Vaccinium bidoupense Smitinand ex Y. H. Tong, N. T. T. Huong & Tagane, 2025

Nguyen, Thi Thanh Huong, Tagane, Shuichiro, Averyanov, Leonid V., Dang, Van Son, Fritsch, Peter W., Tong, Yi-Hua, Souladeth, Phetlasy & Nuraliev, Maxim S., 2025, Vaccinium bidoupense (Ericaceae), a new species from Vietnam and Laos, with notes on V. petelotii and V. pseudobullatum, PhytoKeys 266, pp. 75-96 : 75-96

Vaccinium bidoupense Smitinand ex Y. H. Tong, N. T. T. Huong & Tagane sp. nov.

Figs 3 , 4 , 5 , 6

Type.

Vietnam. Kon Tum Province • NW slopes of Ngoc Linh Mountain system at 1800–1900 m a. s. l., open places in primary evergreen dense mountain forest, 23 February 1995, L. V. Averyanov, N. T. Ban, N. Q. Binh, A. Budantzev, L. Budantzev, N. T. Hiep, D. D. Huyen, P. K. Loc, N. X. Tam, G. Yakovlev VH 053 [fl.] ( holotype: HN!; isotypes: BRIT, BRIT 402341 !; LE, LE 01041972 !; MO, 5168102 !; P, P 04485557 ! & P 04483084 !) .

Diagnosis.

Vaccinium bidoupense is morphologically similar to V. petelotii and V. pseudobullatum in its relatively large leaf blades and umbel-like inflorescence with short rachis. It differs from V. petelotii in having longer calyx lobes ( 5–6 mm vs. 2.5–3 mm), pale red to salmon pink (vs. pale green) corolla, a longer corolla tube ( 11–13.5 mm vs. 3.5–4.5 mm), and longer stamens ( 14–16 mm vs. 5–6.5 mm). The new species differs from V. pseudobullatum in having leaf blades with somewhat less obvious tertiary veins, and longer pedicels ( 7–14 mm vs. 4–7 mm), corolla tube ( 11–13.5 mm vs. 8–9 mm) and stamen filaments ( 8–9 mm vs. 1–4 mm) (Table 1 ).

Description.

Shrubs, epiphytic or epilithic, evergreen; shoots pendent, ca. 2–5 (– 10) m long, sometimes rooting at nodes. Branches more or less angled, glabrous, densely lenticellate. Leaves non-distichously alternate (but leaves of a branch often arranged in one plane due to twisted petioles), evenly scattered. Petiole 0.3–1.2 cm long, glabrous. Leaf blade ovate to lanceolate or sometimes elliptic, 12–22 × 4.7–11.7 cm, 2.0–3.7 times as long as wide, coriaceous; adaxial surface green, glabrous; abaxial surface pale green, densely covered with appressed dark brown trichomes (trichomes caducous, leaving faintly punctate scars); base rounded, subtruncate or shallowly cordate, rarely cuneate or prominently cordate; margin entire, slightly revolute, with 1 basal gland per side, glands 1–1.5 mm in diam.; apex acute to acuminate or shortly caudate; median vein and secondary veins impressed adaxially, strongly raised abaxially; secondary veins pinnately arranged, 10–14 on each side of median vein, usually meeting in a closed loop and forming an intramarginal vein; tertiary veins more prominent in submarginal area than in the rest of leaf blade, stout, reticulate, slightly impressed or sometimes flat adaxially, slightly raised abaxially. Inflorescences axillary, 1 per axil, on leafy shoots and older leafless branches, sessile (peduncle absent), racemose, umbel-like, determinate (developing mostly within the confines of the perennating buds), 4–10 - flowered; rachis pale green, 0.5–2 cm long, glabrous; bracts caducous, crimson, ovate, 1.0–1.5 × 0.5–0.6 cm, thinly coriaceous, glabrous, margin entire, apex obtuse. Flowers pendent, articulated with pedicels, 5 - merous. Pedicels red to pale green, 0.7–1.4 cm long, glabrous; bracteoles 2, attached at base of pedicel, subopposite, acicular, early caducous. Calyx (excluding ovary) pale red to salmon pink, becoming greenish with age, at base appressed to corolla and distally diverging to spreading, glabrous on both sides; tube ca. 1 mm long; lobes 5, triangular-lanceolate, 5–6 × 2–3 mm, distinctly 1 - veined. Corolla pale red to salmon pink, glabrous outside and inside; tube cupulate, 11–13.5 × 13–14 mm; lobes 5, strongly recurved, triangular to broadly triangular, 3–4 × 4–5 mm. Stamens 10, dimorphic with respect to spurs, included in corolla, free from each other, 14–16 mm long; filaments white to pale pink, slightly incurved, 8–9 mm long, glabrous in proximal half and puberulent in distal half; anthers tightly appressed to style, golden yellow, dorsifixed, 7–9 mm long, each with 2 spurs; thecae 3–3.5 mm long, slightly papillate; tubules parallel, 4–6 mm long (ca. 1.3 times as long as thecae), opening by oblique ventral apical pores; spurs borne dorsally at base of tubules, strongly curved, ca. 1 mm long, those on antesepalous stamens extending laterally outside of antepetalous anthers and overlapping with spurs of next antesepalous stamens, those on antepetalous stamens strongly hooked outward below spurs of antesepalous stamens. Ovary inferior, pale red to salmon pink, obconic, terete, 1–2 × 2–2.5 mm, glabrous, pseudo- 10 - locular; disk pale yellow, annular, broadly dome-shaped, ca. 2.5 mm diam., glabrous; style 1.4–1.6 cm long, exserted from corolla for 2.5–4 mm, linear, glabrous; stigma truncate. Infructescences with rachis 1–3 cm long. Fruiting pedicel 1.2–2.4 cm long. Fruit (when young) globose, ca. 6 mm in diam., glabrous, with persistent calyx lobes 5–6 mm long. Mature fruits and seeds unknown.

