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3. B. viridipallidum Vuong, Aver. & V.C.Nguyen sp. nov. (Fig. 2). Type:— VIETNAM. Kon Tum Province, Dak Ha District, Dak Psi Commune, Dak Trua Forest, epiphyte on tall trees, 16 February 2023, Truong Ba Vuong, BV 1688 (holotype VNM00043087!). Etymology: —the specific epithet refers to the pale greenish yellow lateral sepals, a character common with related species. Description:—Herb perennial, epiphytic. Pseudobulbs densely clustering, ovoid to broadly ovoid, sometime slightly compress, 7–16 mm long, 5–17 mm in diameter, 2-leaved. Leaves deciduous, plant leafless at anthesis. Inflorescence from base of pseudobulbs; peduncle greenish-yellow, 39 – 40 cm long, at base with 2 scarious, brownish overlapping tubular bracts, above with 2 similar bracts; rachis pendulous, 3.5 – 4 cm long, bearing 6 simultaneously opening flowers; floral bract triangular, brown 1.7–2 mm long, acute; pedicel and ovary 2.5–3 mm long, pedicel terete shorter than conoid ovary. Flowers odorless, lateral sepals pale greenish yellow; median sepal and petals pale reddish brown, lip white speckled with pink or pink purple, callus yellow, with many pink dots at apex dark purple. Median sepal ovate to broadly ovate, ca. 5.5 mm long, ca. 3 mm wide, acuminate to attenuate, adaxially in middle with 2 prominent keels, in apical half sparsely hairy with stiff hairs. Lateral sepals obliquely oblong lanceolate, ca. 4 cm long, ca. 0.3 cm wide, acute, twisted at base, lower margin free at base, connate to the tip, adaxial surface sparsely hairy with short stiff hairs. Petals obliquely triangular, glabrous, 4–4.5 mm long, 1–1.5 mm wide, margin fimbriate, acuminate to attenuate. Lip simple, oblong in outline, 3–3.2 mm long, 1–1.5 mm wide, movably adnate to column foot by small ligament, apex rounded; margins in basal half erect, finely papillose, apical half fimbriate along the margin; adaxial surface at base with 2 rounded longitudinal calli fused distally into a single prominent central longitudinal keel inflated at the lip apex turn into prominent half-ovoid callus; abaxial sparely pillose. Column ca. 1.5 mm long, at front with inconspicuous rounded wings; column foot 2–2.5 cm long, forward directed, straight; stelidia subulate, ca. 1 mm long, slightly curved; stigma half circular, concave, ca. 1 mm across; rostelum non protruding; anther cap helmet shaped, ca. 1 mm long, apex with a gibbose densely papillose inflation; pollinia 4, bright yellow, half ovoid, inner smaller than outer. Fruits not seen. Habitat and phenology: —Epiphyte on tall trees in evergreen broad-leaved forest. Flowering observed during February. Distribution: — VIETNAM (Kon Tum Province, Dak Ha District). Endemic. Proposed conservation status:—According to currently available data, the new species is very rare and found only from one location. More field studies are required for preparing its conservation assessment. In view of gaps in data and in accordance with IUCN criteria (IUCN, 2022), the species should be assessed as Data Deficient (DD). Notes:—The new species in its entire median sepal is similar B. kanburiense and B. khaoyaiense. It also similar with B. wallichii in two prominent calli placed on the lip base. The dorsal sepal and flower comparison is presented on Fig. 3. The morphological differences of the new species and morphologically similar species are presented in the table. Data of B. wallichii based on BV 1484 (VNM 00043086), BV 1483 (LE 01123508 & LE 01169312); data of B. kanburiense based on Seidenfaden (1970: 344); data of B. khaoyaiense based on Seidenfaden & Smitinand (1965: 795) and Seidenfaden (1970: 342).

4. B. refractum (Zollinger 1847: 456) Reichenbach (1861: 259), Seidenfaden (1970: 347), Averyanov (1994: 284), Seidenfaden (1992: 263). (Fig. 4). ≡ Cirrhopetalum refractum Zollinger 1847: 456. Type:— INDONESIA. Java, Zollinger, 2261 (G00165064 photo!). ≡ Phyllorkis refracta (Zollinger 1847: 456) Kuntze (1891: 677). ≡ Tripudianthes refracta (Zollinger 1847: 456) Szlachetko & Kras (2007: 96). Habitat and phenology: —Epiphyte on tall trees in primary evergreen broad-leaved forests. Flowering observed in December–February. Distribution: — Vietnam (Lam Dong, Gia Lai, Dak Nong, Binh Phuoc, Dien Bien provinces), Bhutan, India, Myanmar, Thailand, Java and Sumatra. Proposed conservation status:—According to currently available data, B. refractum seems quite common in Vietnam. Due to attractive nature of flowers, the species is widely collected for trade. Based on the national EOO 148,826.741 km 2 and AOO 28.000 km 2, and in accordance with IUCN criteria (IUCN, 2022), the species should be assessed in Vietnam as VU B2ab(v). The verifiable data for this species’ conservation status outside Vietnam is not available. Note:—Common in Vietnam, with relatively large flowers having a large dorsal sepal. The species is sometime misidentified as B. kanburiense; the main differences is indicated under the note for B. kanburiense. The drawing of Pham Hoang Ho (1992: 844) named as B. refractum possibly based on specimens of Tixier 15 (P 00348218) having a very small dorsal sepal typical for B. wallichii. Studied specimens: — VIETNAM, Lam Dong Province, Annam: piste de Fyan, 1957, Tixier, 15 (P 00348218 photo!). VIETNAM, Gia Lai Province, 1987, Averyanov, LX-VN 2143a/190a (photos LE 01057662!, LE 01087253!). VIETNAM, Binh Phuoc Province, 2005, Averyanov et al., HLF 4932a (photos LE 01087116!). VIETNAM, Lam Dong Province, 2011, NPT 006 (photos LE 0105766!, LE 01070245!). VIETNAM, Lam Dong Province, 2018, Truong Ba Vuong, Ngo Quang Dang, BV 1035 (VNM 00043084!). VIETNAM, Gia Lai Province, Truong Ba Vuong, BV 1083 (VNM 00043085!). VIETNAM, Dak Nong Province, 2019, Averyanov, Nguyen Van Canh, T. Maisak, AL 1183.4 (photos LE 01067185!). VIETNAM, Dak Lak, 2019, Truong Ba Vuong, BV 532 (VNM 00043069!). VIETNAM, Lam Dong Province, 2021, Truong Ba Vuong, Ngo Quang Dang, BV 1046 (photos LE 01089814!, VNM 00043072!). VIETNAM, Dien Bien Province, 2023, Nguyen Sinh Khang, AL 2191 (photos LE 01123884!). INDONESIA, Java, 1844, Zollinger, 2261 (isotype P 00347107 photo!)., Published as part of Nguyen, Van Canh, Averyanov, Leonid V., Maisak, Tatiana V., Nguyen, Thi Lien Thuong, Nguyen, Van Khuong, Pham, Thi Thanh Dat, Nguyen, Danh Duc, Dang, Van Son, Aromyen, Warapong & Truong, Ba Vuong, 2023, The review of Bulbophyllum section Tripudianthes (Orchidaceae) in the flora of Vietnam with the description of new species, B. viridipallidum, pp. 59-68 in Phytotaxa 598 (1) on pages 66-67, DOI: 10.11646/phytotaxa.598.1.4, http://zenodo.org/record/7958804, {"references":["Zollinger, H. (1847) Orchidaee. In: Observationes phytographicae, praecipue genera et species nova nonnulla respicientes. Flora oder Botanische Zeitung: welche Recensionen, Abhandlungen, Aufsatze, Neuigkeiten und Nachrichten, die Botanik betreffend, enthalt 30: 456.","Reichenbach, H. G. (1861) Orchides. In: Mueller, C. (ed.) Synopsis plantarum phanerogamicarum novarum omnium. Walpers Annales Botanices Systematicae 6: 167 - 933.","Seidenfaden, G. (1970) Contributions to the Orchid Flora of Thailand II. Botanisk Tidsskrift 65 (4): 313 - 370.","Averyanov, L. V. (1994) Identification guide to Vietnamese orchids. World & family. Saint-Petersburg. 432 pp.","Seidenfaden, G. (1992) The Orchid of Indochina. Opera Botanica 114: 1 - 502.","Kuntze, O. (1891) Cirrhopetalum refracta. Revisio generum plantarum: vascularium omnium atque cellularium multarum secundum leges nomenclaturae internationales cum enumeratione plantarum exoticarum in itinere mundi collectarum. Vol. 2. Leipzig. 1011 pp. https: // doi. org / 10.5962 / bhl. title. 124064","Szlachetko, D. L. & Kras, M. (2007) Contribution a la revision generique de Bulbophyllinae (Epidendroideae) 5 - Tripudianthes (Seidenfaden). Richardiana 7: 94 - 96.","IUCN Standards and Petitions Committee (2022) Guidelines for Using the IUCN Red List Categories and Criteria. Version 15.1. Prepared by the Standards and Petitions Committee. Available from: https: // nc. iucnredlist. org / redlist / content / attachment _ files / RedListGuidelines. pdf (accessed 2 April 2023)"]}

2. B. wallichii Reichenbach (1861: 259). (Fig. 1). Type:— NEPAL. 1832, Wall. Cat. n. 1980 (K000894326 photo!). ≡ Cirrhopetalum wallichii Lindley (1839: 72), non Wallich (1830: 51). ≡ Tripudianthes wallichii (Reichenbach) Szlachetko & Kras (2007: 96). ≡ Bulbophyllum refractoides Seidenfaden (1970: 342), nom. superfluum. Habitat and phenology: —Epiphyte on tall trees in evergreen broad-leaved forest. Distribution: — Vietnam (Lam Dong Province), Nepal, NE India, Myanmar, China, Thailand, Laos. Proposed conservation status:—According to currently available data, B. wallichii is found only in one location as a clustering epiphyte on tall tree in primary broad-leaved forest in Lam Dong Province. There is no direct threat to this habitat. Hence the species can be assessed in Vietnam as Vulnerable based on small AOO, VU D2. Meanwhile, there is insufficient data for global distribution area of this specie where its conservation status should be identified as Data Deficient (DD). Note:— Seidenfaden (1970: 342) considered the collection, Tixier 15 (P00348218) as Bulbophyllum refractoides, which is currently accepted as a synonym of B. wallichii. However, the line drawing of Tixier on the herbarium sheet clearly shows the dorsal sepal with stiff hairs on inner surface and on the margin (not fimbriate as in B. wallichii). We suspect the identification of this specimen may be incorrect. Meanwhile, additional specimens of the true B. wallichii were recently collected in Vietnam, in Lam Dong Province. These collections are presently confirmed by the voucher specimens (BV 1483, 1484) stored at LE (LE01169312! & LE01169312!) and VNM (VNM00043086!) Herbaria. At the same time, the specimen from NE India collected by Hooker and Thomson (P00362039) seem different from the type in a longer dorsal sepal with acuminate (not caudate) apex, and may represent separate variety or even species; which require detailed study. Studied specimens: — VIETNAM, Lam Dong Province, 14 December 2021, Truong Ba Vuong & Nguyen Phi Tam, BV 1483 (photos LE01123508!, LE01169312), BV 1484 (VNM00043086!). INDIA, Sikkim, Donné par M. M. J-D. Hooker et Thomson 1859 s.n. (P00362039 photo!). INDIA, Sikkim Himalaya, December 1892, Pantling 24 (P00362038 photo!)., Published as part of Nguyen, Van Canh, Averyanov, Leonid V., Maisak, Tatiana V., Nguyen, Thi Lien Thuong, Nguyen, Van Khuong, Pham, Thi Thanh Dat, Nguyen, Danh Duc, Dang, Van Son, Aromyen, Warapong & Truong, Ba Vuong, 2023, The review of Bulbophyllum section Tripudianthes (Orchidaceae) in the flora of Vietnam with the description of new species, B. viridipallidum, pp. 59-68 in Phytotaxa 598 (1) on page 61, DOI: 10.11646/phytotaxa.598.1.4, http://zenodo.org/record/7958804, {"references":["Reichenbach, H. G. (1861) Orchides. In: Mueller, C. (ed.) Synopsis plantarum phanerogamicarum novarum omnium. Walpers Annales Botanices Systematicae 6: 167 - 933.","Lindley, J. (1839) Cirrhopetalum in Miscellaneous Notices. Edwards's botanical register 25: 72.","Wallich, N. (1830) Cirrhopetalum wallichii. In: Plantae Asiaticae rariores, or, Descriptions and figures of a select number of unpublished East Indian plants. London, Treuttel and Wu ¨ rtz. pp. 53, Tab. 67. https: // doi. org / 10.5962 / bhl. title. 468","Szlachetko, D. L. & Kras, M. (2007) Contribution a la revision generique de Bulbophyllinae (Epidendroideae) 5 - Tripudianthes (Seidenfaden). Richardiana 7: 94 - 96.","Seidenfaden, G. (1970) Contributions to the Orchid Flora of Thailand II. Botanisk Tidsskrift 65 (4): 313 - 370."]}

1. B. tripudians Parish & Reichenbach (1875: 154), Seidenfaden (1970: 341, 1979: 189), Ormerod et al. (2021: 50). Type:— MYANMAR. Mon State: Mawlamyine District, Parish 308 (K 000829091 photo!). ≡ B. tripudianthe Shaw (2016: 124), nom. superfluum. ≡ Tripudianthes tripudians (Parish & Reichenbach 1875: 154) Szlachetko & Kras (2007: 96). Habitat and phenology: —Epiphyte on tall trees in broad-leaved evergreen forest. Flowering observed in February– March. Distribution: — Myanmar, Thailand, Laos, Vietnam (?). Proposed conservation status:—According to currently available data, B. tripudians is a very rare species recorded from a single collection made by Poilane in 1933. More field studies are necessary for the identification of its conservation status. In view of lack of current data and in accordance with IUCN criteria (IUCN, 2022), the species should be assessed as Data Deficient (DD). Note: —The occurrence of this species in Vietnam is based on a single collection by Poilane (P 00362016) made in Lam Dong Province, in Bao Loc District. However, specimens on the herbarium sheet (especially on the rightside) show a large dorsal sepal do not attenuate at apex that is typical for B. refractum, hence the identification on our opinion may be doubtful. Studied specimens: — VIETNAM, Lam Dong Province, “Annam: un peu au sud de la station agricole de Blao, prov. du Haut Donaï”, 1933, Poilane, 22157 (P 00362016 photo!)., Published as part of Nguyen, Van Canh, Averyanov, Leonid V., Maisak, Tatiana V., Nguyen, Thi Lien Thuong, Nguyen, Van Khuong, Pham, Thi Thanh Dat, Nguyen, Danh Duc, Dang, Van Son, Aromyen, Warapong & Truong, Ba Vuong, 2023, The review of Bulbophyllum section Tripudianthes (Orchidaceae) in the flora of Vietnam with the description of new species, B. viridipallidum, pp. 59-68 in Phytotaxa 598 (1) on pages 60-61, DOI: 10.11646/phytotaxa.598.1.4, http://zenodo.org/record/7958804, {"references":["Seidenfaden, G. (1970) Contributions to the Orchid Flora of Thailand II. Botanisk Tidsskrift 65 (4): 313 - 370.","Seidenfaden, G. (1979) Orchid genera in Thailand 8: Bulbophyllum. Dansk Botanisk Arkiv 33 (3): 1 - 228.","Ormerod, P, Kurzweil, H. & Watthana, S. (2021) Annotated List of Orchidaceae for Myanmar. Phytotaxa 481 (1): 1 - 262. https: // doi. org / 10.11646 / phytotaxa. 481.1.1","Shaw, J. M. H. (2016) Bulbophyllum tripudianthe in Orchid Review 124 (1314): 35.","Szlachetko, D. L. & Kras, M. (2007) Contribution a la revision generique de Bulbophyllinae (Epidendroideae) 5 - Tripudianthes (Seidenfaden). Richardiana 7: 94 - 96.","IUCN Standards and Petitions Committee (2022) Guidelines for Using the IUCN Red List Categories and Criteria. Version 15.1. Prepared by the Standards and Petitions Committee. Available from: https: // nc. iucnredlist. org / redlist / content / attachment _ files / RedListGuidelines. pdf (accessed 2 April 2023)"]}

5. B. kanburiense Seidenfaden (1970: 344), Seidenfaden (1979: 190), Ormerod et al. (2021: 36). Type: — THAILAND, Thawng Phaphum, Kanburi, Seidenfaden & Smitinand, GT 4259 (C). ≡ Tripudianthes kanburiensis (Seidenfaden) Szlachetko & Kras (2007: 95). Habitat and phenology: —Epiphyte on tall trees in primary evergreen broad-leaved forests. Distribution: — Myanmar, Thailand, Vietnam (?) Proposed conservation status:—According to currently available data, the occurrence of B. kanburiense in Vietnam is unclear. More field studies are required to confirm the distribution of this species in Vietnam. In view of lack of current data and in accordance with IUCN criteria (IUCN, 2022), the species is assessed nationally as Data Deficient (DD). The conservation status of this species outside Vietnam has not been evaluated yet. Studied specimens:— MYANMAR, 1932, Dickason 5770, (A02386360 photo!,AMES45519photo!). VIETNAM, Lam Dong, 1982, Averyanov, LX-VN 973 (photos LE01055686!, LE01055687!). Note:—This species is similar to B. refractum, from which it differs by having a smaller median sepal, less than 5.5 mm long (vs. median sepal longer than 8 mm), shorter lateral sepals 2.5 cm (vs. longer than 3 cm), and acuminate petals (vs. petals acute). Two collections housed in LE Herbarium: LE01055686 and LE01055687 identified as B. kanburiense show entire dorsal sepal and subulate petals typical for B. refractum according to Seidenfaden (1992: 261). However, these specimens have lateral sepals 3.5–4 cm long (vs. median sepal of B. kanburiense according to protologue is about 2.5 cm long), hence the identification of mentioned collection remains somewhat doubtful. We have not seen any more collections from Vietnam, which can confirm the occurrence of B. refractum in Vietnam., Published as part of Nguyen, Van Canh, Averyanov, Leonid V., Maisak, Tatiana V., Nguyen, Thi Lien Thuong, Nguyen, Van Khuong, Pham, Thi Thanh Dat, Nguyen, Danh Duc, Dang, Van Son, Aromyen, Warapong & Truong, Ba Vuong, 2023, The review of Bulbophyllum section Tripudianthes (Orchidaceae) in the flora of Vietnam with the description of new species, B. viridipallidum, pp. 59-68 in Phytotaxa 598 (1) on page 67, DOI: 10.11646/phytotaxa.598.1.4, http://zenodo.org/record/7958804, {"references":["Seidenfaden, G. (1970) Contributions to the Orchid Flora of Thailand II. Botanisk Tidsskrift 65 (4): 313 - 370.","Seidenfaden, G. (1979) Orchid genera in Thailand 8: Bulbophyllum. Dansk Botanisk Arkiv 33 (3): 1 - 228.","Ormerod, P, Kurzweil, H. & Watthana, S. (2021) Annotated List of Orchidaceae for Myanmar. Phytotaxa 481 (1): 1 - 262. https: // doi. org / 10.11646 / phytotaxa. 481.1.1","Szlachetko, D. L. & Kras, M. (2007) Contribution a la revision generique de Bulbophyllinae (Epidendroideae) 5 - Tripudianthes (Seidenfaden). Richardiana 7: 94 - 96.","IUCN Standards and Petitions Committee (2022) Guidelines for Using the IUCN Red List Categories and Criteria. Version 15.1. Prepared by the Standards and Petitions Committee. Available from: https: // nc. iucnredlist. org / redlist / content / attachment _ files / RedListGuidelines. pdf (accessed 2 April 2023)","Seidenfaden, G. (1992) The Orchid of Indochina. Opera Botanica 114: 1 - 502."]}

