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Aerides phongii (Orchidaceae), loài lan mới phát hiện ở miền Nam Việt Nam

Cập nhật ngày 26/5/2014 lúc 3:46:00 PM. Số lượt đọc: 3476.

Bài báo này mô tả một loài lan mới đặt tên là Aerides phongii, loài được tìm thấy ở khu vực rừng cây lá rộng trên đất thấp trước đây là rừng nguyên sinh nhưng đã bị tác động nặng ở miền Nam Việt Nam. Loài được đặt tên để tri ân ông Phong, người đã mua được cây lan này tại nơi nó được thu hái và đem trồng tại vườn nhà.

Lan giáng hương phong có kích thước trung bình từ 20 cm đến 30 cm, lá hình trụ tròn, phần cuống lá có rãnh không rõ rệt dài khoảng 20 cm. Thân không phân nhánh. Rễ nhiều, màu trắng mọc dày ở phần gốc.

Cụm hoa chùm một, hoa to khoảng 1 cm, màu xanh nhạt, lưỡi có 2 chấm mầu tím, mọc thành chùm 15 - 20 bông cuống màu xanh lá cây, hoa mọc từ lá nách lá gần gốc thân , hoa mọc thẳng, cứng, dài 2-5 cm , 2,5-3 mm. Lá bắc hoa nhỏ, dựng lên, hình tam giác rộng, gần hình trứng.

Lan giáng hương phong được tìm thấy tại vùng Ninh Thuận ở miền Nam Việt Nam. Trong các khu rừng nguyên sinh thường xanh khô ven biển nhiệt đới gió mùa trên đá silicate ở độ cao trên mực nước biển 50-150m. Hoa nở từ tháng Hai đến tháng Ba hang năm.

Đây là loài hoa lan thứ 8 thuộc giống Aerides sp tìm thấy ở Việt Nam và là loài thứ 12 trên thế giới.

Dưới đây là toàn văn bài báo của các tác giả đăng trên Turczaninowia17 (1): 6–9 (2014):

Introduction

Aerides Lour. is a relatively small orchid (Orchidaceae) genus which consists of approximately 21species ranging from India to Papua New Guinea (Christenson, 1993; Kocyan et al., 2008) with main center of species diversity in mainland tropical Asia. Regional floras of the area of highest diversity include 5 species in China, 6–7 in Thailand and Laos, 4 in Cambodia and 7 species in Vietnam (Averyanov, 1994, 2013; Averyanov, Averyanova, 2003; Chen, Wood, 2009; Newman et al., 2007; Orchids of Cambodia, 2014; Schuiteman, de Vogel, 2000; Schuiteman et al., 2008; Seidenfaden, 1988, 1992). One more species of the genus new for science was discovered recently in Pacific coastal forests of southern Vietnam in limited area with arid climate driest in the eastern Indochina. Thus Vietnam becomes certainly the richest country in the world with respect of species diversity of Aerides . Illustrated description of the new species with brief notes on its ecology, expected distribution, assumed protection status, taxonomic position and biology is provided below.

Aerides phongii Aver., sp. nov. (Fig. 1) Described from Vietnam (“Southern Vietnam, Ninh Thuan Prov., Bac Ai Distr., in heavily disturbed primary seasonal tropical broad-leaved lowland woodland on silicate rocky slope. Branch epiphyte on old tree. Rare. Plants were collected and offered for sale on local market by local collectors in February – March 2014, type specimen was purchased by Mr. Nguyen Phong at early March 2014”). Type (“Flowered under cultivation in private garden in Hanoi, collected at 12 March 2014 by Nguyen Phong and Phan Ke Loc P 11235”) – HNU (holotype), LE (isotype).