Ecology and phenology.

Vaccinium bidoupense grows as an epiphyte on tree trunks or as a lithophyte on mossy rocks in broad-leaved and mixed forests at elevations of 1100–2200 m. It flowers from October to February; young fruits are documented from May to June.

Distribution.

Vaccinium bidoupense is known from Laos ( Sekong Province) and Vietnam (provinces Kon Tum, Lam Dong, and Quang Nam). The species is therefore endemic to the area comprising the Central Highlands of Vietnam (also called Tay Nguyen Plateau) and their extension in Laos known as Dak Cheung (or Dakchung) Plateau, being broadly distributed across this region. The region comprises three main mountainous areas, i. e., Dak Lak Plateau, Kon Tum — Gia Lai Plateau and Langbian Plateau ( Poyarkov et al. 2021), and V. bidoupense is documented to inhabit the latter two areas. As the known locations suggest, the species probably occurs throughout the Central Highlands, and its presence in the provinces Dak Lak, Dak Nong and Gia Lai is especially probable.

Etymology and history of documentation of Vaccinium bidoupense .

The species name “ Vaccinium bidoupense ” was initially proposed by Tem Smitinand on the determination slips of three of Poilane’s specimens kept in P ( 30292, 30763 and 30909, included below as paratypes of the species). Two of these specimens originated from the Bidoup Massif (and 30292 was collected nearby), which is reflected in the species epithet. Although such a name has never been formally published until now, it was used by Vander Kloet and Avery (2007) (as “ V. bidoupense Smithin ”) who included the specimen Poilane 30763 in a morphophenetic analysis of stamen characters in the tribe Vaccinieae . Here, we follow Smitinand’s choice of epithet to ensure the clearness of the species identity and to acknowledge his recognition of this distinct species.

Conservation status.

Vaccinium bidoupense is an integral element of highland vegetation of the Central Highlands of Vietnam (including their extension in Laos) with an expected total extent of occurrence ( EOO) of about 55,000 km 2, which does not fit any of the threatened IUCN Red List conservation categories ( IUCN, Standards and Petitions Committee 2025). In intact habitats of montane forests, the species meets no damage factors. However, the vast degradation of primary vegetation across the distribution area of the species, including the legally protected territories, leads to a continuing decline in the extent of its occurrence, quality of habitat, number of populations, and number of mature individuals. In this connection, we preliminarily assess V. bidoupense as Near Threatened ( NT); we also consider that the species is close to being qualified as Vulnerable ( VU) in the near future.

Additional specimens examined ( paratypes).

