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Research Article
Oreocharis polyneura, a new species of Gesneriaceae from southern Yunnan, China
expand article infoYan-Xiong Gong, Hong-Bo Ding§|, Xiang-Shuai Yan, Fang Wen#¤, Yao-Hua Tian, Yun-Hong Tan|§
‡ Yunnan Institute of Tropical Crops, Jinghong, China
§ Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, China
| Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences, Mengla, China
¶ Core Botanical Gardens, Chinese Academy of Sciences, Mengla, China
# Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and Chinese Academy of Sciences, Guilin, China
¤ Guilin Botanical Garden, Chinese Academy of Sciences, Guilin, China
Open Access

Abstract

Oreocharis polyneura, a new species from southern Yunnan, China, is described and illustrated. It is morphologically similar to O. rhytidophylla by having more obvious lateral veins forming a crosslinked network on the adaxial surface of leaf blades, but can be distinguished by having more lateral veins (12–15 pairs vs. 7–9 pairs) of leaf blades, shorter corolla tubes (the length ratio of corolla tube to corolla lobes = 1.2–2.9 vs. 3.4–6) and shorter pistils (6–8 mm long vs. 27–30 mm long). In addition, a detailed morphological description, a photographic illustration, the distribution and phenology of the new species are presented.

Keywords

flora of Yunnan, morphology, new taxon, Oreocharis rhytidophylla, taxonomy

Introduction

In recent years, the genus Oreocharis Benth. has been a hotspot for the research of the family Gesneriaceae. The newly circumscribed genus Oreocharis is recently enlarged by incorporating ten other genera (Ancylostemon Craib, Bournea Oliv., Dayaoshania W.T.Wang, Deinocheilos W.T.Wang, Isometrum Craib, Opithandra B.L.Burtt, Paraisometrum W.T.Wang, Thamnocharis W.T.Wang, Tremacron Craib, Briggsia Craib s.str.) with high floral diversity (Möller et al. 2011; Weber et al. 2013), although Bournea was later reinstated as an independent genus (Chen et al. 2020a). Hitherto, Oreocharis s.l. contains ca. 150 taxa mainly distributed in southern and southwestern China (Wen et al. 2021), with a few of them (ca. 15 species) expanding to Bhutan, India, Japan, Myanmar, Thailand, and northern and central Vietnam (Möller et al. 2016, 2017, 2018; Cai et al. 2020a; Le et al. 2022). In China, southern Yunnan is rich in species diversity of the genus, with about 38 species recorded in this area (Li and Wang 2004; Möller et al. 2011; Chen et al. 2012, 2013, 2020b; Tan et al. 2013, 2015; Rossini and Freitas 2014; Cai et al. 2015, 2020; Cai and Dao 2020).

In 2021, during the expedition of the plant resources of tropical Yunnan in China, we collected an interesting plant of Gesneriaceae from Lancang county at anthesis (Figs 1, 2). Judging from the vegetative habit and floral characteristics, we considered it a member of Oreocharis. Upon careful comparisons of diagnostic morphological and anatomical features from the closely related species from China and adjacent regions, we determined that the plant is new to science and thus describe it herein. Its morphological characters are compared with the closely related species Oreocharis rhytidophylla C.Y. Wu ex H.W. Li (Li 1983; Zhang et al. 2019) (Fig. 3).

Figure 1. 

Oreocharis polyneura Y.H.Tan, F.Wen & Y.X.Gong, sp. nov. A habit B inflorescence C behind view of flower D fruit E whole plant F inflorescence with scale G adaxial and abaxial leaf surfaces H bracts I, J calyces K opened corolla showing stamens and staminode L pistil with disc and calyces M cross section of fruit. Photographed by Yan-Xiong Gong.

Figure 2. 

Type sheet of Oreocharis polyneura Y.H.Tan, F.Wen & Y.X.Gong, sp. nov.

Figure 3. 

Type sheet of Oreocharis rhytidophylla C.Y. Wu ex H.W. Li.

Materials and methods

Vouchers of the new species were collected from Lancang County, Yunnan Province, China. Photographs and phenology data were obtained during field expeditions. Morphological examinations and measurements of the new species were conducted on both living plants in the wild and herbarium specimens. All morphological characters are described according to the terminology presented by Wang et al. (1990, 1998). The preliminary conservation assessment for the new species was evaluated according to the guidelines of the IUCN Red List Categories and Criteria (IUCN 2019).

Taxonomic treatment

Oreocharis polyneura Y.H.Tan, F.Wen & Y.X.Gong, sp. nov.

Figs 1, 2

Diagnosis

Oreocharis polyneura is similar to O. rhytidophylla in having more obvious lateral veins forming crosslinked network on the adaxial surface of leaf blades, but can be distinguished by having more lateral veins (12–15 pairs vs. 7–9 pairs) of leaf blades, shorter corolla tubes (the length ratio of corolla tube to corolla lobes = 1.2–2.9 vs. 3.4–6) and shorter pistils (6–8 mm long vs. 27–30 mm long).

Type

China. Yunnan Province, Puer City, Lancang County, Zhutang Town, on rocks or cliffs in evergreen broad-leaved forests in ravines, 22°45'44.28"N, 99°43'26.81"E, elev. 2137 m, 29 July 2021, Y.X. Gong G344 (holotype: HITBC0079099; isotypes: HITBC, IBK). Fig. 2.

