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Primulina papillosa (Gesneriaceae), a new species from limestone areas of Guangxi, China
expand article infoZi-Bing Xin§|, Wei-Chuen Chou|, Stephen Maciejewski§|, Long-Fei Fu§|, Fang Wen§|
‡ Guangxi Institute of Botany, Guilin, China
§ Gesneriad Committee, China Wild Plant Conservation Association, Guilin, China
| Gesneriad Conservation Center of China, Guilin, China
¶ The Gesneriad Society, Philadelphia, United States of America
Open Access

Abstract

Primulina papillosa Z.B. Xin, W.C. Chou & F. Wen, a new species from limestone areas of Guangxi, China, is described and illustrated here. It morphologically resembles P. linearifolia (W.T. Wang) Yin Z. Wang and P. pseudolinearifolia W.B. Xu & K.F. Chung, but can be easily distinguished by some combined characters, especially its leaf blades densely papillose-hispid. We found only one population at the type locality with no more than 200 individuals, so that this new species is provisionally assessed as Critically Endangered (CR) using IUCN Criteria.

Keywords

Cliff-dwelling, flora of Guangxi, limestone flora, new taxon, taxonomy

Introduction

By the end of 2020, the genus Primulina Hance (1883) of the family Gesneriaceae comprised 201 species and 27 varieties (IPNI 2021; Tropicos 2021). It is mainly distributed throughout southern, south-western China and northern Vietnam (Wang et al. 2011; Weber et al. 2011). China is the centre of diversity for Primulina with at least 183 species and 27 varieties occurring there at present, especially in limestone areas (e.g. Wei 2018; Wen et al. 2019, 2021; Ge et al. 2020; Liu et al. 2020; Xin et al. 2020a, b, c). The tropical and subtropical karst limestone mountainous areas of Guangxi are the centres of species diversity and differentiation of this genus (Li et al. 2019). An acceleration of Primulina species discovery has been seen over the last five years, with an average of over ten new species per year (Wen et al. 2019, 2021). Assuming this trend persists, more new Primulina species from China will most likely be discovered (Möller 2019).

A Gesneriaceae enthusiast from Guangxi found this unknown plant species in the wild on 6 April 2020. One of authors, W.C. Chou, went to the type locality and collected the specimens for it. At the same time, some living plants were introduced and cultivated in the gardens of the Gesneriad Conservation Center of China (GCCC) and National Gesneriaceae Germplasm Resources Bank for further study. Detailed comparisons of the specimens and living plant materials with the type specimens and protologues of some related known Primulina species revealed that these specimens neither fit the existing protologues nor conform to the type specimens of these species. Nevertheless, its leaf shape and rhizome are most similar to those of P. linearifolia (W.T. Wang) Yin Z. Wang (Wang and Pan 1982; Wang et al. 2011) and P. pseudolinearifolia W.B. Xu & K.F. Chung (Xu et al. 2011, 2012) and it can be easily distinguished from the latter two by the combination of several morphological characters (Table 1), especially its leaf blades densely papillose-hispid. Thus, we confirmed that it represents a new species of Primulina and describe it here.

Table 1.

Detailed comparison of Primulina papillosa and its two relatives.

Characters P. papillosa P. linearifolia P. pseudolinearifolia
Leaf blades densely papillose-hispid densely appressed pubescent densely appressed pubescent
Cymes 1–2-flowered 4–7-flowered 4–12-flowered
Pedicel 20–35 mm long 5–12 mm long 7–15 mm long
Calyx lobes 7.5–9 × ca. 2 mm 3.2–4 × 0.6–1.1 mm, 5–6 × ca. 1 mm
Central staminodes ca. 0.5 mm long none ca. 3 mm long
Disc ca. 1.2 mm high, margin entire ca. 0.5 mm high, margin repand ca. 2.5 mm high, margin repand
Flowering time September to November April April to May
Capsule 5–6.5 cm long 2.2–3.6 cm long 3–4.5 cm long

Taxonomic treatment

Primulina papillosa Z.B. Xin, W.C. Chou & F. Wen, sp. nov.

Figs 1, 2E–F

Diagnosis

The new species resembles Primulina linearifolia (Fig. 2A, B) and P. pseudolinearifolia (Fig. 2C, D), but can be easily distinguished from the latter two by both surfaces of its leaf blades being densely papillose-hispid. It differs from P. linearifolia by its 1–2-flowered per cyme (vs. 4–7-flowered); pedicel 20–35 mm long (vs. 5–12 mm); calyx lobes 7.5–9 mm long (vs. 3.2–4 mm); disc ca. 1.2 mm high, margin entire (vs. ca. 0.5 mm, margin repand); capsule 5–6.5 cm long (vs. 2.2–3.6 cm). It also differs from P. pseudolinearifolia by its 1–2-flowered per cyme (vs. 4–12-flowered); pedicel 20–35 mm long (vs. 7–15 mm); central staminodes ca. 0.5 mm long (vs. ca. 3 mm); disc ca. 1.2 mm high, margin entire (vs. ca. 2.5 mm, margin repand).

Figure 1. 

Primulina papillosa A, B habitat C habit D front view of the corolla E lateral view of the corolla F top view of the corolla G adaxial and abaxial surface of leaf blades H papillose-hispid hairs on leaf blade surface I stamens J pistil, calyx and opened corolla with stamens and staminodes. (A, B photos by W.C. Chou, C–J photos by F. Wen; arranged by Z.B. Xin).

