Camellia ngheanensis (Sect. Chrysantha: Theaceae), a new species from Central Vietnam

Phytotaxa 452 (3): 209–216 https://www.mapress.com/j/pt/ Copyright © 2020 Magnolia Press

Camellia ngheanensis (Sect. Chrysantha: Theaceae), a new species from Central Vietnam

NGOC-DAI DO1,2,6, VAN-DUNG LUONG3,7, THI-HUONG LE4,8, DANH-HUNG NGUYEN1,9, THANH-NHAN

NGUYEN4,10 & NGOC-SAM LY1,5,11*

1 Graduate University of Science and Technology, Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay District, Ha Noi, Vietnam.
2 Faculty of Agriculture, Forestry and Fishery, Nghe An College of Economics, 51 Ly Tu Trong, Vinh City, Nghe An Province, Vietnam. 3 Faculty of Biology, Da Lat University, 1 Phu Dong Thien Vuong, Ward 8, Da Lat City, Lam Dong Province, Vietnam.

4 Department of Interior Nghe An, 30 Phan Dang Luu, Vinh City, Nghe An Province, Vietnam.
5 Department of Biological Resources, Institute of Tropical Biology, VAST, 85 Tran Quoc Toan Road, District 3, Ho Chi Minh City, Vietnam.
6 daidn23@gmail.com; https://orcid.org/0000-0002-7741-9454
7 luongvandungdl@gmail.com; https://orcid.org/0000-0001-5985-1975
8 lehuong223@gmail.com; https://orcid.org/0000-0003-1123-2037
9 danhhung.vfu@gmail.com; https://orcid.org/0000-0002-8719-4009
10 thanhnhan_pm@yahoo.com; https://orcid.org/0000-0002-1791-279X
11 lysamitb@gmail.com; https://orcid.org/0000-0002-9925-5171
*Corresponding author: lysamitb@gmail.com

Abstract

Camellia ngheanensis, a new species of Theaceae, is described and illustrated from Nghe An Province, Central Vietnam. It is most similar to C. ninhii in pubescent hairs on twigs and abaxial leaf blades, colour of flowers, pubescent ovary, glabrous filament, free styles from the base but differing by the glabrous petioles, pubescent bracteoles, 5-pubesncent sepals, 12 or 13 pubescent petals, and pubescent styles. The comparison between the new species and C. euphlebia, C. petelotii, and C. velutina is presented. Data on ecology, phenology, vernacular name and uses, expected conservation status are given along with an illustration and a coloured plate.

Keywords: Camellia, new species, sect. Chrysantha, Theaceae, Vietnam

Introduction

Camellia Linnaeus (1753: 698) is the most species-rich genus in the family Theaceae, with 119 to 280 species recognized (Sealy 1958, Chang & Bartholomew 1984, Gao et al. 2005, Ming & Bartholomew 2007). It is distributed mainly in southern, eastern and south-eastern Asia, from the Himalayas east to Japan and Indonesia (Chang & Ren 1998, Ming & Bartholomew 2007). The highest species diversity is found in China and Vietnam (Sealy 1958, Chang & Bartholomew 1984, Chang & Ren 1998, Ming 2000, Orel & Wilson 2010a,b, Orel & Wilson 2012). Camellia is distinguished from other genera of Theaceae in having usually apically dehiscent capsules, and wingless (semi-)globose or polygonal seeds with umbilicate hilum (Ming & Bartholomew 2007). In Vietnam, more than 75 species are known which are distributed throughout the entire country (e.g. Pitard 1910, Gagnepain1941, Pham 2000, Tran 1998a,b, Rosmann 1999, Orel 2006, Orel & Wilson, 2010a,b, 2012, Tran & Hakoda 1998, Tran & Le 2015, Tran & Luong, 2012, 2013, Orel & Wilson 2010a,b, 2012, Orel et al. 2012, 2013, 2014a,b, Orel & Curry 2015, Luu et al. 2015, 2018, Luong et al. 2016a,b, Le et al. 2017, Nguyen et al. 2018, Pham et al. 2019, Do et al. 2019). However, this number is expected to increase in the future with the description of new taxa.

