Aristolochia tonkinensis T.V. Do & S. Wanke, 2015

Do, Truong Van, Luu, Truong Hong, Wanke, Stefan & Neinhuis, Christoph, 2015, Three New Species and Three New Records of Aristolochia Subgenus Siphisia from Vietnam Including a Key to the Asian Species, Systematic Botany (Basel, Switzerland) 40 (3), pp. 671-691 : 678-684

Aristolochia tonkinensis T.V. Do & S. Wanke sp. nov. —TYPE: VIETNAM. Ninh Binh: Nho Quan district, Cuc Phuong National Park, Silver cloud top, Bong headquarters 2 km Southeast, 20°21′37″N, 105°36′62″E, plot number CP1046 , 21 Sept 2001, Nguyen 1493 (holotype: MO!; isotype: CPNP!, L!).

Aristolochia tonkinensis is morphologically similar to A. hainanensis and A. saccata but it is distinguishable from them by the following characters: leaf blade ovate to broadly-ovate, leaf base round to truncate; cymes solitary on old woody stems and young branches; lower tube slightly inflated, upper tube narrowly oblong funnel-shaped, 1.5–1.8 cm high; limb nearly rectangular, 1.2–1.3 cm high, 0.9–1 cm wide; throat white without visible dots.

Perennial, woody liana, 6–8(–10) m high with many fasciculate and cylindrical roots. Stem terete, the young branches densely grey pubescent, becoming glabrescent, with a deeply irregularly longitudinally fissured bark when mature, internodes 15–20 cm long. Petiole 6–10 cm long, twisted, densely villous, becoming glabrescent. Leaf blade ovate to broadly-ovate, rarely deltoid, subcoriaceous, 20–25(–30) cm long, 12–14(–20) cm wide, base round to truncate, margin entire, apex acute to shortly acuminate, the adaxial surface dark-green and glabrous, the abaxial surface densely villous, basal veins three, palmate, one pair reaching one-third of the leaf length, secondary veins five to six pairs, pinnate, venation loosely reticulate, veinlets parallel, prominent abaxially, slightly sunken adaxially. Inflorescence cymose on old woody stems and young branches, solitary, each cyme with three or four flowers, clearly separated from each other. Inflorescence axis 1.5–2.5 cm long, densely villous. Bracteole clasping the axis, ovate, 2–2.2 mm long, 1–1.5 mm wide, sessile, both surfaces densely brown villous, persistent. Pedicel 1.2–1.5 cm long, pendulous, densely brown villous. Ovary 0.6–0.8 cm long, 0.2–0.3 cm in diam, densely brown villous. Perianth horseshoe-shaped, 3.2–3.5 cm high, outside white, densely villous with several longitudinal purple veins (variable in number, usually fewer than 6). Utricle poorly developed, sometimes indistinct from the tube, cylindrical, 0.8–0.9 cm high, 0.5– 0.6 cm in diam at base, 0.7–0.8 cm in diam at apex, inside with a dark purple band and densely glandular hairs. Tube 3.2–4.5 cm high, lower tube horseshoe-shaped, slightly inflated, 1.1–1.3 cm in diam, upper tube narrowly oblong funnel-shaped, parallel to the utricle, 1.5–1.8 cm high, base constricted, 0.5–0.6 cm in diam, apex slightly broader, 0.8–0.9 cm in diam, inside glabrous. Limb with three unequal lobes valvate pre-anthesis: two lateral lobes triangular, 1.1–1.2 cm wide, 0.5– 0.6 cm high, middle lobe broadly triangular, 0.8–0.9 cm wide, 0.4–0.5 cm high, margins of all lobes revolute during anthesis forming a trumpet-shaped limb, nearly rectangular, 1.2–1.3 cm high, 0.9–1 cm wide, two lateral lobes rib-like and narrower than the middle one (1.5 vs. 3–4 mm in diam), inner surface dark purple, densely covered with dark purple bristles. Throat white without visible dots. Annulus absent. Gynostemium with truncated apices, smooth, 3–4 mm high, 2–3 mm in diam, anthers 1.2–1.5 mm long. Capsule cylindrical, (8–) 10–12 cm long, 2.5–3 cm in diam, distinctly 6-ridged, greenish-brown, densely pubescent, basipetally dehiscent. Seeds ovoid, 8–9 mm long, 5–6 mm in diam, not winged, the abaxial surface convex, the adaxial surface deeply concave with a prominent, central, longitudinal, funiculus, both surfaces smooth. Figures 7 , 8 .

