Aristolochia carinata Merr. Chun, Sunyatsenia

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 : 684-688

Aristolochia carinata Merr. Chun, Sunyatsenia 2: 219, pl. 42. 1935.—TYPE: CHINA. Hainan: Fanya, Ng Chi Leng, 25 Oct 1932, Chun & Tso 44161 (holotype: PE, isotypes: IBK!, NY!).

Distribution and Ecology — Aristolochia hainanensis was primarily reported from Hainan province, southern China. During recent investigations, we also found this species in northern Vietnam (Ha Giang, Dien Bien, Tuyen Quang, and Hai Phong) ( Fig. 4 ) in closed lowland evergreen forests, valleys or thickets, as well as edges of secondary forests on limestone, dominated by representatives of Fagaceae , Lauraceae , and Sapindaceae , at 600–1,100 m.

Phenology — Aristolochia hainanensis has been observed to flower from December to March and fruit from April to July in Vietnam.

Conservation Status — Aristolochia hainanensis has been found mostly in well-protected areas in northern Vietnam. The individuals grow and regenerate well. Additionally, many saplings are growing from seed. We propose to assign the species ‘near threatened’ (NT) although it is currently listed as vulnerable (VU B2ab) according to the IUCN (2013).

Notes — Vietnamese and Chinese populations of A. hainanensis are morphologically identical ( Fig. 10 ). This species is morphologically close to A. saccata . The latter species is widely distributed in Bhutan, India, Myanmar, Nepal, Vietnam, and China ( Samanta et al. 1999; Pham 2000; Nguyen 2003; Hwang et al. 2003). However, A. hainanensis differs from the latter by the villous abaxial leaf surface and cuneate to rounded leaf base as well as the acute leaf apex. In contrast, A. saccata is characterized by the silky adpressed villous abaxial leaf surface, deeply cordate leaf base and acuminate leaf apex. This species is most similar to A. tonkinensis , but it clearly differs from the latter by the characters of inflorescence and perianth (shape, size of upper tube, limb, and color of throat, Table 3).

Additional Specimens Examined — VIETNAM. Ha Giang: Tay Con Linh Nature Reserve, 22°48′17″N, 104°73′15″E, elevation 1,100 m, 7 Nov 2013, Do 78 ( VNMN, DR); Dien Bien: Dien Bien Dong district, Muong Phang community, 4 Jul 1997, Nguyen 8812 ( NIMM). Tuyen Quang: Na Hang district, Thanh Tuong community, Bung village, Na Nieng mountain, 22°16′87″N, 105°26′30″E, elevation 680 m, 15 Jan 2013, Do 26 ( VNMN, DR), 20 Apr 2002, Nguyen 6490 ( NIMM): Chiem Hoa district, Yen Nguyen community, 27 Sept 2002, Ngo & Nguyen 6492 ( NIMM). Hai Phong: Cat Ba district , Ang Re Bo Da mountain , Ca Ba National Park , 3 Dec 1986, Nguyen 826 ( HN), 6 Jan 1988, LX-VN 3716 ( HN) .

ARISTOLOCHIA UTRIFORMIS S. M. Hwang, Acta Phytotax. Sin , 19: 228, Fig. 7 : 1–3. 1981.—TYPE: CHINA. Yunnan: Wenshan, elevation 1,900 m, 24 Apr 1962, Feng 22205 (holotype: KUN!, isotype: IBSC).

Distribution and Ecology — This species was considered to be endemic to Yunnan, China where borders the northwestern part of Vietnam, including Lao Cai province. Thus, it is not surprising that A. utriformis has been discovered and recorded for the flora of Vietnam ( Fig. 4 ). It grows along streams in montane bamboo forest, at 1,800 –2,000 m.

Phenology — Aristolochia utriformis has been observed to flower in April and May in Vietnam which is the same flowering period as has been reported for the type locality. The fruiting period however remains unknown.

Conservation Status — Only two small populations of Aristolochia utriformis were found within the buffer zone of Hoang Lien National Park, but few saplings growing from seeds were observed. Furthermore, the local farmers continue to impose strong pressure on the remaining primary forest patches converting it mostly into Bengal cardamom plantation ( Amomum aromaticum Roxb. ). Thus, it might be at high risk of extinction in Vietnam. This species was primarily assessed as critically endangered (CR) according to the IUCN (2013).

Notes — The Vietnamese populations of Aristolochia utriformis slightly vary in shape, size of limb, and limb lobes ( Fig. 11 ). The species is morphologically close to A. ovatifolia Hwang. The latter is widely distributed in the provinces of Guizhou, Sichuan, and Yunnan ( Hwang et al. 2003). Flowers of both species are solitary on young branches with a saccate-shaped limb that is erectly 3-lobed. However, A. utriformis differs from the latter in its ovate-lanceolate leaf blade (vs. ovate), an adaxial leaf surface with scattered hairs (vs. both leaf surfaces densely villous) and a yellowish-green perianth (vs. purple-red).

Additionally Aristolochia utriformis is characterized by the presence of a distinct semicircle-like annulus in contrast to a ring-like annulus of other Siphisia species from the Old World.

Additional Specimens Examined — VIETNAM. Lao Cai: Sapa district, 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 38 ( VNMN, DR) ; along third national road to Ton forest station, 10 Dec 1997, Nguyen & Ngo 8813 ( NIMM) .

Figures

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

FIG. 10. Aristolochia hainanensis. A. Branch. B. Front view of open flower. C. Close up of gynostemium. D. Capsule. E. Abaxial view of seed. F. Adaxial view of seed. Drawings by Nguyen Huu Quyet from the specimens Do 26 (VNMN, DR) and LX-VN 3716 (HN).

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. 11. Aristolochia utriformis. A. Branch bearing solitary, terminal flower. B. Lateral view of open flower. C. Longitudinal section of flower. D. Close up of gynostemium. Drawings by Nguyen Huu Quyet from the specimen Do 38 (VNMN, DR).