During extensive floristic explorations in provinces of the North Central Coastal region, Vietnam, several interesting specimens of Camellia were collected by the first author’s team in 2018–2019. Critical examination of these specimens, and comparison with type material and protologues of presumed closely related species in Vietnam and China (e.g. Seal 1958, Chang 1981, Chang & Bartholomew 1984, Gao et al. 2005, Ming 2000, Ming & Bartholomew 2007, Pham 2000, Orel & Curry 2015) provided evidence for the existence of several new taxa, one of which was recently described, namely C. pukhangensis Do et al. (2019: 90) (Do et al. 2019). In this paper, we describe a further new species of Camellia from Nghe An Province. The overall shapes and sizes of leaf, bracteole, sepal, petal, ovary and glabrous stamen of these plants are only similar with C. euphlebia Merr. ex Sealy (1949: 216), C. petelotii (Merr. (1924: 427)) Sealy (1949: 219), C. ninhii (2016b: 117) and C. velutina Pham et al. (2019: 1441). However, it shows significant differences in its vegetative and floral structures (see Table 1) and we describe and illustrate here as a new species to science, namely C. ngheanensis. 

FIgure. 1. Camellia ngheanensis. A. Leaf, adaxial view; B. Venation detail of leaf (abaxial view); C. Flower (lateral view); D. Flower (top view); e. Bracteoles (adaxially shown); F. Sepals (adaxially shown); g. Petals (adaxially shown); H. Androecium; I. Sepals and Gynoecium; J. Gynoecium (other floral parts removed). Drawn from type materials by Van-Dung Luong. 

FIgure 2. Camellia ngheanensis. A. Adult branch showing axillary leaf buds; B. Twigs; C. Flower buds; D. Flower (side view); e. Flower (top view); F. Close-up of flower; g. Leaf (from left): adaxiallyand abaxially; H. Flower details (from left): side, bottom and top views; I. Bracteoles (adaxially shown); J. Sepals (from left): adaxially and abaxially; K. Petals (adaxially shown); L. Androecium; M. Cross-section of androecium; N. Stamen; O. Gynoecium with styles free to the base; P. Young fruit. Photos by Ngoc-Dai Do, the coloured plate by Ngoc-Sam Ly. 

The description and all measurements were carried out from mature individuals of living flowering plants in the field, supplemented by measurements from herbarium specimens. Type specimens of the most closely-related species of yellow camellias were examined from herbaria DLU, HN, P, NSW, VAFS, and VNM (herbarium codes follow Thiers (2018))as well as digitized specimen images of Camellia species available on the web from Muséum National d’HistoireNaturelle (https://science.mnhn.fr/) and Chinese Virtual Herbarium (http://www.cvh.org.cn/), Australian Virtual Herbarium (https://avh.ala.org.au/), and Jstor Global Plant (https://plants.jstor.org/).The general terminology follows the standard works of Seal (1958), Chang & Bartholomew (1984) and Ming & Bartholomew (2007). Conservation status was assessed using the IUCN Red list Categories and Criteria (IUCN 2018)

Taxonomic treatment

Camellia ngheanensis N.D. Do, V.D. Luong, N.S. Lý, T.H. Le & D.H. Nguyen, sp. nov. (Figs. 1& 2)

Diagnosis:—Most similar to C. ninhii in having pubescent hairs on twigs and abaxial leaf blades, colour of flowers, pubescent ovary, glabrous filament, free styles from the base but differing by the glabrous petioles (vs. glabrous), pubescent bracteoles (vs. adaxially puberulous), 5-pubesncet sepals (vs. 6–7, adaxially puberulous), 12 or 13 pubescent petals (vs. 9–11, adaxially puberulous), and pubescent styles 2.3–2.5 cm long (vs. glabrous, 0.8–0.9 cm).

Type:—VIETNAM. Nghe An Province: Tuong Duong District, Nhon Mai Commune, Na Lat Village, 440 m elev., 27 December 2018, Do Ngoc Dai, Le Thi Huong, Nguyen Danh Hung, DHH718 (holotype VNM; isotypes P, DLU).

