Le, V.S., Curry, A.S., Truong, Q.C. et al. Camellia flosculora: a new species of Camellia section Thea series Sinenses (Theaceae) from Vietnam. Brittonia (2021). https://doi.org/10.1007/s12228-020-09646-5

Camellia flosculora: a new species of Camellia section Thea series Sinenses (Theaceae) from Vietnam

VAN SON LE1, ANTHONY S. CURRY2, QUANG CUONG TRUONG1, VAN DUNG LUONG3, AND THI LIEU NGUYEN4

1 Vườn Quốc Gia Bidoup Núi Bà, Trụ sở chính: Tiểu khu 97, Đạ Nhim, Lạc Dương, Lâm Đồng; Văn phòng ĐD: 5E Trần Hưng Đạo, Phường 10, Tp Đà Lạt, Lâm Đồng, Vietnam; e-mail: leson1502@gmail.com; e- mail: quangcuongvqg@gmail.com

2 ACurry|hortbot, 3 Ferguson Road, Springwood, NSW 2777, Australia; e-mail: anthonycurry55@gmail.com

3 Đại học Đà Lạt, 1 Phù Đổng Thiên Vương, Phường 8, Thành phố Đà Lạt, Lâm Đồng, Vietnam; e-mail: luongvandungdl@gmail.com

4 Graduate School of Science, Botanical Gardens of Osaka City University, Osaka 558-8585, Japan; Faculty of Biology, VNU University of Science, Hanoi, 100000, Vietnam; e-mail: lieunt_sh@dlu.edu.vn

Abstract. 

A new species of Camellia is described from material collected from Hon Giao Mountain, Bidoup-Nui Ba National Park, southern Vietnam. The analysis and figures dem- onstrate how Camellia flosculora differs from other known Camellia species and illustrate the new species, which is characterized by relatively small leaf blades, short pedicels, and very small flowers with short stamens and styles. The morphology of the newly described species justifies its taxonomic placement in Camellia section Thea series Sinenses.

KeywWordrs: 

Bidoup-Nui Ba National Park, cool-temperate evergreen forest, Hon Giao Mountain, Taxonomy.

Camellia L. is the largest genus of Theaceae with more than 300 species (Chang & Bartholomew, 1984; Mabberley, 2017; Gao et al., 2005). The genus is distinguished within the family by large seeds and dehiscent, capsular fruit, with wide spreading, but persistent valves (Sealy, 1958).

China and Vietnam are major centers of diversity for Camellia (Sealy, 1958; Chang & Bartholomew, 1984; Macoboy, 1998; Ninh, 2002). Over the last 20–30 years many new spe- cies of Camellia have been described from these two countries (Rosmann, 1995; Chang, 1996; Rosmann et al., 1998; Chang & Ren, 1999; Rosmann, 1999; Chang, 2000; Orel, 2006; Ninh et al., 2012; Orel et al., 2012; Ninh & Luong, 2013; Luu et al., 2015; Ninh & Ninh, 2015; Orel & Curry, 2015; Ninh & Luong, 2016; Ninh et al., 2017; Orel & Curry, 2017; Nguyen et al., 2018; Orel & Curry, 2019; Pham et al., 2019). These discoveries and their subsequent publication have contributed greatly to the scientific knowledge of the Camellia floras of both China and Vietnam, as well as highlighting the need for further fieldwork and research.

As part of a field trip to Hon Giao Mountain, Khanh Hoa Province, Vietnam in July 2019, Messrs. Van Dung Luong and Truong Quang Cuong discovered a population of a distinctive Camellia species. The specimens had relatively small leaves, short pedicels and very small flowers with short stamens, and styles. These morphological features suggested that the specimens they collected represented a Camellia species new to science.

A herbarium study of closely related species was not conducted by the authors. However, the three taxonomic classificatory systems (i.e., Sealy, 1958; Chang & Bartholomew, 1984; Ming & Bartholomew, 2007) currently in use for Camellia were consulted for the analysis of this putative new species. Our study was grounded primarily by the taxonom- ic treatment of Sealy (1958), as we believe it to be relatively well-substantiated and complete. Chang and Bartholomew (1984), a pro- gression from Sealy’s treatment, was also consulted, especially for species collected since 1958, and the assignment of the new species to subgenus, section, and series followed their intersectional taxonomy. The works of Wen (2004)-onwards, Gao et al. (2005) and Ming and Bartholomew (2007) were consulted for additional data.