Description

Perennial herbs. Rhizomes subterete, short, straight, with numerous fibrous roots. Leaves basally forming a rosette, 4–8, petiolate; petioles terete, 1.2–7.0 cm long, 3–5 mm in diameter, densely rust-brown pannose, leaf blade thickly chartaceous, elliptic to ovate-elliptic, 4–13 × 2–7 cm, apex rounded, base rounded to subcordate, margin serrate to crenate, adaxially green, glabrous, abaxially whitish-green, densely rust-brown pannose along veins, lateral veins 12–15 on each side of the midrib, adaxially conspicuously sunken, abaxially conspicuously prominent, anastomosed forming on both surfaces. Inflorescences cymose, axillary, 2–4, 2–4-branched, 4–10-flowered; peduncles 4.5–9.0 cm long, ca. 1–3 mm in diameter, rust-brown lanate; bracts 3, verticillate, each 8.5–9.5 × 3.2–4.2 mm, lanceolate to elliptic, margins usually entire, occasionally 2–3-denticulate, adaxially glabrous, abaxially rust-brown pannose; pedicels 1.0–3.5 cm long, ca. 1 mm in diameter, sparsely puberulent. Calyces actinomorphic, 5-parted from the base, segments equal, linear-lanceolate, 7.5–9.0 × 1.5–2.5 mm, margin dentate, adaxially glabrous, abaxially rust-brown pannose. Corollas yellow, 1.8–2.2 cm long, outside glabrous, inside sparsely glandular-puberulent in the throat on adaxial lobes; tube narrowly infundibuliform, slightly bent near the throat, 1–1.5 cm long, 4–5.5 mm in diameter, proximally and distally almost equal in width; limb indistinctively bilabiate, adaxial lip 2-lobed, lobes obovate to elliptic, 5.8–6.2 × 3.8–4.8 mm, apex obtuse, margin entire, abaxial lip 3-lobed, lobes obovate to elliptic, almost equal, 6.2–8.2 × 5.2–6.2 mm, apex rounded, margin entire. Stamens 4, included, two pairs of stamens cohering at the anther tips, adnate to corolla tube 4–6 mm from base; adaxial stamens 3.5–4.5 mm long, abaxial stamens 5–6 mm long; filaments yellow, linear, glabrous; anthers basifixed, reniform, 2-locular, dehiscing transversely; staminode 1, 1.4 mm long, adnate to corolla tube 1.8 mm from the base. Pistils 6–8 mm long, glabrous; ovary 5–6.5 mm long, ca. 1.5 mm in diameter, glabrous, with two parietal placentae; style 1–1.5 mm long; stigma 1, disciform, retuse, edge flipped outwardly, 1.5–2.0 mm in diameter. Discs ring-shaped, ca. 2.3 mm high, margin slightly undulate with 5 irregularly and shallow lobes. Capsules indistinctively 4-angled to subterete, ca. 4 cm long, ca. 3 mm in diameter, glabrous.

Phenology

Flowering from July to October; fruiting from September to November.

Etymology

Greek polys, many, and neuron, nerve, alluding to abaxially conspicuous lateral leaf veins

Habitat and distribution

Endemic to Zhutang town, Lancang county, Puer city, Yunnan Province, China (Fig. 4). It grows on rocks or cliffs under evergreen broad-leaved forests in ravines at elevations of 1900–2200 m.

Figure 4. 

Distribution of Oreocharis polyneura (black triangle) and O. rhytidophylla (black circle).

Conservation status

Oreocharis polyneura is currently known only from its type locality. Based on our present knowledge and available data, its conservation status is assessed as “Data Deficient” (DD; IUCN 2019).

Vernacular name

The Chinese name of the new species is “Duō Mài Mǎ Líng Jù Tái” (多脉马铃苣苔). The first two words, Duō Mài mean the numerous veins of the leaf blades, and the rest four words mean the genus Oreocharis in mandarin.

Notes

Morphologically, Oreocharis polyneura is most similar to O. rhytidophylla in its leaves and inflorescences but is readily distinguishable by an array of characters (see Table 1).

Table 1.

Morphological comparison between Oreocharis polyneura and O. rhytidophylla.

Character Oreocharis polyneura Oreocharis rhytidophylla
Petiole terete plane
Leaf lateral veins 12–15 pairs lateral veins 7–9 pairs
Peduncle 4.5–9 cm long up to 14 cm long
Corolla 1.8–2.2 cm long; tube narrowly infundibuliform 3.5–3.7 cm long; tube cylindric
Length ratio of corolla tube to corolla lobes 1.2–2.9 3.4–6
Stamen two pairs cohered at the anther tips, adnate to corolla tube 4–6 mm from base adaxial stamens cohered in pair, abaxial stamens free, adnate to corolla tube 8–9 mm from base
Pistil 6.0–8.0 mm long; ovary 5.0–6.5 mm long 27–30 mm long; ovary 17–18 mm long

Acknowledgements

We are grateful to Dr. Eberhard Fischer and Dr. You-Pai Zeng for their valuble comments on the manuscript. We thank Shi-Wei Guo and Jian-Wu Li for providing scanned images of specimens. We also thank Bing-Fan Yang, Guo-Yun Chen and Yi-Gang Wei for their kind help in the fieldwork. This work was financially supported by Funds of Sci-Tech Innovation System Construction for Tropical crops Yunnan Province (RF2021-3), Xishuangbanna Rubber Ecosystem Research Station of Yunnan Province (202205AM070004), National Natural Science Foundation of China (31970223), the Project of the Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences (Y4ZK111B01), the Key Sci. & Tech. Research and Development Project of Guangxi (Guike AD20159091 & ZY21195050) and the capacity-building project of SBR of CAS (KFJ-BRP-017-68).

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