Bulbophyllum sect. Tripudianthes Seidenfaden (1979: 188). Type:— B. tripudians Parish & Reichenbach (1875: 154). = Tripudianthes Szlachetko & Kras (2007: 94). 10–11 species in Nepal, Bhutan, NE India, Myanmar, S China, Thailand, Laos, Vietnam, Java, and Sumatra. In Vietnam 3–5 species, 1 endemic. Identification key to species of Bulbophyllum section Tripudianthes reported in the flora of Vietnam Species, the occurrence of which needs confirmation are designated by asterisk (*) 1. Median sepal with entire margin........................................................................................................................................................2 –. Median sepal with ciliate or fimbriate margin....................................................................................................................................4 2. Median sepal attenuate, with filiform appendage at apex................................................................................................. B. wallichii –. Median sepal acuminate, rarely with short seta at apex.....................................................................................................................3 3. Median sepal ovate, acuminate; lateral sepals 3–5.5 cm long; petals acuminate.......................................................... B. tripudians * –. Median sepal narrowly ovate, acute; lateral sepals ca. 2.5 cm long; petals aristate.................................................. B. kanburiense * 4. Median sepals ovate, attenuate................................................................................................................................. B. viridipallidum –. Median sepal elliptic, obtuse to acute............................................................................................................................... B. refractum, Published as part of Nguyen, Van Canh, Averyanov, Leonid V., Maisak, Tatiana V., Nguyen, Thi Lien Thuong, Nguyen, Van Khuong, Pham, Thi Thanh Dat, Nguyen, Danh Duc, Dang, Van Son, Aromyen, Warapong & Truong, Ba Vuong, 2023, The review of Bulbophyllum section Tripudianthes (Orchidaceae) in the flora of Vietnam with the description of new species, B. viridipallidum, pp. 59-68 in Phytotaxa 598 (1) on page 60, DOI: 10.11646/phytotaxa.598.1.4, http://zenodo.org/record/7958804, {"references":["Seidenfaden, G. (1979) Orchid genera in Thailand 8: Bulbophyllum. Dansk Botanisk Arkiv 33 (3): 1 - 228.","Szlachetko, D. L. & Kras, M. (2007) Contribution a la revision generique de Bulbophyllinae (Epidendroideae) 5 - Tripudianthes (Seidenfaden). Richardiana 7: 94 - 96."]}

Panisea sondangii (Vuong, Aver. & V.H.Bui) Aver., comb. nov. ≡ Coelogyne sondangii Vuong, Aver. & V.H.Bui in, D.T. Vo et al. (2022: 201, fig. 1). Type: — VIETNAM. Lai Chau Province, Sin Ho District, Lang Mo Commune, forest around Tu Cua Phin Village, 23 March 2022, Truong Ba Vuong, Bui Van Huong, BV 1357 (holotype VNM 00069946). Notes:—Following almost all recent orchid assessments and monographs (Seidenfaden 1986, 1992, Lund 1987, Pearce & Cribb 2002, Schuiteman et al. 2008, Chen et al. 2009, Rokaya et al. 2013: 539, Zhou et al. 2016: 34, Ormerod et al. 2021: 74), we accept Panisea (Lindley 1833: 44) Steudel (1841: 265) as a genus separate from Coelogyne Lindley (1821: t. 33) due to clear morphological evidence. Hence, we proposed the new nomenclatural combination made above. Data on ecology, phenology, distribution, and conservation status were reported earlier (Vo et al. 2022)., Published as part of Averyanov, Leonid V., Nguyen, Van Canh, Truong, Ba Vuong, Nguyen, Khang Sinh, Nguyen, Cuong Huu, Maisak, Tatiana V., Doan, Nga Thi, Nguyen, Tuan Hoang, Pham, Van The, Dat, Pham Thi Thanh, Thai, Tran Huy, Nguyen, Van Khuong & Trinh, Ngoc Bon, 2023, New orchids in the flora of Vietnam VI (Orchidaceae, tribes Arethuseae, Cymbidieae, Diurideae, Epidendreae, Vandeae, and Vanilleae), pp. 87-110 in Phytotaxa 597 (2) on page 93, DOI: 10.11646/phytotaxa.597.2.1, http://zenodo.org/record/7929197, {"references":["Vo, D. T., Averyanov, L. V., Maisak, T. V., Bui, V. H., Nguyen, V. C., Dang, M. Q., Nguyen, Q. B. & Truong, B. V. (2022) New species, Coelogyne sondangii (Orchidaceae), and a new national record, C. moi, in Vietnam. Phytotaxa 559 (2): 200 - 206. https: // doi. org / 10.11646 / phytotaxa. 559.2.9","Seidenfaden, G. (1986) Orchid genera in Thailand 13. Thirty-three epidendroid genera. Opera Botanica 89: 1 - 216.","Seidenfaden, G. & Wood, J. J. (1992) The orchids of Peninsular Malaysia and Singapore. Olsen & Olsen, Fredensborg, 779 pp.","Lund, I. D. (1987) The genus Panisea (Orchidaceae), a taxonomic revision. Nordic Journal of Botany 7 (5): 511 - 527. https: // doi. org / 10.1111 / j. 1756 - 1051.1987. tb 02018. x","Pearce, N. R. & Cribb, P. J. (2002) The orchids of Bhutan. In: Flora of Bhutan. Vol. 3 (3). Royal Botanic Garden Edinburgh, UK & Royal Government of Bhutan, 643 pp.","Schuiteman, A., Bonnet, P., Svengsuksa, B. & Barthelemy, D. (2008) An annotated checklist of the Orchidaceae of Laos. Nordic Journal of Botany 26: 257 - 316.","Chen, S. C., Liu, Z. J., Zhu, G. H., Lang, K. Y., Ji, Z. H., Luo, Y. B., Jin, X. H., Cribb, P. J., Wood, J. J., Gale, S. W., Ormerod, P., Vermeulen, J. J., Wood, H. P., Clayton, D. & Bell, A. (2009) Orchidaceae. In: Wu, Z. Y., Raven, P. H. & Hong, D. (Eds.) Flora of China, vol. 25. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis, pp. 211 - 235.","Rokaya, M. B., Raskoti, B. B., Timsina, B. & Munzbergova, Z. (2013) An annotated checklist of the orchids of Nepal. Nordic Journal of Botany 31: 511 - 550.","Zhou, X., Cheng, Z., Liu, Q., Zhang, J., Hu, A., Huang, M., Hu, C. & Tian, H. (2016) An updated checklist of Orchidaceae for China, with two new national records. Phytotaxa 276 (1): 1 - 148. https: // doi. org / 10.11646 / phytotaxa. 276.1.1","Ormerod, P., Kurzweil, H. & Watthana, S. (2021) Annotated List of Orchidaceae for Myanmar. Phytotaxa 481: 1 - 262.","Steudel, E. G. (1841) Nomenclator botanicus. Stuttgartiae, Tubingae, typis et sumptibus J. G. Cottae. 810 pp. https: // doi. org / 10.5962 / bhl. title. 655","Lindley, J. (1821) Collectanea botanica. Richard and Arthur Taylor, London, 41 plates and text."]}

Tribe Arethuseae Coelogyne fuliginosa Lodd. ex Hooker (1849 t. 4440), Seidenfaden (1975: 19, fig. 4 & 5), Comber (1990: 112), Pearce & Cribb (2002: 327), Clayton (2002: 52, pl. 3B). Type:— INDIA. Loddiges collector 1838 s.n. (holotype K “ Coelogyne fuliginosa m Herb. Loddiges” no barcode, specimen on herbarium sheet K000079262). Ecology and phenology:—Lithophyte and epiphyte on tall mossy trees, commonly along streams. Primary and secondary evergreen broad-leaved montane forests on limestone and granite at an elevation of 1000–1300 m a.s.l. Occasional. Flowers in February and September. Distribution:— Vietnam, provinces Hoa Binh (with no exact location), and Lam Dong (Lac Duong District). Bhutan, NE India, Myanmar, Java? Conservation status:—The evaluation of this species by the criteria proposed by the Red List ICUN (2019) is based on two poor collections, which give insufficient data to identify a certain conservation status. Hence, the national conservation status for this species should be identified as nationally Data Deficient (DD). Outside Vietnam, the species status should be designated as NE. Notes:—The species is very close to Coelogyne fimbriata Lindley (1825 t. 868) and Coelogyne ovalis Lindley (1838: 91), with which it is synonymized by some recent authors (Pelser et al. 2000, Schuiteman et al. 2008, Ormerod et al. 2021). However, in a series of monographic works, it is kept as a separate species (Seidenfaden 1975, Pearce & Cribb 2002, Clayton 2002: 52). With some uncertainty, we also keep it separately in Vietnam before studying more collections from Eastern Indochina. The plant reported for Java (Comber 1990) has flowers twice as large as those reported in the protologue and most probably represents another species, rather than belonging to the Coelogyne sect. Speciosae Pfitzer & Kraenzlin in Engler (1907: 28) rather than C. sect. Fuliginosae Pfitzer & Kraenzlin l.c. (1907: 33). Studied specimens:— VIETNAM, limestone area in Hoa Binh Province, September 2014, Chu Xuan Canh, s.n. (LE01059405 https://en.herbariumle.ru/?t=occ&id=10290). VIETNAM, Lam Dong Province, Lac Duong District, Lat Municipality, Pang Tien Village, around point 11°38´35´´N 108°18´44´´E, remnants of primary evergreen, humid montane forest along rocky mountain stream at an elevation of about 1250 m a.s.l., lithophyte on mossy granite cliff, also as an epiphyte on old trees, 1 May 2015, L. Averyanov, T. Maisak, Nguyen Phi Tam, Nong Van Duy, flowered in cultivation on 15 February 2017, flowers light greenish-yellow, lip with dark brown keels and irregular marks in the center, L. Averyanov, AL 054 (LE01077606 https://en.herbariumle.ru/?t=occ&id=115161)., Published as part of Averyanov, Leonid V., Nguyen, Van Canh, Truong, Ba Vuong, Nguyen, Khang Sinh, Nguyen, Cuong Huu, Maisak, Tatiana V., Doan, Nga Thi, Nguyen, Tuan Hoang, Pham, Van The, Dat, Pham Thi Thanh, Thai, Tran Huy, Nguyen, Van Khuong & Trinh, Ngoc Bon, 2023, New orchids in the flora of Vietnam VI (Orchidaceae, tribes Arethuseae, Cymbidieae, Diurideae, Epidendreae, Vandeae, and Vanilleae), pp. 87-110 in Phytotaxa 597 (2) on pages 88-89, DOI: 10.11646/phytotaxa.597.2.1, http://zenodo.org/record/7929197, {"references":["Hooker, W. J. (1849) Coelogyne fuliginosa. Dark-flowered Coelogyne. Curtis's Botanical Magazine 75: t. 4440.","Seidenfaden, G. (1975) Orchid genera in Thailand, 3: Coelogyne Lindl. Dansk Botanisk Arkiv 29 (4): 1 - 94.","Comber, J. B. (1990) Orchids of Java. Bentham-Moxon Trust, Kew, 407 pp.","Pearce, N. R. & Cribb, P. J. (2002) The orchids of Bhutan. In: Flora of Bhutan. Vol. 3 (3). Royal Botanic Garden Edinburgh, UK & Royal Government of Bhutan, 643 pp.","Clayton, D. (2002) The genus Coelogyne: A synopsis. Natural History Publications, Kota Kinabalu, Royal Botanic Garden Kew, 316 pp.","Lindley, J. (1825) Coelogyne fimbriata. Fringed Coelogyne. Botanical Register 11: t. 868.","Lindley, J. (1838) 171. Coelogyne ovalis. Edwards's Botanical Register 1838: 91.","Pelser, P. B., Gravendeel, B. & de Vogel, E. F. (2000) Revision of Coelogyne section Fuliginosae (Orchidaceae). Blumea 45: 253 - 273.","Schuiteman, A., Bonnet, P., Svengsuksa, B. & Barthelemy, D. (2008) An annotated checklist of the Orchidaceae of Laos. Nordic Journal of Botany 26: 257 - 316.","Ormerod, P., Kurzweil, H. & Watthana, S. (2021) Annotated List of Orchidaceae for Myanmar. Phytotaxa 481: 1 - 262.","Engler, E. (1907) Das Pflanzenreich. Regni vegetablilis conspectus. 32 Orchidaceae-Monandrae-Coelogyninae. Leipzig, Verlag von Wilhelm Engelmann, 169 pp."]}

Tribe Diurideae Stigmatodactylus sikokianus Maxim. ex Makino (1891: 70 t. 43), Ohwi (1965: 337), Chen et al. (2009: 88), Pedersen, Suksathan (2013: 65), Lin et al. (2016: 118), Zhou et al. (2016: 128). Type: — JAPAN. Tosa, Mt. Yohogura, Sept. 4, 1859, T. Makino (not located). (Fig. 6) Ecology and phenology:—Small lithophytic and terrestrial herb. Primary evergreen broad-leaved forests, commonly on mossy rocks along streams at an elevations of 1000–1500 m a.s.l. Very rare. Flowers in July–August. Distribution:— VIETNAM, Dak Lak Province (Lak, and Krong Bong districts). Thailand, E China, Japan. Conservation status:—In Vietnam, this species is extremely rare. Although numerous particular fieldworks were conducted, only a few plants in one population were found in a vulnerable habitat with miserable occupancy. According to formal Red List IUCN (2022) criteria the species meets in Vietnam with the following conditions: the observed population reduction for 10 years or 3 generations ≥ 80% are not reversible (A2), based on direct observation (a) and observed decline of the area of occupancy, extent of occurrence and habitat quality (b); the area of occurrence Notes:—Species of this genus have a relatively broad distribution in the humid forests of tropical and subtropical Asia (Robinson et al. 2016). However, individually, all of them are very rare plants, usually with limited distribution. Our discovery of Stigmatodactylus sikokianus in Vietnam, together with its recent report from northern Thailand (Pedersen & Suksathan 2013), dramatically expands the area of the known species previously known only in Japan and eastern China (including Taiwan). Considering newly discovered locations, the species has the largest area among all other species in the genus. Studied specimen:— VIETNAM, Dak Lak Province, Chu Yang Sin Mountains, lithophytic, tuberiferous herb on mossy rocks along a stream in evergreen broad-leaved forest, very rare, 7 August 2022, Nguyen Van Canh, s. n. (photo LE01123479 https://herbariumle.ru/?t=occ&id=140359).

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. 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)., Published as part of Averyanov, Leonid V., Nguyen, Van Canh, Truong, Ba Vuong, Nguyen, Khang Sinh, Nguyen, Cuong Huu, Maisak, Tatiana V., Doan, Nga Thi, Nguyen, Tuan Hoang, Pham, Van The, Dat, Pham Thi Thanh, Thai, Tran Huy, Nguyen, Van Khuong & Trinh, Ngoc Bon, 2023, New orchids in the flora of Vietnam VI (Orchidaceae, tribes Arethuseae, Cymbidieae, Diurideae, Epidendreae, Vandeae, and Vanilleae), pp. 87-110 in Phytotaxa 597 (2) on pages 101-104, DOI: 10.11646/phytotaxa.597.2.1, http://zenodo.org/record/7929197, {"references":["Xiang, X., Li, D., Jin, X., Hu, H., Zhou, H., Jin, W. & Lai, Y. (2012) Monophyly or paraphyly - the taxonomy of Holcoglossum (Aeridinae: Orchidaceae). PLOS ONE 7 (12): e 52050. https: // doi. org / 10.1371 / journal. pone. 0052050","Phukan, S. & Odyuo, N. (2006) Penkimia nagalandensis Phukan & Odyuo. Orchid Review 114 (1272): 331.","Chen, S. C., Liu, Z. J., Zhu, G. H., Lang, K. Y., Ji, Z. H., Luo, Y. B., Jin, X. H., Cribb, P. J., Wood, J. J., Gale, S. W., Ormerod, P., Vermeulen, J. J., Wood, H. P., Clayton, D. & Bell, A. (2009) Orchidaceae. In: Wu, Z. Y., Raven, P. H. & Hong, D. (Eds.) Flora of China, vol. 25. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis, pp. 211 - 235.","Zhou, X., Cheng, Z., Liu, Q., Zhang, J., Hu, A., Huang, M., Hu, C. & Tian, H. (2016) An updated checklist of Orchidaceae for China, with two new national records. Phytotaxa 276 (1): 1 - 148. https: // doi. org / 10.11646 / phytotaxa. 276.1.1","Hayata, B. (1906) Supplements to the enumeration plantarum Formosanarum. Botanical Magazine (Tokyo) 20: 77 - 78."]}