Small to medium tree, 3–8 m tall; trunks 2 or 3-upright stems, somewhat robust, sparsely branched towards the apex; twigs pubescent, purple to greenish-purple toward apices; semi-mature branches brown, slightly rough, distally pubescent, leaf scars somewhat prominent; adult branches and trunk light grey, smooth with lighter-coloured patches and covered by lichens. Axillary leaf buds rudimentary, ±triangular, flat, pubescent, brown, apex rounded, bud scales small but prominent and 1–3 mm long; terminal leaf buds prominent, long and narrow, 10–12 × 2–3 mm, laterally compressed, slightly curved, pubescent, apex sharp. Leaves: juvenile leaves forming a narrow tube when young, soft, slightly pendulous, purple or almost brown; developing leaves ascending, blade narrowly, shiny, tinted green-purple, lower surface white-pubescent; young leaves slightly serrate, shiny, dark purple, adaxially glabrous, abaxially puberulous; mature leaves regularly serrate at the base, irregularly so towards the apex, 11–14 × 4–6 cm; lamina thick, coriaceous, broadly elliptic to broadly ovate, apex long-acuminate or caudate, base obtuse to rounded, adaxially dark green and glabrous, abaxially pale green and microscopically pubescent on the midrib; petiole straight when young, curved when mature, adaxially dark green, abaxially paler, 5–6 × 4–5(–7) mm, brownish pubescent; primary vein continues as a shallow channel on the adaxial side of the petiole, 1.5–2 mm wide proximally, less than 1 mm distally, proximally light green and shiny on both sides; secondary venation pinnate with 9–11 pairs of veins, indistinctly brochidodromous, partially eucamptodromous on some leaves; midrib and lateral veins adaxially sunken, abaxially protruding; veins distinct proximally, less so towards the apex and the margins; tertiary venation very indistinct, sometimes lacking, more prominent at the leaf margins. Flowers almost sessile, usually solitary, sometimes together in groups of 2 flowers born on a short bracteate shoot, terminal, lacking scent; pedicels stouts short, covered by greenish perules, 3–5 mm long, pubescent; flower buds irregularly circular, ca. 2.9 × 2.7 cm, pale green when young but aging pale yellow, open flowers regularly circular, 5–6.5 cm in diameter; bracteoles (sensu Sealy 1958) 2 or 3, suborbicular, 1.5–3 × 2–4 mm, tinted pale purplish green, pubescent on both surfaces, deciduous, indistinctly differentiated from sepals; sepals 5, persistent, suborbicular or orbicular, 4–7 × 6–10 mm, pale yellow tinged pale greenish-yellow, sometimes with red blotch/patch on abaxailly of the outer whorl, pubescent on both surfaces, margins ciliate, arranged in 2 whorls forming a rather loose spiral, outer whorl of 2 sepals and inner whorl of 3 sepals; petals 12 or 13, arranged in 3 whorls, bright yellow; outermost whorl comprising 2 or 3 petals, orbicular, 1.2–1.6 × 1.3–2.2 cm, pubescent on both surfaces; middle whorl comprising 2 or 3 petals, orbicular to broadly obovate, 2–2.5 × 2.2–2.6 cm, abaxially pubescent at tip; innermost whorl of 7 or 8 petals, broadly obovate, 2.5–2.6 × 2.5–3 cm, glabrous, basally united with outermost filaments for 6–7mm. Androecium numerous stamens, arranged in 4 or 5whorls, light yellow, 2.2–2.7 cm long, glabrous; outer filaments basally united to each other for 1.4–1.8 cm and forming a cup, free above union, inner ones basally united for 3.5–6 mm, free above union; anthers yellow, 3.0–3.2 × 1.1–1.5 mm, with two longitudinal veins, dorsifixed; styles 3(rarely 4), free to the base, 2.3–2.5 cm long, 1–1.2 mm wide at base, ca. 0.5 mm at apex, sparsely pubescent, stigma indistinct. Ovary superior, ovoidal terminating into 3(–4) styles, slightly longitudinal striations, pubescent, 3–(4)-carpellate, 2–2.5 × 2.5–3 mm, 2 ovules per locule. Young capsule ca. 1.5 cm in diameter, ca. 1 cm in deep, with persistent sepals and styles, dehiscing distally into 4 parts. Mature capsule and seed not seen.

Phenology:—Camellia ngheanensis has been observed to flower from December to January, with young fruits present in February.

Etymology:—The specific epithet “ngheanensis” is named after the geographic locality, Nghe An Province, where the new species was discovered and collected.

Distribution and habitat:—Camellia ngheanensis is currently known only from three localities in the Nghe An province, where some subpopulations of scattered mature individuals of sterile and flowering plants grow in secondary evergreen broadleaf forests on hill slopes and along stream composed of sandstone at elevations of 200–600 m.

