Rubia urceolata X.F. Wang & C.H. Wang, 2018

Wang, Chun-Hui, Liu, Zhi-E, Li, Ya & Wang, Xiao-Fan, 2018, A new species Rubia urceolata (Rubiaceae: Rubieae) from Shennongjia National Park, central China, Phytotaxa 357 (3), pp. 220-224 : 221-222

Rubia urceolata X.F. Wang & C.H. Wang , sp. nov. ( Figs 1 , 3 )

Diagnosis: —The new species is distinguished from R. ovatifolia , by its urceolate corolla, longer corolla tube (1.3–2 mm) and flowers with purplish red lobes.

Type: — CHINA. Hubei Province, Shennongjia National Park, Yanziya, sparse forests or thickets on mountains, elev. 2119 m, 31º42’ 59.38’’ N, 110º27’36.13’’ E, 17 July 2017, WCHH 17061 (holotype WH!).

Description: —Climbers, herbaceous, glabrescent, perennial with red rhizomatous base and roots; stems quadrangular, 4-ridged, glabrous and sparsely aculeolate. Leaves in whorls of 4; petiole 2.9–12.3 cm, aculeolate; leaf blade drying papery to thin papery, sub-orbicular to ovate, 5.5–10.6×3.3–8.0 cm, strigillose on the upperside; base cordulate to cordate, apex acute to acuminate, margins glabrous, smooth or retrorsely aculeolate; main veins 5–7, palmate, retrorsely scabrid on abaxial midribs. Inflorescences thyrsoid, leafy, with terminal and axillary cymes, 3.8–19.9 cm and 1.5–3.6 cm respectively, few-to many-flowered. Corolla urceolate, tube pale yellow, glabrous, 1.3–1.9× 2.1–2.8 mm; lobes predominantly 4, occasionally 3 or 5, purplish red, triangular, ca. 1.0–1.7× 0.8–1.4 mm. Stamens usually 4, filaments developed to reduced; stigmas 2-lobed, included; styles cleft to base. Ovary inferior, ellipsoid, ca. 1.2 mm in diam, 2- celled, ovules 1 in each cell, glabrous. Mericarp berry black at maturity, 5.6–8.5 mm in diam, glabrous, often 1 ovule aborted and 1 mericarp developed, sometimes with 2 mericarps developed.

Distribution: — Rubia urceolata is an endemic species and known only from two localities (Yanziya and Tianmenya) in SNP, western Hubei Province.

Phenology: —The species was observed flowering in the whole of July, and fruiting in October.

Etymology: —The specific epithet refers to its urceolatus flowers, this being the main diagnostic character separating it from its allied species.

Pollen morphology: —Pollen grains shape of R. urceolata in equatorial view are oblate spheroidal, and outline circular in polar view (P=15–19 μm, E=10–14 μm), with 6–7 aperturate, colpus ends obtuse to truncate, colpi are conspicuously wide, membrane is covered with large granules, and same as sexine ornamentation ( Fig. 2 ).

Additional specimens examined (paratypes): — CHINA. Hubei: SNP, Yanziya , 2144 m elev., 31º42’ 53.38’’ N, 110º27’42.81’’ E, 17 July 2017, WCHH17064 (holotype WH!) ; at the same place, 11 October 2017, LZHE17082 (holotype WH!) ; Tianmenya , 2098 m elev., 31º42’ 12.75’’ N, 110º27’18.6’’ E, 21 July 2017, WCHH17113 (holotype WH!) .

Figures

FIGURE 1. Rubia urceolata X.F. Wang & C.H. Wang, sp. nov.A. habitat; B. habit; C, D. inflorescence and leaves; E. fruits; F, G. flowers; H. opened flower; I. fruits and seeds. scale bar: H, I = 1 mm.

FIGURE 2. SEM micrographs of pollen grain of R. urceolata. A. polar view of pollen grain; B. equatorial view of pollen grain. scale bars:A, B = 1 μm.

FIGURE 3. Rubia urceolata X.F. Wang & C.H. Wang, sp. nov. A. branch with leaves and inflorescences; B. stem; C, D. flower; E. hypanthium and style; F. fruit. Figure elaborated by Ya Li based in the specimen WCHH17061 (holotype WH!).