Aristolochia sinoburmanica Y.H.Tan & B.Yang, 2018

Yang, Bin, Ding, Hong-Bo, Zhou, Shi-Shun, Zhu, Xinxin, Li, Ren, Maw, Mya Bhone & Tan, Yun-Hong, 2018, Aristolochia sinoburmanica (Aristolochiaceae), a new species from north Myanmar, PhytoKeys 94, pp. 13-22 : 14-15

Aristolochia sinoburmanica Y.H.Tan & B.Yang sp. nov. Figures 1 , 2

Diagnosis.

Aristolochia sinoburmanica is morphologically similar to A. hainanensis Merrill, A. saccata Wallich, A. xuanlienensis ( Huong et al. 2014), A. faviogonzalezii T. V. Do, S. Wanke & C. Neinhuis and A. tonkinensis T.V. Do & S. Wanke from Vietnam ( Do et al. 2015a), but is distinguishable from these species by the following diagnostic characters: leaf blade ovate or ovate-lanceolate to narrowly ovate, subcoriaceous, base rounded to slightly cordate; cyme solitary on old woody stems and young branches, each cyme with 1-2 flowers; perianth claret (deep purple red), outside densely brown hirsute with parallel dark purple veins, 6.5-7.5 cm high; tube horseshoe-shaped, 8.3-8.5 cm, uniformly claret (deep purple red), with visible dark purple veins, limb trumpet-shaped, 4.2-4.8 cm high, 4-4.4 cm wide, 3-lobed, lobes subequal; throat deep purple red, glabrous. The summary and main characters comparison is presented in Table 1 .

Type.

MYANMAR. Kachin State: Putao, near Shinshanku, on the roadside slope of a mountain range bordering the zone of Hkakaborazi National Park , perennial lianas under tropical mountain broadleaf forest, 27°38'48.65"N, 97°54'01.61"E, 900 m a.s.l., 11 May 2017, Myanmar Exped. 1532 (holotype HITBC!) .

Description.

Perennial woody liana, 8-12 m high. Stem terete, circular in cross section, ca. 1 cm in diam., young branches green, sparsely pubescent, becoming glabrescent, bark deeply irregularly longitudinally fissured when mature, internodes 7-15 cm long. Petiole 3.5-6.0 cm long, twisted, pubescent. Leaf blade ovate or ovate-lanceolate to narrowly ovate, subcoriaceous, 15-31.5 × 5.8-12.5 cm, base rounded to slightly cordate, apex acuminate, margin entire, both surfaces densely villous when young, then the adaxial surface dark-green and glabrous, the abaxial surface densely villous; basal veins five, palmate, secondary veins four to six pairs, pinnate; tertiary veins coarsely reticulate, slightly sunken adaxially, prominent abaxially. Inflorescence cymose on old woody stems and young branches, solitary or two cymes, each cyme with one or two flowers, clearly separated from each other. Inflorescence axis 2-6 mm long, tomentose. Bracteole clasping the axis, ovate-triangular, 2-4.5 × 1.5-2 mm, subsessile, both surfaces densely brown villous. Pedicel 1.3-1.6 cm long, pendulous, densely brown villous. Ovary oblong, 1.5-1.7 × 0.3-0.4 cm, densely brown villous. Perianth horseshoe-shaped (in lateral view), 6.5-7.5 cm high, claret (deep purple red), outside densely brown hirsute with parallel dark purple veins, inside glabrous to white villous. Utricle distinct from the tube, bell-shaped, 2.3-2.5 cm high, 1.2-1.3 cm in diam. at base, 1.6-1.8 cm in diam. at apex, inside vinaceous (purplish red) with densely white trichomes. Tube horseshoe-shaped, 8.3-8.5 cm, uniformly claret (deep purple red), with visible dark purple veins, lower tube strongly inflated, saccate, 2.5-2.7 cm high, 1.8-2.0 cm in diam. and upper tube obliquely shortened funnel-shaped, parallel to the utricle, inner surface stramineous dyed with purple red patches, 3-3.5 cm high, narrower at base, 1-1.1 cm in diam. and broader at apex, 1.3-1.4 cm in diam. Limb discoid-rotund or trumpet-shaped, 4.2-4.8 cm high, 4-4.4 cm wide, with three subequal lobes, valvate preanthesis, lobes broadly ovate-triangular, each 3.3-3.8 cm wide, 1.8-2.2 cm high, margins of all lobes revolute during anthesis, warty on inner surface of lobes dark purple. Throat deep purple red, glabrous, without dots. Annulus present. Gynostemium with trilobed stigma on top, 7-7.5 × 5.5-6.5 mm in diam., anthers 6 in 3 pairs, oblong, 4.3-4.5 × 1.2-1.4 mm, yellow. Fruit and seeds were not seen.

