Aristolochia luudamcui T.V.Do, 2021

Phan, Long Ke, Wanke, Stefan, Neinhuis, Christoph & Do, Truong Van, 2021, Aristolochia luudamcui (Aristolochiaceae), a new species from northern Vietnam, Phytotaxa 527 (1), pp. 67-74 : 68-73

Aristolochia luudamcui T.V.Do , sp. nov. ( Figs. 1–3 )

Aristolochia luudamcui is most similar to A. pseudoutriformis and A. utriformis by sharing an ovate to lanceolate-ovate leaf blade, a light yellow perianth, and a saccate-shaped limb, but it clearly differs from these two species by having a deeply 3-lobed limb (vs. shallowly 3-lobed limb in both A. pseudoutriformis and A. utriformis ) and a yellow, glabrous inner surface of limb lobes (vs. darkred, dense processes in A. pseudoutriformis and black-purple, sparse processes in A. utriformis ).

Type: — VIETNAM. Lao Cai province: Sa Pa city, Hoang Lien National Park , 16 May 2021, 22°20’03”N, 103°46’47”E, alt. 1926 m, flowering, Do Van Truong ĐVT407 (holotype VNMN; isotypes HN, VNMN) .

Perennial climber, twiner, 3–4 m long. Stem terete, young branch pubescent, becoming glabrous when older. Petiole 3– 4 cm long, straight, glabrescent. Leaf blade ovate, narrowly ovate to lanceolate, 7–11 × 3–4 cm, papery, base cordate, auriculate, sinus 1–1.5 cm deep, 0.1–0.3 cm wide, apex acute to shortly acuminate, adaxial surface sparsely pubescent, abaxial surface densely pubescent, basal veins palmate, three pairs from base, lateral veins pinnate, 3–4 pairs, venation foveolate-reticulate, flattened on the adaxial surface, and prominent on the abaxial surface. Flower terminal, solitary or paired, axillary or sometimes along old branches; peduncle 5–10 mm long, brown, pubescent. Bracteole subulate, 2–3 × 2 mm, both surfaces densely pubescent, sessile, persistent, inserted near base of the peduncle. Pedicel 2–2.5 cm long, brown, pubescent. Ovary oblong, 1–1.2 × 0.2–0.3 cm in diam., brown, glabrescent. Perianth geniculately curved, outer surface yellowish-green, with few parallel brown striations, glabrous. Utricle cylindric, 5–6 × 6–8 mm, inner surface sparsely covered by trichomes and a dark-purple patch. Tube strongly curved, inflated and almost as wide as the utricle, 8–9 mm high, 6–8 mm in diam., inner surface reddish-purple, glabrous. Limb saccate-shaped, cylindric, strongly inflated, larger than the tube and utricle, 2.6–3 × 0.7–1.2 cm, forming an obtuse angle with upper tube, deeply 3-lobed, lobes deltoid-ovate, clearly separated from each other, 1–1.2 × 0.8–1 cm, obtuse at apex, inner surface yellow, glabrous. Throat ca. 1 mm in diam., yellow. Annulus present at the transition between the apical part of tube and the basal part of limb, projection on the apical tube, semicircle-like, dark-yellow. Gynostemium 3-lobed, 2–3 × 2.5–3 mm, yellowish-white, the lobes with obtuse apices. Anthers oblong, 1–1.5 mm long, yellow. Capsule not seen.

Etymology: —The specific epithet honors Prof. Dr. Luu Dam Cu, a former vice-director of Vietnam National Museum of Nature who strongly supported botanical research at the museum during the past years.

Vernacular name: —Mộc hương Cư.

Phenology: —Flowering plants have been observed from April to May. Fruits unknown.

Distribution and ecology: — Aristolochia luudamcui is known from two localities in northern Vietnam, i.e. Hoang Lien National Park, Lao Cai province and Tay Con Linh Nature Reserve, Ha Giang province. It grows in moist places under broad-leaved evergreen forest or mixed bamboo and broad-leaved forests, at 1,400 –2,000 m, together with dominant plants of Dryopteridaceae ( Dryopteris sp. ), Ebenaceae ( Diospyros sp. ), Lauraceae ( Machilus sp. ), Poaceae ( Schizostachyum sp. , Lophatherum sp. ), and Rosaceae ( Eriobotrya sp. ).