Cymbidium sangii Aver. & V.C.Nguyen, sp. nov. (Fig. 5) Type:— VIETNAM, Lam Dong Province, Di Linh District, evergreen broad-leaved forest at an elevation of 800–900 m a.s.l., terrestrial herb, locally common, 22 October 2019, Nguyen Van Canh, AL 1134 (holotype LE01168112 https://en.herbariumle. ru/?t=occ&id=133898, isotypes LE01066643 https://en.herbariumle.ru/?t=occ&id=133881, LE01066644 https://en.herbariumle. ru/?t=occ&id=133882, analytical photos from living plants used for the preparation of the type specimen LE01061322 https:// en.herbariumle.ru/?t=occ&id=12436, LE01088315 https://en.herbariumle.ru/?t=occ&id=46953). Paratypes:— VIETNAM, herbarium specimen is prepared from a cultivated plant on 1 September 2022, L. Averyanov, T. Maisak, AL 1134.1 originated from a clone of the plant used for the preparation of the type specimens (herbarium voucher specimen LE01169533 https://en.herbariumle.ru/?t=occ&id=142651, analytical photos LE01123538 https:// en.herbariumle.ru/?t=occ&id=141845). Herb terrestrial, perennial, rosulate, rhizomatous. Stem erect, with (1)2–3(4) imbricate, cuneate, conduplicate cataphylls and 2–3 leaves; swelling at the base in form of an erect, epigeous, green, conoid pseudobulb (3.5)4–4.5(5) cm tall, (1.2)1.4–1.8(2) cm in diameter; naked with age; all stems densely clustered each other on a very short plagiotropic rhizome; with a dense nest of numerous thick, fleshy, white to dull grey, flexuose roots (5)6–7(8) mm in diameter. Cataphylls narrowly triangular to cuneate, acute to acuminate, (4)5–7(8) cm long, (0.8)1.2–2(2.4) cm wide, grassy greenish, becoming light gray brownish, papyraceous, and eventually fibrous with age. Leaves sessile, arching, dark glossy green, rigid or coriaceous, conduplicate, linear to narrowly lanceolate, (40)50–70(80) cm long, (1)1.2–2.8(3) cm wide, obscurely articulate at the base, tapering into an acute apex, evergreen around the year. Inflorescence lax erect raceme, (40)45–60(65) cm tall; peduncle arising from the base of pseudobulb, light grassy green, (15)20–27(30) cm long, with (3)4–5(6) scarious, lanceolate, acute, sterile bracts; rachis (18)20–30(35) cm long with (5)8–16(18) spirally arranged flowers; floral bracts pale green, narrowly triangular-lanceolate, acute, (0.8)1.2–1.6(2) cm long. Pedicel and ovary pale green, slender, at a wide angle to the rachis, (1.2)1.5–2(2.4) cm long, (1)1.2–1.4(1.6) mm in diameter, ovary slightly broadening distally, shallowly ribbed. Flowers widely opening, odorless, (7)8–9(11) cm across; sepals and petals light yellowish green, with one longitudinal purple brownish stripe, sometimes with few unclear purplish spots near the base; lip very light yellowish to almost white, with purple-brown marks and spots; column very light yellowish to almost white, with many longitudinal purple brown streaks at front; anther cap pale yellow. Sepals subsimilar, spreading, narrowly lanceolate to lanceolate, (3.8)4–5.4(5.6) cm long, (4.5)5(5.5) mm wide, 3-veined, acute to acuminate; lateral sepals slightly oblique, twisted at apex. Petals broader than sepals, spreading or slightly forward directed, broadly oblanceolate, slightly oblique, 5-veined, acute, (3.2)3.4–4(4.2) cm long, (6)7–8(9) mm wide. Lip narrowly oblong in outline, not fused to the column base, (2.3)2.4–2.7(3) cm long, (1)1.1–1.2(1.3) cm wide in widest part, 3-lobed; lateral lobes suberect, almost semicircular (2)2.2–2.6(2.8) mm tall, (6.5)7–8(8.5) mm broad; median lobe oblong, more than twice longer than side lobes, (1.6)1.8–2(2.2) cm long, (5)6–7(8) mm wide, strongly recurved, finely papillose; disk with 2 longitudinal glabrous keels extending from the middle of epichile to the base of median lobe, rising and connivent distally, forming an almost close tube. Column stout and short, slightly curved, (1)1.1–1.2(1.3) cm tall, slightly broadening toward the apex, with a small, concave stigma at the front. Anther cup hemispheric, 2.8–3 mm across, truncate at front. Pollinia 4, in 2 pairs, dull yellow, obscurely triangular, flattened, 1–1.2 mm across, with a small scarious triangular viscidium. Fruits erect, cylindric capsules, 3–3.5 cm long, about 6 mm in diameter, on a stalk 6–8 mm long. Ecology and phenology:—Perennial terrestrial herb. Primary and old secondary broad-leaved evergreen forests on granite at an elevations of 800–900 m a.s.l. Locally common. Flowers in July–November. Distribution:— VIETNAM, Lam Dong Province (Lac Duong District). Endemic. Conservation status:—Formally, the species may be estimated as globally Critically Endangered, CR: B1a,b(i-iii,v)+ 2a,b(i-iii,v); D. Available observations indicate that the species meets the following IUCN Red List categories and criteria (IUCN 2022): only one population was discovered, with the extent of occurrence (EOO) much less than 100 km 2 (B1a) and the area of occupancy (AOO) surely less than 10 km 2 in one known location (B2a); observed and expected continuing decline (b) of the extent of occurrence (i), the area of occupancy (ii), area, extent, and quality of habitat (iii), and the number of mature individuals (v); the population is very small, with the estimated number of mature individuals less than 50 (D). Notes:—The species is remarkable for its large flowers with an unusually long lip. Morphologically, it is most similar to C. kanran Makino (1902: 10), but differs in pseudobulbs with 2 (rarely 3) dark green, rigid, or coriaceous leaves, 1–3 cm wide (vs. pseudobulbs with 3–7 grassy green, leathery leaves, 9–17 mm wide), inflorescence distinctly longer than leaves bearing 5–18 flowers (vs. inflorescence as long as leaves, bearing 5–12 flowers), median lip lobe 16–22 mm long, 4–8 mm wide, more than twice longer than side-lobes (vs. median lip lobe 11–16 mm long, 8–12 mm wide, as long as side-lobes, or little longer), and shorter column, 10–13 mm long (vs. column 10–17 mm long). In the coloration of flowers, the new species is similar to C. munronianum King & Pantling (1895: 338), but has sepals, petals, and a lip twice as long, or longer. The new species has a stout, erect inflorescence with numerous widely opening attractive flowers and represents interest for cultivation as an ornamental plant perspective for breeding and further selection., Published as part of Averyanov, Leonid V., Nguyen, Van Canh, Truong, Ba Vuong, Nguyen, Khang Sinh, Nguyen, Cuong Huu, Maisak, Tatiana V., Doan, Nga Thi, Nguyen, Tuan Hoang, Pham, Van The, Dat, Pham Thi Thanh, Thai, Tran Huy, Nguyen, Van Khuong & Trinh, Ngoc Bon, 2023, New orchids in the flora of Vietnam VI (Orchidaceae, tribes Arethuseae, Cymbidieae, Diurideae, Epidendreae, Vandeae, and Vanilleae), pp. 87-110 in Phytotaxa 597 (2) on pages 96-99, DOI: 10.11646/phytotaxa.597.2.1, http://zenodo.org/record/7929197, {"references":["IUCN Standards and Petitions Committee (2022) 19) Guidelines for Using the IUCN Red List Categories and Criteria. Version 145. 1. Prepared by the Standards and Petitions Committee. Available from: https: // nc. iucnredlist. org / redlist / content / attachment _ files / RedListGuidelines. pdf; https: // www. iucnredlist. org / documents / RedListGuidelines. pdf (accessed 2 May 2023)","Makino, T. (1902) Observations on the flora of Japan. Botanica Magazine (Tokyo). 16: 10 - 16.","King, G. & Pantling, R. (1895) On some new orchids from Sikkim. Journal Asiatic Society of Bengal. 64 (2): 329 - 344."]}

Biermannia averyanovii (Vuong, Kumar, V.H. Bui, V.S.Dang in Pham et al.) Averyanov, comb. nov. ≡ Chamaeanthus averyanovii Vuong, Kumar, V.H. Bui & V.S.Dang in Pham et al. (2021: 132, fig. 1). Type:— VIETNAM. Son La Province: Thuan Chau District, 18 June 2021, Truong Ba Vuong, Bui Van Huong, BV 1194 (VNM 00069908). Notes:—We can not see any fundamental differences between Biermannia King & Pantling (1897: 591) and Chamaeanthus Schlechter ex J.J. Smith (1905: 552) except for insufficient variation on the length of the column foot. Following Seidenfaden & Wood (1992), we consider these genera congeneric and use here earlier valid name. Data on ecology, phenology, distribution, and conservation status for this species were reported earlier (Pham et al. 2021)., Published as part of Averyanov, Leonid V., Nguyen, Van Canh, Truong, Ba Vuong, Nguyen, Khang Sinh, Nguyen, Cuong Huu, Maisak, Tatiana V., Doan, Nga Thi, Nguyen, Tuan Hoang, Pham, Van The, Dat, Pham Thi Thanh, Thai, Tran Huy, Nguyen, Van Khuong & Trinh, Ngoc Bon, 2023, New orchids in the flora of Vietnam VI (Orchidaceae, tribes Arethuseae, Cymbidieae, Diurideae, Epidendreae, Vandeae, and Vanilleae), pp. 87-110 in Phytotaxa 597 (2) on page 101, DOI: 10.11646/phytotaxa.597.2.1, http://zenodo.org/record/7929197, {"references":["Pham, P. D., Kumar, P., Dang, V. S., Nguyen, D. H., Bui, V. H., Tu, B. N., Dang, M. Q. & Truong, B. V. (2021) Notes on the genus Chamaeanthus (Orchidaceae, Epidendroideae, Vandeae, Aeridinae) with a new species from Vietnam. Phytotaxa 524 (2): 131 - 134. https: // doi. org / 10.11646 / phytotaxa. 524.2.9","King, G. & Pantling, R. (1897) Some new Indo-Malayan orchids. Journal of the Asiatic Society of Bengal 66 (pt. 2): 578 - 605.","Smith, J. (1905 - 1914) Die Orchideen von Java. E. J. Brill, Leiden, 672 pp. https: // doi. org / 10.5962 / bhl. title. 86938","Seidenfaden, G. & Wood, J. J. (1992) The orchids of Peninsular Malaysia and Singapore. Olsen & Olsen, Fredensborg, 779 pp."]}

Miguelia shenzhenica (Z.J.Liu & S.C.Chen) Aver., comb. nov. (Fig. 10) ≡ Vanilla shenzhenica Z.J.Liu & S.C.Chen (2007: 301), Chen et al. (2009: 168), Barretto et al. (2011: 97), Zhou et al. (2016: 136). Type: — CHINA. Guangdong: Shenzhen, Longgang, Meishajian, alt. 300 m, on tree trunk and rock along a valley, 22 February 2005, Z. J. Liu 3025 (holotype NOCC). Ecology and phenology:—Creeping succulent herbaceous lithophytic or epiphytic vine. Primary and secondary lowland evergreen broad-leaved forests on shale and granite. Very rare. Flowers in March. Distribution:— VIETNAM, Thua Thien Hue Province (Phu Loc and Nam Dong districts within the territory of Bach Ma National Park), Da Nang City Area (Ba Na Mountain). SE China. Conservation status:—Only two locations of this easily recognizable species have been discovered in Vietnam untill now. They are located in the lowland areas of Bach Ma National Park and Ba Na–Nui Chua Nature Reserve in the central part of the country. Taking into consideration the high recreation pressure and vigorously increasing tourism activity in both areas, the species meets the following formal Red List IUCN (2022) criteria: observed population reduction for 10 years or 3 generation ≥ 80% are not reversible (A2), based on direct observation (a) and observed decline of the area of occupancy, extent of occurrence and habitat quality (c); the area of occurrence Notes:—This remarkable species is easily recognizable from other species of Miguelia Aver. (2011: 45) by its inflorescence, which regularly bears 4–5 simultaneously opening flowers distinctly larger than in other species of the genus. The plant has some interest in ornamental horticulture. Studied specimen:— VIETNAM, Thua Thien Hue Province, Bach Ma Nation Park, 18 March 2021, Phạm Th ị Thanh D ạt s.n. (LE01090412 https://en.herbariumle.ru/?t=occ&id=79882). VIETNAM, Da Nang City Area, Ba Na - Nui Chua Nature Reserve, Ba Na Mountain, evergreen broad-leaved lowland forest on granite at anelevation of about 500 m a.s.l., common in the area, March 2021, Nguyen Van Canh, s.n ., Published as part of Averyanov, Leonid V., Nguyen, Van Canh, Truong, Ba Vuong, Nguyen, Khang Sinh, Nguyen, Cuong Huu, Maisak, Tatiana V., Doan, Nga Thi, Nguyen, Tuan Hoang, Pham, Van The, Dat, Pham Thi Thanh, Thai, Tran Huy, Nguyen, Van Khuong & Trinh, Ngoc Bon, 2023, New orchids in the flora of Vietnam VI (Orchidaceae, tribes Arethuseae, Cymbidieae, Diurideae, Epidendreae, Vandeae, and Vanilleae), pp. 87-110 in Phytotaxa 597 (2) on page 107, DOI: 10.11646/phytotaxa.597.2.1, http://zenodo.org/record/7929197, {"references":["Chen, S. C., Liu, Z. J., Zhu, G. H., Lang, K. Y., Ji, Z. H., Luo, Y. B., Jin, X. H., Cribb, P. J., Wood, J. J., Gale, S. W., Ormerod, P., Vermeulen, J. J., Wood, H. P., Clayton, D. & Bell, A. (2009) Orchidaceae. In: Wu, Z. Y., Raven, P. H. & Hong, D. (Eds.) Flora of China, vol. 25. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis, pp. 211 - 235.","Barretto, G., Cribb, P. & Gale, S. (2011) The wild orchids of Hong Kong. Natural History Publications (Borneo), Kota Kinabalu, 715 pp.","Zhou, X., Cheng, Z., Liu, Q., Zhang, J., Hu, A., Huang, M., Hu, C. & Tian, H. (2016) An updated checklist of Orchidaceae for China, with two new national records. Phytotaxa 276 (1): 1 - 148. https: // doi. org / 10.11646 / phytotaxa. 276.1.1","IUCN Standards and Petitions Committee (2022) 19) Guidelines for Using the IUCN Red List Categories and Criteria. Version 145. 1. Prepared by the Standards and Petitions Committee. Available from: https: // nc. iucnredlist. org / redlist / content / attachment _ files / RedListGuidelines. pdf; https: // www. iucnredlist. org / documents / RedListGuidelines. pdf (accessed 2 May 2023)"]}

Tribe Cymbidieae Cymbidium cochleare Lindley (1858: 28), Pearce & Cribb (2002: 265, pl. 8), Liu et al. (2006: 149), Puy & Cribb (2007: 175), Chen et al. (2009: 272), Zhou et al. (2016: 38), Ormerod et al. (2021: 82). Type: — INDIA. Sikkim, Hooker 235 (holotype K000852995, isotype K000838851). (Figs. 3 D–F) Ecology and phenology:—Clustering epiphyte on mossy trees. Primary evergreen broad-leaved humid montane forests on sandstone at an elevations of 1500–1800 m a.s.l. Very rare. Flowers in October–December. Distribution:— VIETNAM, provinces Lai Chau (Sin Ho District), and Lam Dong (Lac Duong District). Bhutan, NE India, Bangladesh, Myanmar, China. Conservation status:—The national record of this species is based on a single herbarium specimen collected almost twenty years ago in the north-west and on a few cultivated plants collected recently in southern Vietnam. According to the formal criteria of the Red List IUCN (2022), based on scarcely available data, it may be assessed nationally as Critically Endangered (CR), meeting in Vietnam the following conditions: A2a,c; B1a,b(i-iii,v)+2a,b(i-iii,v); C1+2(i,ii); D1; observed population reduction for 10 years or 3 generation ≥ 80% are not reversible (A2), based on direct observation (a), observed decline of the area of occupancy, and extent of occurrence and habitat quality (b); the area of occurrence Notes:—A series of publications (Liu et al. 2006, Puy & Cribb 2007, Chen et al. 2009, Zhou et al. 2016, Ormerod et al. 2021) declare the occurrence of this species in Vietnam without citing any specimens from the country’s territory. Here we report this rare species based on the only verified herbarium collection known up to now. Studied specimen:— VIETNAM, Lai Chau Province, Sin Ho District, Ma Quai Municipality, Tua Vang mountain ridge, around point 22°24´01´´N 103°22´22´´E, broad-leaved evergreen closed wet primary forest on steep mountain slopes composed with sandstone at an elevation of 1500–1650 m a.s.l., clustering epiphyte on mossy trees on a shady mossy rocky slope, flowers light yellowish, rare, 18 November 2006, Nguyen Tien Hiep, L. Averyanov, Pham Van The, HAL 9950 (LE01059752 https://en.herbariumle.ru/?t=occ&id=11524, photos LE01088255 https://en.herbariumle. ru/?t=occ&id=46887). VIETNAM, Lam Dong Province, Lac Duong District, Bidoup Nui Ba National Park, humid evergreen broad-leaved mountain forest at an elevation of 1600–1800 m a.s.l., plant cultivated in Lam Dong Province near Ta Nung Pass, photo made on February 2022, Nguyen Van Canh, s.n. (LE01123801 https://en.herbariumle.ru/?t=occ&id=163346)., Published as part of Averyanov, Leonid V., Nguyen, Van Canh, Truong, Ba Vuong, Nguyen, Khang Sinh, Nguyen, Cuong Huu, Maisak, Tatiana V., Doan, Nga Thi, Nguyen, Tuan Hoang, Pham, Van The, Dat, Pham Thi Thanh, Thai, Tran Huy, Nguyen, Van Khuong & Trinh, Ngoc Bon, 2023, New orchids in the flora of Vietnam VI (Orchidaceae, tribes Arethuseae, Cymbidieae, Diurideae, Epidendreae, Vandeae, and Vanilleae), pp. 87-110 in Phytotaxa 597 (2) on pages 93-95, DOI: 10.11646/phytotaxa.597.2.1, http://zenodo.org/record/7929197, {"references":["Lindley, J. (1858) Contributions to the Orchidology of India. Journal of Proceedings of the Linnean Society, Botany 3: 1 - 63.","Pearce, N. R. & Cribb, P. J. (2002) The orchids of Bhutan. In: Flora of Bhutan. Vol. 3 (3). Royal Botanic Garden Edinburgh, UK & Royal Government of Bhutan, 643 pp.","Liu, Z. J., Chen, S. C. & Ru, Z. Z. (2006) The genus Cymbidium in China. Science Press, Beijing, 237 pp.","Du Puy, D. J. & Cribb, P. J. (2007) The genus Cymbidium. Royal Botanic Gardens, Kew, 359 pp.","Chen, S. C., Liu, Z. J., Zhu, G. H., Lang, K. Y., Ji, Z. H., Luo, Y. B., Jin, X. H., Cribb, P. J., Wood, J. J., Gale, S. W., Ormerod, P., Vermeulen, J. J., Wood, H. P., Clayton, D. & Bell, A. (2009) Orchidaceae. In: Wu, Z. Y., Raven, P. H. & Hong, D. (Eds.) Flora of China, vol. 25. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis, pp. 211 - 235.","Zhou, X., Cheng, Z., Liu, Q., Zhang, J., Hu, A., Huang, M., Hu, C. & Tian, H. (2016) An updated checklist of Orchidaceae for China, with two new national records. Phytotaxa 276 (1): 1 - 148. https: // doi. org / 10.11646 / phytotaxa. 276.1.1","Ormerod, P., Kurzweil, H. & Watthana, S. (2021) Annotated List of Orchidaceae for Myanmar. Phytotaxa 481: 1 - 262.","IUCN Standards and Petitions Committee (2022) 19) Guidelines for Using the IUCN Red List Categories and Criteria. Version 145. 1. Prepared by the Standards and Petitions Committee. Available from: https: // nc. iucnredlist. org / redlist / content / attachment _ files / RedListGuidelines. pdf; https: // www. iucnredlist. org / documents / RedListGuidelines. pdf (accessed 2 May 2023)"]}

