15/06/2014

Phát hiện loài cây gỗ mới Hopea vietnamensis ở Quảng Bình

 
Figure 1: Hopea vietnamensis H. V. Sam & D. Vu a, leaves and inflorescence, b, flower, c fruit (A & B Le Van Thuan 6974 (VNF), C Le Van Thuan 6975 (VNF)). Theo Global Journal of Botanical Science, 2014.
A New Species of Hopea (Dipterocarpaceae) from Vietnam 
Hoang Van Sam*1; Xia Nanhe 2, Vu Van Dung 3 and Luu Hong Truong  4.
 1 - Vietnam Forestry University, Xuan Mai, Ha Noi, Vietnam; 2 - South China Botanical Garden, Xingke Road 723, Tianhe District, Guangzhou, China; 3-Vietnam Forest Inventory and Planning Institute, Van Dien, Thanh Tri, Ha Noi, Vietnam; 4 - Centre for Biodiversity and Development, 85 Tran Quoc Toan, Dítrist 3, Ho Chi Minh City, Vietnam 
*Address correspondence to this author at the Vietnam Forestry University, Xuan Mai, Ha Noi, Vietnam; E-mail: samhv@vfu.edu.vn
Tóm tắt: Đây là loài cây gỗ lớn, cao đến 40m, đường kính thân lên đến gần 1m, được phát hiện tại rừng núi đá vôi thuộc Vườn Quốc Gia Phong Nha - Kẻ Bàng, Quảng Bình, Việt Nam. Được công bố trên tạp chí lobal Journal of Botanical Science năm 2013 nhưng mới chính thức được miễn phí xem vào tháng 6 năm 2014.
Abstract: A new species of Hopea (Dipterocarpaceae) from Vietnam, Hopea vietnamensis, has been described and depicted. This species was previously misidentified as Hopea exalata Lin, Yang & Hsue. Hopea vietnamensis is somewhat similar to Hopea exalata and Hopea reticulata, but the sepals are dense hairy outside, slightly hairy inside, and have a pale yellow color. 
INTRODUCTION : The Dipterocarpaceae include about 600 species in three subfamilies and 17 genera, with 6 genera and 44 species in Vietnam. A careful examination of Indochinese specimens of Hopea at Vietnam Forestry University and the Vietnam Forest Inventory and Planning Institute found some unusual specimens that had been collected by Le Van Thuan in Thua Thien Hue and Quang Binh provinces, which are almost 500 km south of Hanoi, Vietnam. These specimens were collected in 1978, and they were assigned the numbers Le Van Thuan 6792, 6794, 6795, 6796 and 6797. These specimens were identified by Nguyen Ngoc Chinh and Vu Van Dung as Hopea exalata. In 2011 we conducted fieldwork in Quang Binh province (Phong Nha Ke Bang National Park) to try and recollect this species, and we were able to discover a similar specimen in the karst formation of the National Park. We studied literatures [1-4, 8-10] and many specimens including types of Indochineses and Chinese Hope After comparing this specimen with type specimens and many other specimens in Paris (P), Leiden (L), South China Botanical Garden Herbarium (IBSC) and most herbaria in Vietnam, it became obvious that our materials differed significantly from Hopea exalata Lin, Yang & Hsue and Hopea reticulata Tardieu 
RESULTS AND DISCUSSION: Hopea vietnamensis H. V. Sam & D. Vu Typus Le Van Thuan 6795 (Holo type, VNF) 
Figure 2: Hopea vietnamensisH. V. Sam & D. Vu (Le Van Thuan 6975 (VNF)). Theo Global Journal of Botanical Science, 2014.
Evergreen trees, 30-40 m tall, 60-80 cm in diameter. Bark thin, white grey, not peeling when young, peelingoff into large pieces when old. Branches slender, white grey. Leaves simple, alternate, distichous ovoid or lanceolate, tip attenuate, base rounded, a little bit asymmetrical, 5-11cm long, 3-5cm wide. Basal veins 5-6 pairs, the two lower veins usually not obvious, lateral veins 3-5 pairs, without domatia at the lower surface of the leaves. There is no reticulate tertiary venation. Petioles thin, 6-10 mm long, covered with yellow grey tomentum when young, soon caducous. Inflorescence and axillary panicle, 6-11cm long, rachis glabrous, bud c. 6 mm long. Sepals 5, nearly rounded or ovoid, 2-2,5 mm long, top convex, tomentose at margin and outside. Petals 5, obovoid or elliptical, pale yellow, c. 5 mm long; apex acuminate and oblique, dense, grey tomentose outside and slightly pubescent inside. Stamens 15, arranged in two rings; inside round with 10 and outside round with 5 stamens Anthers ellipsoid, 0,5-0,7mm long, filaments 1,3-1,6 mm long, connectival appendage about 2 times as long as anther, Ovary superior, pyriform, shortly fine pubescent with short style, 3-locular, two ovules in each locule. Fruits ovoid, c. 1,7cm long and c. 0,9cm wide, pointed at top, brownish-yellow when mature, wings 2, 4-6cm long, c. 1,2 cm wide; apex obtuse, glabrous, about 11 parallel veins on each wing. 
Note: According to “Flora of China”, Hopea exalata is a synonym for Hopea reticulata. However, my research shows that they are two different species (see Table 1). Hopea exalata has glans on the lower surface of the leaves while Hopea reticulata does not have glans; Hopea exalata has 15 stamens while Hopea reticulata only has 10 stamens. The sepal of Hopea exalata is of a pink color and smooth on both surfaces while the sepal of Hopea reticulate has a reddish color, and is slightly hairy outside and smooth inside. 
Distribution: This species is an endemic species of Vietnam. To date it has only been found in limestone forests in Nam Dong and Phong Nha Ke Bang National Park, Quang Binh province, central Vietnam. These areas are about 500 km south of Hanoi (Figure 3). 
Ecology: Flowering in July-September; fruiting in February-March. 
Figure 3:Distribution of Hopea vietnamensisH. V. Sam & D. Vu. Theo Global Journal of Botanical Science, 2014.
This species grows in limestone forests in Nam Dong and Phong Nha Ke Bang National Park, Quang Binh province, Vietnam. 
Additional specimens: Le Van Thuan 6800, Le Van Thuan 6790, Le Van Thuan 6791, Le Van Thuan 6792, Le Van Thuan 6796, Le Van Thuan 6797, Le Van Thuan 6976, Le Van Thuan 6977 (FIPI); Le Van Thuan 6794 and Le Van Thuan 6795 (VNF) in Quang Binh, Vietnam. Date of collection June 1978. Hoang Van Sam BC-TV 1445 (VNF) in Quang Binh, Vietnam. Date of collection November 2011.
Theo: Global Journal of Botanical Science, 2013, 1, 29-32; Savvy Science Publisher
DOI: http://dx.doi.org/10.12974/2311-858X.2013.01.01.5