Vaccinium chaozhouense Y.H.Tong & J.H.Ding, 2023

Tong, Yi-Hua, Ye, Pei-Zhao, Ding, Jian-Hong, Huang, Wei-Chao, Huang, Wei & Ni, Jing-Bo, 2023, Vaccinium chaozhouense (Ericaceae), a new species from East Guangdong, China, PhytoKeys 236, pp. 113-119 : 113

Vaccinium chaozhouense Y.H.Tong & J.H.Ding sp. nov.

Fig. 1

Type.

China. Guangdong Province: Chaozhou City, Chao'an Fenghuangshan Provincial Nature Reserve , 980 m a.s.l., 10 May 2023 (fl.), Yi-Hua Tong et al. TYH-2699 (holotype: IBSC, isotypes: KUN, PE) .

Diagnosis.

The new species is most similar to V. wrightii A. Gray (including its variety with smaller habit and leaf blades, V. wrightii var. formosanum (Hayata) H. L. Li) by having flowers with persistent and leaf-like bracts, and white spherical-urceolate corollas, but is distinguished by the presence of glandular trichomes on the abaxial surface of the leaf blade (vs. glabrous), shorter pedicels (4-6 mm vs. 5-15 mm), sparsely pilose (vs. glabrous) ridges of the corolla, and anther thecae longer than the tubules (vs. equal to or shorter than the tubules). A more detailed comparison of the two species is provided in Table 1 .

Description.

Evergreen shrubs, 0.3-1.5 m tall. Young branchlets densely pubescent, glabrescent. Leaves dense, spirally alternate; blades leathery or thickly leathery, elliptic or ovate, 1.5-3.1 × 0.7-1.8 cm, apex acute, base cuneate to broad cuneate, margin serrate, each serra tipped with a gland, abaxially with evenly distributed glandular trichomes throughout, adaxially glabrous, midvein raised abaxially, slightly impressed adaxially, lateral veins 4-7 on each side, slightly conspicuous abaxially, inconspicuous adaxially; petiole 2-3 mm long, initially pubescent, glabrescent at maturity. Racemes pseudoterminal and axillary, 1.5-4 cm long, with 3-7 flowers, rachis pubescent or sometimes glabrous; bracts persistent, leaf-like, ovate, elliptic or obovate, 3.5-8 × 2-4 mm, nearly glabrous on both sides, margin with (1-)5-15 glandular teeth per side, occasionally ciliolate at the apex; pedicel glabrous or sparsely pubescent on upper part, 4-6 mm long; bracteoles 2, caducous, usually borne at the middle and lower part (towards rachis) of the pedicel, occasionally at the upper part (towards hypanthium), lanceolate, 1.5-3 × 0.5-1 mm wide, glabrous on both sides, margin with (0-)1-2 glandular teeth, occasionally ciliolate at the apex. Hypanthium obconical, densely white-pubescent or sometimes glabrous; calyx limb 5-lobed to near base, calyx lobes triangular or broadly triangular, 1-1.5 × 1.2-1.5 mm, glabrous on both sides or sparsely pubescent abaxially, often with glandular teeth on the margin, apex acuminate, sometimes ciliolate. Corolla white, spherical-urceolate, slightly 5-ridged, 5-6 × 4-5 mm, sparsely pilose on the ridges abaxially, otherwise glabrous, pilose adaxially, apex shallowly lobed, lobes recurved, triangular, ca. 1.2 × 1.2 mm; stamens 10, 4.5-4.8 mm long, filaments 2-2.2 mm long, densely white-villous, anthers 2.5-2.7 mm long, thecae 1-1.2 mm long, tubules 1.5-1.7 mm long, spurs present, borne at the base of tubules, obliquely projected, ca. 0.8 mm long; style 4-5.5 mm long, stigma truncate, ovary pseudo-10-locular, each with several ovules, disk white-pubescent or sometimes nearly glabrous. Fruit globose, 4-4.5 mm in diameter, black when ripe; fruiting pedicel 4-6 mm long.

Etymology.

The species epithet is named after the type locality, Chaozhou City. The Chinese name is given as 潮州越橘 (Chinese pinyin: cháo zhōu yuè jú).

Distribution, habitat and conservation status.

