19/06/2014

Loài Cọ núi lào mới Trachycarpus ravenii từ bắc Lào

Cọ núi lào Trachycarpus ravenii. Ảnh Leonid Aver.
(biodivn.blogspot.com) Tạp chí Nordic Journal of Botany vừa công bố một loài cọ núi mới được phát hiện tại khu vực núi đá vôi miền Bắc nước Lào. Công bố này hiện vẫn đang ở phiên bản Xem trước (Early View), nghĩa là chưa có số tập, số trang nhưng về mặt nội dung thì có thể xem là phiên bản cuối cùng. Loài mới có tên Cọ núi lào Trachycarpus ravenii nhằm vinh danh GS. Peter Raven - Cựu Giám đốc Vườn Thực vật Mít su ri, Hoa Kỳ - với những đóng góp tài trợ kinh phí và tổ chức điều phát phát hiện rất nhiều loài mới từ vùng Đông Dương. Chi cọ núi Trachycarpus trên thế giới có khoảng 10 loài. Cọ núi lào Trachycarpus ravenii  có chiều cao chừng 6 m, mọc rải rác. Chúng có hình dạng khá đẹp, có giá trị về mặt tài nguyên cây cảnh cao. Phân bố của chúng là khu vực rừng thứ sinh, trảng cỏ, cây bụi với diện tích phân bố rất hạn chế, khoảng dưới 100km2. Với vùng xuất hiện ít như vậy nên Cọ núi lào Trachycarpus ravenii  được đề nghị xếp ở trình trạng bảo tồn Rất nguy cấp (Critically Endangered-CR), theo thứ hạng và hạng mục của Danh lục đỏ thế giới IUCN.

