Taiwania 65(4): 473‒477, 2020 DOI: 10.6165/tai.2020.65.473 

Bulbophyllum sridithii (Orchidaceae), new species from Vietnam

Ba Vuong TRUONG1,2,*, Van Son DANG1,2, Hop TRAN3, Tatiana V. MAISAK4, Leonid V. AVERYANOV4 

1. Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay District, Hanoi, Vietnam. 

2. Institute of Tropical Biology, Vietnam Academy of Science and Technology, 85 Tran Quoc Toan Street, District 3, Ho Chi Minh City, Vietnam. 

3. 480A Le Van Sy Street, District 3, Ho Chi Minh City, Vietnam. 

4. Komarov Botanical Institute, Russian Academy of Sciences, Prof. Popov Street 2, 197376, St. Petersburg, Russia. 

Corresponding author’s email: bavuong2019@yahoo.com 

(Manuscript received 1 July 2020; Accepted 28 September 2020; Online published 3 October 2020) 

ABSTRACT: Bulbophyllum sridithii a new species to science is described and illustrated from Kon Ka Kinh National Park of Vietnam. The new species belongs to the section Cirrhopetaloides and resembles B. layae, B. hirundinis, B. electrinum, B. pecten-veneris and B. tingabarinum but differs in the size and shape of pseudobulbs, the shape of the leaf blade, and flower size. Morphological description, illustrations, data on habitat, phenology, and conservation status are provided. 

KEY WORDS: Cirrhopetaloides, endemism, Kon Ka Kinh National Park, new orchid species, plant diversity, plant taxonomy. 

INTRODUCTION 

The genus Bulbophyllum Thouars (1822) is one of the largest plant genera, with over 2200 species distributed in tropics and subtropics of the world (Vermeulen et al., 2014). Currently, more than 145 species from 15 sections have been recorded in Vietnam (Seidenfaden, 1992; Averyanov, 1994; Averyanov and Averyanova, 2003; Averyanov et al., 2015, 2016, 2018, 2019a,b; Nong and Averyanov, 2015; Nguyen and Averyanov, 2017; Truong et al., 2019a-c). 

The new species according to its morphology belongs to Bulbophyllum section Cirrhopetaloides Garay, Hamer & Sigerist (Vermeulen et al., 2014), and is characterized by creeping rhizome; 1-leaved pseudobulbs; subumbellate raceme arising from the base of pseudobulbs; free dorsal sepal, entire, erose, fimbriate, ciliate, or paleate along the margin; lateral sepals twisted at the base and adnate (entirely or in part) along one or both margins. Petals are denticulate or fimbriate along the margin, lip simple, entire; stelidia usually shorter about half of the column length. Pollinia 4, without stipe. 

During the botanical survey in Kon Ka Kinh National Park, an unknown miniature Bulbophyllum species belonging to the section Cirrhopetaloides, was found. After careful examination of available taxonomic literature, herbarium specimens from VNM, HN, VNMN, as well as herbaria images presented in JSTOR website, LE, K and P databases, we concluded that this species is new for science. It is described and illustrated below. 

MATERIALS AND METHODS 

The measurements and species description made from living plants. Type herbarium and additional liquid 

fixed material (preserved in 70% ethanol) are stored at VNM herbarium (ITB - Ho Chi Minh City). All the photos were taken with a Canon 600D fitted with an EF– S 60mm f/2.8 Macro USM lens. The terminology for the morphological description follows Beentje (2012). 

TAXONOMIC TREATMENT 

Bulbophyllum sridithii Vuong, Aver., H. Tran & V.S. Dang, sp. nov. 

Fig. 1–3 

(B. sect. Cirrhopetaloides Garay, Hamer & Sigerist) Type: VIETNAM, Gia Lai Province, K’Bang District, Son Lang Commune, Ha Lam Village, Kon Ka Kinh National Park, 11 December 2019, Truong Ba Vuong, Dang Van Son, BV 459 (holotype: VNM00023643!, photo - LE, http://en.herbariumle.ru/?t=occ&id=17658, analytical photo-plate - LE, http://en.herbariumle.ru/?t=occ&id=17630). 