Additional specimens examined (Paratypes):—VIETNAM. Nghe An Province, Tuong Duong District, Nhon Mai Commune, Na Hy Village, 220 m elev., 26 December 2018, Do Ngoc Dai, Nguyen Danh Hung, DH 732 (VNM, DLU); Que Phong District, Cam Muon Commune, Po Village, Pu Hoat NR, 562 m elev., 10 December 2018, Do Ngoc Dai DND746 (DLU, HN, VNMV); Quy Chau District, Chau Hoan Commune, Lat Tren Village, Pu Huong NR, 16 January 2018, Do Ngoc Dai DND298 (VNM).

Conservation status:—Endangered (B1 a,b(ii,iii) Civ). Fairy large three subpopulation, with a total of about 1000 mature individuals of the new species were observed near Na Lat village (Tuong Duong District), with a total area less than 2 km2 and a population of 12 mature individuals at Pu Hoat NR (Que Phong District), with a total area less than 5 km2, and a population of 60–70 mature individuals at Pu Hoat NR (Quy Chau District)were observed in Nghe An province. The extent of occurrence (EOO) is estimated at less than 858 km2. Its forest habitats are fragmented and still faces some at risks due to loss of the habitat within its range (in particular the clearing of forest land for Acacia plantations). These plants are regarded as highly threatened due to high market demands for wild, yellow-flowered camellias which are intensively collected for sale by local peoples. Based on currently available data, we therefore provisionally assess this species as Endangered (EN B1a,b(ii,iii) Civ) according to the IUCN Red list criteria (IUCN, 2019). Further exploration of the region is required to understand the situation better and amend the conservation status if necessary.

Use:—Leave and flowers were harvested and used as tea by the local people.
Vernacular name:—Vietnamese name: Trà hoa vàng nghệ an.
Notes:—Morphologically, the undifferentiated and persistent bracts and sepals, 3-free style and 3(4)-loculi capsule

of the new species are affinities with sections Corallina Sealy (1958: 132) and Chrysantha Chang (1979: 69) (sensu Chang & Bartholomew 1984). However, the yellow flowers that are born on distinct peduncle with 5 bracts 5 and 5 sepals, the filaments are arranged in 5–6 circles and united about 1⁄2 length at the base of the new species are distinctive to sect. Corallina but consistent to sect. Chrysantha (Chang 1979). In Vietnam, more than 20 species of yellow camellias have been enumerated throughout the country (e.g. Tran, 1998a,b, Tran & Hakoda 1998, Pham 2000, Hakoda & Tran 2001, Hakoda et al. 2007, Tran & Le 2015, Tran et al. 2012, Yang et al. 2014, Le & Luong 2016) included three new species were recently described, namely C. ninhii Luong & Le, C. tuyenquangensis Luong et al. (2017: 95) and C. velutina Pham et al. (Luong & Le 2016a,b, Le et al. 2017, Phạm et al. 2019). Of which, C. ngheanensis shows most morphological similar to C. ninhii in the characters of general vegetative habit, ligule, peduncle length, the shape of lamina, spike, the shape and size of calyx and corolla lobes. The compared characters between them are given in the above diagnostic. Camellia ngheanensis is also similar to C. euphlebia, C. petelotii, and C. velutina in several vegetative and reproductive characters, as shrub or small tree habit, hairy perianth and 3-free style but differs from the latter three species by the pubescent twigs (vs. glabrous), leaves abaxially pubescent (vs. glabrous), pubescent petioles 5–6 mm long (vs. glabrous, 10–13 mm, 10–12 mm, and 12–16 mm in the latter three species, respectively), pubescent bracteoles (vs. glabrous in C. euphlebia, abaxially puberulous in C. petelotii and adaxially velutinous in C. velutina), pubescent sepals (vs. adaxially velutinous in C. euphlebia and C. velutina, abaxially puberulous in C. petelotii), 12 or 13 pubescent petals (vs. 7–9 and adaxially velutinous, abaxially glabrous in C. euphlebia, ca. 14 and abaxially puberulous in C. petelotii, and 10(–11) and velutinous in C. velutina), pubescent ovary and styles (vs. glabrous). A detailed morphological comparison between C. ngheantensis and four species closest to it is provided in the above diagnosis and in Table 1.

Acknowledgements

We are grateful to the managers and staffs of both Pu Hoat and Pu Huong Nature Reserves and to Mr. Tran Quoc Thanh, director of Nghe An Provincial Department of Science and Technology, for their helpful cooperation during the field trips. We thank to Mr. Bruce Maslin (WA herbarium) for helping improve the English text. We thank the two anonymous reviewers for their constructive comments that helped improve the manuscript.

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