Taxonomic treatment

Camellia flosculora Curry, V. S. Le, C. Q. Truong & V. D. Luong, sp. nov. Type: Vietnam, Lam Dong Province, Bidoup-Nui Ba National Park., Hon Giao Mountain, [precise locality details are held by DLU but have been suppressed for conservation reasons], 1740 m elevation, 20 Jul. 2019 [fl, fr], Truong Quang Cuong, Luong Van Dung, DL 190701 (holotype: DLU; isotype: HNU). (Figs. 1 and 2.)

Diagnosis: 

Camellia flosculora is placed in C. sect. Thea ser. Sinenses Chang due to its possession of 3-loculed, pubes- cent ovaries and 3-parted, free styles (Chang & Bartholomew, 1984). It is readily distinguished from other species of sect. Thea (L.) Dyer ser. Sinenses Chang by its small leaf blades (3– 7 × 1.5–2.5 cm), short pedicels (0.3–0.4 mm), very small flowers (0.5–0.7 cm diameter), short stamens (2–3 mm) and short styles (1.5–1.7 mm).

Small to medium-sized, evergreen tree, 3–8 m tall; branches pubescent when young, becom- ing glabrous. Leaves stalked, lanceolate to oblong-ovate, 3–7 × 1.5–2.5 cm, thickly cori- aceous, the apex acuminate or narrowly acu- minate, the base nearly rounded or broadly obtuse, the margins regularly serrate, dark green and shiny above, paler green below, glabrous on both sides except the midrib, the midrib and lateral veins sunken above, protruding below, the secondary venation pin- nate, with 7–10 pairs of lateral veins; petiole slightly curved-falcate, terete, pale green, 4– 5 mm long, pubescent. Flowers solitary or geminate, axillary, 5–7 mm diameter; pedicel 3–4 mm long, pubescent, light green to yel- lowish green; bracts 2(−3), the scales 0.5–1 × 0.5–1 mm, light green, pubescent abaxially, persistent. Sepals 5–6, orbicular or subglobose, 1.5–2 × 1–1.5 cm, light green, pubescent abaxially, the margins ciliate, per- sistent. Petals 5(−6), orbicular or broadly ob- ovate, white, 4–5×2.5–3.5 mm, glabrous, united for about 0.2 mm at the base with the outermost filaments. Androecium of 60– 70 stamens in 3 series; filaments 2–3 mm long, white, glabrous, the outer filaments united for about 0.5 mm from the base; an- thers light yellow. Gynoecium 3-locular; ova- ry ovate, 1.2–1.5 × 1–1.2 mm, pubescent; styles 3-parted, free to base, 1.5–1.7 mm long, pubescent. Capsule asymmetrically glo- bose, dehiscent, pubescent, the apex acute, 7– 12 mm wide, 1-loculed with 1 seed per loc- ule, columella abortive, pericarp thinly leath- ery. Seeds globose, 6–10 mm wide, glabrous.

Distribution and habitat.

— Under dense, cool- temperate evergreen forest, at elevations between 1600 and 1700 m, Hon Giao Mountain, Bidoup- Nui Ba National Park, Lam Dong Province, Viet- nam (Fig. 3).

Phenology.

— The species was observed flowering between September and November, and fruiting between April and May.

Etymology.

— The specific epithet refers to the tiny flowers of this species.

Common name.

— Trà bông hoa nhỏ (Trà = Camellia; bông hoa nhỏ = flosculora).

Conservation status.

– This species is known only from the type locality near the border of Bidoup-Nui Ba National Park. A thorough search of the area around the type locality found about 50 individual plants in an area of about 1 ha. As the type population is situated near the boundary of the national park some degree of protection is afforded this species. However, due to the small population size, limited known area of occupancy, recent fluctuations in monsoonal weather patterns, poaching, traditional plant collecting and cutting by ethnic minority peoples, as well as the en- croachment of agriculture along the border of the national park, the IUCN category of Endangered (EN B2 D) is considered appropriate for this spe- cies (IUCN, 2012; see also Beech et al., 2017).