Monopodial perennial herb with short, erect, unbranched stem to 2(2.5) cm tall, 3–5 mm in diameter. Roots many, at the base of stem, light grey to almost white, rigid, wiry and flexuose, creeping and densely adpressed to substrate. Stem covered with loosely adpressed, overlapping, distichous, partially disintegrated, more or less rigid, brown leaf sheaths, leafy and slightly twisted at apex. Leaves 3–5, distichous, rigid, subulate, canaliculate at lower portion, terete toward acute apex, recurved to arcuate or slightly flexuose, (15)20–30(35) cm long, 3.5–4.5 mm wide, articulate at the base, suddenly broadening at the base into a closed sheath enveloping the stem. Inflorescencea raceme; peduncle green, arising from leaf axil near stem base, erect, rigid, 2–5 cm long, 2.5–3 mm in diameter, bearing 1–2(3) short, small, broadly triangular, obtuse sterile bracts 2–4 mm long; rachis rigid (2)3–6 cm long, with (1)5–12(14) distant flowers. Floral bracts small, erect, triangular to broadly ovate, acute, 1.5–2.5 mm long and wide. Pedicel and ovary white or yellowish-green, shallowly ridged, 1.2–1.6 cm long, curved, slightly flexuose to almost straight. Flowers resupinate, shallowly campanulate to widely opened, (1.2)1.4–1.8 cm across; sepals and petals slightly incurved, white to light yellowish, greenish at apex. Dorsal sepal and petalssubsimilar in shape, ovate to broadly elliptic, 6–7 mm long, 4.5– 5 mm wide, round at apex, petals a little smaller, almost flat, dorsal sepal with slightly reflexed lateral margins. Lateral sepals oblique broadly ovate, concave or with reflexed lower margin, (6.5)7–8 mm long, 5.5–6.5 mm wide, blunt to obtuse. Lip firmly attached to the column foot, not mobile, white to light yellowish, 3–lobed, spurred at the base. Lip side lobes triangular, obtuse, straight, erect, 4.5–5.5 mm long, 2–3 mm wide, broadly attached to column foot, white or light yellowish, with 4–5 broad, purple, longitudinal stripes. Median lip lobe narrowly rhomboid obovate, 8.5–10 mm long, 6–7 mm wide, white or light yellowish, curved, concave, with round apex, finely erose along margin, disk verruculose with 2 large gibbous verrucose purple calluses at center. Spur white or pinkish, broadly conical, (3.5)4–4.5 mm long, 1.5–2 mm wide, attenuate into inflated, slightly laterally flattened green apex. Columnpure white, shortly cylindric, 2–2.5 mm tall and broad, truncate, with slightly concave clinandrium and small 2-lobed rostellum, at front with round concave stigma. Column foot prominent, fleshy, rectangular, slightly incurved to almost straight, 4–5 mm long, 2–2.5 mm wide. Operculum white to light yellowish, hemispheric, 1.5–2 mm in diam., 2-chambered inside, smooth, frontally with a short, triangular beak rounded or blunt at apex. Pollinarium consisting of 2 pollinia, caudicles, stipe and viscidium. Polliniasolid, spherical, 0.6 mm in diameter, yellow, smooth, entire but distinctly notched abaxially. Caudicles very short, insignificant. Stipehyaline, saddle shaped. Viscidiuma thin, flat, round disk. Fruitnot seen.

Etymology

Species is named after its discoverer, Mr. Nguyen Phong.

Ecology

Miniature branch epiphyte. Primary dry evergreen coastal tropical monsoon forests on silicate rocks at elevations 50–150 m a.s.l. Rare. Flowers in February – March.

Distribution

Species probably inhabits seasonal tropical broad-leaved lowland coastal woods and woodlands in Ninh Thuan province of southern Vietnam.

IUCN status

Following to IUCN Red List criteria (IUCN. 2013) species status should be tentatively estimated as endangered (EN) or critically endangered (CR) due to the overall reduction of endemic primary lowland forests and woodlands in the area when remained species populations are restricted to extremely small, highly fragmented subpopulations standing on the verge of full extinction. Timely assessment of the species in nature and its introduction into culture are living important actions for salvation of this interesting orchid which has good prospects for cultivation as miniature ornamental plant.

Notes

Most probably discovered species represents local endemism of ancient xerophilous flora spreading along narrow coastal belt shaded from monsoon winds and experienced by annual precipitation with rains falling during short rain season lasting from the end of September to middle December. This rather limited biogeographic region of Vietnam is recognized in modern geography as climatic area of monsoon tropical climate with warm winter and autumn-winter rains (Averyanov et al., 2003; Nguyen et al., 2000). Newly described species looks appropriately adapted to semi-desert, strongly seasonal climate conditions by its succulent fleshy cylindric leaves, unique in the genus. Plant differs strikingly in its unusual habit from all other its congeners and resembles superficially some species of the genus Holcoglossum Schltr. with which has hardly direct relations. Verruculose lip with two warty purple gibbosities on the disk is another peculiar character which differ new species from all other known species of Aerides . Taxonomically species may be also related to Rhynchostylis Blume and Vanda R. Br., from which it is distinguished by the presence of a well-developed column foot as it is observed in all other species of Aerides . Discovered novelty undoubtedly desires artificial propagation and cultivation as an unusual beautiful miniature ornamental orchid that may be one of the ways for its effective protection.

