Aristolochia xuanlienensis N.T.T Huong, B. H. Quang & J. S Ma, 2014

Huong, Nguyen Thi Thanh, Hai, Do Van, Quang, Bui Hong, Cuong, Nguyen The, Khang, Nguyen Sinh, Vu, Dang Quoc & Ma, Jin-Shuang, 2014, Aristolochia xuanlienensis, a new species of Aristolochiaceae from Vietnam, Phytotaxa 188 (4), pp. 176-180 : 176-179

Aristolochia xuanlienensis N.T.T Huong, B. H. Quang & J. S Ma , sp. nov. ( Figs. 1 , 2 )

Aristolochia xuanlienensis is similar to A. hainanensis Merrill (1922: 341) , A. balansae Franchet (1898: 311) and A. quangbinhensis Do (2014: 52) , but its white perianth with light purple veins on the outside and dark purple spots both in tube and on limb has never been reported before among the Asian species.

Type:— VIETNAM. Thanh Hoa Province: Xuan Lien Nature Reserve , 19°59’44.5’’N, 105°00’08.7’’E, elevation about 870 m, 7 November 2011, Hai, Quang, Cuong, Vu, Thanh & Thanh 129 (holotype HN 00000 68875; isotypes: CSH) .

Other specimens examined:— VIETNAM. Thanh Hoa Province: Xuan Lien Nature Reserve , 19°50’51.3’’N, 105°14’40.6’’E, elevation about 200 m, 17 April 2014, Huong, Hai, Quang & Khang 105 ( HN, VNMN) .

Liana with a woody stem, terete, striate, yellow, hairs brown, old branchlets glabrous, up to more than 1 cm in diameter. Leaves with the petioles 3–8 cm long, densely yellow-brown villous; leaf blade ovate or ovate-lanceolate to narrowly ovate, 12–25 x 7–15 cm, both surface densely villous when young, becoming glabrous when old; margin entire; veins palmate, 4–5 pairs from base; base rounded, apex acuminate. Racemes usually in axils of leafy shoots or on old woody stems, 3–4(–5) flowers, ca 3.5 cm long; peduncle often pendulous, ca. 3 cm long, densely pubescent. Perianth white with light purple veins outside and dark purple spots both in tube and on limb; limb obliquely trumpet-shaped, ca 2.5 cm in diameter, trilobed; lobes subequal, densely papillate, upper 2 oblong, lower one broadly deltoid. Gynostemium is with trilobed stigma on top, anthers 6 in 3 pairs, oblong, ca. 2 mm long. Capsule narrowly cylindric, yellow, 8.0–10.0 x 2.0– 2.5 cm. Seeds cordate, ca. 4–6 x 3–4 mm.

Vernacular name:— Phòng kỷ Xuân Liên (Vietnamese)

Distribution and habitat:— Aristolochia xuanlienensis is currently known only from Xuan Lien Nature Reserve, Thanh Hoa Province, Vietnam, at elevations between 200– 900 m. The new species usually grows in the understory of primary subtropical evergreen forests, along with tree species including Raphidophora sp , Alocasia sp. , Pothos sp. , Paraborea sp., Tarenna latifolia Pit. , Boehmeria sp. , Ficus sp , ferns and others.

Phenology: —Flowering September–January and fruiting March–May.

Etymology:— Named after the location of Xuan Lien, Thanh Hoa Province, Vietnam, to which the species is endemic.

Conservation status:— Within Xuan Lien Nature Reserve, Aristolochia xuanlienensis is known only from a single population, with fewer than five individuals observed among our two expeditions in the past few years. It is therefore assigned a preliminary status of Vulnerable (VU) according to IUCN Red List criteria ( IUCN, 2001), which indicates a population with a very restricted area (typically less than 20 km 2). More populations of this species remain to be found in similar habitats in the area. However, an extensive field survey is needed since the species is small liana that is inconspicuous in the forests and thus usually difficult to observe in the field.

Figures

FIGURE 1. Aristolochia xuanlienensis. A. Habit. B. Young branchlets. C. Old branchlets. D. Cross section of branchlets. E. Flowers (front view). F. Gynostemium with three lobes of stigma. G. Anthers magnified. H. Capsules. I. Cross section of capsules (illustrated by Le Kim Chi, A–C & E–G from XL 129, D & H–I from DVH 105).

FIGURE 2. Aristolochia xuanlienensis. A–B. Habit. C. Young branchlets. D. Old branchlets. E. Cross section of branchlets. F. Leaf, adaxial view. G. Leaf, abaxial view. H. Racemes. I. Flowers (front view). J. Flowers (side view). K. Anthers. L. Gymnostemium. M. Capsules. N. Cross section of capsules. O. Young seed. (Photographs by Hai D.V (A–J) and Quang B.H (K–O).)