Notes on the genus Chamaeanthus (Orchidaceae, Epidendroideae, Vandeae, Aeridinae) with a new species from Vietnam Author Pham, Phuoc Dien 0000-0002-3552-2963 Faculty of Pharmacy, Ton Duc Thang University, 19 Nguyen Huu Tho, Ho Chi Minh City, Vietnam & phamphuocdien @ tdtu. edu. vn; https: // orcid. org / 0000 - 0002 - 3552 - 2963 phamphuocdien@tdtu.edu.vn Author Kumar, Pankaj 0000-0002-3469-5731 Kadoorie Farm and Botanic Garden, Lam Kam Road, Lam Tsuen, Tai Po, New Territories, Hong Kong SAR, PR China & pkumar @ kfbg. org; https: // orcid. org / 0000 - 0002 - 3469 - 5731 pkumar@kfbg.org Author Dang, Van Son 0000-0001-8681-4141 Graduate University of Science and Technology, VAST, 18 Hoang Quoc Viet, Cau Giay District, Ha Noi, Vietnam & Institute of Tropical Biology Vietnam Academy of Science and Technology, 85 Tran Quoc Toan, District 3, Ho Chi Minh City, Vietnam & dvsonitb @ gmail. com; https: // orcid. org / 0000 - 0001 - 8681 - 4141 dvsonitb@gmail.com Author Nguyen, Dinh Hiep 0000-0001-8605-4568 Faculty of Pharmacy, Ton Duc Thang University, 19 Nguyen Huu Tho, Ho Chi Minh City, Vietnam & nguyendinhhiep @ tdtu. edu. vn; https: // orcid. org / 0000 - 0001 - 8605 - 4568 nguyendinhhiep@tdtu.edu.vn Author Bui, Van Huong 0000-0002-6219-1055 Vietnam National Museum of Nature, Vietnam Academy of Science and Technology, No. 18, Hoang Quoc Viet Road, Cau Giay District, Hanoi, Vietnam. & bvhuong 90 @ gmail. com; https: // orcid. org / 0000 - 0002 - 6219 - 1055 bvhuong90@gmail.com Author Tu, Bao Ngan 0000-0001-6971-3111 UFR de Chimie et de Biologie, Université Grenoble Alpes & Department of Biosciences, Università degli Studi di Milano & baongan. botany @ gmail. com; https: // orcid. org / 0000 - 0001 - 6971 - 3111 baongan.botany@gmail.com Author Dang, Minh Quan 0000-0002-0613-8532 School of Education, Can Tho University, 3 / 2 Street, Ninh Kieu District, Can Tho City, Vietnam & dmquan @ ctu. edu. vn; https: // orcid. org / 0000 - 0002 - 0613 - 8532 dmquan@ctu.edu.vn Author Truong, Ba Vuong 0000-0003-3452-8455 Graduate University of Science and Technology, VAST, 18 Hoang Quoc Viet, Cau Giay District, Ha Noi, Vietnam & Institute of Tropical Biology Vietnam Academy of Science and Technology, 85 Tran Quoc Toan, District 3, Ho Chi Minh City, Vietnam & bavuong 2019 @ yahoo. com; https: // orcid. org / 0000 - 0003 - 3452 - 8455 bavuong2019@yahoo.com text Phytotaxa 2021 2021-11-03 524 2 131 134 journal article 3626 10.11646/phytotaxa.524.2.9 784cadb6-9971-4d92-beed-92e6413a5080 1179-3163 5642124 Chamaeanthus averyanovii Vuong, Kumar, V.H. Bui, V.S.Dang , sp. nov. ( Fig. 1 ) Type :— VIETNAM . Son La Province : Thuan Chau District , 18 June 2021 , Truong Ba Vuong , Bui Van Huong, BV 1194 ( VNM 00069908 !) Etymology :—The specific epithet honors Prof. Leonid Averyanov for his outstanding contribution to the orchid science in Asia. Description . Miniature clustered epiphyte. Stem ca. 5 mm long, covered with distichous leaf sheaths. Leaves fleshy, oblong, slightly concave and falcate, 3–4 cm long, 5–7 mm wide, acute, unequally 2-lobed at the apex, sheathed at the base, sheaths ca. 7 mm long embracing the stem. Inflorescence spike, arising from lower leafless part of the plant, glabrous; peduncle green, terete, 6–7 mm long, with 1 to 4 distantly bracts; rachis clavate, ca. 11 mm long; flowers up to 15, with 1–3 flowers blooming at the same time, not open widely; floral bract green, concave, narrowly triangular, ca. 2 mm long, acuminate; pedicel with ovary faintly greenish-white, glabrous, ca. 2 mm long, terete; tepals white, sub-similar, pale yellow towards the apex, lip white, pale yellow at the base. Dorsal sepal narrowly elliptic, 5–5.5 mm long, 1.5 mm wide, tapering to caudate at the apex; lateral sepals narrowly elliptic, 5.5–6 mm long, 1.5 mm wide, tapering at the apex. Petals narrowly elliptic, 4.5–5 mm long, 1 mm wide, tapering at the apex. Lip 3-lobed, spur absent, glabrous, conical in outline shaped, attached to column foot by a small appendage; midlobe conical, ca. 2.5–3 mm long, entire, apex pugioniform; side lobes erect, rectangular, ca. 1.2 mm long, 1 mm wide, margin irregularly dentate. Column ca. 1 mm long, lower margin with triangular wing; column foot as long as or slightly longer than ovary, oblique, ca. 1.1 mm long; anther cap helmet shape, ca. 1mm long; pollinia 2, subglobose. Fruit not seen. Habitat and phenology :—Epiphytic on small tree branches on canopy. Flowering in June to July. Distribution :— Vietnam ( Son La Province ), endemic Additional specimens studied: MALAYSIA :— Chamaeanthus brachystachys August 190, R. Schlechter s.n. (Isosyntype, AMES00106675 ) Notes :— C. averyanovii looks similar to C. brachystachys and C. canhii , however, they are different. The comparative account is presented in Table 1 . TABLE 1. The comparison of morphological characters of C. averyanovii with C. brachystachys and C. canhii .

C. averyanovii	C. brachystachys	C. canhii
Leaves	oblong, ca. 3.9 cm long, 0.7 cm wide, apex acute unequally bi-lobed	linear, up to 5 cm long, 0.7 cm wide, apex with 3 toothed.	oblong-elliptic, 4 – 9 cm long, 1.2 – 2 cm wide, apex acute unequally bi-lobed
Pedicel and ovary	Glabrous	Glabrous	Hairy with sparse brownish rough hairs
Lip	2.5 – 3 mm long	1.7 mm long	6.6 – 7.4 mm long
Lip lateral lobes	rectangular, erect, dentate	rounded, convex, denticulate	broadly triangular, erect entire
Lip mid lobe	conical, apex pugioniform, ca. 2 mm long	conical, apex acute, ca. 0.7 mm long	broadly conical, apex sub-acute …
Callus on lip	without callus	without callus	2 calli
Color	white-yellowish	pale yellow-yellow	pale yellow

Morphological data of C. brachystachys is based on Schlechter (1905) and Pridgeon et al. (2014) : t. 636.1 by Judi Stone, from KEW spirit collection: Borneo, 1989 A. Lamb AL1154/89 (number 56439)