Rubia hangii

Yang, Li-E, Meng, Ying, Zhou, Zhuo & Nie, Ze-Long, 2017, Rubia hangii (Rubiaceae), a new species from Guangxi Province, China, Phytotaxa 291 (1), pp. 43-52 : 48-49

Rubia hangii L.-E. Yang & Z.-L. Nie, sp. nov. ( Figs 2 , 3 )

Diagnosis: —The new species is distinguished from R. siamensis and R. falciformis , by its membranous to thin papery leaf blades, without revolute margins (flat), slender petioles (<1 mm wide), ovate-lanceolate stipules, triangular corolla lobes, glabrous fruit, with 1 ovule often aborted and 1 mericarp (rarely 2) developed. It also differs from R. argyi and R. pallida , by its opposite, lanceolate leaves, number of principal veins, axillary inflorescences and campanulate flowers.

Type: — CHINA. Guangxi: Rongshui County, Pingshi Town, Jiuwan Mountain, in valley or forests, 20 August 1958, Shaoqin -Chen 15233 (Holotype: KUN! No.0329193).

Description: —Climbers and vines, herbaceous, perennial; stems quadrangular, 4-ridged, smooth. Leaves opposite; petiole 2.1–6.5 cm, aculeolate, slender (<1 mm wide); leaf blade drying membranous to thin papery, lanceolate or narrowly lanceolate, 3–7.8 × 0.8–2.2 cm, glabrous on both surfaces, scaberulous and aculeolate on principal veins, base rounded, apex acuminate or caudate, margins flat, aculeolate; principal veins 3, palmate; stipule, ovate-lanceolate 0.2–0.3 × 0.1–0.15 cm, with petiole 0.1–0.25 cm, caducous. Inflorescences thyrsoid, with axillary, ca. 2–6.2 cm, many-flowered cymes long. Ovary inferior, ellipsoid, subglobose, 2-celled, ovules 1 in each cell, erect, axile, glabrous. Corolla light yellow, campanulate; tube ca. 1 mm; lobes 5, triangular, ca. 3 mm wide. Stamens usually 5, inserted in throat of tube, included, anthers dorsifixed; stigmas 2-lobed, included, styles cleft to base. Mericarp a berry 4–5.6 mm in diam, glabrous, often 1 ovule aborted and 1 mericarp developed, rarely with 2 mericarps developed.

Distribution: —In Guangxi province, R. hangii was only found in Liuzhou and Hezhou. Based on herbarium records, it is also recorded in Guangdong province at the Yangshan county.

Phenology: —The new species was observed flowering in late June to early September.

Etymology: —The species epithet honors Prof. Hang Sun, Director of the Kunming Institute of Botany, Chinese Academy of Sciences, who worked on plant taxonomy and biogeography and made great contributions on eastern Asian flora.

Additional specimens examined (paratypes): — China. Guangxi: Rongshui County, Pingshi Town , 428 m, 29 Aug 2014, YangLE 45 ( KUN! No. 1299700) ; ibidem, 22 Jul 1958, Shaoqin-Chen 15036 ( IBK! IBK00103228 , IBSC! IBSC0509835 ) ; Rongshui County, Antai Town , 1124 m, 31 Aug 2014, YangLE 69 ( KUN! No. 1299702) ; ibidem, 22 Oct 1958, Shaoqin-Chen 16922 ( IBK! IBK00103208 ) ; Hezhou City, Babu District, Gupo Montain , 800m, 2 Sep 2014, YangLE 84 ( KUN! No. 1299701) ; China, Guangdong, Yangshan County, Xuegen-Li 201279, 24 Nov 1957 ( IBK! IBK00103216 ) .

Figures

FIGURE 2. Rubia hangii L.-E. Yang & Z.-L. Nie, sp. nov. A, B. habit and habitat; C. leaves; D. fruits; E. inflorescence; F. flowers.

FIGURE 3. Rubia hangii L.-E. Yang & Z.-L. Nie, sp. nov.A. branch with leaves and inflorescences; B. node with leaves and stipules; C. fruit; D. calyx and hypanthium; E. corolla, style and stigmas; F. hypanthium and style. Drawn from the holotype, Shaoqin-Chen 15233 (KUN! No.0329193).