Two endangered ornamental orchid species, Bulbophyllum coweniorum and Esmeralda bella (Orchidaceae), new in the flora of Vietnam

Two rare endangered ornamental species of orchids (Orchidaceae) – Bulbophyllum coweniorum J. J. Verm. et P. O’Byrne and Esmeralda bella Rchb. f., new for the flora of Vietnam were discovered during botanical field surveys of medicinal plants conducted by Department of Pharmacognosy of Hanoi University of Pharmacy in years 2015–2016. According to people from local minorities, both species are used in traditional medicine, but no scientific data on medicinal activity of any substances obtained from these plants are yet available. Meanwhile, the wide deforestation in areas of discovered species is the main fatal factor of their fast extinction in known localities. Hence, they should be regarded as nationally critically endangered (CR) in terms of IUCN Red List categories and criteria. The extensive commercial collecting of both species as highly demanded medicinal and ornamental plants is additional factor of their extinction even in intact habitats. At the same time, any present field data on both species are very scarce for understanding of their current distribution, natural resources, ecology, biology and morphological variation. The paper provides relevant information for these species including valid name, main synonyms, data about type materials, common names, short morphological description, data on ecology and phenology, distribution, threat and estimated IUCN Red List status, use in traditional medicine, notes on taxonomy and related species and data on studied specimens with indication of herbaria where they are housed. Data on medicinal use of studied species in folk medicine were obtained by talks and interview with old local people from national minorities living in areas of species distribution. Identification of collected specimens was performed in Department of Pharmacognosy (Hanoi University of Pharmacy) on the base of comparative morphologic analysis with use of relevant taxonomic literature.


Introduction
The orchid flora of Vietnam includes presently at least 1210 documented species belonging to 172 genera according to the last available accounts (Averyanov, 2015(Averyanov, , 2016)).Meanwhile, it still remains far from complete inventory, and each new botanical investigation, particularly in remote mountainous areas, reveals new discoveries.Thus, two rare species of orchids, Bulbophyllum coweniorum J. J. Verm.et P. O'Byrne and Esmeralda bella Rchb.f., new for the flora of Vietnam, were discovered during botanical field surveys of medicinal plants conducted by Department of Pharmacognosy of Hanoi University of Pharmacy in years 2015-2016.According to people from local minorities both species are used in traditional medicine, but any scientific data on medicinal activity of any substances obtained from these plants are not yet available.The wide deforestation in areas of discovered species is the main fatal factor of their fast extinction in known localities.Hence, they should be regarded as nationally critically endangered (CR) in terms of IUCN Red List categories and criteria (The IUCN Red List, 2016).The extensive commercial collecting of both species as highly demanded medicinal and ornamental plants is additional factor of their extinction even in intact habitats.At the same time, any present field data on both species are very scarce for acceptable understanding of their current distribution, resources, ecology, biology and morphological variation.Below we provide relevant available information of these species including valid name, main synonyms, data about type materials, common names, short morphological description, data on ecology and phenology, distribution, threat and estimated IUCN Red List status, use in traditional medicine, notes on taxonomy and related species and data on studied specimens with indication of Herbaria where they are housed.

