversity, Silviculture Research Institute, Vietnamese Academy of Forest Sciences, Hanoi, Vietnam. text Phytotaxa 2023 2023-05-12 597 2 87 110 http://dx.doi.org/10.11646/phytotaxa.597.2.1 journal article 10.11646/phytotaxa.597.2.1 1179-3163 7929197 Holcoglossum nagalandense (Phukan & Odyuo) X.H.Jin in Xiang (2012: 8) . ( Fig. 8 ) ≡ Penkimia nagalandensis Phukan & Odyuo (2006: 331) , Chen et al. (2009: 503) , Zhou et al. (2016: 105) . Type: — INDIA . Nagaland , Odyuo 102808A ( holotype CAL). Ecology and phenology :—Miniature epiphyte on tall mossy trees. Primary humid evergreen broad-leaved montane forest on granite at an elevation of about 1600 m a.s.l. Very rare. Flowers in January. Distribution :— VIETNAM , Lam Dong Province (Lac Duong District). NE India, SW China. FIGURE 7. Cremastra malipoensis G.W.Hu. A, B. Flowering plant in nature (specimen 16.03.201 8, Pham Van The, s.n. ). C, D. Intact apical part of inflorescence. E. Intact flowers, frontal view. F. Flattened leaves. G. Floral bracts Abaxial and adaxial sides. H. Flattened separate flowers, side view. I. Flattened sepals and petals. J. Flattened lip, view from different sides. K. Apical part of the lip, adaxial surface. L. Column, view from different sides. M. Pollinarium. N. Ovary, side view. O. Ovary, cross section (specimen 22.2.202 0, P. Nguyen, T.H. Nguyen, s.n. ). Photos were made by V.T. Pham (A, B) and T.H. Nguyen (C–O), with photo correction and design by T.H. Nguyen, L. Averyanov, and T. Maisak. FIGURE 8. Holcoglossum nagalandense (Phukan & Odyuo) X.H.Jin. A. Flattened flowering plant. B. Stem and base of leaves. C, D. Leaves. E. Intact inflorescence. F. Apical part of inflorescence. G. Intact flowers, view from below. H. Floral bracts, adaxial and abaxial side. I. Flowers, view from different sides. J. Flower with sepals and petals removed. K. Median sepal, abaxial and adaxial side. L. Lateral sepals, adaxial and abaxial side. M. Petals, adaxial and abaxial side. N. Lips, view from different sides. O. Spur, frontal wall removed. P. Column, view from different sides. Q. Anther cap, view from different sides. R. Pollinarium, view from different sides. All photos were made by B.V. Truong from the specimen, Truong Ba Vuong, AL 2032 , with photo correction and design by L. Averyanov and T. Maisak. Conservation status :—Before our study, this species was known from one location in Assam (NE India ) and two close locations in W Yunnan (SW China ). Its somewhat surprising discovery in southern Vietnam expands the formal species area to the SE and SSE directions on more than 2200 km . Meanwhile, in Vietnam , a few plants of the species were collected from felled trees in logging areas where plants have no chance of surviving. Following our observation, the species stands on the verge of full extinction in Vietnam with the current national conservation status, nationally Extinct (EX). Notes :—This rare species is superficially similar to Taiwanese H. pumilum ( Hayata 1906: 77 ) X.H.Jin in Xiang (2012: 8) . However, it distinctly differs in light yellowish to almost white flowers with tepals having a reddish brown tint outside (vs. flowers entirely pink purple except for the bright yellow base of the lip), sepals and petals almost flat or slightly concave, blunt or roundish at the apex (vs. sepals and petals acute and slightly conduplicate), a bailer-shaped lip with an ovate median lobe having a roundish apex (vs. lip almost flat or slightly conduplicate, its median lobe rhomboid, with an acute apex), and side lobes as large as the median lobe (vs. side lobes much smaller than the median lobe, having the form of small auricles). Studied specimen :— VIETNAM , Lam Dong Province , Lac Duong District , Dung K’No Commune , around point 12.08N 108.23E , humid dense primary evergreen montane broad-leaved forest on granite at elevation of about 1600 m a.s.l. , miniature epiphyte on tall mossy trees, very rare, 3 December 2022 , L. Averyanov , Nguyen Van Canh , T. Maisak , Truong Ba Vuong , Nguyen Quoc Bao , Nong Van Duy , Nguyen Phi Tam , AL 2032 , fl. and coll. in cult., 08.01.202 3, Truong Ba Vuong, AL 2032 (photo LE01123793 https://en.herbariumle.ru/?t=occ&id=160775) .