Primulina cerina F.Wen, Yi Huang & W.Chuen Chou, 2019

Li, Shu, Xin, Zi-Bing, Chou, Wei-Chuen, Huang, Yi, Pan, Bo, Stephen Maciejewski, & Wen, Fang, 2019, Five new species of the genus Primulina (Gesneriaceae) from Limestone Areas of Guangxi Zhuangzu Autonomous Region, China, PhytoKeys 127, pp. 77-91 : 83

Primulina cerina F.Wen, Yi Huang & W.Chuen Chou sp. nov. Fig. 3

Diagnosis.

Primulina cerina most closely resembles P. renifolia (D. Fang & D.H. Qin) J.M. Li & Y.Z. Wang ( Fig. 6 C ) ( Fang and Qin 2004, Wang et al. 2011, Weber et al. 2011) in having similarly shaped leaf blades, but differs in their indumentum of the peduncle (densely erectly eglandular-puberulent in P. cerina vs spreading white pubescent and glandular puberulent in P. renifolia ; same order as following), corolla tube shape (tubular, abaxially straight and not swollen vs. obliquely campanulate, abaxially swollen), corolla color (beige to pale yellow mixed slightly reddish brown vs. pale purple to purple inside longitudinally purple lines), indumentum of filaments (glabrous vs glabrous but base glandular puberulent), the indumentum of calyx lobes inside (glabrous vs sparsely glandular-pubescent) and stigma shape (obtrapeziform and 2-lobed vs obliquely hippocrepiform but unlobed).

Type.

CHINA. Yizhou city, Beiya Town , Xiaozhudong village , 24°22'N, 108°23'E, 220 m a.s.l., only known from crevices of moist rock surfaces at the entrances of a big limestone cave, 3 Apr 2018, Chou Wei Chuen et al. CWC171116 -01 (holotype: IBK!, isotypes: IBK!)

Description.

Perennial herbs. Rhizome small and short, indistinctive but nearly cylindrical, 3-8 mm long, 2-3 mm in diam. Leaves numerous, 8-20 or more, all basal, petiolate; petiole pale brownish purple to dark brownish purple, cylindrical, 7.5-12 cm long, 3-3.2 mm in diam., extremely short puberulent to nearly glabrous; leaf blade dark green, slightly fleshy to thickly chartaceous, herbaceous when dried, nearly rounded to cordate rounded, 3-5.5 × 3.5-5.5 cm, apex obtuse to rounded, base cordate to deeply cordate, margin undulant to crenate; lateral veins 3-4 on each side, slightly impressed adaxially and apparently prominent abaxially. Cymes 8-16, 1-3-branched, 16-30-flowered per cyme; peduncle 8-15 cm long, ca. 2.5 mm in diam., densely erectly eglandular-puberulent; pedicel 5-10 mm long, ca. 1 mm in diam., indumentum same as pedicel; bracts 2, opposite, brownish purple, linear to oblanceolate, 5-12 × 1-4 mm, margin entire to inconspicuously dentate, apex acuminate to acute, adaxially very shortly puberulent, abaxially nearly glabrous. Calyx 5-parted nearly to base, lobes brownish purple, narrowly lanceolate, 3-4 × ca. 1 mm, margin entire, outside sparsely extremely short puberulent, inside nearly glabrous. Corolla beige to pale yellow mixed slightly reddish brown, 1.8-2 cm long, 4-5 mm in diam. at mouth, outside sparsely eglandular-puberulent to nearly glabrous, inside glabrous; tube tubular, 1.5-1.8 cm long, 3.5-4 mm in diam. at the middle, tube base slightly constricted, 1-1.5 mm in diam. at base; limb distinctly 2-lipped, adaxial lip 2-lobed to base, lobes oblong, apex rounded, 2.5-3 × 2-2.5 mm, abaxial lip 3-lobed to over middle, lobes oblong, apex rounded, ca. 3.5 × 3 mm. Stamens 2, adnate to ca. 3 mm above corolla tube base, filaments ca. 6 mm long, curved at middle, anthers elliptic or reniform, ca. 1.8 mm long, glabrous; staminodes 2, extremely small and inconspicuous, punctate, ca. 0.05 mm long, adnate to corolla tube base. Disc annular, ca. 0.9 mm in height, margin entire to sinuate. Pistil 10.5-11 mm long, ovary ovoid, ca. 2.5 × 1 mm, densely eglandular-puberulent; style ca. 8 mm long, ca. 0.2 mm in diam. at the middle, the lower part of style sparsely eglandular- and glandular-puberulent but the upper half part of style nearly glabrous; stigma obtrapeziform, ca. 0.5 mm long, apex 2-lobed. Capsule ovoid, valvate dehiscence when mature, 4-4.5 × ca. 3 mm.

Phenology.

Flowering from April to May; fruiting from June to July.

Etymology.

The specific epithet, ' cerina ', refers to the special color of the flowers; ' cerina ' is derived from the Latin, ' cerinus ', meaning dark yellow or sulfur yellow, but mixed with a little pale reddish brown. The color seems like the hue of the natural brimstone (sulphur) ore. The Chinese name is "Àn Líu Sè Xiáo Huā Jù Tái” (暗硫色小花苣苔).

Distribution and habitat.

Primulina cerina is currently known only from the type locality. The species grows in the crevices of rocks with wet surfaces at the entrances of a large limestone cave in Yizhou, Guangxi, China.

Provisional IUCN conservation assessment.

Primulina cerina is rarer than the species mentioned above, P. persica . At present, only a single population with ca. 20 individuals is known, counted and confirmed from 2016 to 2018. Although the type locality is in an outlying mountain area and surrounded by limestone forest, this species should be assessed as 'Critically Endangered, CR B2a+C2a(i,ii)+ D’, given the few known individuals and a single population based on the IUCN categories and criteria ( IUCN 2012).

Figures

Figure 3. Primulina cerina F. Wen, Yi Huang & W. Chuen Chou sp. nov. A plant in flower, cultivated in GCCC B cyme with flowers C front view of corolla D lateral view of corolla E dorsal view of corolla F opened corolla for showing stamens G pistil and calyx lobes for showing their adaxial surfaces H disc and one of calyx lobes for showing its abaxial surface I pistil without calyx lobes for showing ovary and style and their indumentum. Photographed by Fang Wen, charted by Wen-Hua Xu.

Figure 6. The morphologically similar congeners of the five new species of Primulina 1 habit 2 flowers. A P. leprosa, the congener of P. purpureokylin B P. gongchengensis, the congener of P. persica C P. renifolia, the congener of P. cerina D P. repanda, the congener of P. niveolanosa E P. longgangensis, the congener of P. leiyyi. Photographed by Fang Wen, charted by Wen-Hua Xu.