Cymbidium macrorhizon Lindley (1833: 162), Seidenfaden (1992: 344), Pearce & Cribb (2002: 270, fig. 60, pl. 9), Liu et al. (2006: 231), Puy & Cribb (2007: 323), Schuiteman et al. (2008: 279), Chen et al. (2009: 279), Rokaya et al. (2013: 523), Jalal & Jayanthi (2015: 18), Lin et al. (2016: 91), Zhou et al. (2016: 40), Ormerod et al. (2021: 85). Type: —KASHMIR. Kashmir, icon. Role (holotype K000395362). (Fig. 4) = Cymbidium sikkimense auct. non Hooker (1890: 9): Gagnep. in Gagnepain & Guillaumin (1934: 412 p. p.), Seidenfaden (1973: 116). Ecology and phenology:—Achlorophyllous leafless terrestrial herb. Secondary coniferous forests and grassy woodlands derived from an old plantation of Pinus kesiya on granite at an elevations of 1300–1400 m a.s.l. Very rare. Flowers in April–May. Distribution:— VIETNAM, Lam Dong Province (Dalat Town Area). Pakistan, Nepal, Bhutan, N India, Myanmar, Thailand, Laos, China, Korea, Japan. Conservation status:—The only population of this species discovered in Vietnam occupies less than 500 m 2 of territory and according to the formal Red List IUCN (2022) criteria, it meets in Vietnam with the following conditions: extent of occurrence Notes:—All earlier records of this species for Phu Quoc Island treated in the past as a territory of Cambodia or Vietnam are based solely on one wrongly identified specimen (Ile de Phú Quốc, № 75, Contest-Lacour) housed in the P Herbarium (P00392341) and belonging in fact to C. finlaysonianum Lindley (1833: 164). No more records of this remarkable, easily recognizable species in these countries were reported. In this regard, our discovery is the first to be supported by herbarium material. Studied specimen:— VIETNAM, Lam Dong Province, Dalat Town area, secondary open grassy old coniferous forest and woodlands derived from old Pinus kesiya plantation at an elevation of 1300–1400 m a.s.l., erect terrestrial achlorophyllous aphyllous herb with inflorescences to 30 cm tall and thick rhizome to 25 cm long on a steep grassy slope, very rare, 31 May 2022, L. Averyanov, T. Maisak, Nguyen Van Khang, Truong Ba Vuong, Nguyen Huu Cuong, AL 1300 (LE01168960 https://herbariumle.ru/?t=occ&id=140407, photos LE01123416 https://herbariumle.ru/?t=occ&id=137206, LE01123417 https://herbariumle.ru/?t=occ&id=137207., Published as part of Averyanov, Leonid V., Nguyen, Van Canh, Truong, Ba Vuong, Nguyen, Khang Sinh, Nguyen, Cuong Huu, Maisak, Tatiana V., Doan, Nga Thi, Nguyen, Tuan Hoang, Pham, Van The, Dat, Pham Thi Thanh, Thai, Tran Huy, Nguyen, Van Khuong & Trinh, Ngoc Bon, 2023, New orchids in the flora of Vietnam VI (Orchidaceae, tribes Arethuseae, Cymbidieae, Diurideae, Epidendreae, Vandeae, and Vanilleae), pp. 87-110 in Phytotaxa 597 (2) on page 96, DOI: 10.11646/phytotaxa.597.2.1, http://zenodo.org/record/7929197, {"references":["Seidenfaden, G. & Wood, J. J. (1992) The orchids of Peninsular Malaysia and Singapore. Olsen & Olsen, Fredensborg, 779 pp.","Pearce, N. R. & Cribb, P. J. (2002) The orchids of Bhutan. In: Flora of Bhutan. Vol. 3 (3). Royal Botanic Garden Edinburgh, UK & Royal Government of Bhutan, 643 pp.","Liu, Z. J., Chen, S. C. & Ru, Z. Z. (2006) The genus Cymbidium in China. Science Press, Beijing, 237 pp.","Du Puy, D. J. & Cribb, P. J. (2007) The genus Cymbidium. Royal Botanic Gardens, Kew, 359 pp.","Schuiteman, A., Bonnet, P., Svengsuksa, B. & Barthelemy, D. (2008) An annotated checklist of the Orchidaceae of Laos. Nordic Journal of Botany 26: 257 - 316.","Chen, S. C., Liu, Z. J., Zhu, G. H., Lang, K. Y., Ji, Z. H., Luo, Y. B., Jin, X. H., Cribb, P. J., Wood, J. J., Gale, S. W., Ormerod, P., Vermeulen, J. J., Wood, H. P., Clayton, D. & Bell, A. (2009) Orchidaceae. In: Wu, Z. Y., Raven, P. H. & Hong, D. (Eds.) Flora of China, vol. 25. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis, pp. 211 - 235.","Rokaya, M. B., Raskoti, B. B., Timsina, B. & Munzbergova, Z. (2013) An annotated checklist of the orchids of Nepal. Nordic Journal of Botany 31: 511 - 550.","Jalal, J. S. & Jayanthi, J. (2015) An annotated checklist of the orchids of Western Himalaya, India. Lankesteriana 15 (1): 7 - 50.","Lin, T. - P., Liu, H. - Y., Hsieh, C. - F. & Wang, K. - H. (2016) Complete list of the native orchids of Taiwan and their type information. Taiwania 61 (2): 78 - 126. https: // doi. org / 10.6165 / tai. 2016.61.78","Zhou, X., Cheng, Z., Liu, Q., Zhang, J., Hu, A., Huang, M., Hu, C. & Tian, H. (2016) An updated checklist of Orchidaceae for China, with two new national records. Phytotaxa 276 (1): 1 - 148. https: // doi. org / 10.11646 / phytotaxa. 276.1.1","Ormerod, P., Kurzweil, H. & Watthana, S. (2021) Annotated List of Orchidaceae for Myanmar. Phytotaxa 481: 1 - 262.","Hooker, J. D. (1890) Orchidaceae. In: Hooker, J. D. (Ed.) The flora of British India 6. Reeve, London, pp. 1 - 198.","Seidenfaden, G. (1973) An enumeration of Laotian orchids. Bulletin du Museium national d'histoire naturelle ser. 3, 71 (5): 1 - 152.","IUCN Standards and Petitions Committee (2022) 19) Guidelines for Using the IUCN Red List Categories and Criteria. Version 145. 1. Prepared by the Standards and Petitions Committee. Available from: https: // nc. iucnredlist. org / redlist / content / attachment _ files / RedListGuidelines. pdf; https: // www. iucnredlist. org / documents / RedListGuidelines. pdf (accessed 2 May 2023)"]}

Cymbidium goeringii (Rchb.f.) Reichenbach (1852: 547), Pearce & Cribb (2002: 268), Liu et al. (2006: 195), Puy & Cribb (2007: 283), Chen et al. (2009: 276), Zhou et al. (2016: 40), Ormerod et al. (2021: 84). (Figs. 3 G–I) ≡ Maxillaria goeringii Reichenbach (1845: 334). Type: — JAPAN. Göring s.n. (holotype W, Herb. No. 45003). Ecology and phenology:—Terrestrial rosulate herb. Primary and secondary evergreen broad-leaved, mixed, and coniferous forests on rocky limestone. Very rare. Flowers in November–December. Distribution:— VIETNAM, Ha Giang Province (Quan Ba District). Bhutan, N India, Myanmar, China, Korea, Japan. Conservation status:—Available data on this species occurrence in Vietnam are very scarce. They give a tentative supposition on one or two close locations in a densely populated and highly deforested area. Considering extensive plant collecting and very high market demands, this species may be estimated as nationally Critically Endangered (CR). Formally, according to the Red List IUCN (2022) criteria, it currently meets in Vietnam the following conditions: A2ac; B1a,b,c(i-iii,v)+2a,b(i-iii,v); C1+2(i,ii); D1; observed population reduction for 10 years or 3 generation ≥ 80% are not reversible (A2), based on direct observation (a), observed decline of the area of occupancy, extent of occurrence and habitat quality (b), and actual levels of exploitation (c); the area of occurrence Notes:—Some Vietnamese plants differ from the type in their rigid, dark green linear leaves, somewhat longer scapes, and thick-textured, greenish flowers. On these characters, they fit with form, which sometimes is recognized as a separate variety, C. goeringii var. serratum (Schltr.) Y.S.Wu & S.C.Chen (1980: 300), or species, C. serratum Schleichter (1919: 73). Type: — CHINA. Guizhou, Esquiril, s.n. (holotype B, destroyed). This ornamental plant has a high demand in the market for wild-collected plants. However, it is difficult to cultivate in a warm tropical climate, and most attempts to grow at low elevations in Vietnam are unsuccessful. Studied specimen:— VIETNAM, Ha Giang Province, street market (also found in Lai Chou province), October 2022, Nguyen Van Canh, herbarium prepared on 25 November 2022, Nguyen Van Canh, L. Averyanov, T. Maisak, AL 1697 (LE01170149 https://herbariumle.ru/?t=occ&id=162849). VIETNAM, photo of the wild collected plant originated from Ha Giang Province, Quan Ba District, street market in November 2022 and cultivated in private Mr. Loc Bao Sang garden in Di Linh Town (Lam Dong Province), photo made on 2 December 2022 by L. Averyanov, N.V. Canh, T.B. Vuong, T. Maisak, AL 1901 (photo LE01123717 https://en.herbariumle.ru/?t=occ&ea=new). VIETNAM, Ha Giang Province, Quan Bạ District, inflorescence 1-flowered, flowers with a light sweet scent, 1 January 2023, Truong Ba Vuong, BV 1670 (photos LE01123803 https://en.herbariumle.ru/?t=occ&id=163454)., Published as part of Averyanov, Leonid V., Nguyen, Van Canh, Truong, Ba Vuong, Nguyen, Khang Sinh, Nguyen, Cuong Huu, Maisak, Tatiana V., Doan, Nga Thi, Nguyen, Tuan Hoang, Pham, Van The, Dat, Pham Thi Thanh, Thai, Tran Huy, Nguyen, Van Khuong & Trinh, Ngoc Bon, 2023, New orchids in the flora of Vietnam VI (Orchidaceae, tribes Arethuseae, Cymbidieae, Diurideae, Epidendreae, Vandeae, and Vanilleae), pp. 87-110 in Phytotaxa 597 (2) on pages 95-96, DOI: 10.11646/phytotaxa.597.2.1, http://zenodo.org/record/7929197, {"references":["Pearce, N. R. & Cribb, P. J. (2002) The orchids of Bhutan. In: Flora of Bhutan. Vol. 3 (3). Royal Botanic Garden Edinburgh, UK & Royal Government of Bhutan, 643 pp.","Liu, Z. J., Chen, S. C. & Ru, Z. Z. (2006) The genus Cymbidium in China. Science Press, Beijing, 237 pp.","Du Puy, D. J. & Cribb, P. J. (2007) The genus Cymbidium. Royal Botanic Gardens, Kew, 359 pp.","Chen, S. C., Liu, Z. J., Zhu, G. H., Lang, K. Y., Ji, Z. H., Luo, Y. B., Jin, X. H., Cribb, P. J., Wood, J. J., Gale, S. W., Ormerod, P., Vermeulen, J. J., Wood, H. P., Clayton, D. & Bell, A. (2009) Orchidaceae. In: Wu, Z. Y., Raven, P. H. & Hong, D. (Eds.) Flora of China, vol. 25. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis, pp. 211 - 235.","Zhou, X., Cheng, Z., Liu, Q., Zhang, J., Hu, A., Huang, M., Hu, C. & Tian, H. (2016) An updated checklist of Orchidaceae for China, with two new national records. Phytotaxa 276 (1): 1 - 148. https: // doi. org / 10.11646 / phytotaxa. 276.1.1","Ormerod, P., Kurzweil, H. & Watthana, S. (2021) Annotated List of Orchidaceae for Myanmar. Phytotaxa 481: 1 - 262.","Reichenbach, H. G. (1845) Notiz uber einige Orchideen der G ˆ ringschen Sammlung japanischer Pflanzen. Botanische Zeitung (Berlin) 3: 333 - 335.","IUCN Standards and Petitions Committee (2022) 19) Guidelines for Using the IUCN Red List Categories and Criteria. Version 145. 1. Prepared by the Standards and Petitions Committee. Available from: https: // nc. iucnredlist. org / redlist / content / attachment _ files / RedListGuidelines. pdf; https: // www. iucnredlist. org / documents / RedListGuidelines. pdf (accessed 2 May 2023)"]}

Tribe Epidendreae Cremastra malipoensis G.W. Hu (2013: 64), Zhou et al. (2016: 36). Type: — CHINA. Yunnan Province: Malipo County, Xiajinchang Village, 23°09´N, 104°51´E, alt. 1,300 m, under evergreen, broad-leaved forest, on a stony slope along stream, 4 March 2011, G.W. Hu HGW-00622 (holotype KUN, isotypes KUN, HNNU). (Fig. 7) Ecology and phenology:—Terrestrial herb. Primary evergreen broad-leaved forests on rocky limestone at an elevations of 1000–1600 m a.s.l., commonly along streams. Very rare. Flowers in February–March. Distribution:— VIETNAM, Ha Giang Province (Dong Van and Quan Ba districts). China (SE Yunnan). Conservation status:—This species is a typical local endemic of the central part of the region recognized as a South-Chinese floristic province (Averyanov et al. 2003). It is known for three very close locations near the border between Vietnam and China. The single known population in China is categorized under the ICUN criteria as Critically Endangered (Hu et al. 2013). In Vietnam, the species also has the same status following the next Red List IUCN (2022) conditions: observed population reduction for 10 years or 3 generations ≥ 80% are not reversible (A2), based on direct observation (a), observed decline of the area of occupancy, extent of occurrence and habitat quality (b), and actual levels of exploitation (c); the area of occurrence Notes:—This is an extremely rare species in rich primary limestone forests. It probably stands, in all its former areas, on the verge of full extinction. Studied specimen:— VIETNAM, Ha Giang Province, Quan Ba District, Cao Ma Po commune, Va Thang 2 village, lat. & long. 0430534X 2553087Y, elevation of 1620 m a.s.l., heavily disturbed primary limestone forest along a stream, terrestrial herb in a wet place, 50 cm tall; yellow flowers with purple-black spots, very rare; less than 10 individuals, 16 March 2018, Pham Van The, Trinh Ngoc Bon, Dinh Thi Kim Van, Dao Cong Anh, TB029 (photo LE01073002 http://en.herbariumle.ru/?t=occ&id=14200). VIETNAM, Ha Giang Province, Dong Van District, Van Chai Commune, evergreen broad-leaved forests at an elevation of about 1000 m a.s.l., 22.02.202 0, Nguyen Phong, Nguyen Hoang Tuan, s.n. (photo LE01073006 http://en.herbariumle.ru/?t=occ&id=14204)., Published as part of Averyanov, Leonid V., Nguyen, Van Canh, Truong, Ba Vuong, Nguyen, Khang Sinh, Nguyen, Cuong Huu, Maisak, Tatiana V., Doan, Nga Thi, Nguyen, Tuan Hoang, Pham, Van The, Dat, Pham Thi Thanh, Thai, Tran Huy, Nguyen, Van Khuong & Trinh, Ngoc Bon, 2023, New orchids in the flora of Vietnam VI (Orchidaceae, tribes Arethuseae, Cymbidieae, Diurideae, Epidendreae, Vandeae, and Vanilleae), pp. 87-110 in Phytotaxa 597 (2) on page 101, DOI: 10.11646/phytotaxa.597.2.1, http://zenodo.org/record/7929197, {"references":["Hu, G. - W., Long, C. - L. & Motley, T. J. (2013) Cremastra malipoensis (Orchidaceae), a new species from Yunnan, China. Systematic Botany 38 (1): 64 - 68. https: // doi. org / 10.1600 / 036364413 X 662033","Zhou, X., Cheng, Z., Liu, Q., Zhang, J., Hu, A., Huang, M., Hu, C. & Tian, H. (2016) An updated checklist of Orchidaceae for China, with two new national records. Phytotaxa 276 (1): 1 - 148. https: // doi. org / 10.11646 / phytotaxa. 276.1.1","Averyanov, L. V., Loc, P. K., Hiep, N. T. & Harder, D. K. (2003) Phytogeographic review of Vietnam and adjacent areas of Eastern Indochina. Komarovia 3: 1 - 83.","IUCN Standards and Petitions Committee (2022) 19) Guidelines for Using the IUCN Red List Categories and Criteria. Version 145. 1. Prepared by the Standards and Petitions Committee. Available from: https: // nc. iucnredlist. org / redlist / content / attachment _ files / RedListGuidelines. pdf; https: // www. iucnredlist. org / documents / RedListGuidelines. pdf (accessed 2 May 2023)"]}

Pelatantheria bicuspidata (Rolfe ex Downie) Tang & F.T.Wang (1951: 101), Seidenfaden (1988: 116), Chen et al. (2009: 457), Zhou et al. (2016: 105). Type: — THAILAND. FLORA OF SIAM, Chiengmai, 1000 ft., Me Sue, 1400 ft., August 8 1912, A.F.G. Kerr 151 (lectotype K000942419, designated here, isolectotype K000942420). (Fig. 9) ≡ Sarcanthus bicuspidatus Rolfe ex Downie (1925: 391), non Smith (1912: 84). Ecology and phenology:—Creeping epiphyte and lithophyte. Primary and secondary evergreen broad-leaved forests on limestone and sandstone at an elevations of 500–700 m a.s.l. Locally common. Flowers in May–July. Distribution:— VIETNAM, provinces Dien Bien (Muong Nhe District) and Son La (Mai Son District). Thailand, S China. Conservation status:—Discovered populations of this species do not currently exhibit a clear tendency to decrease, according to available collections and field observations. However, the deforestation, the decreasing habitat quality, and the occurrence area are observed obvious factors that may affect the species in the near future. According to our estimation, the conservation status of this species may be nationally Near Threatened (NT). The conservation status of this species outside Vietnam was not evacuated (NE). Notes:—The distribution of this species in Vietnam may be wider than reported here on the basis of verified herbarium specimens. Some herbarium specimens of this species may be mixed with doubtfully identified sterile specimens of the more common P. ctenoglossum Ridley (1896: 372), or P. insectifera (Reichenbach 1857: 159) Ridley (1896: 373). Among two type specimens housed at K Herbarium, the specimen K000942419, which has a better-preserved flower, is chosen as a lectotype. Studied specimen:— VIETNAM, Son La Province, Mai Son District, Hat Lot Town, around point 21°13´05´´N 104°06´44´´E, secondary evergreen dry open broad-leaved forest on very steep rocky slopes and tops of a remnant mountain composed with highly eroded marble-like solid crystalline limestone at an elevation of 550–650 m a.s.l., lithophytic herb on open rocky slope, common, 21 December 2010, L. Averyanov, P.K. Loc, P.V. The, N.T. Vinh, CPC 1148 (LE01074983 https://en.herbariumle.ru/?t=occ&id=45126, photos LE01123130 https://en.herbariumle. ru/?t=occ&id=136902); fl. in cult 17.06.202 2, L. Averyanov, CPC 1148 (LE01168945 https://en.herbariumle.ru/?t=occ&id=140381). VIETNAM, Dien Bien Province, Muong Nhe District, Muong Nhe Natural Reserve, Chung Chai Municipality, near Doan Ket Bridge, around point about 22º17´16´´N 102º23´58´´E, elevation of 550–650 m a.s.l., secondary evergreen broad-leaved lowland forest on mountain slopes composed with sandstone at an elevations of 550–650 m a.s.l., epiphyte on tall tree, not common, 20 May 2022, L. Averyanov, Tran Huy Thai, Khang Sinh Nguyen, T. Maisak, VR 1779 (LE01169003 https://en.herbariumle.ru/?t=occ&id=140480, photo LE01123344 https:// en.herbariumle.ru/?t=occ&id=137132)., Published as part of Averyanov, Leonid V., Nguyen, Van Canh, Truong, Ba Vuong, Nguyen, Khang Sinh, Nguyen, Cuong Huu, Maisak, Tatiana V., Doan, Nga Thi, Nguyen, Tuan Hoang, Pham, Van The, Dat, Pham Thi Thanh, Thai, Tran Huy, Nguyen, Van Khuong & Trinh, Ngoc Bon, 2023, New orchids in the flora of Vietnam VI (Orchidaceae, tribes Arethuseae, Cymbidieae, Diurideae, Epidendreae, Vandeae, and Vanilleae), pp. 87-110 in Phytotaxa 597 (2) on page 104, DOI: 10.11646/phytotaxa.597.2.1, http://zenodo.org/record/7929197, {"references":["Seidenfaden, G. (1988) Orchid genera in Thailand XIV. Fifty-nine Vandoid genera. Opera Botanica 95: 1 - 399.","Chen, S. C., Liu, Z. J., Zhu, G. H., Lang, K. Y., Ji, Z. H., Luo, Y. B., Jin, X. H., Cribb, P. J., Wood, J. J., Gale, S. W., Ormerod, P., Vermeulen, J. J., Wood, H. P., Clayton, D. & Bell, A. (2009) Orchidaceae. In: Wu, Z. Y., Raven, P. H. & Hong, D. (Eds.) Flora of China, vol. 25. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis, pp. 211 - 235.","Zhou, X., Cheng, Z., Liu, Q., Zhang, J., Hu, A., Huang, M., Hu, C. & Tian, H. (2016) An updated checklist of Orchidaceae for China, with two new national records. Phytotaxa 276 (1): 1 - 148. https: // doi. org / 10.11646 / phytotaxa. 276.1.1","Downie, D. C. (1925) Contributions to the flora of Siam. Add. XVI - XVII. Kew Bulletin 1925: 367 - 394, 404 - 423.","Smith, J. J. (1912) Sarcanthus Lndl. Und die nachstver-wandten Gattungen. Natuurkundig tijdschrift voor Nederlandsch Indie 72 (1): 79 - 115.","Ridley, H. (1896) The Orchideae and Apostasiaceae of the Malay Peninsula. Journal Linnean Society Botany 32: 213 - 416.","Reichenbach, H. G. (1857) Gartenorchideen. Botanische Zeitung (Berlin) 15: 157 - 159."]}