Type

China. Guangxi: cultivated material in the Gesneriad Conservation Center of China and National Gesneriaceae Germplasm Resources Bank, harvested on 24 October 2020, wild-collected, from Dingdang Town, Longan County, Nanning City, 23°07'N, 107°57'E, 9 April 2020, W.C. Chou 20200409-01 (Holotype, IBK!; Isotypes, IBK!).

Figure 2. 

Comparison of three species of Primulina A, B P. linearifolia C, D P. pseudolinearifolia E, F P. papillosa. (photos by F. Wen; arranged by Z.B. Xin).

Description

Herbs perennial. Rhizome thickened, woody, subterete, 10–15 cm long, 1.5–2 cm in diameter, internodes inconspicuous, commonly branched at the apex of the rhizome or not branched. Leaves 15–25, congested at the apex of the rhizome, subsessile; leaf blade fleshy, linear-lanceolate, 5–15 × 0.9–1.8 cm, densely papillose-hispid on both surfaces, apex obtuse to round, base attenuate, margin entire, lateral veins 2–4 on each side of the mid-rib, conspicuous on the abaxial surface, inconspicuous on the adaxial surface. Cymes 2–5, axillary, 1–2-flowered; peduncle 4–8 cm long, ca. 2 mm in diameter, glandular-pubescent and sparsely pilose; bracts 2, opposite, linear-lanceolate, 6–8 × 1–1.5 mm, apex acute, margin entire, pubescent on both surfaces, pedicel 2–3.5 cm long, ca. 2 mm in diameter, glandular-pubescent. Calyx 5-parted from the base, segments equal, lanceolate, 7.5–9 × ca. 2 mm, abaxially glandular-pubescent, adaxially sparsely glandular-pubescent to glabrous, apex acute, margin entire. Corolla purple, throat with two yellow stripes inside, 3.5–4.5 cm long, outside puberulent with both glandular and eglandular hairs, inside glabrous, tube 2.5–3 cm long, orifice 0.8–1.5 cm in diameter; limb distinctly 2-lipped, adaxial lip 2-parted to the middle, with a yellow patch between the two adaxial lobes, lobes ovate, 6–7 × 8–9 mm, abaxial lip 3-parted to near the base, lobes ovate, 8–9 × 9–10 mm. Stamens 2, adnate ca. 1.2 cm above the corolla base; filaments 1.3–1.5 cm long, geniculate near the middle, sparsely pubescent; anthers reniform, 3.5–4 mm long, bearded; staminodes 3, lateral ones linear, glabrous, ca. 9 mm long, apex capitate, sparsely pubescent, adnate to ca. 1 cm above the corolla tube base, the central one ca. 0.5 mm long, apex capitate, adnate to 3.5 mm above the corolla tube base. Disc annular, ca. 1.2 mm high, margin entire, glabrous. Pistil 2.5–3 cm long, ovary 1.4–1.6 cm long, ca. 2 mm in diameter, densely glandular-pubescent and eglandular-pubescent; style 0.9–1.2 cm long, 1.5 mm in diameter, glandular-pubescent and eglandular-pubescent; stigma obtrapeziform, ca. 2 mm long, apex shallowly 2-lobed. Capsule linear, 5–6.5 cm long, 2–3 mm in diameter, puberulent with both glandular and eglandular hairs.

Phenology

Flowering from September to November, fruiting from October to December.

Etymology

The specific epithet ‘papillosa’ is derived from the leaf blade densely papillose-hispid on both surfaces.

Vernacular name

The Chinese name ‘刺疣报春苣苔’ (Cì Yóu Bào Chūn Jù Tái) is newly coined for this species because of its special leaf blades surface full of densely papillose-hispid hairs.

Distribution and habitat

Primulina papillosa is only known from the type locality, Dingdang Town, Longan County, Nanning City, Guangxi, China. It only grows in crevices of the cliff near the top of limestone hills in a subtropical evergreen seasonal rain forest.

Conservation status

Primulina papillosa is only found from the type population with less than 200 individuals. The EOO and AOO of the new species are about 1.05 km2 and 0.01 km2, respectively. The beautiful flowers, thickened rhizomatous woody stem and leaves with dense papillose-hispid hairs, have led to its over-harvesting by local people who have sold it as an ornamental plant. Furthermore, the natural habitat is mostly disturbed due to local farmers imposing intense pressure on the remaining patches of primary forest. Thus, following the IUCN Red List Categories and Criteria (IUCN 2019), it is temporarily assessed as Critically Endangered [CR B1+B2ab (iii, v)].

Acknowledgements

We wish to thank Michael LoFurno, an Adjunct Professor from Temple University, Philadelphia, the USA, for his editorial assistance. This study was financially supported by the Foundation of Guangxi Key Laboratory of Plant Conservation and Restoration Ecology in Karst Terrain (19-050-6; 19-185-7), the National Natural Science Foundation (31860047), Guilin Science and Technology Foundation (20180107-6), the Key Science and Technology Research and Development Project of Guangxi (GuikeAD20159091), Guangxi Natural Science Foundation (2020GXNSFBA297049), Basal Research Fund of GXIB (Guizhiye20009) and the 21st Talent project of “Ten-Hundred-Thousand” in Guangxi.

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