Materials and methods
The surveys of medicinal plants were conducted in northwestern part of Vietnam (Lai Chau province, Sin Ho district, Ta Ngao commune) and on the south of the country (Kon Tum province, Ngoc Linh Mountains) with assistance of famous Vietnamese orchid enthusiasts Mr. Nguyen Phong and Mr. Chu Xuan Canh.Observed and reported species were confirmed by photographs and voucher herbarium specimens housed presently in Herbarium of Department of Pharmacognosy, Hanoi University of Pharmacy.Some previously collected herbarium specimens were also used in the current studies.Data on medicinal use of studied species in folk medicine were obtained from talks and interview with old local people from national minorities living in areas of species distribution.Identification of collected specimens was performed in Department of Pharmacognosy (Hanoi University of Pharmacy) by Nguyen Hoang Tuan on the base of comparative morphologic analysis with use of relevant taxonomic literature (Vermeulen, O'Byrne, 2003;Chen Xinqi, Wood, 2009;Muennig, 2010).
Common names.English -Cowen's Bulbophyllum (named after Mr. and Mrs. Cowen, who cultivated this species and successively made it flowering in their garden in Thailand), proposed Vietnamese name -Long hoa lon.
Threat and conservation.The wide deforestation due to uncontrolled primitive burning and shifting agriculture, as well as forest logging throughout the Lao PDR territory, is the leading factor of the species extinction (Cockel, 2013).Additional threat factor is commercial plant collecting, mainly for export to China as ornamental and medicinal plant used in traditional oriental medicine (Lamxay, 2009).While this species appears rather common in the orchid trade and in cultivation, its distribution and occurrence in Lao PDR remains unclear (Vermeulen, O'Byrne, 2003;Schuiteman et al., 2008;Cockel, 2013).Beside the type, two additional available reports in Laos are based on cultivated specimens originated from Champasak province without indication of exact locality and data on ecology (Schuiteman et al., 2008).Present record of this species in Vietnam is based on the single observed, highly depleted population standing on the verge of full extinction due to overexploitation and habitat loss.The absence of any current field data makes IUCN Red List criteria not well applicable for identification of species' status.Data deficient (DD) status should be formally applied for this species in formal terms, whereas in fact it may be very near to full extinction in the nature (nationally CR).
Use.This and similar related species are used in traditional medicine for treating hemoptysis, pneumonia, sore throat and chronic gastritis according to verbal information obtained from people of local minorities.Scientific data on medicinal activity of any substances obtained from these plants are not yet available.
Described without indication of origin ("… Mr W. Bull, whose No. 1022 it is among the Orchids sent me out of his large stores.").Type ("W.Bull, 1022") -not located, W?
Common names.English -The Beautiful Arachnanthe, Chinese -Kou Gai Hua Zhi Zhu Lan, proposed Vietnamese name -Bo cap sin ho.
Threat and conservation.Almost total deforestation in areas of known populations is the main fatal factor of species extinction in Vietnam.Habitats harboring few discovered populations are currently degrading fast due to forest logging, road construction and agricultural landscape transformations.The gathering of mature samples for local and international trade (mainly to China) as a highly demanded ornamental plant is also significant factor of the species extinction even in intact natural conditions.Very strict area of distribution and rapid habitat loss lead to strong declining of populations during last decade.Therefore, species should be tentatively estimated as nationally critically endangered (CR) in terms of IUCN Red List categories and criteria (The IUCN Red List, 2016).
Use.According to people from local minorities, the leaves may be used in traditional medicine for treating stomach pain and pimple.However, scientific data on medicinal activity of any substances obtained this species are not yet available.
Notes.This species was previously recorded in Vietnam under the name Esmeralda clarkei Rchb.f. s. l. (Averyanov, 2006) regarding its probable synonymy with E. bella Rchb.f.However, later some taxonomists accept these species as separate taxa (Chen, Wood, 2009).Subquadrate lip side lobes, truncate at apex and disk with moveable lidlike appendage at the base were reported as the main morphological characteristics separating E. bella from E. clarkei.These characters well fits the studied Vietnamese specimens; hence, their re-identification as E. bella is proposed here as a new record for the flora of Vietnam.At the same time, E. bella remains purely studied, extremely rare species.Except northwestern Vietnam, it is expectedly occurs also in Nepal, northeastern India, Myanmar, northern Thailand and in southwestern China (Chen, Wood, 2009).However, its distribution and morphological variation needs further studies as presently available herbarium collections are very scarce.
Studied specimen.Northern Vietnam, Lao Cai province, Sa Pa district, vicinity of Sa Pa town, mountain forest at 1500 m, epiphyte with pendulous ascending shoots 25-40 cm long, flowers odorless, sepals and petals light yellowish with purple-brown Nguyen Hoang Tuan, Averyanov L. V. Two endangered ornamental orchid species new in the flora of Vietnam

Fig. 1 .
Fig. 1.Bulbophyllum coweniorum J. J. Verm.et P. O'Byrne.A -Flowering plant.B -Flower, frontal, back and side views.C -Flower, pedicel and ovary, side view.D -Floral bracts.E -Median sepal, abaxial and adaxial views.F -Petals, abaxial and adaxial views.G -Lip, view from above and side view.H -Lateral sepals, abaxial and adaxial views.I -Column and column foot, frontal view, side view and view from back.J -Operculum, view from below, view from above and frontal view.K -pollinia.L -Pedicel and ovary.M -Transversal ovary section.N, O -Portion of rhizome with leaf and pseudobulbs.P -Dissected floral parts.Photos of Nguyen Hoang Tuan, design and correction by Leonid V. Averyanov.

Fig. 2 .
Fig. 2. Esmeralda bella Rchb.f.A -Dissected floral parts and leaf.B -Flower, frontal view.C -Sepals and petals from behind.D -Lip, frontal view, view from behind and side view.E -Column, frontal view, side view and view from behind.F -Pollinaria.G -Anther cap.H -Floral bract.I -Transversal ovary section.J -Pedicel and ovary.K -Leaf, view from adaxial and abaxial side.L -Flowering plant.Photos of Nguyen Hoang Tuan, design and correction by Leonid V. Averyanov.

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Bulbophyllum coweniorum belongs to the group of closely related species of B. lobbii Lindl.complex including B. microglossum Ridl.(found in Thailand, Malacca Peninsula, Kalimantan), B. smitinandii Seidenf.et Thorut (Thailand, Vietnam) and B. orectopetalum Garay, Hamer et Siegerist (Myanmar, Thailand, Cambodia, Laos), but well differs in purple spotted tepals and purple lip ciliate at the base and lacking central callus on the disk near the base.The present discovery represents first record of this species in Vietnam.