Parahellenia trongduyii Juan Chen, V.C.Nguyen, K.S.Nguyen & N.H.Xia, sp. nov. Diagnosis:—It is similar to P. tonkinensis, but differs in unbranched or barely branched (vs. densely branched) stems, narrowly triangularlanceolate (vs. broadly triangular) and glabrous (vs. densely pubescent) axillary buds, softly mucronate (vs. pungent, making a finger bleeding if touched) bract apex, yellow to whitish yellow labellum with longitudinal orange to red lines at center (vs. yellow labellum with longitudinal red lines at center), anther crest 9‒12 mm (vs. 3‒5 mm) long and slightly bilobed (vs. deeply bilobed) dorsal appendage of stigma. Type:— Collected from the material cultivated at V. C. Nguyen’s private garden on 25 August 2021, V. C. Nguyen & V. K. Nguyen CD 01 (holotype HN; isotypes HN, IBSC). Originally collected by T. D. Nguyen in July 2019 from Vietnam, Dak Lak Province, Krong Bong District, Chu Yang Sin National Park, Yang Mao Commune, along banks of small streams at elevations of 700‒900 m a.s.l. (Figs. 1‒3). Terrestrial evergreen perennial herb. Rhizome plagiotropic, tuberous, 2‒4 cm in diam., brown externally, white internally, glabrous. Leafy shoot 75‒140(‒250) cm tall, up to 3 cm in diam. at base. Stem more or less straight, erect to suberect, unbranched or barely branched at higher nodes. Axillary bud 1 at each node, narrowly triangular-lanceolate, 12‒15 × 5‒6 mm, green with red tip, glabrous. Bladeless sheaths closed, reddish brown, membranous, caducous, glabrous. Leaves 10‒20, consistently clustered toward the shoot apex; sheaths closed, pale green when young, later becoming reddish brown, glabrous; ligule 1.8‒2.5 mm long, glabrous, upper margin minutely fimbriate; petiole 0.9‒2.2 cm long, 0.8‒1 cm in diam., adaxially grooved, yellowish green, reddish brown at base, glabrous; blades 20‒35 × 5‒8 cm, the lowest ones obovate to oblanceolate, the upper ones oblanceolate to elliptic, base narrowly attenuate, apex acuminate, adaxial surface deep green, abaxial surface pale green, glabrous on both sides, midvein slight sunken adaxially and conspicuously raised abaxially. Inflorescence arising directly from the rhizome, 20‒25 cm long (including peduncle and bracts only), lax; peduncle horizontal to ascending, terete, 4‒6 cm long, 1.4‒1.6 cm in diam., bearing 4‒6 sheaths, sheaths tubular, coriaceous, reddish brown, glabrous; spike 16‒20 × 6‒9 cm, narrowly ellipsoid or nearly cylindrical; secondary peduncle very short, glabrous; bracts 4‒5 × 2‒2.5 cm, the lowest bracts broadly elliptic, the upper ones elliptic, cucullate, apex softly mucronate (not pungent), coriaceous, pale brown to reddish brown, glabrous, each subtending 1 flower with 1 bracteole; bracteoles 2.5‒2.8 × 0.7‒0.9 cm, narrowly lanceolate, apex acuminate to spiny (but not pungent), coriaceous, pale brown to reddish brown, glabrous. Flowers 8.5‒10 cm long; calyx 3.2‒4 cm long, coriaceous, pale green when young, becoming reddish brown when old, glabrous, tube 2.5‒3.3 cm long, 7‒9 mm in diam., lobes 3, 0.7‒1 × 0.6‒0.7 cm, broadly ovate, slightly involute, apex softly mucronate, pale green with reddish brown apex when young, becoming reddish brown when old; floral tube (from apex of ovary to base of divergence of corolla lobes) 2.2‒2.5 cm long, 0.3‒0.5 cm in diam., fused with style in basal 1.6 cm, white, glabrous externally; corolla lobes 4.3‒5 × 1.9‒2.2 cm, obovate, white, glabrous; staminal tube (from the point of divergence of corolla lobes to base of divergence of labellum and stamen) 1.4‒1.7 cm long, yellow, with dense yellow hairs internally, pubescent externally; labellum 6.5‒7.5 × 5.5‒6.5 cm, flabellate after full expansion, yellow to whitish yellow with longitudinal orange to red lines at center, covered with glutinous papillae at center and base, margin rugose and pubescent; stamen 3.2‒3.6 cm long (when crest flattened), 0.6‒1 cm wide, petaloid, oblong, yellow, adaxially concave, glabrous, abaxially slightly convex and thickened, with sparse long glandular hair; anther crest 0.9‒1.2 cm long, 5.5‒6.2 mm wide, oblong, strongly recurved to revolute on abaxial side, yellow with longitudinal red lines at adaxial side, broadly acute to obtuse at apex, margin pubescent; thecae 0.9‒1 cm long, 1.8‒2.4 mm wide in the middle, slightly broadening towards ends. Ovary inferior, 1.1‒1.4 cm long, 5‒6 mm in diam., glabrous, trilocular with axile placentation and apically embedded beige-coloured gynopleural nectaries, each locule with numerous ovules; style 4.5‒4.8 cm long (free part), glabrous; stigma 1.7‒1.8 mm long, 2.8‒3.3 mm wide, semi-circular, flattened, 2-lobed, lobes overlapping, white, margin ciliate, dorsal appendage slightly bilobed, white. Infructescence of almost the same size as inflorescence, often continuously formed (with fruits at base when flowers still anthetic at apex), with persistent bracts and bracteoles. Fruits 1.8‒2.2 cm long, 1.1‒1.2 cm in diam., nearly ellipsoid, reddish brown, glabrous, with persistent calyces. Seeds 3‒4 × 2‒2.3 mm, irregularly barrel-shaped, black, aril basal and not enclosing the seed, white. Phenology:—Flowering from June to August; fruiting from July and likely continuing till October. Etymology:—The specific epithet is named after Mr. Nguyen Trong Duy, who collected the living material of the species in its type locality. Suggested common names:—Mía dò Trọng Duy (Vietnamese), Øṃṁƛąae (duō lè dì wō sŭn huā) (Chinese). Distribution, habitat and conservation:—This species is currently known from Chu Yang Sin National Park in Dak Lak Province and Thach Nham protected forest in Kon Tum Province in Vietnam. Parahellenia trongduyii grows in shady, moist places along small streams, in evergreen broad-leaved forests at elevations of 700–900 m a.s.l. We observed five clumps of the species in Chu Yang Sin National Park, a protected area where agricultural activities and exploitation of non-timber forest products are prohibited. Due to lack of information on the distribution (extent of occurrence (EOO) or areas of occupancy (AOO)) and population size of P. trongduyii, its conservation status is assessed here as Data Deficient (DD), following the IUCN Red List Categories and Criteria (IUCN 2012). Notes:—As elaborated in the diagnosis, Parahellenia trongduyii closely resembles P. tonkinensis but is readily distinguished from it in the field even by vegetative characters, e.g., barely branched leafy shoots and narrowly triangular-lanceolate glabrous buds. Parahellenia trongduyii is also similar to P. candida, but differs in reddish brown (vs. brown) and glabrous (vs. densely puberulent) bladeless sheaths, glabrous (vs. puberulous) abaxial side of leaf blade, softly (vs. sharply) mucronate bract apex and yellow (vs. white) flowers. A detailed comparison is provided in Table 1. Additional specimen examined (paratype):— VIETNAM. Kon Tum Province: Kon Plong District, Thach Nham protected forest, 17 km N of Mang Den Town, near river, 14°45’26’’N 108°18’35’’E, 900 m, 8 June 2016, M. S. Nuraliev 1673 (MW: MW0753815) (Fig. 4)., Published as part of Chen, Juan, Nguyen, Van Canh, Nguyen, Van Khuong, Nguyen, Khang Sinh, Nuraliev, Maxim S. & Xia, Nianhe, 2023, Taxonomic studies on Parahellenia (Costaceae) in Vietnam: a new species, P. trongduyii, and a new combination, P. candida, pp. 72-80 in Phytotaxa 583 (1) on pages 73-79, DOI: 10.11646/phytotaxa.583.1.7, http://zenodo.org/record/7609199, {"references":["IUCN (2012) IUCN Red List Categories and Criteria: Version 3. 1. Second edition. Gland, Switzerland and Cambridge, UK, 32 pp."]}

Key to the species of Parahellenia in Vietnam 1. Leaf blade puberulent abaxially; labellum cream white...................................................................................................... P. candida - Leaf blade glabrous; labellum yellow with longitudinal orange to red markings at center...............................................................2 2. Plants unbranched or barely branched; bract apex with a soft mucro............................................................................. P. trongduyii - Plants densely branched; bract apex with a sharp mucro............................................................................................... P. tonkinensis, Published as part of Chen, Juan, Nguyen, Van Canh, Nguyen, Van Khuong, Nguyen, Khang Sinh, Nuraliev, Maxim S. & Xia, Nianhe, 2023, Taxonomic studies on Parahellenia (Costaceae) in Vietnam: a new species, P. trongduyii, and a new combination, P. candida, pp. 72-80 in Phytotaxa 583 (1) on page 79, DOI: 10.11646/phytotaxa.583.1.7, http://zenodo.org/record/7609199

Parahellenia candida (Škorničk., Böhmová & H.Ð.Trẫn) N.H.Xia & Juan Chen, comb. nov. Basionym:— Cheilocostus candidus Leong-Škorničková, Böhmová & Trẫn (2022: 105). Type:— VIETNAM. Lam Dong Province (cultivated in the Singapore Botanic Gardens, Singapore), collected from cultivation on 21 September 2021, Leong-Škorničková GRC-421 (holotype SING; isotypes E, P, SGN). Phenology:—Flowering in the natural habitat was observed in June; in cultivation, it extends to October; fruiting unknown. Distribution, habitat and conservation:—Endemic to Vietnam, occurring near rocky streams in lowland broadleaved evergreen forest, at elevations about 200– 300 m. According to Leong-Škorničková et al. (2022), there is no reliable information on the population sizes or distribution of this species. It was therefore treated as Data Deficient (IUCN 2012). Notes:— Parahellenia candida is characterized by unbranched or barely branched stems, radical inflorescence, long and narrow floral tube fused with the style base more than halfway (assessed from Fig. 2 in Leong-Škorničková et al. 2022) and bilamellate stigma. With these features, this species fits well the concept of the genus Parahellenia. Parahellenia candida is very similar to P. tonkinensis in producing the inflorescence radically, obovate to elliptic leaf blades and bract apex with a sharp mucro, but can be distinguished easily from the latter by its unbranched or barely branched leafy shoots, densely puberulent leaf sheaths, densely puberulous abaxial side of leaf blade and white flowers (Leong-Škorničková et al. 2022)., Published as part of Chen, Juan, Nguyen, Van Canh, Nguyen, Van Khuong, Nguyen, Khang Sinh, Nuraliev, Maxim S. & Xia, Nianhe, 2023, Taxonomic studies on Parahellenia (Costaceae) in Vietnam: a new species, P. trongduyii, and a new combination, P. candida, pp. 72-80 in Phytotaxa 583 (1) on page 73, DOI: 10.11646/phytotaxa.583.1.7, http://zenodo.org/record/7609199, {"references":["Leong-Skornickova, J., Bohmova, A. & Tr an, H. D. (2022) A new species and new combination in basally flowering Vietnam Costaceae. PhytoKeys 190: 103 - 111. https: // doi. org / 10.3897 / phytokeys. 190.76494","IUCN (2012) IUCN Red List Categories and Criteria: Version 3. 1. Second edition. Gland, Switzerland and Cambridge, UK, 32 pp."]}

Cleisostoma equestre Seidenfaden (1992: 393). (Figs. 1 H, I, 2) Type: — VIETNAM. S Vietnam, Soviet-Vietnamese Expedition, Province Quangnam – Danang, Da Nang, Son Tra, 09.07.1986, LX-VN 0-14, fl. et coll. in horto 25 11 1987, herbarium prepared by Averyanov L., 1987) – LE (holotype – LE01059075 https://en.herbariumle.ru/?t=occ&id=9915, epitype – LE01059069 https://en.herbariumle. ru/?t=occ&id=9909, photos – LE01088036 https://en.herbariumle.ru/?t=occ&id=46070). Habitat, phenology and conservation status. Epiphyte. Broad-leaved evergreen lowland forests on granite at elevation of 50–400 m a.s.l. Fl. June–July. Very rare. Suggested IUCN Red List status – DD. Distribution. Central Vietnam (Da Nang City Area). Endemic. Note. This species, very curious for its unusual column and pollinarium structure, was described thirty years ago on the basis of rather insufficient material collected from cultivated plants originating from Son Tra Island. Recently, it was rediscovered on the continent also near Da Nang City in forest of Ba Na Mountain in 20 km to the SW from the locus classicus. The new collection provides additional data on the floral morphology of this extremely rare species, which is presented below in the form of an amended description and fig. 2. More surveys are needed to check the presence of this species in adjoining areas. Accordingly, based on IUCN (2019) C. exuestre should be formally estimated as Data Deficient – DD. Amended description. Flowers not widely opening, campanulate, (9.5)10–11(11.5) mm across; sepals and petals rather fleshy, glabrous, white with two broad purple-brown longitudinal stripes, or with entirely purple-brown center; lip including spur white, with few purple speckles on lobes, bright yellow at base. Sepals obovate, concave, blunt to obtuse, (6)6.2–6.4(6.5) mm long, (3.6)3.8–4.2(4.4) mm wide, median sepal cucullate, lateral sepals slightly oblique. Petals narrowly obovate, almost flat, blunt to round at apex, (5.4)5.6–6(6.2) mm long, (2)2.2–2.4(2.6) mm wide, slightly oblique. Lip spurred, (6.8)7–7.8(8) mm long (from spur apex to the apex of epichile), 3-lobed; sidelobes broadly triangular, obtuse, forward protruding, 2.4–2.5 mm long and wide at the base; median lobe fleshy, halfglobular, 2–2.2 mm long, 3–3.5 mm wide, forward directed, round or obscurely trilobe at apex, at base with prominent uprising conoid callus; spur saccate, almost parallel to ovary, 4–4.2 mm long, 2.8–3 wide, slightly dorso-ventrally flattened, with round, slightly emarginate apex and incomplete longitudinal septum inside. Back-wall callus in form of large, erect, T-shaped, flattened, papillose outgrowth about (1.6)1.8–2(2.2) mm tall, at apex with two recurved conoid horns, at base connected with fleshy side-lobes by fleshy papillose rollers. Column short, broad, obscurely cubic, (3.6)3.8–4(4.2) mm high, (1.8)2–2.2(2.4) mm wide, at front with small rostellum lobes supporting viscidium horns; stigma in form of transversely oblong hollow. Anther cap helmet shaped, skinny, sac-like, 2.2–2.4 mm tall and wide, without beak. Pollinia 2, each deeply split into 2 half-globular bodies. Stipe (tegula) in form of circular scarious plate 1.8–2 mm in diameter (being flattened), enveloping pollinia in form of narrow funnel after removing anther cap, viscidium in form of two narrow subulate forward directed acute horns 0.8–0.9 mm long. Studied specimen. Vietnam, Da Nang City Area, Ba Na Mt., evergreen broad-leaved forest at elevation of 300–400 m a.s.l., epiphyte, rare, June 2019, Nguyen Van Canh, AL 1123a (LE01167438 https://en.herbariumle.ru/?t=occ&id=133067, drawings LE01123081 https://en.herbariumle.ru/?t=occ&id=133320, photos LE01123087 https:// en.herbariumle.ru/?t=occ&id=134257)., Published as part of Averyanov, Leonid V., Thai, Tran Huy, Truong, Ba Vuong, Nguyen, Van Canh, Nguyen, Tuan Hoang, Maisak, Tatiana V., Nguyen, Khang Sinh & Nguyen, Van Khuong, 2022, New orchids in the flora of Vietnam (Orchidaceae, Aeridinae), pp. 113-135 in Phytotaxa 555 (2) on page 118, DOI: 10.11646/phytotaxa.555.2.1, http://zenodo.org/record/6875853, {"references":["Seidenfaden, G. & Wood, J. J. (1992) The orchids of Peninsular Malaysia and Singapore. Fredensborg, Olsen & Olsen, 779 pp.","IUCN Standards and Petitions Subcommittee (2019) Guidelines for using the IUCN Red List categories and criteria Ver. 14. Available from: https: // cmsdocs. s 3. amazonaws. com / RedListGuidelines. pdf (accessed 1 May 2022)"]}

