VietNamNet Bridge - Scientists have discovered a new species of pipevines near the buffer zone of the Phong Nha - Ke Bang National Park.

The new species is called Aristolochia quangbinhensis Do, of the Aristolochia genus, Isotrema subgenus. It is discovered by a group of scientists from the Vietnam Nature Museum, the Vietnam Academy of Science and Technology.

The Aristolochia genus is generally used in the traditional medicine of Vietnam and China. This group of plants also has an important role in study of co-evolutionary of the living nature.

Aristolochia comprises about 500 species and is the largest genus of Aristolochiaceae. Recent phylogenetic studies of the genus based on morphological and molecular data suggested a subdivision of Aristolochia into three subgenera: Aristolochia, Isotrema and Pararistolochia. Aristolochia subgenus Isotrema comprises about 70 species, 50 of which occur in Asia. In Vietnam two subgenera occur, namely Aristolochia and Isotrema.

Isotrema is well-known for its U- or horseshoe-shaped perianth, the utricle and the tube are not sharply delimited, a strongly folded or curved tube, a 3-lobed limb, sometimes with fused lobes, and a gynostemium consisting of three segments, each of them carrying two anthers on the outer surface. In contrast, subgenus Aristolochia can be recognized by its slightly curved or rectilinear tube, the utricle and the tube are sharply distinct, a one- to three-lobed perianth limb, a gynostemium with more than three lobes; each of them carrying a single anther on the outer surface. Based on these characters, the new species can be easily assigned to subgenus Isotrema.

In an illustrated Flora of Vietnam, Ho (2000) reported 11 species of Aristolochia, including four belonging to Isotrema.

Aristolochia quangbinhensis is known from a single population found on the north-eastern slope of a mountain range bordering the buffer zone of Phong Nha-Ke Bang National Park in the Hoa Luong community, Minh Hoa district, Quang Binh province.

Aristolochia quangbinhensis occurs in humid mountain sites, in the understory of disturbed lowland evergreen broad-leaved forest and mainly evergreen scrubs.

Flowering specimens have been collected in April and May but it is possible that blooming already begins in March.

In the past, large areas of primary, broad-leaved, evergreen forest covered the Hoa Luong community. Excessive logging, however, resulted in the loss of large extensions of primary forest. Although logging was prohibited in the 1990s, local farmers continued to impose strong pressure on the remaining forest patches converting it mostly into corn and soybean fields. As a result, the flora of the area should be regarded as threatened by extinction.

Within the area, Aristolochia quangbinhensis is known from a single population; in fact, during the present study, only two healthy individuals were located growing about 50 m apart from each other. Therefore, the new species is assigned a preliminary status of vulnerable according to IUCN Red List criteria (IUCN 2013), indicating a population with a very restricted area of occupancy (typically less than 20 km2) or the number of locations (typically five or fewer) being both at hand for Aristolochia quangbinhensis. The lack of data currently does not allow a final risk evaluation, but the species might also be regarded as endangered.

Na Son