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Research Article
Primulina nana (Gesneriaceae), a new species from eastern Guangxi, China
expand article infoChi Xiong, Wei-Chuen Chou, Yi Huang, Fang Wen
‡ Guangxi Institute of Botany, Guilin, China
Open Access

Abstract

Primulina nana C.Xiong, W.C.Chou & F.Wen, a new species of Gesneriaceae from limestone areas of Guangxi, China, is described and illustrated here. It morphologically resembles P. yangshuoensis Y.G.Wei & F.Wen in papillose leaf surface, but can be easily distinguished from the latter by noting a combination of characteristics, especially in its leaf blades, leaf blade indumentum characteristic, calyx lobes, corolla and the disc. We found only one population at the type locality, about 200 mature individuals. According to the IUCN Red List Categories and Criteria (Version 3.1), the new species is provisionally assessed as Critically Endangered (CR).

Keywords

Flora of Guangxi, Gesneriaceae, new taxon, Primulina yangshuoensis, taxonomy

Introduction

The genus Primulina s.l. was redefined in 2011, comprising Chiritopsis W.T.Wang, Wentsaiboea D.Fang & D.H.Qin (except W. tiandengensis Yan Liu & B. Pan) and the large number of species described in Chirita sect. Gibbosaccus C.B.Clarke (Wang et al. 2011; Weber et al. 2011). This genus now exhibits the most diversity in the Chinese Gesneriaceae, including approximately123 species and eight varieties of Primulina s.l. after the revision (Wang et al. 2011; Weber et al. 2011). An acceleration of Primulina species discovery has been seen over the last decade, with an average of about 10 new species per year. As of February 2022, there were 221 species (excluding infraspecific taxa) (GRC 2022) in this genus. China is the centre of diversity for Primulina with at least 204 species and 15 varieties occurring there at present (Wen et al. 2022), especially in limestone areas (Wei 2018; Wen et al. 2019; Ge et al. 2020; Liu et al. 2020; Xin et al. 2020a, b, c, 2021; Zhang et al. 2021). The tropical and subtropical karst limestone mountainous areas of Guangxi, China, are the centres of species diversity and differentiation of this genus (Li et al. 2019).

In October 2021, Y. Huang, a Gesneriaceae enthusiast from Guangxi, found this unknown plant in the wild. One of the authors, W.C. Chou, went to the type locality and collected specimens. Some of the living plants were introduced and cultivated at the Gesneriad Conservation Center of China (GCCC) and the National Gesneriaceae Germplasm Bank for further research. Comparison of the live plants with the type specimens and protologues of all known species of Primulina led to the determination that these specimens neither fit the existing protologues nor conform to the type specimens of these species. Nevertheless, the leaves’ tiny shape and texture make them very particular and most similar to P. yangshuoensis Y.G.Wei & F.Wen (Wen et al. 2012). However, a combination of characteristics easily distinguished it from other species, especially in its leaf blades, leaf blade indumentum, calyx lobes, corolla and the disc characters. We confirmed that it represents a new species of Primulina and describe it here.

Taxonomic treatment

Primulina nana C.Xiong, W.C.Chou & F.Wen, sp. nov.

Figs 1, 2A1–F1

Diagnosis

The new species resembles Primulina yangshuoensis (Fig. 2A2–F2) in papillose leaf surface, namely numerous single pubescent hair on papilla on surface, but can be easily distinguished from the latter by its leaf blade elliptic to ovate, 1.6–1.8 × 1.1–1.3 cm (vs. broadly ovate-round, subround or round, 3.5–6.5 × 2–4.5 cm); leaf nearly erect semi-transparent papillose-puberulent and white pubescent (vs. densely erect semi-transparent and white multicellular papillose-hispid); peduncle 3–5 cm long (vs. 8–9 cm); calyx lobes with one serration (vs. entire); corolla ca. 1.5 cm long, tube tubular (vs. 2–3 cm, broadly infundibuliform); disc ca. 0.6 mm high (vs. ca. 1 mm). Detailed morphological comparisons with P. yangshuoensis are provided in Table 1.

Figure 1. 

Primulina nana sp. nov. A habit B adaxial side of leaves C abaxial side of leaves D alabastrum E bracts and calyx F abaxial side of calyx lobes G adaxial side of calyx lobes H lateral view of a flower I ventral view of a flower J top view of a flower K front view of a flower s howing the internal structure L opened corolla M stamens and staminodes N pistil with calyx O disc and ovary P capsule. Photographs by Chi Xiong.

Table 1.

Detailed comparison of Primulina nana and its relative P. yangshuoensis.

Characters P. nana P. yangshuoensis
Leaf-blades elliptic to ovate, 1.6–1.8 × 1.1–1.3 cm broadly ovate-round, subround or round, 3.5–6.5 × 2–4.5 cm
Leaf indumentum densely nearly erect semitransparent papillose-puberulent on adaxial surface, 1–2 mm long, abaxially purple, densely white pubescent, 1–2 mm long densely erect semitransparent or white multicellular papillose-hispid on both surfaces, 0.8–1 cm long on the adaxial surface, 4–5 mm long on the abaxial surface
Peduncle 3–5 cm long 8–9 cm long
Bracts oblong to linear, 2.5–3 × ca.1 mm lanceolate or subulate, 1–2 × 0.3–0.5 mm
Calyx lobes Usually, one serrate at the middle entire
Corolla ca.1.5 cm long, tube tubular and gradually narrow to the bottom 2–3 cm long, tube broadly infundibuliform
Disc ca. 0.6 mm high ca. 1 mm high

Type

China. Guangxi Zhuangzu Autonomous Region: Wuzhou City, Mengshan County, Xinxu Town, 24°19'N, 110°22'E, altitude ca. 530 m, November 26, 2021, Chou Wei-Chuen & Huang Yi CWC211126-01 (IBK!)