Trichoglottis maculata (Smith) Smith (1918: 106). ≡ T. lanceolaria Blume (1825: 360) var. maculata Smith (1905: 619). = T. lanceolaria auct. non Blume, 1825: Averyanov & Averyanova (2003: 59). (Figs. 8 E, F) Type: — INDONESIA. Java: Bobodjong (J. J. S.); Goenoeng Batoe (not located). Habitat, phenology and conservation status: —Epiphyte. Broad-leaved evergreen lowland forests at elevations 300–400 m a.s.l. Fl. April–June. Very rare. Suggested IUCN Red List status – EN. Distribution: —Southern Vietnam (Dong Nai, Dak Lak and Lam Dong provinces), Thailand, Cambodia, Malaysia, E Indonesia. Note: —The discovery of this species in three locations in Dak Lak, one in Lam Dong, and one in Dong Nai Provinces is not much surprising. Vietnamese records naturally extend the known area of this species typical for lowland warm-loving forests of the southern part of Indochinese Peninsula to the east. Field observations in all recorded locations indicate this species in Vietnam as a very rare plant presented by very small, highly fragmented populations. According to discovered locations closely allied to each other, the area of its occurrence (EOO) in Vietnam are surely less than 10000 km 2, and the area of the species occupancy (AOO) in all five known populations may be very small due to intensive deforestation and agricultural land exploitation in the area of the species occurrence. The wide loss of habitats identify the tentative conservation status of this species as a nationally Endangered – EN A3(c), B1ab(i, iii), B2ab(i, iii) according to formal IUCN criteria (IUCN 2019). Studied specimens: — VIETNAM, Dac Lac Province, Buon Don District, Krong Na Municipality, Yok Don National Park, Yok Don Ridge around point 12º51’12”N 107º41’18”E, primary dry evergreen forest on thin gray soils derived from sandstone with quartzite dykes along ridge edge at elevation 300–350 m a.s.l., epiphyte on shady place, rare, 18 March 2008, N.T.Hiep, Averyanov L., P.K.Loc, N.T.Vinh, N.S.Khang, T.H. Thai, N.V. Trai HLF 7183, flowered in Hanoi in Hiep Garden at June 2009 (photos LE01122270 https://en.herbariumle.ru/?t=occ&id=82753). VIETNAM, Dak Lac Province, Krong No, Nguyen Van Canh s.n. photo 06 June 2015 (photos LE01122267 https://en.herbariumle. ru/?t=occ&id=82747). VIETNAM, Dak Lak Province, Krong Bong Commune, Pham Dinh Hiep, Nguyen Hoang Tuan s.n. 25.04.2018 (LE01076457 https://en.herbariumle.ru/?t=occ&id=57337, photos LE 01087096 https:// en.herbariumle.ru/?t=occ&id=18618). VIETNAM, Dong Nai Province, sine loc., 9 July 2020, Truong Ba Vuong, BV 685 (VNM, photos LE01087104 https://en.herbariumle.ru/?t=occ&id=18627). VIETNAM, Lam Dong Province, Bao Loc District, 14 July2020, Dinh Quang Diep, s.n. (photos LE01087095 https://en.herbariumle.ru/?t=occ&id=18617), Published as part of Averyanov, Leonid V., Thai, Tran Huy, Truong, Ba Vuong, Nguyen, Van Canh, Nguyen, Tuan Hoang, Maisak, Tatiana V., Nguyen, Khang Sinh & Nguyen, Van Khuong, 2022, New orchids in the flora of Vietnam (Orchidaceae, Aeridinae), pp. 113-135 in Phytotaxa 555 (2) on page 129, DOI: 10.11646/phytotaxa.555.2.1, http://zenodo.org/record/6875853, {"references":["Smith, J. J. (1918) Die Orchideen von Java. Bulletin du Jardin botanique de Buitenzorg Ser. 2, 26: 1 - 135.","Blume, C. L. (1825) Bijdragen tot de flora van Nederlandsch Indie ¨. Batavia, Ter Lands Drukkerij, 1169 pp. https: // doi. org / 10.5962 / bhl. title. 115427","Smith, J. J. (1905) Die Orchideen von Java. Leiden, E. J. Brill, 672 pp. https: // doi. org / 10.5962 / bhl. title. 86938","Averyanov, L. V. & Averyanova, A. L. (2003) Updated checklist of the orchids of Vietnam. Vietnam National University Publishing House, Hanoi, 102 pp.","IUCN Standards and Petitions Subcommittee (2019) Guidelines for using the IUCN Red List categories and criteria Ver. 14. Available from: https: // cmsdocs. s 3. amazonaws. com / RedListGuidelines. pdf (accessed 1 May 2022)"]}

Schoenorchis hungii Aver., V.C.Nguyen & Vuong, sp. nov. (Fig. 7) Type: — VIETNAM. Type herbarium specimen prepared on 25 April 2020 by L. Averyanov, T. Maisak, AL 410 from cultivated plants collected in Lam Dong Province, Bidoup Nui Ba National Park, evergreen broad-leaved forest, at 1500–1600 m a.s.l. on 2 September 2018, Nguyen Van Canh (holotype LE01068479 https://en.herbariumle.ru/?t=occ&id=16592). Authentic photos: — VIETNAM. Photos are made on 25 April 2020 by L. Averyanov, T. Maisak, AL 410 from cultivated plants collected in Lam Dong Province, Bidoup Nui Ba National Park, evergreen broad-leaved forest, at 1500– 1600 m a.s.l. on 2 September 2018, Nguyen Van Canh s.n. (LE 01122887 https://en.herbariumle.ru/?t=occ&id=99509, LE 01073077 https://en.herbariumle.ru/?t=occ&id=15213). Etymology: —The species name refers to Mr. Do Tuan Hung for his great contribution to the conservation of Vietnamese orchids. Description:—Herb miniature monopodial, branch and canopy epiphyte. Stem simple, suberect or ascending (3)4–6(7) cm long, leafy in apical two thirds, with internodes (1.8)2–4(4.5) mm, leafless in basal part, (2)2.5(3) mm in diameter, with few, flexuose whitish roots near the base. Leaves grassy green, finely rugose, sessile, very fleshy, spreading at a wide angle to stem, arching, subterete, adaxially grooved, (1.5)2–3(3.5) cm long, (1.8)2–2.8(3) mm in diameter, acute, slightly constricted near of articulation with leaf sheath; leaf sheaths equitant, rigid, verruculose, completely covering the stem. Inflorescence axillary, suberect or ascending raceme, rarely 1–2 branched panicle, (5)5.5–6.5(7) cm long, scape and rachis light grassy green; scape (2)2.5–3.5(4) cm long, more or less straight; rachis straight or somewhat arching, thin, slightly angled, (1)2–3(3.2) cm long, with many spirally arranged, subdense flowers, distant at (0.6)1(1.4) mm. Floral bracts relatively large, white, light green along median rib, rhomboid, (1.8)2–2.5(2.7) mm long, (1.7)1.8–2(2.2) mm wide, shortly fimbriate along the margin, cuspidate, with prominently attenuate apex. Pedicel and ovary light green, (1.2)1.3–1.4(1.5) mm long, about 0.4–0.5 mm in diameter, terete, glabrous. Flowers odorless, tubular, with recurved apical third of sepals and petals, (1.6)1.8–2(2.2) mm across; sepals white, median sepal with purple apex, lateral sepals with purple median longitudinal stripe; petals entirely bright purple, lip including spur snow-white, column green, anther cap and pollinia bright yellow. Sepals narrowly ovate, little concave, dorsally slightly carinate, blunt to roundish at apex, (1.5)1.6–1.8(1.9) mm long, 0.6–0.7 mm wide, lateral sepals slightly oblique. Petals oblong broadly lanceolate, rounded to blunt at apex, as long as median sepal, 0.3–0.4 mm wide, distally strongly recurved. Lip spurred, (2.6)2.8–3(3.2) mm long (from spur apex to the apex of median lobe), almost entire; median lobe very fleshy, narrowly obovate (when look from below), rhomboid (from side view), 1.4–1.6 mm long, 0.5–0.6 mm wide, round at apex, straight, forward directed; at the base with 2 massive fleshy lateral longitudinal rollers almost completely closing entrance to the spur. Spur shortly conoid, slightly upcurved, parallel to ovary, (1)1.1–1.2(1.3) mm long, about 0.5 mm wide, with no longitudinal septum or back-wall callus inside. Column stout, very short, 0.2–0.3 mm tall and wide, with no wings; rostellum very small, broad, forward directed; stigma obscurely triangular to roundish. Anther cap, hemispherical, 0.2–0.3 mm in diameter, with prominent triangular, obtuse, forward directed beak about 2 mm long. Pollinarium 1, with 2 pollinia, flat oblong stipe (tegula) and flat oblong narrowly ovate viscidium. Pollinium ovoid or globular, splitting into 2 unequal hemiovoid lobes. Fruit unknown. All measurements were taken on fresh floral parts, which become about 1/3 smaller after exsiccation in process of herbarium specimen preparation (Averyanov et al. 2019e). Habitat, phenology and conservation status: —Miniature branch and canopy epiphyte on tall mossy trees. Evergreen broad-leaved submontane and montane forests at 1000–1800 m a.s.l. Rare. Flowers in April–May, October– November. Suggested IUCN Red List status – EN. Distribution: — VIETNAM, Lam Dong Province (Lac Duong and Lam Ha districts). Endemic. Notes: —The new species, like Schoenorchis tatonii Aver. in Averyanov et al. (2019: 295)recently described from the same area, represents one another local sympatric race of the widespread S. gemmata (Lindley 1838: 50) J.J. Smith (1912: 100) endemical to the mountain area known in Vietnamese geography as Central Highlands, or Tay Nguyen Plateau (Averyanov et al. 2003). In its morphology the new species clearly differs from S. gemmata in the small dimensions of the whole plant, with the stem 3–7 cm long having internodes (1.8)2–4(4.5) mm (vs. stem 5–15 cm long, with internodes 7–15 mm long), fleshy, subterete leaves 1.5–3.5 cm long and 1.8–3 mm in diameter (vs. distinctly dorso-ventrally flattened, conduplicate, more or less flat, 5–10 cm long, 5–12 mm wide), inflorescence simple, rarely 1–2 branched, 5–7 cm long (vs. inflorescence almost always branching, 8–15 cm long), floral bracts relatively large, rhomboid, cuspidate, enveloping pedicel and ovary, reaching middle of median sepal, much longer than ovary, finely fimbriate along the margin (vs. floral bract small, triangular, acute, not enveloping and twice shorter than pedicel and ovary, with entire margin), pedicel and ovary light green, 1.2–1.5 mm long (vs. pedicel and ovary green to dirty violet, about 3 mm long), flowers (1.6)1.8–2(2.2) mm across, sepals and petals distinctly recurved in apical half (vs. flowers 3–4 mm across, sepals and petals straight or slightly recurved at apex), sepals white with purple apex of median sepal and light purple stripe on lateral sepals, petals bright purple, lip including spur white (vs. sepals and petals entirely dull lilac violet, lip white often with lilac violet tint), sepals and petals 1.5–1.9 mm long (sepals and petals 2–2.5 mm long), lip almost entire, narrowly obovate, hardly broadening from hypochile, 0.5–0.6 mm wide (vs. obscurely lip 3-lobed, median lobe broadly obovate or flabellate rhomboid, twice broader than hypochile, 1–1.2 mm wide), spur 1–1.3 mm long, about 0.5 mm wide (spur about 2 mm long and 1.5 mm wide), and column 0.2–0.3 mm tall (vs. column 0.6–0.8 mm tall). Schoenorchis hungii is undoubtedly very rare. Up to now it was collected only in three close localities in the densely populated and currently highly urbanized Lac Duong and Lam Ha districts of Lam Dong Province in the center of southern Vietnam. Taking into consideration the vast deforestation in both provinces the estimated extent of occurrence (EOO) is probably limited by the territory of Bidoup – Nui Ba National Park. In this connection, it cannot be larger than 700 km 2 area of occupancy (AOO) is 12 km 2 in terms of IUCN (2019). According to available data and following to criteria proposed by IUCN the conservation status of the new species may be preliminarily estimated as Endangered – EN B2ab(iii) (IUCN 2019). Studied specimens: — VIETNAM, herbarium specimen prepared on 10.11.2019 by L. Averyanov, AL 1221 from cultivated plant collected in Lam Dong Province, Lam Ha District, evergreen broad-leaved submontane forest at elevation about 1000 m a.s.l., epiphyte on tall trees, Ngo Quang Dang s.n, 28 October 2019 LE01066612 https:// en.herbariumle.ru/?t=occ&id=12381. VIETNAM, Lam Dong Province, Bidoup Nui Ba National Park, Bidoup Mountains, primary evergreen broad-leaved forest at elevation 1700–1800 m a.s.l., epiphyte on tall mossy tree, not common. 2019, Nguyen Van Canh, AL 1113, LE01167750 https://en.herbariumle.ru/?t=occ&id=133079., Published as part of Averyanov, Leonid V., Thai, Tran Huy, Truong, Ba Vuong, Nguyen, Van Canh, Nguyen, Tuan Hoang, Maisak, Tatiana V., Nguyen, Khang Sinh & Nguyen, Van Khuong, 2022, New orchids in the flora of Vietnam (Orchidaceae, Aeridinae), pp. 113-135 in Phytotaxa 555 (2) on pages 127-128, DOI: 10.11646/phytotaxa.555.2.1, http://zenodo.org/record/6875853, {"references":["Averyanov, L. V., Truong, B. V., Nguyen, V. C., Nguyen, K. S. & Maisak, T. V. (2019 e) New orchids (Orchidaceae) in the flora of Vietnam II. Vandeae. Taiwania 64 (3): 285 - 298.","Lindley, J. (1838) 88. Saccolabium gemmatum. Edwards's botanical register 24: 50.","Smith, J. J. (1912) Sarcanthus Lindl. und die nachstverwandten Gattungen. Natuurkundig tijdschrift voor Nederlandsch Indie 72: 79 - 115.","IUCN Standards and Petitions Subcommittee (2019) Guidelines for using the IUCN Red List categories and criteria Ver. 14. Available from: https: // cmsdocs. s 3. amazonaws. com / RedListGuidelines. pdf (accessed 1 May 2022)"]}

Chiloschista parishii Seidenfaden (1988: 176) var. minutiflora Aver., N.H.Tuan & V.C.Nguyen var. nov. (Figs. 1 C, D) Type: — VIETNAM. S Vietnam, Dak Nong Province, Krong No District, Nam Nung Commune, shrubs along streams in evergreen forest at elevation 800–900 m a.s.l., flowers in April – May, 13 April 2018, Nguyen Van Canh, Nguyen Hoang Tuan, s.n. (holotype LE01042185 https://en.herbariumle.ru/?t=occ&id=332, photos LE01123088 https:// en.herbariumle.ru/?t=occ&id=134258). Etymology: —Variety name refers small size of its flowers. Description:—Herb leafless, miniature, monopodial, with stem 3–4 mm long and many dense, flexuose, tufted, gray green roots 4–10 cm long. Inflorescence hairy, 2–2.5 cm long; scape 1.2–1.4 cm long, with 2–5 distant sterile triangular scarious bracts. Rachis 8–10 mm long with (2)3(4) flowers; floral bracts triangular, acute, scarious 1.5–2 mm long. Pedicel and ovary 1.8–2.2 mm long. Flowers yellowish, tepals speckled with brown, widely opening, 5.5–6 mm across; median sepal elliptic ovate, (3.4)3.5(3.6) mm long, (2.6)2.7(2.8) mm wide; lateral sepals distinctly smaller, obliquely broadly ovate, (2.1)2.2(2.3) mm long, (1.9)2(2.1) mm wide; petals triangular broadly ovate, (2.7)2.8(2.9) mm long and wide; lip 3-lobed, 1.5–1.6 mm long with erect obovate side-lobes (1.3)1.4(1.5) mm long. Fruit unknown. Habitat, phenology and conservation status: —Epiphyte. Broad-leaved evergreen submontane forests and shrubs at elevations of 800–900 m a.s.l. Fl. April–May. Very rare. Suggested IUCN Red List status – DD. Distribution: —Southern Vietnam (Dak Nong Province, Krong No District). Endemic. Note: — Chiloschista parishii described from Myanmar (Seidenfaden 1988) has a wide distribution in India, Nepal, Bhutan, Myanmar, China, Thailand, Laos and Vietnam. This species is very variable in floral morphology and coloration, and has relatively large flowers, commonly 8–12 mm across (Pearce & Cribb 2002). Such plants were observed and collected in many areas in Vietnam, however, the small flowering variety recently discovered there has not been reported before. It has very similar floral structure to the typical variety C. parishii var. parishii, but differs in all parts of the flower, which are twice smaller, namely flower 5.5–6 mm across (vs. flowers 8–12 mm across), median sepal 3.4–3.6 mm long (vs. median sepal 5–6 mm long), lateral sepals 2.1–2.3 mm long (vs. lateral sepals 4–5 mm long), petals 2.7–2.9 mm long (vs. 5–6 mm long), and lip 1.5–1.6 mm long with side-lobes 1.3–1.5 mm tall (vs. lip and side-lobes 2.5–3 mm long). The new variety has so far only been found in the type locality and may be regarded as a narrow endemic. However, this small and unattractive plant may have a broader distribution but has possibly been overlooked. Under these circumstances, the IUCN conservation status may be tentatively assessed as Data Deficient DD.

