Bulbophyllum section Rhytionanthos (Orchidaceae) in Vietnam with description of new taxa and new national record 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 Averyanov, Leonid V. Author Dang, Van Son 0000-0001-8681-4141 Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay District, Hanoi, 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 Maisak, Tatiana 0000-0001-5919-6755 Komarov Botanical Institute of the Russian Academy of Sciences, Prof. Popov Street 2, 197376, St. Petersburg, Russia & tmaisak @ mail. ru; https: // orcid. org / 0000 - 0001 - 5919 - 6755 tmaisak@mail.ru Author Bui, Van Huong 0000-0002-6219-1055 Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay District, Hanoi, Vietnam & Vietnam National Museum of Nature, Vietnam Academy of Science and Technology, 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 The Faculty of Chemistry and Biology, University Grenoble Alpes & Department of Biosciences, University of Milan & baongan. botany @ gmail. com; https: // orcid. org / 0000 - 0001 - 6971 - 3111 baongan.botany@gmail.com Author Truong, Ba Vuong 0000-0003-3452-8455 Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay District, Hanoi, 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 2022 2022-01-11 530 3 257 270 journal article 2663 10.11646/phytotaxa.530.3.1 72c8c74a-e501-43e1-ab1e-d21ece04d26f 1179-3163 5835973 8 B. truongtamii Vuong, Aver. & V.S.Dang sp. nov. ( Fig. 5 ). Type :— Lai Chau Province , Sin Ho District , forest around Sin Ho Town , 24 July 2021 , Truong Ba Vuong , Truong Quang Tam , BV 1306 ( holotype , VNM00069927 ). Descriptions: — Epiphytic creeping herb . Pseudobulbs 1-leaved, greenish, narrowly ovoid to fusiform, slightly oblique, 3.2–4.5 cm , tapering to the apex, covered by remnant fibrous sheaths, pseudobulbs well-spaced, connected by semiwoody rhizome, 2.5–7 cm long, 4 mm in diameter, roots from base of pseudobulbs or from nodes of rhizome. Leaves green, petiolate; petiole 2.5–3 cm long; leaf blade narrowly oblong, 10–11 cm long, 2.5–3 cm wide, apex obtuse or retuse. Inflorescence subumbellate, arising from base of pseudobulbs, slender, green with purplish marks; peduncle 20–21 cm long; rachis 1–1.5 mm long, with 5–6 flowers opening simultaneously; floral bract greenish to white with pinkish dots, triangular, 6–7 mm long, acute; pedicel and ovary 9–10 mm long, pedicel slightly upcurved, green, ovary green with pink dots. Median sepal white or pinkish with pink stripes, lateral sepals yellowish or white, pale green at apical part, with pink stripes, petals whitish to pink, with pink stripes, lip white or dark pink. Median sepal broadly ovate, concave, 6–6.6 mm long, 4.5–5 mm wide, margin finely erose or dentate, truncate and mucronate. Lateral sepals 27–29 mm long, 5–6 mm wide, cuspidate, twisted at base, upper margin connate throughout all their length, free at base and along lower margin. Petals narrowly ovate, oblique, falcate 4–5 mm long, 2.5–3 mm wide, ciliate along the margin at basal half, at apex hairy, apex acute with short seta. Lip glabrous, entire, narrowly ovate, simple, curved, 3.5–4 mm long, 2–2.5 mm wide, apex rounded, at base adnate to column foot apex by white appendage; adaxially shallowly channeled at base; abaxially with 2 low keels. Column ca. 2 mm long, with deltoid or rounded wings, stigma obovate, ca. 1.5 mm long; column foot ca. 3.5 mm long; stelidia ca. 0.5 mm long, subulate, acute, pointing forward, upper margin with small triangular tooth; anther cap helmet-shaped, ca. 1 mm long, frontal margin ciliate; pollinia 4, obovate. Fruit not seen. Habitat and phenology :—Broad-leaved forest. Trunk or branch epiphyte, commonly along streams. Flowering in July. Distribution: — Vietnam ( Lai Chau Province , Sin Ho District). Endemic. Notes :—The morphological comparison with related species is present on the table.