Primula centellifolia G. Hao, C. M. Hu & Y. Xu 2017, sp. nov.
Creators: name: Xu, Yuan
name: Hu, Chi-Ming
name: Hao, Gang
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Ericales
Primulaceae
Primula
Primula centellifolia

description: Primula centellifolia G.Hao, C.M.Hu & Y.Xu, sp. nov. (Figs. 1 & 2)   
 Type:— CHINA. Sichuan: Xuyong Xian, Shuiwei Xiang, Huagao Xi, on road between conservation station to Yi Du Qiang, on rocks in forest, 28 o 16 ’ 31.111 N, 105 o 32 ’ 12.166 E, elev. ca. 783 m, 18 March 2014, Y. Xu 140035 (holotype IBSC!).   
 Primo visu P. scopulicolae G.Hao, C.M.Hu & Y.Xu persimilis, sed omnibus partibus minoribus, scapis umbellam paucifloram simplicem gerentibus, calyce fere ad basim in lobos lineari-lanceolatos fisso, florescentia serotiniore differt.   
Herbs perennial, efarinose, with a slender rhizome. Leaves including the petiole 2.5−4.5 cm long; petiole very thin, thread-like, 1.5−3 cm long, about one and a half the length of the blade, sparsely covered with rust-colored multicellular hairs; leaf blade suborbicular to orbicular-reniform, 1−2 cm long, 0.8−2.2 cm wide, membranous when dry, sparsely covered with multicellular hairs on adaxial surface, and mainly along lateral nerves on abaxial surface, apex rounded, base cordate, sinus penetrating 2−5 mm into leaf blade, margin obscurely undulate and remotely hydathode-denticulate, more or less ciliate; lateral nerves usually 3 pairs, the lower pair arising from the midnerve at leaf base. Scapes 1−2 in each plant, 4−7 cm long, together with pedicels pilose as petioles, carrying a terminal umbel with 2−4 flowers; bracts linear, 2−3 mm long, sparsely pilose. Pedicel 0.8−1.3 cm long, sometimes lengthening to 2 cm in fruit. Flowers distylous. Calyx campanulate, 2.5−3 mm long, pilose on the outside, split to the base; lobes linear lanceolate, c. 0.8 mm broad, apex obtuse. Corolla pinkish purple, exannulate, limb 8−10 mm across, lobes obovate, c. 4 × 3 mm, bilobed at apex; lobules entire; thrum flower: tube c. 7 mm long, with stamens inserted towards apex of corolla tube, style c. 2.5 mm long, about 1/3 the length of the corolla tube; pin flower: tube 5−6 mm long, with stamens c. 2 mm above base of corolla tube, style slightly shorter than corolla tube. Capsule globose, slightly shorter than persistent calyx, opening by valves.  
 Etymology: —The specific epithet “ centellifolia ” refers to the shape of leaves of the new species, which resemble those of some species of Centella Linnaeus (1763: 1393) (Apiaceae).   
 Distribution, habitat and conservation status: —This new species has a very restricted distribution (Fig. 3). It was found in a small area on the border between SE Sichuan and N Guizhou. The precise locality is situated in a ravine in Longtan Yan, Huagao Xi, Shuiwei Xiang, Xuyong Xian, Luzhou City of Sichuan Province and extends along the ravine eastwards about 23 km to Si Dong Gou scenery district, Da Tong Zhen, Chishui City of Guizhou Province. The total distributional area is about 50 km 2. It grows on shade and humid cliffs of the Danxia landform (marked by red cliff and red continental clastic rock), at elevation range of 350−783 m and accompany with Primula scopulicola G.Hao, C.M.Hu & Y.Xu, P. persimilis G.Hao, C.M.Hu & Y.Xu in Xu et al. (2016b: 409), Pothos chinensis (Rafinesque 1838: 14) Merrill (1948: 210), Myrioneuron faberi Hemsley (1888: 380), Selaginella scabrifolia Ching & C.H.Wang (1959: 157), Begonia labordei H. Léveillé (1904: 323), Elatostema parvum (Blume 1826: 512) Miquel (1854: 102), Arachniodes aristata (G. Forster 1786: 82) Tindale (1961: 89) and a species belongs to Piper Linnaeus (1753: 28). Flowering from mid March to April. According to IUCN red list criteria (IUCN 2001), its conservation status is evaluated as ‘Critically Endangered’ (CR) (B2abiii).   
 Additional specimens examined (paratypes): — CHINA. Sichuan: Xuyong Xian, Shuiwei Xiang, Huagao Xi, on road between conservation station to Yi Du Qiang, on sandstone cliffs with dripping water, elev. ca. 783 m, 1 March 2014, Y. Xu xu140017 (IBSC!); Xuyong Xian, Shuiwei Xiang, Huagao Xi, Hou Er Dong, on cliffs, elev. ca. 588 m, 8 March 2014, Y. Xu xu140023 (IBSC!); the same locality, in sandstone rock crevices, with dripping water, 27 July 2014, Y. Xu & T. J. Liu xu140225 (IBSC!). Guizhou: Chishui City, Da Tong Zhen, Si Dong Gou scenery district, on shade and moist cliffs, elev. ca. 350 m, 10 March 2015, Y. Xu & T. J. Liu xu150012 (IBSC!).   
 Taxonomic remarks: — Primula sect. Monocarpicae Franch. ex Pax is a small group comprising ca. 14 species widely distributed in central and southwestern China, with a few members extending into Vietnam, Thailand and northern Burma (Hu 1990, Hu & Kelso 1996). Morphologically the section is characterized by the plants usually with multicellular hairs, the membranous distinctly petiolate leaves with round or basally heart-shaped blades, a campanulate calyx and the globose or cylindrical capsule dehiscing by valves (Smith et al. 1941−1949, Hu 1990).   
 At first sight, plants of this new species look just like a miniature of P. scopulicola G.Hao, C.M.Hu & Y.Xu, both are dwellers in moist clefts, growing side by side on red sandstone cliffs of Danxia landform area. Apparently they are closely allied. Nevertheless, fairly abundant materials and field observation show that except for its much smaller stature, the new species can be easily recognized by its slender scape carrying a simple terminal umbel with only 2−4 flowers, and by the calyx, which is cut near to base into linear lanceolate and obtuse lobes. Furthermore, the flowering period of the new species is 20−30 days later than P. scopulicola. This interesting phenomenon may provide an example of a sympatric species pair but reproductively separated by seasonal isolation.
description: Published as part of Xu, Yuan, Hu, Chi-Ming & Hao, Gang, 2017, Primula centellifolia (Primulaceae), a new species from south-central China, pp. 259-263 in Phytotaxa 326 (4) on pages 259-262, DOI: 10.11646/phytotaxa.326.4.4, http://zenodo.org/record/13723689