Description: Herb epiphytic, perennial, rhizomatous. Rhizome creeping, stout, ca. 1.5 mm in diameter, brownish-grey, with single-leafed pseudobulbs. Pseudobulbs close to each other or distant ca. 2 mm, glossy green, broadly ovoid to globose, 6–7 mm tall, ca. 7 mm in diameter. Leaves sessile or subsessile, elliptic, 2.4–3 cm long, 1–1.5 cm wide, apex obtuse, leaf blade narrowing at base into short petiole ca. 2 mm long, twisted, with distinct articulation at base. Inflorescence arising from the base of pseudobulb, umbel-like raceme, with (1)3–4 flowers; scape suberect, slender, 2–2.5 cm long, at base covered by 2 to 3 brownish, tubular, papyraceous sheaths, 1–4 mm long; floral bracts triangular, 2.8–3 mm long, apex acuminate; pedicel with ovary 7–8 mm long; ovary with 6 longitudinal grooves. Flowers red, opening simultaneously. Dorsal sepal broadly ovate, 3–3.5 mm long, ca. 2 mm wide, concave, 3-veined, margin fimbriate, apex shortly abruptly acuminate. Lateral sepals somewhat fleshy, ca. 20 mm long, 3 mm wide (at base) adnate to column foot, lower margins joined in basal third, upper margin twisted and free at base, then fuse together (ca. 3.5 mm long), toward the apex attenuate into filiform caudate free part. Petals ovate, slightly oblique, 2.5–2.8 mm long, 1.5–1.8 mm wide, 3-veined, apex obtuse, margin fimbriate. Lip simple, fleshy, ca. 2 mm long, 1 mm wide, narrowly triangular, recurved at middle, at base channeled, adaxially with low median keel from base to the apex, median ridge on abaxial surface runs from the labellum base to the apex, margin revolute, finely hairy at the lip base. Column ca. 1 mm tall, column foot ca. 4 mm long, upcurved; stelidia slender, subulate, straight or somewhat falcate, ca. 0.5 mm long; anther cap rectangular in outline, ca. 0.7 cm long, 0.6 cm wide, laterally somewhat concave, with yellowish brown callus at front. Pollinia 4. Capsule fusiform, ca. 1.6 cm long. 

Etymology: The species epithet refers to the name of Professor Kitichate Sridith, famous researcher of Indochinese flora. 

Habitat and phenology: Clustering miniature branch epiphyte growing in evergreen broad-leaved submontane seasonal forests. Rare. Flowers in December to January. 

Distribution: VIETNAM, Gia Lai Province (Kon Ka Kinh National Park). Endemic of southern Vietnam in limits of Central Highlands (Tay Nguyen Plateau). 

Taxonomic notes: The new species resembles Bulbophyllum layae Aver. & Vuong described in 2019 from northern Vietnam (Averyanov et al., 2019a) but differs in dorsal sepal broadly ovate suddenly narrowing into shortly acuminate apex (vs. narrowly ovate, gradually tapering into attenuate apex), the lower margin of lateral sepals adnate from the base to nearly one third of their length (vs. the lower margin almost free from the base), petals ovate (vs. petals narrowly ovate); stelidia porrect, falcate, slightly downward (vs. stelidia erect, slender, straight forward directed). Moreover, the new species is additionally separated from above species in broadly ovoid or globular pseudobulbs (vs. pseudobulbs ovoid to narrowly ovoid), leaves elliptic 2.4–3 cm long, 1–1.5 cm wide (vs. leaves lanceolate or oblong lanceolate, 3.5–6 cm long, 4.5–7 mm wide), small flowers less than 2.5 cm long (vs. flowers 2.5–3 cm long), 

The new described species resembles to B. electrinum Seidenf. but can be distinguished by the short inflorescence 2–2.5 cm, with up to 4 flowers (vs. inflorescence up to 13 cm long, with up to 11 flowers), lip finely ciliate along the margin at the base (vs. lip glabrous), stelidia porrect, falcate, slightly downward (vs. stelidia very slender, filiform, erect), anther cap glabrous with brown callus at front (vs. anther cap papillose, without callus at front). 

In addition, B. sridithii resembles to B. hirundinis (Gagnep.) Seidenf. but clearly differs by pseudobulbs placed close together or distant on less than 2 mm (vs. pseudobulbs distant on about 15 mm), inflorescence 2– 2.5 cm, with up to 4 flowers (vs. inflorescence 3–4 cm long, with up to 11 flowers), lip at base ciliate along the margin (vs. lip glabrous). 

Furthermore, the new species resembles to the B. pecten-veneris (Gagnep.) Seidenf. and B. tingabarinum Garay, Hamer & Siegerist but recognized by inflorescence 2–2.5 cm long (vs. inflorescence up to 15 cm long), lateral sepals ca. 2 cm long, lower margin fused at basal third (vs. lateral sepals up to 7.5 cm long, lower margin free at base), lip at base densely hairy along the margin (vs. lip glabrous). 