Vernacular Name — Common names in Vietnamese for this species are “Mô. c hýõng Ba˘’c Bô. ” and “Phòng kỷ Ba˘’c Bô. ”.

Distribution and Ecology — Aristolochia tonkinensis is widely distributed in northern Vietnam (Ninh Binh, Hoa Binh, and Ha Giang) ( Fig. 4 ). It was found in primary closed evergreen broad-leaved lowland forest, secondary forest on limestone or granite as well as foggy woodland forest, with the following species: Annonaceae ( Fissistigma , Xylopia ), Begoniaceae ( Begonia ), Clusiaceae ( Garcinia ), Fagaceae ( Castanopsis , Lithocarpus ), Lauraceae ( Machilus, Neolistsea , Phoebe ), Meliaceae ( Aglaia , Toona ), Moraceae ( Streblus ), Myristicaceae ( Horsfieldia , Knema ), Pentaphylacaceae ( Eurya ), Rubiaceae ( Adina , Myrioneuron , Pavetta , Randia ), Selaginellaceae ( Selaginella ), Theaceae ( Camellia ), Urticaceae ( Elatostema , Laportea ), at 450–1,100 m.

Phenology — Aristolochia tonkinensis has been observed to flower from August to October and fruit from October to December.

Etymology — The specific epithet refers to the former name of northern Vietnam where it occurs.

Conservation Status — Aristolochia tonkinensis has been found in the core-zone of Cuc Phuong National Park, one of the best National Parks in Vietnam as well as other well-protected areas from northern Vietnam. Thus, this species is probably not at risk.

Morphological Affinities — Aristolochia tonkinensis was misidentified as A. saccata in recent publications of Cuc Phuong National Park ( Soejarto et al. 2004; Le and Soejarto 2008; Nguyen et al. 2009). However, A. tonkinensis clearly differs from the latter by the following characters: its leaf blade is ovate to broadly-ovate (vs. ovate-oblong to lanceolate), with the leaf base round to truncate (vs. cordate), the cymes solitary on old woody stems and young branches (vs. clusters of several cymes, exclusively on old woody stems), limb nearly rectangular (vs. nearly circular), throat white (vs. yellow). Additionally, A. tonkinensis is morphologically similar to A. hainanensis , which occurs in southern China and northern Vietnam, but it can be distinguished from the latter by the cyme solitary (vs. clusters of several cymes), upper perianth tube narrowly oblong funnel-shaped, 1.5–1.8 cm high (vs. broadly shortened funnel-shaped, 1.1–1.3 cm high), limb nearly rectangular, 1.2–1.3 cm high, 0.9–1 cm wide (vs. nearly circular, 2.2–2.5 cm wide), throat white (vs. yellow) ( Table 3).

Additional Specimens Examined — VIETNAM: Ninh Binh. Nho Quan district, Cuc Phuong National Park , 1 Nov 2012, Nguyen 1564 ( CPNP) ; Bong headquarters to one thousand years tree, 20°21′244″N, 105°36′108″ E, elevation 420 m, 9 Jan 2013, Do 12 ( VNMN, DR); behind the Bong resort, 20°21′110″N, 105°36′006″E, elevation 540 m, 26 Apr 2013, Do 40 ( VNMN, DR): Hoa Binh. Lac Son district, Ngoc Son community, Ngoc Son-Ngo Luong Nature Reserve , 21 Nov 2013, Lu _ NSNL 02 ( VNMN): Ha Giang. Vi Xuyen district , Phuong Do community, Lung Vai village , Tay Con Linh Nature Reserve , 22°49′248″N, 104°53′220″E, elevation 1,012 m, 7 Nov 2013, Do 79 ( VNMN, DR). Bac Me district , Khau Ca community, Khau Ca Gibbon Species Protected Area , 22°50′411″N, 105°07′ 450″E, elevation 1,040 m, 14 Dec 2013, Lu _KC 01 ( VNMN) .

