Vacciniumchaozhouense﻿ (Ericaceae), a new species from East Guangdong, China

﻿Abstract Vacciniumchaozhouense (Ericaceae), a new species from East Guangdong Province, China is described and illustrated. This new species is morphologically similar to V.wrightii by having flowers with persistent and leaf-like bracts, long pedicels, and white spherical-urceolate corollas, but is distinguished by having glandular trichomes on the abaxial surface of the leaf blade, shorter pedicels, sparsely pilose corolla ridges, and anther thecae longer than the tubules. A key to the new species and morphologically similar species is also provided.


Introduction
With 470 accepted species, Vaccinium L. is the largest genus of the subfamily Vaccinioideae Rchb.(Ericaceae) (POWO 2023).In the account of Flora of China, 92 Vaccinium species were recorded (Fang and Stevens 2005).As several new species have been described in recent years, the number of Vaccinium species has now reached 100 for this country (Tong and Xia 2015;Tong et al. 2018Tong et al. , 2020Tong et al. , 2021aTong et al. , b, 2022;;Huang et al. 2022;Qin et al. 2023).Some preliminary molecular phylogenetic studies showed that Vaccinium is polyphyletic, with many sections considered more distinct than some genera (Stevens 1985;Kron et al. 2002;Predraza-Peñalosa and Luteyn 2011;Argent 2019).However, a comprehensive sampling is not easy for such a cosmopolitan genus, as it will need full international cooperation to make it possible.
Recently, one of the co-authors (J.-H.Ding) found an interesting Vaccinium in Chao'an Fenghuangshan Provincial Nature Reserve, Guangdong Province, China.It resembles V. wrightii A. Gray, a species endemic to Taiwan and the Ryukyu Islands, in having leaf-like floral bracts and white spherical-urceolate corollas (Li 1978;Yamazaki 1993;Li et al. 1998).However, after careful comparison of this plant to other similar species similar, we confirmed that it represents a species new to science and is here described and illustrated.

Materials and methods
Flowering and fruiting materials were collected from Fenghuangshan, Chaozhou City, Guangdong Province, China, during several field trips from 2022 to 2023.The description was based on dried herbarium specimens.The online specimen photos (including type specimens) of V. wrightii in GH, K, and W were consulted, as well as physical herbarium specimens deposited at IBSC and PE.Measurements were obtained with a ruler, and small plant parts were observed and measured under a stereo microscope (Mshot-MZ101).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.
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 km 2 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.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 Table 1.Morphological comparison of Vaccinium chaozhouense and V. wrightii.The data for V. wrightii are from Li (1978), Fang and Stevens (2005), and Yamazaki (1993) as well as the examination of the specimens listed in the text.

Abaxial surface of leaf blade With evenly distributed glandular trichomes Glabrous
Inflorescence length (cm) 1.5-4 5-8.5  (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.