Pomatocalpa undulatum (Lindley) J.J. Smith (1912: 107). ≡ Saccolabium undulatum Lindley (1833: 222). (Figs. 8 A, B) Type: — BANGLADESH. Sylhet, Wallich 7301 (syntypes K001127133 & K001127134). Habitat, phenology and conservation status: —Epiphyte. Broad-leaved evergreen. Fl. February–March. Very rare. Suggested IUCN Red List status – DD. Distribution: —Northern Vietnam (Thanh Hoa Province, Quan Son District), NE India, Bangladesh, E China. Note: —The distribution and conservation status of this species here newly recorded from Vietnam remains very unclear. Its discovery in Vietnam is not surprising as it was recorded from adjacent regions of mainland China and from Taiwan (Zhou et al. 2016, Lin et al. 2016). Meanwhile, without flowers, it may be easily confused with the widespread and common species, P. spicatum Breda (1827 t. 15). Hence, the distribution of this rather unattractive species in Vietnam may be much broader than it is indicated by this single record. As a result, the conservation status of this species should be assessed as the Data Deficient – DD, according to the formal IUCN criteria (IUCN 2019). Studied specimens: — VIETNAM, Thanh Hoa Province, Quan Son District, Pu Man Forest, epiphyte, leaf margin undulate, apex unequally 2-lobed, flowers glabrous, slightly fragrant, tepals white, purple spotted, lip white, 26.02.2020, Truong Ba Vuong, BV 517 (LE01073013 https://en.herbariumle.ru/?t=occ&id=14362)., Published as part of Averyanov, Leonid V., Thai, Tran Huy, Truong, Ba Vuong, Nguyen, Van Canh, Nguyen, Tuan Hoang, Maisak, Tatiana V., Nguyen, Khang Sinh & Nguyen, Van Khuong, 2022, New orchids in the flora of Vietnam (Orchidaceae, Aeridinae), pp. 113-135 in Phytotaxa 555 (2) on pages 126-127, DOI: 10.11646/phytotaxa.555.2.1, http://zenodo.org/record/6875853, {"references":["Smith, J. J. (1912) Sarcanthus Lindl. und die nachstverwandten Gattungen. Natuurkundig tijdschrift voor Nederlandsch Indie 72: 79 - 115.","Zhou, Z., Cheng, Z., Liu, Q., Zhang, J., Hu, A., Huang, M., Hu, C. & Tian, H. (2016) An updated checklist of Orchidaceae for China, with two new national records. Phytotaxa 276 (1): 1 - 148. https: // doi. org / 10.11646 / phytotaxa. 276.1.1","Lin, T. - P., Lui, H. - Y., Hsieh, C. - F. & Wang, K. - H. (2016) Complete list of the native orchids of Taiwan and their type information. Taiwania 61 (2): 78 - 126.","Breda, J. G. S. (1827 - 1829) Genera et Species Orchidearum et Asclepiadearum. Batavia, 55 pp.","IUCN Standards and Petitions Subcommittee (2019) Guidelines for using the IUCN Red List categories and criteria Ver. 14. Available from: https: // cmsdocs. s 3. amazonaws. com / RedListGuidelines. pdf (accessed 1 May 2022)"]}

Ascocentropsis malipoensis (Liu Z.-J. & Chen L.-J.) Averyanov in Averyanov et al. (2018d: 123). ≡ Singchia malipoensis Liu Z. -J. & Chen L.-J. (2009: 602); Cleisocentron malipoense (Z.J.Liu & L.J.Chen) R.Rice, (2018: 158). (Figs. 1 A, B) Type: — CHINA. Yunnan: Malipo County, on trees in forest, alt. 1000 m, 27 Aug. 2008, Z. J . Liu 4137 (holotype – NOCC). Habitat, phenology and conservation status: —Epiphyte. Broad-leaved evergreen submontane forests on karstic limestone at elevation about 1000 m a.s.l. Fl. October–November. Very rare. Suggested IUCN Red List status – EN. Distribution: —Northern Vietnam (Ha Giang and Lai Chau provinces), SE China (SE Yunnan). Note: —According to available data, this very rare species has been found only in three documented locations in SE Yunnan (China) and in two provinces of N Vietnam (Ha Giang and Lai Chau) geographically forming triangle with approximate sides 200×200× 40 km and lying along the Vietnamese – Chinese border. In terms of the IUCN Red List, the species has an estimated area of occurrence (EOO) less than 4000 km 2 and area of occupancy (AOO) is 12 km 2. There is continuing decline in the quality of habitat due to intensive deforestation and agricultural exploration throughout occurrence area. The wide loss of habitats and commercial collecting are strong factors affected the species’ population and bringing the number of mature individuals down. Hence, the species is assessed as Endangered – EN B2ab(iii, v) according to formal IUCN criteria (IUCN 2019). Studied specimens: — VIETNAM, Lai Chau Province, broad-leaved limestone forest, plant collected by local collector for Mr. Loc Bao Sang, who cultivated plant in his private garden in Lam Dong, Di Linh Town, 26 October 2019, L. Averyanov, Nguyen Van Canh, T. Maisak, AL 1187 (LE01066616 http://en.herbariumle.ru/?t=occ&id=12384, LE01088196 https://en.herbariumle.ru/?t=occ&id=43730). VIETNAM, the plant was purchased mixed with Renanthera vietnamensis, originating from Ha Giang Province, Quang Ba District and cultivated in Dalat Town, Lam Dong Province by Mr. Nguyen Phi Tam s.n., photo of 08.11.2021, AL 1295 (LE01123004 https://en.herbariumle. ru/?t=occ&id=110370)., Published as part of Averyanov, Leonid V., Thai, Tran Huy, Truong, Ba Vuong, Nguyen, Van Canh, Nguyen, Tuan Hoang, Maisak, Tatiana V., Nguyen, Khang Sinh & Nguyen, Van Khuong, 2022, New orchids in the flora of Vietnam (Orchidaceae, Aeridinae), pp. 113-135 in Phytotaxa 555 (2) on page 114, DOI: 10.11646/phytotaxa.555.2.1, http://zenodo.org/record/6875853, {"references":["Averyanov, L. V., Nguyen, V. C., Truong, B. V., Maisak, T. V., Luu, H. T., Nguyen, K. S., Dinh, Q. D., Nguyen, H. T., Chu, X. C., Tran, G., Nguyen, V. K. & Le, H. S. (2018 d) New orchids (Orchidaceae: Cymbidieae and Vandeae) in the flora of Vietnam. Taiwania 63 (2): 119 - 138.","IUCN Standards and Petitions Subcommittee (2019) Guidelines for using the IUCN Red List categories and criteria Ver. 14. Available from: https: // cmsdocs. s 3. amazonaws. com / RedListGuidelines. pdf (accessed 1 May 2022)"]}

Trachoma rhopalorrhachis (Reichenbach) Garay (1972: 208). ≡ Dendrocolla rhopalarrhachis Reichenbach (1857: 40). (Figs. 8 C, D) Type: — INDONESIA. W Java “Rchb.fil. Provinz Bandong. Zollinger Sine Nr. ” (W? not seen). Habitat, phenology and conservation status: —Epiphyte. Broad-leaved evergreen lowland and submontane forests on granite at elevation 600–800 m a.s.l. Fl. October–November. Rare. Suggested IUCN Red List status – EN. Distribution: —Southern Vietnam (Dak Lak and Lam Dong provinces), Thailand, Malaysia, Indonesia, Philippines, New Guinea, NE Australia. Note: —This widespread species with fugacious, very short lived flowers attracts little attention from orchid collectors and is poorly represented both in living and herbarium collections. Its two documented locations in Dak Lac province (Chu Mu and Chu Yang Sinh Mountains) and two in Lam Dong province (both in Dalat Town area) indicate an area of occurrence (EOO) in Vietnam less than 5000 km 2. All observed populations are very small and surely form very small area of occupancy (AOO) due to severe fragmentation of suitable environment as a result of intensive deforestation and agricultural land development throughout the distribution area. The wide loss of habitats are strong factors that identify the conservation status of this species in Vietnam as nationally Endangered – EN B1ab(iii), B2ab(iii) according to formal IUCN criteria (IUCN 2019). Studied specimens: — VIETNAM, Lam Dong Province, Dalat Town area, 16.05.2000, L. Averyanov s.n. (LE01076678 https://en.herbariumle.ru/?t=occ&id=57557). VIETNAM, Lam Dong Province, wild collected plant cultivated in Dalat Town private collection, Dang s.n. photo, 2010 (LE01122321 https://en.herbariumle. ru/?t=occ&id=82807). VIETNAM, herbarium specimen and photos prepared on 19 October 2017 by L. Averyanov and T. Maisak, AL 335 from plant collected by Nguyen Van Canh, s.n., in Dak Lak Province, M Drac District, Chu Mu Mountain, at 600–800 m a.s.l. on 15 September 2016 (LE01076423 https://en.herbariumle.ru/?t=occ&id=57303, LE01076427 https://en.herbariumle.ru/?t=occ&id=57307, LE01122490 https://en.herbariumle.ru/?t=occ&id=82980). VIETNAM, herbarium specimen on 30 October 2018 by L. Averyanov, T. Maisak, AL 100 from plant collected by Nguyen Van Canh s.n. in Dak Lak Province, Chu Yang Sinh Mountains on 30 November 2015, flowers white, with light sweet fragrance; each tepal with brown round spot near the base; lip with yellow spot at the disc and brown spots on sides; column white with brown spot on lateral sides; anther white (LE01076428 https://en.herbariumle. ru/?t=occ&id=57308)., Published as part of Averyanov, Leonid V., Thai, Tran Huy, Truong, Ba Vuong, Nguyen, Van Canh, Nguyen, Tuan Hoang, Maisak, Tatiana V., Nguyen, Khang Sinh & Nguyen, Van Khuong, 2022, New orchids in the flora of Vietnam (Orchidaceae, Aeridinae), pp. 113-135 in Phytotaxa 555 (2) on page 128, DOI: 10.11646/phytotaxa.555.2.1, http://zenodo.org/record/6875853, {"references":["Garay, L. A. (1972) On the systematics of the monopodial orchids I. B otanical Museum leaflets, Harvard University 23 (4): 149 - 212. https: // doi. org / 10.5962 / p. 168559","Reichenbach, H. G. (1857) Orchideae Zollingerianae itineris primi racensentur. Bonplandia 5: 34 - 43.","IUCN Standards and Petitions Subcommittee (2019) Guidelines for using the IUCN Red List categories and criteria Ver. 14. Available from: https: // cmsdocs. s 3. amazonaws. com / RedListGuidelines. pdf (accessed 1 May 2022)"]}

Uncifera acuminata Lindley (1858: 40). (Fig. 9) Type: — INDIA. Assam and Khasija, Griffith; base of Khasija, J .D. H. & T. T. 193 (syntypes K000895706, K000895708, K000895709). Habitat, phenology and conservation status: —Epiphyte. Broad-leaved evergreen montane forests on granite at 1800–1900 m a.s.l. Fl. July–August. Rare. Suggested IUCN Red List status – VU. Distribution: —Northern Vietnam (Lao Cai Province), Nepal, NE India, China. Note: —All three recorded localities of this species in Vietnam are adjacent to the Chinese part of the species range and slightly extend its area to the southeast. The area of the occurrence (EOO) of this species in Vietnam comprises highlands of Hoang Lien Son Range and adjacent mountains in parts of Lao Cai Province. The total extent of occurrence may be totally estimated as about 3200 km 2 where the species can survive on many steep mountain slopes inaccessible for the direct deforestation. Meanwhile, the species occupancy area (AOO) may be very small (far less than 500 km 2), as the species inhabit canopies of only the oldest emergent trees, which is why its subpopulations are highly fragmented. According to IUCN criteria the species conservation status in Vietnam may be estimated as nationally Critically Endangered – CR ab(iii) (IUCN 2019). Studied specimens: — VIETNAM, Lao Cai Province, flower yellow brown marked on tepals, lip side-lobes indistinct, spur terete, upcurved, nearly touching lip, 31 July 2018, Truong Ba Vuong BV 338 (LE01073486 http:// en.herbariumle.ru/?t=occ&id=17629). VIETNAM, Lao Cai Province, Bat Xat District, Y Ty Commune, Bat Xat Nature Reserve, 22°37’28.8”N 103°37′44.7″E, 1838 m a.s.l., 1 August 2019, Bui Hong Quang, Tran Duc Binh (LE01090928 https://en.herbariumle.ru/?t=occ&id=82373). VIETNAM, cultivated, wild collected plant originated from Lao Cai Province, herbarium specimen and photo prepared on 18 August 2020, Truong Ba Vuong, Ngo Quang Dang, Phan Trong Quyet, BV 790 (LE01087405 https://en.herbariumle.ru/?t=occ&id=38804)., Published as part of Averyanov, Leonid V., Thai, Tran Huy, Truong, Ba Vuong, Nguyen, Van Canh, Nguyen, Tuan Hoang, Maisak, Tatiana V., Nguyen, Khang Sinh & Nguyen, Van Khuong, 2022, New orchids in the flora of Vietnam (Orchidaceae, Aeridinae), pp. 113-135 in Phytotaxa 555 (2) on pages 129-131, DOI: 10.11646/phytotaxa.555.2.1, http://zenodo.org/record/6875853, {"references":["Lindley, J. (1858) Contributions to the Orchidology of India. 2. Journal of the proceedings of the Linnean Society. Botany 3: 1 - 63. https: // doi. org / 10.1111 / j. 1095 - 8339.1858. tb 02055. x","IUCN Standards and Petitions Subcommittee (2019) Guidelines for using the IUCN Red List categories and criteria Ver. 14. Available from: https: // cmsdocs. s 3. amazonaws. com / RedListGuidelines. pdf (accessed 1 May 2022)"]}

Malleola micrantha Aver. & Vuong, sp. nov. (Figs. 5, 6) Type: — VIETNAM. Lam Dong Province, Dalat City area, 20.04.2019, Truong Ba Vuong, Ngo Quang Dang, BV 407 (holotype VNM, isotype LE01123083 https://en.herbariumle.ru/?t=occ&id=133322). Authentic photos and drawings: — VIETNAM. LE 01123084 https://en.herbariumle.ru/?t=occ&id=133330, LE 01123083 https://en.herbariumle.ru/?t=occ&id=133322. Etymology. The species name refers to its relatively small flowers. Description. Herb perennial monopodial epiphytic. Stem simple or basally few branched, pendulous and somewhat distally ascending, (1)2–4(5) cm long, terete, (1.4)1.5–2(2.1) mm in diameter, covered by distichous leaf sheaths, with (4)5–7(8) leaves in apical half, in basal part with many wiry, twisted dull gray roots. Leaves subdistichous, sessile, joined, broadly lanceolate to narrowly elliptic, grassy green, (1.2)1.5–2(2.5) cm long, (2.5)3–5(6) mm wide, spreading horizontally, apex obtuse, sometimes shortly unequally bilobed. Inflorescence axillary lax raceme, glabrous, (1.5)2–3.5(4) cm long; peduncle greenish to dull purple, thin, terete, (0.8)1–1.8(2) cm long, naked or with 2–3 distant, sterile triangular, acute bracts, 1–2 mm long and wide; rachis terete, slightly longitudinally angled with (3)4–11(12) flowers distant on (0.5)1–3(3.2) mm; floral bracts, triangular, acute, (0.5)0.6–0.7(0.8) mm long, 0.4–0.5 mm wide. Flowers subsessile, spirally arranged, spreading at right angle to rachis, opening in succession, (3)3.2–3.8(4) mm across, sepals and petals glabrous, pale yellow, each with two obscure reddish-brown strips, lip white with dull purple marks on epichile, column white or little greenish, anther cap light yellow. Pedicel and ovary light green, glabrous, terete, shallowly grooved, (1.8)2–3(3.5) mm long, (0.4)0.5(0.6) mm in diameter. Sepals concave, obtuse to blunt at apex; median sepal ovate, (1.8)2(2.2) mm long, (1.1)1.2(1.3) wide (being flattened), cymbiform, dorsally gibbous and hooded; lateral sepals broadly obovate, slightly oblique, (2.1)2.2(2.3) mm long, (1.7)1.8(1.9) wide, almost round at apex. Petals concave, obtuse to blunt at apex, ovate, (1.7)1.8–2(2.1) mm long, (0.9)1(1.1) mm wide. Lip simple or obscurely 3-lobed, spurred, (3.8)4–4.2(4.4) mm long from apex of the lip to apex of spur, firmly fused by lateral sides with column base, with spur lying almost parallel to ovary; epichile 1.5–1.6 mm long and wide, entire triangular or with obscure roundish side-lobes, at apex attenuate to small straight or down recurved acute seta 0.3–0.4 mm long, disk with 2 short parallel low keels; spur glossy white, shortly cylindrical, with no constriction, (2)2.2–2.6(2.8) mm long, (0.8)1(1.2) mm in diameter, oblique conical and round at apex. Column footless, erect, stout, 1–1.2 mm tall and wide, at front with 2 large forward directed conoid papillose bosses 0.7–0.8 mm long, 0.6–0.7 mm in diameter at the base; rostellum very small, placed between bosses; stigma large, concave, circular. Anther cap large, as tall and broad as column, half-globular, 1-2 mm in diameter, with narrowly triangular, down directed beak. Pollinia 2, globular, about 0.3 mm in diameter (0.15–0.2 mm when dry), with small groove on outer surface; stipe linear, translucent, longitudinally conduplicate, bent in the middle and suddenly much widening into broad plate with incurved lateral margins, 1.2–1.4 mm long, 0.8–0.9 mm wide in widest part; viscidium very small, ovate, about 0.1 mm long. Fruits unknown. Habitat, phenology and conservation status. Miniature monopodial canopy epiphyte. Primary evergreen broadleaved submontane forests. Fl. April. Very rare. Estimated IUCN Red List status – CR. Distribution. Southern Vietnam (Lam Dong province). Endemic. Notes. Like Malleola luongii Averyanov & V.C.Nguyen in Averyanov et al. (2018: 130) recently discovered in Vietnam, the new species belongs to the so-called Malleola dentifera – vietnamensis complex, taxa of which occur from Indochina and Peninsular Malaysia to the Greater Sunda Islands (O’Byrne, 2017). Our plant is closest to the type subspecies of M. vietnamensis Guillaumin (1964: 268), including M. dentifera J.J. Smith (1927: 191) as a synonym (O’Byrne 2017), in a general appearance and color scheme of the flower. It differs from M. vietnamensis var. vietnamensis discovered plant differs in the distinctly shorter stem 1–5 cm long (vs. stem normally 10–45 cm long), leaves 1.5–2.5 cm long (vs. leaves normally 3.2–10 cm long), inflorescence lax flowered, flowers 3–4 mm across (vs. inflorescence subdense, flowers 5.5–8.5 mm across), lip simple or with obscure roundish side-lobes (vs. lip distinctly 3-lobed, side-lobes triangular acute forming forward directed teeth), lip disc with 2 short low keels, lip apex with small narrowly triangular straight or down curved seta (vs. disc with no ornamentation, lip apex attenuate to linear revolute or helicoid curved processus), spur shortly cylindric without constriction, 2–2.8 mm long (vs. spur commonly dorso-ventrally flattened in apical half, often constricted in apical half, 3.7–7 mm long), column at front with conical swellings (column with hemispheric swellings), pollinarium stipe 1.2–1.4 mm long (vs. pollinarium stipe 1.9–2 mm long), pollinia 0.3 mm in diameter to 0.2 mm in diameter when dry (vs. pollinia 0.4–0.9 mm in diameter). Only few specimens of the new species were found in densely populated area where most lands has been converted into agricultural plantations.Area of Occupancy (AOO) is estimated as 4 km 2, and as the result due to available data and observations the species should be preliminarily estimated as Critically Endangered – CR B2ab(iii) (IUCN 2019). It is noteworthy that like its allies, the new species exhibits certain apomorphic characters such as prominently inflated lateral stelidia and apically broadening pollinarium stipe. These features along with the subulate or caudate, downward revolute lip apex, lack of distinct calli in spur and almost entire pollinia set this group apart from the related genus Robiquetia Gaudichaud-Beaupré in Freycinet (1829: 426), with which Malleola has been merged on the basis of molecular data (Kocyan and Schuiteman, 2014)., Published as part of Averyanov, Leonid V., Thai, Tran Huy, Truong, Ba Vuong, Nguyen, Van Canh, Nguyen, Tuan Hoang, Maisak, Tatiana V., Nguyen, Khang Sinh & Nguyen, Van Khuong, 2022, New orchids in the flora of Vietnam (Orchidaceae, Aeridinae), pp. 113-135 in Phytotaxa 555 (2) on pages 122-126, DOI: 10.11646/phytotaxa.555.2.1, http://zenodo.org/record/6875853, {"references":["O'Byrne, P. (2017) A clarification of the Malleola dentifera - Robiquetia insectifera - R. vietnamensis complex. Malesian Orchid Journal 20: 91 - 121.","Guillaumin, A. (1964) Plantes nouvelles, rares ou critiques des serres du museium (Notules sur quelques orchideies d'Indochine. XXXIV). Bulletin du Museium national d'histoire naturelle 2, 36 (2): 268 - 269.","Smith, J. J. (1927) Malleola dentifera J. J. Sm. Bulletin du Jardin botanique de Buitenzorg. Ser. 3, 9: 191.","IUCN Standards and Petitions Subcommittee (2019) Guidelines for using the IUCN Red List categories and criteria Ver. 14. Available from: https: // cmsdocs. s 3. amazonaws. com / RedListGuidelines. pdf (accessed 1 May 2022)","Kocyan, A. & Schuiteman, A. (2014) New combinations in Aeridinae. Phytotaxa 161 (1): 61 - 85. https: // doi. org / 10.11646 / phytotaxa. 161.1.3"]}