New Aristolochia Subgenus Siphisia Records to the Flora of Vietnam —

ARISTOLOCHIA FANGCHI Y. C. Wu ex L. D. Chow & S. M. Hwang, Fl. China 5: 264. 2003.—TYPE: CHINA. Guangdong: Jilong Shan, 22 Apr 1970, Shi 2 (lectotype: IBSC!) ( Fig. 9 ).

Distribution and Ecology — Aristolochia fangchi was considered an endemic species to southern China (Guangdong

and Guangxi) ( Hwang et al. 2003), but this study demonstrates that it also occurs in northern Vietnam (Ha Giang, Hoa Binh, and Quang Ninh) ( Fig. 4 ). This species mostly grows in lowland evergreen forests, bamboo and woody mixed forest, thickets, edges of secondary forests on limestone, at 700– 900 m.

Phenology — Aristolochia fangchi has been observed to flower from April to May and fruit from June to October.

Conservation Status — Only a few populations of this species were found in non-protected forest areas in northern Vietnam. Furthermore, there are few saplings growing from seeds, thus it might be at high risk of extinction in Vietnam. This species was assessed as critically endangered (CR) according to the IUCN (2013).

Notes — The Vietnamese populations of Aristolochia fangchi are identical in vegetative and reproductive characters to the populations found in China. From diagnostic features, A. fangchi is similar to A. petelotii Schmidt , which also occurs in northern Vietnam and southern China ( Pham 2000; Nguyen 2003; Hwang et al. 2003). Inflorescences of both species grow from the old woody stems (each 2–4-flowered), with a U-shaped purple perianth, and evident parallel veins. However, A. fangchi differs from the latter by the leaf shape (a round leaf base and an acute to obtuse leaf apex vs. a cordate leaf base and an acuminate leaf apex), the shape of the limb (subrotundate-peltate vs. bell-shaped), and the color of the annulus (white vs. dark purple).

Additional Specimens Examined — VIETNAM. Ha Giang: Bac Me Nature Reserve , 22°42′45″N, 105°15′28″E, elevation 750 m, 30 Oct 2013, Do 66 ( VNMN, DR) ; Hoa Binh: Da Bac district, Doan Ket community, PuCanh Nature Reserve , 20°55′13″N, 105°04′43″E, 6 May 2013, Do 31 ( VNMN, DR), 22 Sept 2001, Ngo 5661 ( NIMM). Quang Ninh: Uong Bi district , Yen Tu temple, 21°6′32″N, 106°43′23″E, 28 Apr 2013, Do 35 ( VNMN, DR), medicinal plant station, 19 Sept 1976, Vu 2958 ( NIMM) .

ARISTOLOCHIA HAINANENSIS Merr., Philipp. Journ. Sc. 21: 341. 1922. Hocquartia hainanenis (Merr.) Migo, Journ. Shanghai. Sci. Inst. 14: 334. 1944.—TYPE: CHINA. Hainan: Five Finger Mt., 11 Dec 1921, elevation 1,300 m, McClure 8630 (holotype: K!, isotypes: A!, US!).

Figures

FIG. 7. Aristolochia tonkinensis. A. Branch with a cyme. B. Lateral view of open flower. C. Capsule. Drawings by Nguyen Huu Quyet from the type specimen.

FIG. 8. Aristolochia tonkinensis (A-C). A. Habit. B. Cyme on young branch. C. Branch with cyme and capsule, and adaxial surface of seed. D. Aristolochia hainanensis. Front view of open flower and habit. E. Aristolochia saccata. Front view of open flower. A-C. Photographs by Nguyen Manh Cuong from the type population. D. Photographs by Zhang Rongjing from Hainan Island, China. E. Photographs by Yasushi Yamashita (cultivated).

FIG. 4. Map showing the distribution of new species and new records of Aristolochia subgenus Siphisia from Vietnam.

FIG. 9. Aristolochia fangchi. A. Branch. B. Dorsal view of open flower. C. Front view of open flower. D. Capsule. E. Adaxial view of seed. Drawings by Nguyen Huu Quyet from the specimens Do 31 and Do 35 (VNMN).