 

Fig. 1. Aerides phongii Aver. Flowering plants, flowers and floral details

(all photos from the type specimens by Phan Ke Loc and Chu Xuan Canh, image correction and design by Leonid V. Averyanov).

 

Acknowledgements

Laboratory studies of discovered species were supported from exploration program of U.S.A. National Geographic Society "Exploration of primary woods along constructed highway Hanoi – Ho Chi Minh for their sustainable conservation (in limits of Ha Tinh and Nghe An provinces of central Vietnam)".

References

Averyanov L.V. Identification guide to Vietnamese orchids (Orchidaceae Juss.). – St. Petersburg: World and Family, 1994. – 432 p.

Averyanov L.V. New and rare orchids (Orchidaceae) in the flora of Cambodia and Lao PDR // Turczaninovia, 2013. – Vol. 16, № 4. – P. 26–46.

Averyanov L.V., Averyanova A.L. Updated checklist of the orchids of Vietnam. – Hanoi: Vietnam Nat. Univ. Publ. House, 2003. – 102 p.

Averyanov L.V., Loc P.K., Nguyen T.H., Harder D.K.Phytogeographic review of Vietnam and adjacent areas of Eastern Indochina // Komarovia, 2003. – Vol. 3. – P. 1–83.

Chen X.Q., Wood J.J. AerodesLoureiro // Z.G. Wu, P.H. Raven, Hong D.Y. (eds). Flora of China. – Vol. 25. – Beijing: Science Press & St. Louis: Missouri Botanical Garden Press, 2009. – P. 485–486.

Christenson E.Sarcanthinae genera: 10. Aerides // Amer. Orchid Soc. Bull., 1993. – Vol. 62. – P. 595–609.

IUCN.2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org> (accessed 16 March 2014).

Kocyan A., de Vogel E.F., Conti E., Gravendeel B.Molecular phylogeny of Aerides (Orchidaceae) based on one nuclear and two plastid markers: A step forward in understanding the evolution of the Aeridinae// Molecular Phylogenetics and Evolution, 2008. – Vol. 48. – P. 422–443.

Newman M.F., Ketphanh S., Svengsuksa B., Thomas P., Sengdala K., Lamxay V., Armstrong K. A checklist of the vascular plants of Lao PDR. – Edinburgh: Royal Botanic Garden, 2007. – 394 p.

Nguyen Th.H., Loc P.K., Nguyen T.H. Nguyen.Bioclimatic diagrams of Vietnam. – Hanoi: Vietnam National University, 2000. – 126 p.

Orchids of Cambodia.http://www.orchidcambodia.com (accessed 16 March 2014).

Schuiteman A., Bonnet P., Svengsuksa B., Barthelemy D.An annotated checklist of the Orchidaceae of Laos // Nordic Journal of Botany, 2008. – Vol. 26. – P. 257–316.

Schuiteman A., de Vogel E.F. Orchid genera of Thailand, Laos, Cambodia and Vietnam. – Leiden: Nat. Herb. Nederlands, 2000. – 118 p.

Seidenfaden G.Orchid genera in Thailand XIV. Fifty-nine vandoid genera // Opera Bot. 1988. – Vol. 95. – P. 1–398.

Seidenfaden G. The orchids of Indochina // Opera Bot., 1992. – Vol. 114. – P. 1–502.

 

L.V. Averyanov
Russian Academy of Sciences, Komarov Botanical Institute

P.K. Loc
Faculty of Biology, Hanoi University of Science, Vietnam National University, Hanoi, Vietnam

C.X.Canh
CARE International in Vietnam, 92 To Ngoc Van, Hanoi, Vietnam

 

Key words: Aerides phongii , Orchidaceae, plant diversity, new species, Vietnam, nature protection.

Turczaninowia17 (1): 6–9 (2014)

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