Cleisostoma furcatum Aver & Vuong, sp. nov. (Figs. 3, 4) Type: — VIETNAM. N Vietnam, Lang Son Province, Binh Gia District, Thien Long Commune, forest on karstic limestone mountain near Lan Luong Village, 18 April 2019, Truong Ba Vuong, Hoang Minh Tuan, BV 355a (holotype VNM, isotype LE01066647 https://en.herbariumle.ru/?t=occ&id=133883, authentic photos LE01073485 http:// en.herbariumle.ru/?t=occ&id=17628, drawings LE01123082 https://en.herbariumle.ru/?t=occ&id=133321). Etymology. The species name refers to the furcate apices of the lip side-lobes. Description. Herb perennial monopodial epiphytic. Stem simple or basally few branched, semi-woody, pendulous, (10)12–18(20) cm long, terete or slightly flattened, (3.8)4–5(5.2) mm in diameter, with (3)4–6(8) leaves near the apex, in basal part with few wiry, straight or flexuose dull gray roots branching distally; internodes (0.6)0.8–1.2(1.4) cm long. Leaves subdistichous, sessile, dorsiventral, leathery, straight or slightly recurved and twisted, lanceolate, (5)7– 10(12) cm long, (0.8)0.9–1(1.2) cm wide, obtuse and unequally shortly bilobed at apex. Inflorescence lateral raceme or few branching panicle, (8)10–20(25) cm long, scape and rachis green, speckled with purple to dirty purple; scape (6)8–15(18) cm long, pendulous, slightly flexuose to almost straight, with 2–4 short, tubular, brownish gray sterile bracts, simple or with 2–3(4) branches; rachis (4)6–14(16) cm long, straight to distinctly zig-zag, with (3)5–15(18) spirally arranged, lax flowers distant on (4)5–14(16) mm. Floral bracts dull brown, minute, triangular, acute, 1.2–1.5 mm long, 1–1.2 mm wide. Pedicel and ovary terete, longitudinally grooved, (5)5.5–7(8) mm long, (0.9)1(1.2) mm in diameter, glabrous, dull purple, slightly broadening at the base. Flowers widely opening, (7)8–10(11) mm across; sepals and petals somewhat fleshy, glabrous, spreading, pale yellow with purple- or brownish-violet margin; lip white, bright yellow at base, with violet median lobe and purple-violet apices of side-lobes, spur white; column white with yellow base; anther cap white; pollinia yellow. Sepals obovate, concave, blunt to rounded at apex, (5)5.5–6(6.5) mm long, (3.3)3.5–4(4.2) mm wide, median sepal cucullate, lateral sepals slightly oblique. Petals narrowly obovate, almost flat, blunt to round at apex, (3.6)3.8–4.2(4.4) mm long, 2.4–2.6 mm wide, slightly oblique. Lip spurred, (5.8)6– 6.2(6.4) mm long (from spur apex to the apex of epichile), 3-lobed; side-lobes narrowly conoid, twisted on 90º and furcate at apex, parallel and forward protruding, (1.7)1.8–2(2.1) mm long, (1)1.2(1.4) mm wide at the base, outside finely verruculose; median lobe very fleshy, almost half-globular in outline, (2.8)3(3.2) mm long, 2.8–3 mm wide, forward directed or slightly upright, apiculate, with short uprising mucro, disc at base with fleshy longitudinal keel continuing into the spur in form of spur septum; spur saccate, almost parallel to ovary, (1.7)1.8–2(2.1) mm long, (1.8)2(2.2) wide, slightly dorso-ventrally flattened, with entire, round apex and incomplete longitudinal septum inside. Back-wall callus in form of large, erect, T-shaped, flattened, papillose outgrowth about 1.2–1.4 mm tall, at apex with two recurved conoid teeth or horns, at base connected with fleshy side-lobes by fleshy papillose ridges. Column short, broad, indistinctly cubic, (2.4)2.5–3(3.2) mm high, (1.8)2(2.2) mm wide, at front with small rostellum lobes supporting viscidium horns; stigma in form of transversely oblong hollow. Anther cap helmet shaped, thin-walled, skin-like, 1.6–1.8 mm tall and wide, without beak. Pollinia 2, each deeply split into 2 half-globular bodies. Stipe (tegula) in form of rhomboid scarious plate 1.5–1.8 mm long and wide (being flattened), enveloping pollinia in form of narrow funnel after removing anther cap, viscidium in form of two narrow subulate forward directed acute horns 0.8–0.9 mm long. Fruits unknown. Habitat, phenology and conservation status. Epiphyte. Broad-leaved evergreen forests on karstic limestone. Fl. April. Very rare. Suggested IUCN Red List status – CR. Distribution. Northern Vietnam (Lang Son Province, Binh Gia District). Endemic. Note. This species belongs to Cleisostoma sect. Paniculata Seidenf. (Seidenfaden, 1975, 1992), which is represented in eastern Indochina with five species, namely C. chapaense, C. duplicilobum, C. equestre, C. inflatum and C. paniculatum (Averyanov et al. 2015b). Among them the new species is closest to C. equestre sharing such specific characters as the shape of lip lobes; similar T-shaped back-wall callus; skin-like anther cap tightly fitting the abaxial surface of the pollinarium stipe; flat, broad, plate-like pollinarium stipe covering the pollinia from above (like an umbrella); and prominent subulate forward directed horns of viscidium. This combination of characters has never been observed in other species of the genus. At the same time, the new species differs from C. equestre in: stem to 20 cm long (vs. stem about 5 cm long), leaves lanceolate 0.8–1.2 cm wide (vs. leaves broadly lanceolate 1.5–2 cm wide), inflorescence to 27 cm long, sometimes branching (vs. inflorescence to 25 cm long, simple), background of sepals and petals pale yellow, lip median lobe violet (background of tepals white, lip median lobe white), lip side-lobes narrowly conoid, twisted on 90º, furcate at apex (vs. side-lobes broadly triangular, not twisted, entire at apex), median lip lobe at the base without callus, at apex apiculate, with short ascending mucro (vs. median lobe with prominent conoid callus at the base, apex almost flat, without ascending mucro), column 2.4–3.2 mm high with anther cap 1.6–1.8 mm tall (vs. column 3.6–4.2 mm high, anther cap 2.2–2.4 mm tall), and flattened stipe rhomboid, as long as wide (vs. flattened stipe circular). The new species is probably a strict endemic of the central part of the South Chinese floristic province as circumscribed by Averyanov et al. (2003). It was discovered in Vietnam near the Chinese border, hence it may be also found in similar limestone areas of Yunnan and Guangxi. Up to now, the species has found in only one locality, where less than 50 mature plants were observed. No more samples of this species were detected in the area during additional floristic explorations. Such conditions meets IUCN criteria (2019) that formally identify conservation status of new species as Critically Endangered – CR D. Several plants in the studied population with pure white flowers represent a true albino form: Cleisostoma furcatum Aver & Vuong forma albiflora Aver & Vuong, forma nov. Type: — VIETNAM. Lang Son Province, Binh Gia District, Thien Long Commune, forest on karstic limestone mountain near Lan Luong Village, 18 April 2019, Truong Ba Vuong, Hoang Minh Tuan, BV 355b (holotype VNM), photos LE01061302 http://en.herbariumle.ru/?t=occ&id=12496. Diagnosis: —new form differs from the type in pure white flowers except bright yellow base of the lip and column (vs. sepals, petals and lip heavily marked with dark violet)., Published as part of Averyanov, Leonid V., Thai, Tran Huy, Truong, Ba Vuong, Nguyen, Van Canh, Nguyen, Tuan Hoang, Maisak, Tatiana V., Nguyen, Khang Sinh & Nguyen, Van Khuong, 2022, New orchids in the flora of Vietnam (Orchidaceae, Aeridinae), pp. 113-135 in Phytotaxa 555 (2) on pages 118-119, DOI: 10.11646/phytotaxa.555.2.1, http://zenodo.org/record/6875853, {"references":["Averyanov, L. V., Tich, N. T. & Canh, N. V. (2015 b) New species of the genus Cleisostoma in the flora of Vietnam. Taiwania 60 (3): 107 - 116."]}

Chiloschista sweelimii Holttum (1966: 147). (Figs. 1 E–G) Type: — MALAYSIA. Malay Peninsula, North Perak, June 1965, cult. Penang, Lim Swee Linn sine n. (holotype K000891272). Habitat, phenology and conservation status: —Epiphyte. Broad-leaved evergreen lowland forests. Fl. June. Very rare. Suggested IUCN Red List status – DD. Distribution: — Vietnam. Malaysia (Malay Peninsula). Note: —The occurrence of this species in Vietnam is documented only by a series of photos made an anonymous photographer from cultivated plants in a private garden in Buon Me Thuot Town (Dak Lak Province). It is very close to the widespread C. parishii, differing primarily “in the quite high narrow triangular side-lobes and the hairy edges of the petals” (Seidenfaden & Wood 1992) and may be regarded as its southern allopatric race. The locality of this species in Vietnam, which is more than 1300 km distant from the locus classicus in Malacca Peninsula, needs confirmation by more collections or observations. According to available data its IUCN conservation status should be assessed as Data Deficient DD. Studied specimens: — VIETNAM, wild collected plant cultivated in private garden probably originating expectedly from northern Vietnam, anonymous photo in Nguyen Van Canh archive s.n. (LE01088051 https://en.herbariumle. ru/?t=occ&id=45097)., Published as part of Averyanov, Leonid V., Thai, Tran Huy, Truong, Ba Vuong, Nguyen, Van Canh, Nguyen, Tuan Hoang, Maisak, Tatiana V., Nguyen, Khang Sinh & Nguyen, Van Khuong, 2022, New orchids in the flora of Vietnam (Orchidaceae, Aeridinae), pp. 113-135 in Phytotaxa 555 (2) on page 115, DOI: 10.11646/phytotaxa.555.2.1, http://zenodo.org/record/6875853, {"references":["Holttum, R. E. (1966) A new Chiloschista from Malaya. Orchid Review 174: 146 - 147.","Seidenfaden, G. & Wood, J. J. (1992) The orchids of Peninsular Malaysia and Singapore. Fredensborg, Olsen & Olsen, 779 pp."]}

In this research, CeO2 modified SiO2 powder was prepared for electrodepositing ZnNi alloy–CeO2 modified SiO2 particle composite coatings. Corrosion behavior of the ZnNi/(SiO2)CeO2 composite coatings was studied by the potentiodynamic polarization method and neutral salt spray test. The results show that the composite coating obtained at the plating current density of 3 A/dm2 in 20 min has the chemical composition with the nickel content of 14.90 wt %, which is composed only of the gamma phase. This composite coating has the brightest surface and the best corrosion resistance. The coating has the largest polarization resistance of 2430.48 Ω cm2 from polarization curve and the time for appearing the first red rust spot on the surface of this coating is the longest, lasting 1008 h.

The effects of the number of substituents and molecular weight of polyamines in the non-cyanide alkaline plating bath on the morphology, brightness and bright ranges of zinc electrodeposited coating and cathodic polarization, cyclic voltammogram on the non-cyanide alkaline zinc plating process were investigated. Cathodic polarization measurements showed that the polyamines all increased cathodic polarization of the plating process and shifted the zinc reduced potential to a more negative direction. However, cycle voltammogram curves of the 5 continuous cycles shows that the quaternary polyamine Q7-20 has a more stable adsorption and desorption processes than the secondary polyamine Bt18 has.

Begonia kimlongii V.C.Nguyen, T.S.Hoang & C.W.Lin, sp. nov. § Petermannia (Figs. 1 & 2) Type: — VIETNAM. Dak Lak Province, M’Đr ắk District, Cý Króa Commune, 12.701979 N, 108.798395 E, 480 m alt., on moist land and rocks in broad-leaved evergreen forests, 22 August 2021, flowers and fruits, Nguyen Van Canh, Nguyen Van Khuong, Hoang Thanh Son 9022 (holotype VAFS; isotype VNMN). Plant perennial, monoecious, terrestrial. Stem erect or ascending, unbranched or little branched, olive green to brownishred, ca. 30 cm tall, 3–7 mm across, sparsely appressed villous, glabrescent; internodes 1–3 cm long, nodes swollen. Stipules deciduous, narrowly ovate-triangular, 5–7 × 2.5–4 mm, pinkish-green to brownish-pink, hyaline, slightly keeled, glabrous or glabrescent, margin entire, apex cuspidate, cusp ca. 1 mm long. Petioles terete, reddish-brown to pinkish-olive green, grooved above, 2.5–5 × 2–3.8 mm, appressed villous, glabrescent. Leaves 3–5, oblique, slightly pointing upward; lamina oblanceolate to obovate, basifixed, asymmetric, 10–14 cm long (basal lobes included), 3.5–5.5 cm wide, broadside 2–3.3 cm wide, base unequal, basal lobes cordate on broadside, 1–1.8 mm long, thinly succulent, adaxially emerald green to dusky green, glabrous or subglabrous, sometimes with silvery white irregular dots between veins each with a puberulous hair in center, glabrescent; abaxially pale green to pinkish; venation pinnate, midrib distinguishable, 8.5–12 cm long, ca. 3 major lateral veins on either side of midrib, other primary veins branching dichotomously; margin sparsely denticulate; apex attenuate. Bracts deciduous, yellowish-pink, pale green tinged red at base, hyaline, those at basal nodes of the inflorescence in one or two pairs, ovate-triangular to ovate, ca. 5 × 2.8 mm, aristate, arista ca. 1 mm long, margin entire; bracts at the summit of the inflorescence obovate to oblanceolate, 3–9 × 1.5–5 mm, apex obtuse to truncate, margin denticulate, sometimes with a puberulous hair at the tip of each tooth. Inflorescence a terminal, bisexual, cymosely branching panicle 3.5–6.5 cm long, peduncle crimson to reddish-green, 1.5–3.5 cm long, up to 4 orders of branching, erect or ascending, glabrous, protogynous. Staminate flower: pedicel reddish, 1–2 cm long, glabrous, tepals 4, white to pinkish-white tinged rosy pink, glabrous; outer 2 orbicular to widely ovate, margin entire, 8–11 × 9–13 mm, inner 2 narrowly lanceolate to narrowly elliptic, 5–8 × ca. 2 mm; androecium actinomorphic, stamens 32–40, filaments fused at base; anthers ca. 0.7 mm long, obovate, apex retuse, filaments ca. 1 mm long. Pistillate flower: pedicel white to pink, 3–6 mm long, glabrous; ovary whitish-green to creamy white, body trigonous-ellipsoid, 8–12 × 4–5 mm, 3-winged; wings equal, rounded trapezium, 12–16 × 3–5 mm, margin entire; ovary 3-locular, placenta bilamellate; tepals 5, pinkish-white, sometimes creamy white tinged red at base, glabrous, outer 4 tepals widely ovate to widely obovate, 5–10 × 3–7 mm, inner 1 tepal oblanceolate to obovate, 4–7 × 1.7–3.8 mm; styles 3, yellow, bifid, deeply divided to base, Y-shaped, ca. 2 mm long; stigmas in a spiral band and papillose all around. Fruit pendent on a stalk ca. 6 mm long, capsule ca. 20 × 17 mm (wings included), glabrous; tepals persistent. Distribution and ecology: —The new species is currently known from Cý Króa Commune, M’Ðrắk District, Dak Lak Province, Central Highlands Vietnam and probably also occurs in adjacent areas. The new species grows on humid, moist, or rocky areas in broad-leaved evergreen forests, at elevations of ca. 480 m, associated with Poaceae (Arundinaria sp.), Gesneriaceae (Chrita sp.), Urticaceae (Elatostema sp.), Pentaphragmataceae (Pentaphragma sp.), and Melastomaceae (Sonerila sp.). Etymology: —The specific epithet is named in honor of Mr. Nguyen Kim Long, who first discovered this new species. Conservation status: —A small population of the new species is distributed in an area of about 1 km 2 that is not included in any protected forest, therefore its survival is potentially threatened by Begonia collectors and habitat degradation. However further botanical surveys are needed in this realtively unexplored area for a complete conservation assessment of this species, until then we assess Begonia kimlongii to be Data Deficient (DD) according to IUCN (2019). Notes: — Begonia kimlongii is distinctive for its dimorphic bracts that are relatively unusual in B. sect. Petermannia. However, it is a typical member of the section in having a cane-like habit, 3-locular ovary with bifid placentae, and protogynous inflorescences. This new species is related to Begonia cucphuongensis Nguyen & Tebbitt (2005: 248) in its cane-like habit, sparsely hairy stem, adaxially glabrous leaves and the number of staminate tepals. It is readily distinguished from B. cucphuongensis by its oblanceolate to obovate (vs. lanceolate to narrowly ovate) leaves, terminal inflorescences (vs. axillary, rarely terminal) and pistillate flowers with 5 tepals (vs. 3). Moreover, it resembles B. lamxayiana Souvannakhoummane et al. (2016: 2) and B. hainanensis Chun & Chun (1939: 20) which also share oblanceolate leaves, lax inflorescences and 3-locular ovaries. A comparison of the salient characters of the four species is presented in Table 1., Published as part of Nguyen, Van Canh, Hoang, Thanh Son, Lin, Che-Wei & Nguyen, Van Khuong, 2022, Begonia kimlongii (B sect. Petermannia, Begoniaceae), a new species from Dak Lak, Central Highlands, Vietnam, pp. 193-200 in Phytotaxa 547 (2) on pages 193-198, DOI: 10.11646/phytotaxa.547.2.7, http://zenodo.org/record/6571489, {"references":["IUCN Standards and Petitions Subcommittee (2019) Guidelines for Using the IUCN Red List Categories and Criteria, Version 14. Prepared by the Standards and Petitions Subcommittee. Available from: https: // www. iucnredlist. org / resources / redlistguidelines (accessed 22 March 2022)","Nguyen, H. Q. & Tebbitt, M. C. (2005) An unusual new species of Begonia (Begoniaceae) from Vietnam. Gardens' Bulletin Singapore 57: 247 - 251.","Souvannakhoummane, K., Hughes, M. & Lanorsavanh, S. (2016) Begonia lamxayiana Souvann. (Begoniaceae): a new species from Laos. Thai Journal of Botany 8 (1): 1 - 5.","Chun, W. Y. & Chun, F. (1939) Notes on Begonia. Sunyatsenia 4 (1 - 2): 20 - 28."]}

Pham, Van The, Nguyen, Van Canh, Phan, Long Ke, Tran, Thanh Thi Viet, Nguyen, Van Khuong, Nuraliev, Maxim S., Vislobokov, Nikolay A. (2021): Aspidistra thuongiana (Asparagaceae, Nolinoideae), a new species from the South Central Coast region of Vietnam. Phytotaxa 496 (3): 261-268, DOI: 10.11646/phytotaxa.496.3.4, URL: http://dx.doi.org/10.11646/phytotaxa.496.3.4

In this paper, we investigate the problem of detection of abnormal moving speeds for a coastal surveillance radar. A new definition of normal moving speeds which is based on the historical radar data of maritime targets on the monitoring area is introduced. The historical radar data is mined by the cell-based method, unsupervised machine learning to obtain the vessel normal moving speeds in the monitoring area. Then a logic rule is applied to detect the abnormal targets. The proposed method is tested with real data from a coastal surveillance radar. The test results show that the false alarm rate (FAR) is equal zero. It is also shown that this kind of anomaly detection can be integrated into a coastal surveillance radar for the detection of the maritime illegal activities.