Description

Herbs perennial, acaulescent, rhizome subterete, ca. 1.5 cm long, 4–6 mm in diameter, Leaves 14–23, all basal, petiolate; petiole 1–3 cm long, ca. 1.5 mm in diameter, purple, densely pubescent; leaf blade elliptic to ovate, 1.6–1.8 × 1.1–1.3 cm, leathery, adaxially dark green to purplish-green, nearly erect semi-transparent papillose-puberulent on adaxial surface, 1–2 mm long, abaxially purple, white pubescent, 1–2 mm long, base broadly cuneate, margin entire, apex acute to obtuse, lateral veins inconspicuous, 2–3 on each side. Cymes 2–4, axillary; usually simple, peduncle 3–5 cm long, ca. 0.8 mm in diameter, pubescent;bracts 2, opposite, oblong to linear, 2.5–3 × ca. 1 mm, pubescent on both surfaces, margin entire, apex obtuse. Calyx 5-parted to base, lobes lanceolate, ca. 5 × 1–1.5 mm, nearly equal, outside purple, densely pubescent, inside yellow-green, nearly glabrous, usually with one serrate on the middle of calyx lobe, apex acute. Corolla purple, throat with two yellow stripes inside, ca. 1.5 cm long, outside glandular and eglandular puberulent, inside glabrous, tube tubular and gradually narrowing to the bottom, ca. 1 cm long, orifice 5–6 mm in diameter; limb distinctly 2-lipped, adaxial lip 2-parted to the middle, lobes oblong or round, apex round, 3–4 × 5–6 mm, abaxial lip 3-parted to near the base, lobes oblong, apex round, 6–8 × 4–5 mm. Stamens 2,adnate ca. 8 mm above the corolla base; filaments yellow, ca. 5 mm long, geniculate near the base, glabrous, anthers reniform, slightly constricted at middle, 1.5–2 mm long; staminodes 3, lateral ones linear, glabrous, ca. 3 mm long, apex capitate, glabrous, adnate to ca. 7 mm above the corolla tube base, the central one inconspicuous, adnate near the corolla tube base. Disc annular, ca. 0.6 mm high, margin repand, glabrous. Pistil 1.4–1.6 cm long, ovary 5–6 mm long, ca. 1 mm in diameter, glandular-pubescent; style ca. 1 cm long, 0.6 mm in diameter, glandular-pubescent; stigma obtrapeziform, ca. 1 mm long. Fruit linear, longitudinally dehiscent, 8–9 mm long, ca. 1.5 mm in diameter.

Figure 2. 

Morphological comparison of Primulina nana sp. nov. (1) with P. yangshuoensis (2) A habitat B habit C leaf blades D front view of flowers E lateral view of flowers F top view of flowers. A1 and D1 photographed by Wei-Chuen Chou; B1–C1, E1–F1, C2 photographs by Chi Xiong; A2–B2 and D2–F2 photographed by Fang Wen.

Phenology

Flowering in November, fruiting from December to the following January.

Etymology

The specific epithet ‘nana’ is derived from the dwarf plants of the new species compared with that of most other species of Primulina.

Vernacular name

玲珑报春苣苔 (Chinese name); Líng Lóng Bào Chūn Jù Tái (Chinese pronunciation).

Distribution and habitat

Primulina nana is only known from the type locality, Xinxu Town, Mengshan County, Wuzhou City, Guangxi, China. It grows on moist, shady limestone rock surfaces, at an elevation of ca. 530 m.

Conservation status

Primulina nana is only known from one population of about 200 mature individuals at the type locality. This population has been reduced by 90% from when it was originally found. The EOO and AOO of the new species are about 0.2 km2 and 25 m2, respectively. Its beautiful flowers, thickened woody rhizomes and shapely leaves, led to over-harvesting by locals, who sold it as an ornamental plant. Thus, following the IUCN Red List Categories and Criteria (IUCN 2019), it is temporarily assessed as Critically Endangered [CR B1ab (iii, v) + B2ab (iii, v)].

Notes

The plant size of Primulina nana is dwarf and leaf blade length is less than 2 cm, but length of flowers is about 1.5 cm and the proportion of flowers and leaves is unusual in this genus. These characters differ from other Primulina species and can be clearly distinguished from P. yangshuoensis in morphological characters (Table 1).

Acknowledgements

We want to thank Michael LoFurno (Adjunct Professor, Temple University) and Stephen Maciejewski, the Gesneriad Society, from Philadelphia, the USA, for their editorial assistance; Bin Qiu and Shi-Jun Zheng for their help in the field. This study was financially supported by the Key Sci. & Tech. Research and Development Project of Guangxi (Guike AD20159091 & ZY21195050), the capacity-building project of SBR of CAS (KFJ-BRP-017-68), Basal Research Fund of GXIB (Guizhiye20009 & Guizhifa010) and the Fund of Technology Innovation Alliance of Flower Industry (2020hhlm005).

References

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