Studied specimen (paratype): VIETNAM, herbarium specimen prepared in 11 January 2020, Truong Ba Vuong, Dang Van Son, BV 483 (VNM VNM00023648!) from cultivated plant, originated from Gia Lai Province, K’Bang District, Son Lang Commune, Ha Lam Village, Kon Ka Kinh National Park). 

ACKNOWLEDGMENTS 

The authors would like to express their sincere gratitude to the reviewers for their critical suggestions which are helpful in improvement the manuscript. Field and laboratory studies were supported by Herbarium of Institute of Tropical Biology, Ho Chi Minh City. The work on this publication was supported in part by the RFBR “Inventory, taxonomy and geography of the orchids (Orchidaceae) of Vietnam”, 20-04-00339 А. 

LITERATURE CITED 

Averyanov, L.V. 1994. Identification guide to Vietnamese orchids (Orchidaceae Juss.). World and Family, S.- Petersburg, 432 pp. [in Russian] 

Averyanov, L.V. and A.L. Averyanova. 2003. Updated checklist of the orchids of Vietnam. Vietnam. National University, Hanoi, 102 pp. [bilingual, in Vietnamese & English]. 

Averyanov, L.V., , K.S. Nguyen, T.T. Nguyen, P.T. Nguyen, V.D. Nong, V.C. Nguyen and C.C. Xuan. 2015. New orchids in the flora of Vietnam. Wulfenia 22: 137–188. 

Averyanov, L.V., V.D. Nong, K.S. Nguyen, T.V. Maisak, V.C. Nguyen, Q.T. Phan, P.T. Nguyen, T.T. Nguyen and B.V. Truong. 2016. New species of orchids (Orchidaceae) in the flora of Vietnam. Taiwania 61(4): 319–354. 

Averyanov, L.V., V.D. Nong, H.T. Nguyen, M.S. Nuraliev, T.V. Maisak and C.A. Nguyen. 2018. New species of Bulbophyllum (Orchidaceae) in the flora of Vietnam. Phytotaxa 369(1): 1–14. 

Averyanov, L. V., S.K. Nguyen, B.V. Truong, V.C. Nguyen, T.V. Maisak, H. T. Tran, T.T.D. Pham and B.N. Tu. 2019a. New species of Bulbophyllum (Orchidaceae) in the flora of Vietnam II. Phytotaxa 404(6): 231–244. 

Averyanov, L.V., B.V. Truong and T.V. Maisak. 2019b. Bulbophyllum (Orchidaceae) in the flora of Vietnam III. The revision of B. sect. Lemniscata. Phytotaxa 416(1): 51– 58. 

Beentje, H. 2012. The Kew Plant Glossary, an illustrated dictionary of plant terms (revised edition). Kew: Royal Botanic Gardens, Kew Publishing. 

Nguyen, H.T. and L.V. Averyanov. 2017. Two endangered ornamental orchid species, Bulbophyllum coweniorum and Esmeralda bella (Orchidaceae), new in the flora of Vietnam. Turczaninowia 20(1): 68–74. 

Nong, V.D. and L.V. Averyanov. 2015. Bulbophyllum bidoupense and Schoenorchis hangianae - new species of orchids (Orchidaceae) from southern Vietnam. Phytotaxa 213(2): 113–121. 

Truong, B.V., J.J. Vermeulen and Q.T. Truong. 2019a. A new record of Bulbophyllum section Aeschynanthoides from Vietnam. Lankesteriana 19(1): 1–4. 

Truong, B.V., Q.T. Truong, J. Ponert and J.J. Vermeulen. 

2019b. New Species of Bulbophyllum from Hon Ba Nature 

Reserve in Vietnam. Die Orchidee 5(6): 44–51.

Truong B.V., Q.T. Truong, V.H. Bui and J. Cootes. 2019c. Bulbophyllum claviforme, a new species from Vietnam. 

Die Orchidee 5(7): 52–59.

Vermeulen JJ, G. Fischer, E. de Camargo Smidt, W.L. 

Stern, A.M. Pridgeon, C. Veitch, A. Sieder, R. van Vugt, B. Gravendeel. 2014. Bulbophyllum. In: A.M. Pridgeon, P.J. Cribb, M.W. Chase and F.N. Ramussen (Eds.) Genera Orchidacearum 6, Epidendroideae pt. 3. Oxford University Press, UK, pp. 4–51.