Aristolochia yachangensis B.G.Huang, Yan Liu & Y.S.Huang, 2020

Luo, Ya Jin, Ni, Shi Dong, Jiang, Qiang, Huang, Bo Gao, Liu, Yan & Huang, Yu Song, 2020, Aristolochia yachangensis, a new species of Aristolochiaceae from limestone areas in Guangxi, China, PhytoKeys 153, pp. 49-61 : 49

Aristolochia yachangensis B.G.Huang, Yan Liu & Y.S.Huang sp. nov. Figures 1 , 2 , 3 , 4A-D

Diagnosis.

Aristolochia yachangensis is morphologically similar to A. fangchi Y.C.Wu ex L.D.Chow & S.M.Hwang, A. petelotii O.C.Schmidt and A. championii Merr. & Chun, but can be distinguished from them by stems irregularly striate, sparsely yellowish-brown pubescent or glabrous; leaf blade 1.5-3 cm wide; cymes on old woody stems; basal portion of perianth tube 2-3 cm long, shorter than the upper; limb yellow, with dark purple mural-like stripes; throat yellow; capsule ellipsoid. Detailed morphological comparisons amongst the four species of A. yachangensis , A. championii , A. petelotii and A. fangchi are summarised in Table 1 .

Type.

China. Guangxi Zhuang Autonomous Region: Baise City, Leye County, Huaping Town, Zhongjing (Yachang Orchid National Nature Reserve), 24°49.367'N, 106°24.029'E, 1341 m a.s.l., 29 July 2019, Z. C. Lu et al. 20190729YC4141 (holotype: IBK!; isotypes: IBK!, GXMG!).

Description.

Shrubs climbing. Stems terete, irregularly striate, sparsely yellowish-brown pubescent or glabrous. Branchlets densely yellowish-brown pubescent. Leaf blade leathery, lanceolate to elliptic-lanceolate or linear-lanceolate, 5-15 × 1.5-3 cm, apex narrowly acuminate, base rounded or broadly cuneate, margin entire, adaxially glabrous except the pubescent midnerve and lateral veins, abaxially shallowly yellowish-brown pubescent, basal veins 3, lateral veins 5-8 pairs, conspicuous on both surfaces; petiole 1-1.5 cm long, slightly distorted, densely yellowish-brown pubescent. Cymes on old woody stems, 1-5-flowered; pedicel 1-2 cm long, pendulous, densely yellowish-brown pubescent; bracteole ovate-lanceolate, ca. 4 × 2 mm, densely yellowish-brown pubescent; perianth tube horseshoe-shaped; basal portion of tube 2-2.5 × 0.6-1 cm, shorter than the upper part, near the base of inner dark purple, densely villous, outside of tube mauve, densely yellowish-brown pubescent; upper portion of tube 2.5-3 × 0.5-0.8 cm, inner yellow, with dark purple stripes; limb subrotund-peltate, 4-6 cm in diam., yellow, with dark purple mural-like stripes, abaxially densely brown pubescent, margin shallowly 3-lobed, lobes apex mucronate; throat suborbicular, 0.5-1 cm in diam., yellow; anthers oblong, 2-4 × 1 mm, adnate to the gynostemium base, opposite to the lobes; ovary terete, ca. 1.5 × 0.3-0.5 cm, 6-angled, densely brown pubescent; gynostemium 3-lobed, margin glabrous and papillary. Capsule ellipsoid, 6-10 × 2.5-3.5 cm, 6-angled, glabrous.

Phenology.

The new species was observed flowering from March to May and fruiting from June to August.

Etymology.

The specific epithet is derived from the type locality, Yachang Orchid National Nature Reserve, Guangxi, China. The Chinese name is given as “雅长马兜铃”.

Distribution and habitat.

At present, Aristolochia yachangensis was found only in Yachang Orchid National Nature Reserve of north-western Guangxi, China. It grows on limestone hillside at an elevation of ca. 1340 m. The slope direction is to the southwest, the slope is up to 40°, the tree layer is up to 15 m tall, the canopy cover is 70%, the shrub layer cover is 80% and the herb layer cover is 45%. Its associated species include Quercus variabilis Blume ( Fagaceae ), Celtis sinensis Pers. ( Ulmaceae ), Platycarya longipes Wu ( Juglandaceae ), Toxicodendron succedaneum (L.) Kuntze ( Anacardiaceae ), Yua thomsonii (Laws.) C.L.Li ( Vitaceae ), Pteridium aquilinum (L.) Kuhn var. latiusculum (Desv.) Underw. ex A.Heller ( Pteridiaceae ), Miscanthus sinensis Andersson ( Gramineae ) etc.

Conservation status.

Thus far, Aristolochia yachangensis has been found only from the type locality. The only subpopulation is located within a protected region and has seven individuals, including two mature ones. Based on the present study, its Extent of Occurrence (EOO) is less than 100 km2 and the known Area of Occupancy (AOO) is less than 0.5 km2. According to Guidelines for Using the IUCN Red List Categories and Criteria (IUCN Standards and Petitions Committee 2019), A. yachangensis should be given a Vulnerable (VU) status, based on the criteria D2 of IUCN. As a newly-found species, however, it is probable that more subpopulations of A. yachangensis could be found in similar habitats of limestone areas of north-western Guangxi and southern Guizhou, China in the future.

Additional specimens examined (paratypes).

China. Guangxi Zhuang Autonomous Region: Baise City, Leye County, Huaping Town, Zhongjing (Yachang Orchid National Nature Reserve), 24°49.367'N, 106°24.029'E, 1341 m a.s.l., 21 April 2019, Y. J. Luo & S. W. Li 20190421001 (IBK); the same location, 17 May 2019, Y. J. Luo et al. YC4439 (IBK).

Figures

Figure 1. Aristolochia yachangensis B. G. Huang, Yan Liu & Y. S. Huang, sp. nov. A habit B flowering branch C flower (front view) D longitudinally dissected flower (showing the inside structure) E anthers and gynostemium (lateral view) F old phase of gynostemium (vertical view) G capsule. Drawn by Wenhong Lin (IBK).

Figure 2. Aristolochia yachangensis B. G. Huang, Yan Liu & Y. S. Huang, sp. nov. A habitat B flowering branch C flowers (front view) D flower (lateral view) E flower bud F longitudinally dissected flower (showing the inside structure) G longitudinally dissected flower (dorsal view) H old phase of gynostemium (vertical view) I old phase of anthers and gynostemium (lateral view) J ovary K young capsule L mature capsule. Photographed by Shuwan Li.

Figure 3. Holotype of Aristolochia yachangensis B. G. Huang, Yan Liu & Y. S. Huang, sp. nov. Z. C. Lu et al. 20190729 YC 4141 (IBK).

Figure 4. A-D Aristolochia yachangensis B. G. Huang, Yan Liu & Y. S. Huang, sp. nov. A habitat B inflorescence and flowers (lateral view) C flower (front view) D anthers and gynostemium E-H A. championii Merr. et Chun: E habitat F inflorescence and flower (front view) G flower (lateral view) H anthers and gynostemium I-L A. fangchi Y. C. Wu ex L. D. Chow et S. M. Hwang: I habitat J inflorescence and flower (lateral view) K flower (front view) L anthers and gynostemium M-P A. petelotii O. C. Schmidt: M habitat N inflorescence and flower (lateral view) O flower (front view) P anthers and gynostemium. Illustration by Wenhong Lin (based on the illustrations from Flora Reipublicae Popularis Sinicae).