This species is currently known only from the type locality, i.e., Fenghuangshan, the highest mountain in the Chaoshan district (an area of nearly 16,000 km2 in East Guangdong) with an elevation of 1497.8 m at the summit. Vaccinium chaoanense grows among shrubs on sunny volcanic rocks at an elevation of ca. 980 m. This kind of habitat where this species grows is actually a little unusual in Fenghuangshan, as most of Fenghuangshan area is covered with evergreen broadleaf forests. Only one population with <30 individuals was found despite a careful search in the area. Thus, it is assigned a status of 'Critically Endangered’ (CR, criterion D) following the IUCN Red List categories and criteria ( IUCN 2012) and guidelines ( IUCN Standards and Petitions Committee 2022). Because its distribution area is under the protection of Chao’an Fenghuangshan Provincial Nature Reserve, and it is not economically valuable, the threat risk seems low.

Phenology.

Flowering in May and fruiting in October-November.

Additional specimens examined.

Vaccinium chaozhouense : the same locality as the type, 18 May 2022 (fl), Jian-Hong Ding s.n. (IBSC) ; ibid., 31 October 2022 (fr.), Jian-Hong Ding s.n. (IBSC) ; ibid., 10 May 2023 (fl.), Yi-Hua Tong et al. TYH-2700 (IBSC) .

Vaccinium wrightii : Japan. Ryukyu: without precise locality, without date, C. Wright 170 (holotype GH00015982, image, isotypes K000780593, image, NY00010772, image); without precise locality, 1887, O. Warburg s.n. (W, image); Gneka-Kesaji, 9 June 1930, K. Kondo 1975 (PE00245894); Higashi-son, Gaji, in windy scrubs, 100 m a.s.l., 12 October 1990, T. Yamazaki 6486 (PE00197326); Iriomote Island , Shirahama , on the seaside, 29 April 1980, K. Inoue 1469 (IBSC0457605, PE00197336); Iriomote Island , on the way from Ootomi to Mt. Goza , in evergreen forest, 20-200 m a.s.l., 4 August 1981, N. Fukuoka & M. Ito 180 (IBSC0457604); Iriomote Island , valley of Yuchin-gawa River , on rocky cliff at shady riverside, 6 April 2004, K. Yonekura et al. 11346 (IBSC0741637); Iriomote Island , along Shirahama Forest Road , ca. 1 km from the entrance, on sunny slope around a marsh in a small valley, 120-130 m a.s.l., 3 April 2004, Koji Yonekura 11213 (PE); Iriomote Island , in evergreen forest, 50 m a.s.l., 8 November 1985, Toshiyuki Nakaike s.n. (PE00197345); Nago-shi, NW slope of the Mt. Nago-dake , 200 m a.s.l., 11 March 1978, J. Murata 4717 (PE00438051). CHINA. Taiwan : Hualien , Hsiaochingshui , 350 m a.s.l., 17 April 2002, Tien-Tsai Chen 11872 (PE); Taipei , Taluntoushan, 13 June 1997, Her-Long Chiang 496 (PE00197448) .

Discussion.

Vaccinium chaozhouense can be assigned to V. sect. Bracteata Nakai according to Sleumer’s or Vander Kloet & Dickinson’s infrageneric classification system ( Sleumer 1941; Vander Kloet and Dickinson 2009) by its terrestrial habit, pinninerved leaf blade with a serrate margin, persistent and leaf-like floral bracts, pseudo-10-locular ovary and black fruit, which match the characters of that section. Two other species are also similar to this new species in having the same leathery leaf texture, persistent, large, and leaf-like floral bracts, and similar urceolate or spherical-urceolate corolla shape, i.e., V. eberhardtii Dop from Vietnam and Thailand, which has also been recently reported from Guangxi, China ( Tong et al. 2018), and V. boninense Nakai endemic to the Bonin Islands (also known as Ogasawara Islands). A key to the four species is provided below summarizing the morphological differences among them. Although these four species were assigned to V. sect. Bracteata for now, they bear unusual urceolate shape of corolla, while many other species in this section have tubular corolla. Meanwhile, a continuous coastal distribution from western Pacific Ocean islands to Indochina is presented by the four species. Thus, according to their morphological characteristics and distribution pattern, these four species may represent a distinct lineage in V. sect. Bracteata , and studies on their biogeography and speciation seem warranted.

Figures

Figure 1. Vaccinium chaozhouense A habitat B habit and flowering branchlets C flowering branch D fruiting branches E abaxial surface of leaf blade showing glandular trichomes F flower G bracts, adaxial (left) and abaxial (right) surfaces H bracteoles, adaxial (left) and abaxial (right) surfaces I stamens, ventral (left), lateral (middle) and dorsal (right) view J hypanthium (with calyx lobes removed), showing disk and style K disk, top view L ovary cross-section, showing the pseudo- 10 - locular ovary. Scale bars: 5 mm (F-G, J); 3 mm (H); 2 mm (I, L); 1.5 mm (E, K). Photographs by Yi-Hua Tong, except D by Jian-Hong Ding.