Trachycarpus ravenii sp. nov. (Arecaceae, Corypheae) from central Laos
Leonid V. Averyanov, Khang Sinh Nguyen, Tien Hiep Nguyen, The Van Pham and Shengvilai Lorphengsy
L. V. Averyanov (av_leonid@mail.ru), Komarov Botanical Inst., Russian Acad. of Science, Prof. Papov Srt. 2, RU-197376 St Petersburg, Russia. – K. S. Nguyen, Inst. of Ecology and Biological Resources, 18 Hoang Quoc Viet, Cau Giay, Ha Noi, Vietnam. – H. T. Nguyen, Center for Plant Conservation, no. 25/32, Lane 191, Lac Long Quân Rd, Nghia Dô, Cau Giay District, Ha Noi, Vietnam. – T. V. Pham, Inst. of Ecology and Biological Resources, 18 Hoang Quoc Viet, Cau Giay, Ha Noi, Vietnam. – S. Lorphengsy, National Science Council Dept, National Herbarium of Laos.
A new species Trachycarpus raveniidiscovered in Kasi district, Vientiane province of central Laos is described and illustrated. Morphologically, it is closest to T. oreophilusandT. princeps, but differs by having a shorter stem of mature plants; glabrous, dull green petiole; almost circular leaf blade, waxy bluish–white abaxially; narrow leaf segments with narrow free lobes densely adpressed to each other, as well as in oblique-round apices of median leaf segments.
Trachycarpus H. Wendl.
10 species. Nepal, Bhutan, northern India, southwestern China, Myanmar, northwestern Thailand, central Laos, northern Vietnam.
Trachycarpus ravenii Aver. & K. S. Nguyen sp. nov. (Fig. 1–2)
Etymology. This superb, kinglike tree is named after Prof. Peter H. Raven in recognition of the truly outstanding and essential role that this noble person has played in the organization and support of field botanical explorations and new species discoveries within unexplored areas of Indochina.
Cọ núi lào Trachycarpus ravenii. Ảnh Leonid Aver.
Description. Erect unbranched dioecious fan palm. Stem solitary, straight or slightly ascending, to 6 m tall and 15 cm in diameter, with few insignificant remnants of leaf sheaths near apex or entirely naked, ringed. Leaves (15)18–25(30), palmate, forming a compact, dense hemispherical to almost spherical crown; old, dry, marcescent leaves hang downward, form a dense, broad skirt embracing an almost naked trunk.  Leaf petiole slender, (40)45–55(60) cm long, triangular in cross section, 3.0–1.5 cm in diameter, glabrous, dull green, straight to slightly curved, at base strongly recurved, with few stiff, rigid, almost straight bristles; leaf sheaths rather short, fibrous; old sheaths forming a mass of interwo-ven fibers, fibers at apex of sheath on younger leaves form-ing a short ocrea; petiole margins with very small blunt teeth to almost unarmed. Leaf blade semicircular to almost circular in outline, 0.7–1.0 m long and wide, dark green adaxially, waxy bluish–white abaxially, divided to about half of their length into 50–60 stiff segments; hastula triangular-ovate, obtuse, 2.2–3.0 cm long and wide, with entire, light yellowish–brown, coriaceous margin. Leaf segments arranged in one plane, producing a nearly flat leaf profile, conduplicate, 1.5–2.0 cm wide, their lobes densely adpressed to each other toward the apex; apex of lobes bi-lobulate, lobules acute to strongly oblique round-ish, often with small reflexed seta placed between lobules; secondary veinlets parallel, transverse veinlets almost invisible. Inflorescences (1)2–5(6), interfoliar. Male inflo-rescences with short peduncle, erect, 0.3–0.5 m long, oval in cross section, 8–12 cm wide, enveloped at base by 3–4(5) bracts, branched to 3–4 orders; rachillae 1–3 cm; inflorescence bracts base tubular, ovate, leathery, coriaceous, yellowish to chestnut-brown (when old), shortly hairy, concave, 20–30 cm long, (6)8–12 cm wide; flowers densely arranged, subsessile, white, not widely opening, globose, 2–3 mm in diameter, sepals ovate-triangular, 1.5–2.0 mm long, shortly connate at base; petals oblong-orbicular, twice as long as sepals; stamens 6, exceeding the petals; anthers bean-shaped, 1.2–1.4 mm long; pistillodes insignificant, less than half the length of stamens. Female inflorescences erect or spreading, robust, 0.8–1.2 m long, 15–20 cm wide, branched to 3 orders; rachillae 1–8 cm long; inflorescence rachis oval in section, with (4)6–8 broad sterile bracts; inflorescence bracts chestnut-brown, concave, coriaceous, 10–20(25) cm long, 5–8(10) cm wide; flowers solitary, subtended by minute triangular bracteoles. Old fruits brown to dull black, grooved, 1-seeded, almost globu-lar, 7–8(10) mm in diameter.
Ecology. Primary and secondary forests, secondary scrub and grass-lands on rocky highly eroded solid, crystalline limestone at elevations 1600–1800 m a.s.l., commonly on very steep cliffy rocky north-faced outcrops near mountain tops. Flowering in March to June and fruiting in September to October?
Sinh cảnh sống của Cọ núi lào Trachycarpus ravenii. Ảnh Leonid Aver.
Distribution. Central Laos, Vientiane province, Kasi district, Thong Mout and Namken villages. Local endemic.
Similar species. Discovered plant clearly differs from all previously known Trachycarpusspecies. Morphologically, it is more or less close to three species occurring in Indochina: T. geminisectus,T. oreophilusand T. princeps. Trachycarpus raveniidistinctly differs from T. geminisectusin having tall, naked (not densely furry) stems, a large number of leaves with a small insignificant leaf sheath and ocrea, large hastula and narrow leaf segments. The new species differs from T. oreophilusand T. princepsin having a much shorter stem on mature plants; a glabrous, dull green petiole; an almost circular leaf blade with waxy bluish–white abaxially; narrow leaf lobes with narrow free lobules densely adpressed to each other, as well as oblique-round apices of median leaf segments. A comparison of selected morphological and taxonomic features of Trachycarpus species native to Indochina is shown in Table 1.
Conservation status. A number of earlier studies confirmed that all Trachycarpus species apart from T. fortuneiare more or less seriously threatened and very close to full extinction in the wild  (Gibbons and Spanner 1998, Kholia 2009, Kholia and Rajbhawan 2010). All of these species were recorded as local endemics whose limited distribution may be caused by the widespread and nearly complete destruction of primary plant communities in their native ranges. Degradation of primary native habitats continues across the distribution of the genus and is the main factor of Trachycarpus species threathened status and extinction. This is true for the survival status of T. raveniias well. The estimated total known area of its distribution is less than 100 kmwith no more than 100 observed mature individuals tentatively qualifying this palm as ‘Critically Endangered’ (CR) according IUCN criteria B1, C2 ai, aii and D (IUCN 2012). Conservation of all populations of this relictual species represents the highest priority of nature protection activity in central Indochina. As a first step, T. raveniimay be effectively protected in-situ in suitable habitats within the highest limestone formations in Indochina–Phachao Mountain. Establishing a protected area at Phachao Mountain will also protect large stands of intact, upper elevation limestone forests containing a rich diversity of native endemic species. Trachycarpus raveniiis an attractive tree providing a unique characteristic to the upland limestone landscape of central Laos. (biodivn.blogspot.com).

Phiên bản cuối cùng có thể tìm thấy tại: Nordic Journal of Botany
 

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