We assign the new species to subgenus Thea (L.) Dyer due to its possession of the characteristics of the section as described by Changand Bartholomew (1984), including one or two axillary, pedicellate, medium to relatively small flowers; the bracts and sepals usually differentiated; five or six persistent sepals; capsules with columellae. The capsules, how- persistent or deciduous bracts; free stamens ever, have only a single locule due to the in 3 series, with the outer whorl connate; 3- abortion of two of the ovary locules during parted, free styles; a 3-locular ovary; and development (Table I). 

Within subgenus Thea, Chang and Bartholomew (1984) recognized eight sections based on the morphology of the ovary; num- ber, differentiation and persistence of the bracts and sepals; number of flowers per in- florescence and whether they are sessile or pedicellate; number and morphology of the styles; arrangement of stamens into series and whether the filaments are free or connate into a short tube; number of locules in the ovary; and type of dehiscence of the capsules. The following features align the new species with section Thea: 1–2, small, axillary, pedi- cellate, bracteolate flowers, 5–6, persistent sepals, 5–6 petals, stamens in 3 series, outer filaments basally shortly connate, a 3-locular ovary, 3-parted, free styles, and capsules dehiscent from the apices with columellae. Within section Thea, Chang and Bartholomew (1984) recognized four series based on features of the ovaries and styles (Table II). The morphological characteristics of Camellia flosculora, namely 3-loculed, pubescent ovaries and 3-parted, free styles, sup- port placement of the new species in series Sinenses Chang. Within series Sinenses, the new species appears to be most like Camellia sinensis (L.) 

Kuntze, the type species of the series. The two species share relatively small leaves, axillary, white flowers, pendulous pedicels, similar numbers of bracts and sepals, glabrous filaments, and a 3-locular ovary. Camellia flosculora differs from I in having smaller leaves, regularly serrate leaf margins (vs. bluntly serrulate to sinuate-serrulate in C. sinensis), shorter pedicels, smaller flower diameter, fewer petals, shorter stamens which are longer than the styles (vs. equal to, or slightly longer) and 3-parted and free (vs. 3- fid), and shorter, pubescent (vs. glabrous, or rarely sparsely hairy) styles (Table I).

Camellia flosculora also has many traits in common with C. parvisepala Chang, including similar petiole length, axillary, white flowers, similar sepal and petal numbers, glabrous fila- ments, stamens longer than styles, and a pubescent ovary. However, it differs in having larger leaves with more pairs of lateral veins, larger diameter flowers, pendulous pedicels (vs. erect in C. parvisepala), longer stamens and longer styles, which are 3-parted, free, and pubescent (vs. 3-cleft and glabrous) (Table I). Another species of ser. Sinenses, C. angustifolia Chang was described by Chang (1981) from an incomplete specimen from Guangxi Zhuang Autonomous Region, China, and its flowers are unknown. However, that species differs from C. flosculora in having larger leaves with fewer lateral veins, a longer petiole, and serrulate margins (vs. serrate), and longer, erect (vs. pendulous) pedicels (Table I). 

Table 2. FEATURES OF THE FOUR SERIES OF CAMELLIA SECTION THEA.

Key to the species of Camellia section Thea series Sinenses

1. Styles 3-parted, free to base.
2. Styles glabrous.............................................................................................................................. C. parvisepala 2. Styles pubescent or long-hairy almost to the apex.

3. Styles 1.5–1.7 mm long............................................................................................................ C. flosculora

3. Styles 8–9.5 mm long.............................................................................................................. C. pubicosta 1. Styles 3-parted but not free to base, 3-cleft or 3-fid.

4. Styles pubescent or hairy, 6–10 mm long.
5. Leaves 7–11 × 1.8–2.8 cm with 6–8 pairs of lateral veins................................................................... C. angustifolia 5. Leaves 13.5–29 × 5.5–12.5 with 11–17 pairs of lateral veins............................................................... C. fangchensis

4. Styles glabrous, or rarely sparsely hairy.
6. Flowers terminal.....................................................................................................................C. ptilophylla 6. Flowers axillary.

7. Number of sepals 5; number of petals 6......................................................................................C. parvisepala 7. Number of sepals 5–6, number of petals 7–8.....................................................................................C. sinensis

Acknowledgements

We give special thanks to the management and staff of the Bidoup-Nui Ba National Park and Dalat University for their cooperation and support throughout the fieldwork that resulted in the discov- ery of Camellia flosculora. We also thank the man- uscript reviewers for their constructive feedback.

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Camellia flosculora; Photos Truong Quang Cuong