Usage: —The root is used for treatment of stomachache, dysentery and also for the treatment of arthritis and rheumatism (following indigenous knowledge of Dao people interviewed during field work).

* Morphological characters following Zhu et al. (2019) ** Morphological characters following Ma (1989), Hwang et al. (2003), Zhu et al. (2019)

Provisional conservation status: —Only two small populations of A. luudamcui were found within the buffer zone of Hoang Lien National Park, Lao Cai province and Tay Con Linh Nature Reserve, Ha Giang province, northern Vietnam, but few seedlings were observed. Furthermore, the local farmers continue to impose strong pressure on the remaining primary forest patches converting them mostly into Bengal cardamom plantation ( Amomum aromaticum Roxb. (1820: 44)) in the first locality and corn field ( Zea mays L. (1753: 971)) in the second one. Thus, the new species is preliminarily assessed as Endangered [EN C1] following the IUCN Red List Categories and Criteria ( IUCN 2019).

Additional specimens examined:— Vietnam, Lao Cai province: SaP city, Hoang Lien National Park, 22°20’03”N, 103°46’47”E, on path from Cat Cat village to 3,143 m peak, 17 Apr. 2013, Do Van Truong ĐVT 38 (DR, VNMN); along 3 rd national road to Ton forest station, 10 Dec. 1997, Nguyen & Ngo 8813 (NIMM) ; Ha Giang province: Vi Xuyen district, Cao Bo commune, Tay Con Linh Nature Reserve , 7 June 2021, Do Van Truong ĐVT506a (VNMN) .

Taxonomic notes: —Morphologically, A. luudamcui is most similar to A. pseudoutriformis ( Fig. 3 D-F) in the shape and color of perianth, but it differs from the latter by the morphology of the leaf lamina, the inner surface of the limb, and the size of the throat. The new species is also similar to A. utriformis ( Fig. 3 G-I) with respect to the morphology of the leaf lamina and the coloration of the flower perianth, but they can be distinguished by the morphology and the inner surface of the limb. A detailed morphological comparison of A. luudamcui with A. pseudoutriformis and A. utriformis is summarized in Table 1 and presented in Fig. 3 .

This new discovery, along with many species of Aristolochia subgen. Siphisia recently described from Vietnam and neighboring countries ( Zhu et al. 2016, 2017, 2018, 2019, Do et al. 2019, 2021), characterized by a saccate-shaped limb, provide further evidence that Aristolochia subgen. Siphisia in general and species with a saccate-shaped limb in particular are very diverse in the Indo-Chinese floristic region, especially in southern China and northern Vietnam.

Figures

FIGURE 1. Aristolochia luudamcui T.V.Do sp.nov. A. Branch bearing a terminal flower; B. Lateral view of the flower; C. Lateral view of the longitudinally dissected perianth; D. Gynostemium. Drawn by Nguyen Huu Quyet from the type specimen.

FIGURE 2. Aristolochia luudamcui T.V.Do sp.nov. A. Habit; B. Adaxial leaf surface; C. Abaxial leaf surface; D. Branch bearing a terminal flower; E. Lateral view of the flower (red arrow showing a subulate bracteole); F. Lateral view of the perianth; G. Lateral view of the longitudinally dissected perianth; H. Lateral view of the longitudinally dissected limb; I. Close up of the throat (showed by a blue arrow); J. Gynostemium.All photographed by Truong Van Do.

FIGURE 3. Morphological comparison of Aristolochia luudamcui T.V.Do sp.nov. (A–C) with A. pseudoutriformis (D–F) and A.utriformis (G–I). A, D, G. Shape of both leaf surfaces; B, E, H. Lateral view of the flower; C, F, I. Lateral view of the longitudinally dissected perianth. A–C photographed by Truong Van Do; D–I photos in Zhu et al. (2019).