Laos. Sekong Province • [ Dak Cheung District,] new road along the border with Vietnam , 15°34′36.0′′N, 107°20′11.5′′E, 1224 m a. s. l., 17 July 2021, P. Souladeth, M. Soukhavong, N. Thongphakdee, T. Boutavong 1141 [st.] ( FOF, FOF 0009576 ; KAG, KAG 181621 ) . Vietnam. Quang Nam Province • Nam Giang District, Song Thanh Nature Reserve , 15°33′07′′N, 107°23′02′′E, 1100 m a. s. l., 6 May 2019, M. S. Nuraliev 2509 [young fr.] ( BRIT, BRIT 1150627 ; IBSC; MW, MW 0758862 , MW 0758863 & MW 0758864 ) . Lam Dong Province • N of Dalat , 1500 m a. s. l., 2 September 1940, E. Poilane 30292 [young fr.] ( L, L.3786302 , image; P, P 04484682 , P 04484683 , P 04484684 , P 04484685 , P 05244320 & P 05244322 , images) • Bidoup Massif , 2200 m a. s. l., 12 October 1940, E. Poilane 30763 [fl.] ( L, L.3786303 , image; P, P 00647856 , P 04484686 , P 04484688 , P 05244702 & P 05244703 , images) • ibid., 2000 m a. s. l., 14 October 1940, E. Poilane 30909 [fl.] ( P, P 04484687 , P 05244317 & P 05244321 ) • Lac Duong District, Da Chay Municipality, 29 km to NE from Dalat City , 12°6′N, 108°39′E, 1900–2000 m a. s. l., 23 March 1997, L. V. Averyanov, N. Q. Binh, P. K. Loc VH 3118 [st.] ( HN; LE, LE 01041973 ; MO, MO-5172316 ) • ibid., 12°6′N, 108°39′E, 2150 m a. s. l., 1 May 1997, L. V. Averyanov, N. Q. Binh, N. T. Hiep, P. K. Loc, P. Lowry VH 4463 [fr.] ( HN; LE, LE 01041976 ; MO, MO 2080998 ; MW, MW 1045967 ; P, P 04483084 ) • Lac Duong District, Bidoup Nui Ba National Park , 12 October 2011, N. H. Xia, J. B. Ni, Y. H. Tong & X. R. Zheng TYH- 1070 [st.] ( IBSC) • ibid., SE of Giang Ly station , 12°11′07.7′′N, 108°41′14.6′′E, 1509 m a. s. l., 23 December 2012, A. N. Kuznetsov, S. P. Kuznetsova, A. N. Demidova, N. G. Prilepsky 404 [st.] ( MW, MW 0750311 ) • ibid., 12°10′21.03′′N, 108°41′49.76′′E, 1504 m a. s. l., 19 November 2014, H. Toyama, S. Tagane, V. S. Dang, H. Nagamasu, A. Naiki, H. Tran, C. J. Yang et al. V 1857 [fl.] ( FU; VNM) • ibid., 12°11′11.18′′N, 108°42′53.12′′E, 1639 m a. s. l., 23 February 2016, S. Tagane et al. V 4287 [fl.] ( DLU; FU; VNM) • ibid., 12°11′09.23′′N, 108°42′55.46′′E, 1637 m a. s. l., 22 December 2018, S. Tagane et al. V 9614 [fl.] ( DLU; FU; KAG, KAG 127364 ) • ibid., 22 April 2019, T. Yahara et al. V 9879 [young fr.] ( DLU; FU; KAG, KAG 182510 ) • ibid., 12°4.076′N, 108°38.927′E, 2000–2200 m a. s. l., 8 November 2023, L. V. Averyanov, V. C. Nguyen, B. V. Truong, T. Maisak AL 2537 [fl.] ( LE, LE 01253935 , photos LE 01124590 ) .

Figures

Figure 3. Vaccinium bidoupense. A. Flowering branch; B. Bud and base of leaf (abaxial side) showing dense appressed trichomes; C. Inflorescence; D. Stamen, dorsal view; E. Flower with part of corolla and some stamens removed to show disk and style. Drawn by S. Tagane.

Figure 4. Vaccinium bidoupense. A. Flowering branch; B – D. Inflorescences; E. Flower, apical view. Photos by L. V. Averyanov, based on Averyanov et al. AL 2537.

Figure 5. Vaccinium bidoupense. A. Habit; B. Leafy branch; C. Leaf blade, abaxial view; D. Base of leaf, abaxial view, showing appressed dark brown trichomes; E. Young leafy branch. Photos by S. Tagane, A. unvouchered; B. based on Toyama et al. V 1857; C – E. based on Tagane et al. V 4287.

Figure 6. Vaccinium bidoupense. A, B. Inflorescences; C. Flower with a half of perianth removed; D, E. Androecium. Photos by S. Tagane, based on Tagane et al. V 4287.