Phenology.

Flowering specimens have been collected in May but it is possible that flowering begins in April and fruiting may be from July to August.

Etymology.

The species epithet refers to the type locality in Myanmar and adjacent regions of China. It also shows that the two countries are friendly neighbours, their friendship being retained over a long period and also expresses our appreciation for the whole-hearted cooperation amongst members of the China-Myanmar joint expedition.

Distribution and habitat.

Aristolochia sinoburmanica is hitherto known from the type locality of Putao, Kachin state in north Myanmar and adjacent regions of Gongshan County, northwest Yunnan, southwest China, where, according to one sheet of the specimen deposited in KUN, it is a perennial liana which grows under the montane broadleaf forests, at an elevation of ca. 900-1400 m.

Preliminary conservation status.

In Nov. 2014, the China-Myanmar joint expedition conducted the first field investigation of plant diversity along the same route in north Myanmar, within the area which included the type locality of this new species. The path through the mountains could only be accessed by foot, but in the most recent expedition in May 2017, with the development of road construction, most of the trees and habitats have been destroyed. A. sinoburmanica is known from a single population on the roadside. In fact, during the present study, only two healthy individuals were located growing about 20m apart from each other. Therefore, the new species is assigned a preliminary status of vulnerable (VU) according to the IUCN Red List Categories ( IUCN 2012). However, since very few details exist about its natural distribution, a detailed investigation of the same habitats may identify more populations and individuals of this new species. The lack of sufficient data currently does not allow a final risk evaluation and the species might be regarded as data deficient (DD). Further field surveys in northern Myanmar are needed to gain more information on its distribution.

Additional specimens examined.

China. Yunnan: Gongshan, east of Dulong River , 27°41'51.81"N, 98°19'11.22"E, 1400 m a.s.l., 12 Nov. 1959, G.M. Feng. 24217 (KUN, No. 0163232) .

Key to the species of Aristolochia sinoburmanica and closely related species

1	Perianth claret (deep purple red), outside densely brown hirsute with parallel dark purple veins	A. sinoburmanica
-	Perianth yellowish, yellowish-white or white with purple to dark purple veins or dots	2
2	Leaf base slightly to deeply cordate	3
-	Leaf base round, cuneate to rounded or rounded to truncate	4
3	Leaf blade broadly ovate to cordate	A. faviogonzalezii
-	Leaf blade ovate-oblong to ovate-lanceolate	A. saccata
4	Throat yellow	A. hainanensis
-	Throat white	5
5	Limb 3-lobed, lobes unequal, throat without visible dots	A. tonkinensis
-	Limb 3-lobed, lobes subequal, throat densely covered with purple dots	A. xuanlienensis

Figures

Figure 1. Aristolochia sinoburmanica Y. H. Tan & B. Yang, sp. nov. A Habitat B Flowering branch C Flower (front view) D Anthers and gynostemium E Opened flower (showing the inside structure) F Opened flower (showing the inside structure). Illustration by Zhengmeng Yang.

Figure 2. Aristolochia sinoburmanica Y. H. Tan & B. Yang, sp. nov. A young branch and adaxial leaf B young branch and abaxial leaf C cymes on old woody stems D front view of preanthesis flower E front view of open flower F lateral view of open flower G lateral view of young flower H longitudinal section of flower I gynostemium, ovary and pedicel. (Photographed by Y. H. Tan, H. B. Ding & B. Yang).