4 TAXONOMIC TREATMENT
Cynanchum pingtaoi S.Jin Zeng, G.D.Tang & Miao Liao, sp. nov. Figures. 2–3
Diagnosis. Cynanchum pingtaoi is similar to C. longhushanense morphologically in having large and deeply cordate to reniform leaves, large and campanulate corolla, follicles solitary, triangulate, fusiform, with three ribs. But it differs from the latter by its broadly ovate corolla lobe (vs. oblong), outer surface greenish-white and inner surface purple-red corolla (vs. outer surface greenish-white, inner surface white, usually with purple spots on the top of corolla lobe), corona tip connivent, slightly exceeding corolla throat (vs. corona tips connivent, not exceeding the throat of the corolla)
Type. CHINA. Yunnan (云南): Dehong Dai and Jingpo Autonomous Prefecture (德宏傣族景颇族自治州), Ruili City(瑞丽市), Nongdao Town (弄岛镇), Tongbiguan Provincial Nature Reserve, 24 August 2020,Lin Ya Zeng & S.Jin Zeng. 4825 (holotype, IBSC!; isotypes, KUN!).
Description. Twining liana. White latex in stems and leaves.Branchlets fistulous, smooth, glabrous, slightly woody.Leaves opposite; petiole 6–14 cm long, smooth, sparely white puberulent, later glabrescent, with small yellowish-brown glands at the tip, inter petiole with small glands; leaf blade deeply cordate to reniform, 7–15 × 4–13 cm, membranous, base cordate, apex acuminate, margin entire, adaxial surface dark green, glabrous, abaxially light green, sparely white puberulent on veins, gradually glabrescent laterly; basal veins five or seven, palmate, secondary veins three to five pairs, pinnate, tertiary veins reticulate, smooth adaxially, raised abaxially.Inflorescences extra-axillary, subumbellate to subracemic, 5–11 flowers; peduncle 10–12 cm long, smooth; pedicel 3.0–5.5 cm long, smooth, sparely white puberulent near the base, base with bracteoles triangular, ca. 0.1 × 0.1 cm. Calyx yellowish-green, basally fused, lobe elliptic, ca. 0.6 × 0.5 cm, base with small glands, apex obtuse, margin ciliate. Corolla campanulate, glabrous, external surface greenish white, inner surface purplish red, 3.3–3.5 cm in diam; lobe slightly longer than tube, tube 1.2–1.4 cm, lobe broadly ovate, 1.3–1.8 × 1–1.2 cm, apex reflexed, overlapping to right.Corona lobe linear-subulate, white, separate, ca. 1.1 cm long, inserted at base of gynostegium, longer than gynostegium and corona tips connivent, slightly exceeding corolla throat. Anthers with inwardly incurved paleolae.Stigma head broadly rounded, slightly depressed, white.Pollinia 2 per pollinarium, ellipsoid, yellow, pendulous, ca. 0.13 × 0.08 cm, caudicle ca. 0.05 cm long, retinaculum ca. 0.1 cm long.Follicles solitary, fusiform, ca. 14.5 cm long, ca. 5 cm diam., glabrous, with a thick fibrous pericarp, triangulate, tip curved outwards; seeds ovoid, 0.8 cm × 0.6 cm, tipped with a white silky coma; coma 3.8–4.2 cm long. Flowering in September–October. Fruiting in November–December.
Etymology. The specific epithet honors the eminent botanist Ping-Tao Li (李秉滔), an expert in the Apocynaceae.
Chinese name. Bing-tao-da-hua-teng (秉滔大花藤).
Distribution. Endemic to China, only one population was found at the border of China-Myanmar in Ruili, Yunnan Province, China.
Habitat and phenology. This species occurs near open woods and climbing up trees. Flowering was observed in September to October, fruiting in November to December.
Provisional IUCN assessment. The species is known only from the type locality so far, where only a few individuals were seen. A suitable habitat exists in the proximity of the type locality. Nevertheless, as there is no reliable information on the population sizes or distribution of this species, we propose to treat it currently as Data Deficient (IUCN 2019).
Notes. Cynanchum pingtaoi is a distinctive species for its larger flowers. The large and reniform leaves, campanulate corolla and lanceolate corona indicate that it is close with formerRaphistemma which has been included in Cynanchum . The results of molecular phylogenetic analyses also showed thatCynanchum pingtaoi is close to the former Raphistemmaspecies. It is the sister to C. pulchellum (R. pulchellum(Roxb.) Wall.) and C. longhushanense (R. brevipedunculatumY. Wan) (Figure 1). Although the molecular data of C. hooperianum (R. hooperianum (Blume) Decne) was absent, but it can be distinguished between C. pingtaoi and C. hooperianum by corolla outer surface greenish-white, inner surface purple-red (vs. corolla outer surface light green, inner surface white with purple spots on the top of lobe), corolla lobe broadly ovate ( vs. corolla lobe ovate ), corona tips connivent, slightly exceeding corolla throat (vs. corona tips not connivent, stretching reaching to the middle of the corolla lobe), calyx-segments longer (6 mm vs. 3–4 mm), and corolla-tube longer (12–14 mm vs. 8–9 mm). Thus, we would like to propose Cynanchum pingtaoi to be a new species.
Cynanchum longhushanense G.D.Tang & Miao Liao,nom. nov., non C. brevipedunculatum J.Y.Shen (2019).
Raphistemma brevipedunculatum Y.Wan, Guihaia 3(3): 197 (1983).
Type. CHINA. Guangxi (广西): Long’an county (隆安县), Longhushan Nature Reserve, open woods, 2 July 1981, D.H. Tan 82329 (holotype: GXMS!; isotypes: CANT!).
Chinese name. Long-hu-shan-da-hua-teng (龙虎山大花藤).
Notes. Four names were recorded inRaphistemma . R .ciliata Hook.f. was treated as the synonym of Pergularia daemia (Forssk.) Chiov. (Goyder, 2006); R. pulchellum (Roxb.) Wall. was revised to C. pulchellum (Roxb.) Liede & Khanum (Khanum et al., 2016). R. brevipedunculatum Y. Wan was considered as the synonym of R. hooperianum (Blume) Decne without any evidence (Li et al., 1995). Geographically, R. brevipedunculatumwas found in Guangxi, China (Wan, 1983), while R. hooperianum , first discovered in Java island, Indonesia, was recorded asOxystelma hooperianum Blume (Blume, 1826) initially, and the later was revised as R. hooperianum (Candolle, 1844). However, the description of R. hooperianum was poor in these two works, and its type specimen was absent (Blume, 1826; Candolle, 1844). We collected and checked the more clear description of R. hooperianum from Flora of Java(Backer & Bakhuizen van den Brink, 1965). Furthermore, we collected the living samples of R. brevipedunculatum from type location (Longhushan Nature Reserve, Longan County, Guangxi Zhuang Autonomous Region, China.) and Jinping County, Yunnan Province, China, which very close to the former. We found that R. brevipedunculatum are significantly different from R. hooperianum by contrasting the descriptions and the living samples, the former has longer calyx (6 mm vs. 3–4 mm), longer corolla-tube (12–16 mm vs. 8–9 mm), different corolla lobe (oblong vs. ovate) and corona lobe (corona tips connivent, not exceeding the throat of the corolla vs. corona tip not connivent, stretching to the middle of the corolla lobe). R. brevipedunculatum is flowering in June–July (Wan 1983) and in September (S.Jin Zeng and Lin Ya Zeng 4887 ), but R. hooperianum is flowering almost all the years (Blume, 1826). So, we suggested that R. brevipedunculatum should be separated fromR. hooperianum (=C. hooperianum ) as an independent species. And we renamed it as Cynanchum longhushanense because the Latin word of ‘brevipedunculatum’ had been used to name another species of Cynanchum brevipedunculatum J. Y. Shen (Shen et al., 2019)
Other specimens examined. CHINA. Guangxi (广西), Long’an (隆安), Pingshan (屏山), 10 Oct. 1977, Longan Investigation Team2-040 (GXMI031735 [photo!]); Long’an (隆安), Longhushan Nature Reserve, 25 Jun. 2021, Miao Liao 78 (IBSC!). Yunnan Province (云南). Honghe Hani and Yi Autonomous Prefecture (红河哈尼族彝族自治州), Jinping Miao and Yao Dai Autonomous County (金平苗族瑶族傣族自治县), Jinshuihe Town (金水河镇), 9 Sept. 2020,Lin Ya Zeng & S.Jin Zeng 4887 (IBSC!).