﻿Vacciniumusneoides (Ericaceae), a new species from Yunnan, China

﻿Abstract Vacciniumusneoides (Ericaceae), a new species from Fugong County of Yunnan Province, China is described and illustrated. This new species belongs to Vacciniumsect.Calcicolus and is most similar to V.brachyandrum, but differs in its branches hanging down, much smaller leaf blades, shorter inflorescences and pedicels, non-glandular tomentellate or densely pubescent inflorescence rachis and pedicels, densely white-pubescent hypanthium and pilose filaments.


Introduction
The genus Vaccinium L. (Ericaceae), with about 450-500 species distributed worldwide, is the largest genus of the blueberry tribe (Fang 1991;Fang and Stevens 2005;Vander Kloet and Dickinson 2009).This genus is a morphologically diverse group, which was divided into 33 (Sleumer 1941) or 30 sections (Vander Kloet and Dickinson 2009) with most sections of this genus allopatric.In China, 100 species of Vaccinium have been recorded, including the very recently published V. jiuwanshanense Ying Qin, Yan Liu & Y. H. Tong and Vaccinium bangliangense Y. S. Huang & Y. H. Tong (Huang et al. 2022;Qin et al. 2023).Yunnan Province, with 47 species of Vaccinium, harbours the highest diversity of this genus in China (Fang 1986;Huang and Fang 1991).
During several field trips to Gaoligong Mountain, we encountered an interesting Vaccinium species.This species is epiphytic on large trees with long hanging-down branches, which looks just like beard lichens from a distance.The inflorescence of this species is very hairy and shorter than and shaded by leaf blades, suggesting a close relationship with V. brachyandrum C. Y. Wu & R. C.
Fang, another sympatrically distributed species in Gaoligong Mountain.However, V. brachyandrum owns scrambling branches and much larger leaf blades, which are totally different from this unknown species.After a careful comparison of morphology with similar congeneric species from China and adjacent Myanmar (Kress et al. 2003;Fang and Stevens 2005), it was confirmed that this plant represents a new species, which is described and illustrated below.

Material and methods
Flowering and fruiting materials were collected from Gaoligong Mountain during three field trips in May 2022, October 2022 and March 2023.Descriptions were based on both living and dried collections.The voucher specimens were deposited at the Herbaria of Kunming Institute of Botany, Chinese Academy of Sciences (KUN) and South China Botanical Garden, Chinese Academy of Sciences (IBSC).Measurements were performed with a ruler and small plant parts were observed and measured under a stereomicroscope (Mshot-MZ101).Diagnosis.This new species is close to V. brachyandrum in the short and hairy inflorescences (less than 3.5 cm) with many flowers and the abaxially glandular leaf blades with one basal gland per side and a caudate-acuminate apex, but can be immediately distinguished by its hanging-down (vs.scrambling) branches, much smaller leaf blades (2.5-5.5 × 0.9-1.8cm vs. 8.5-11 × 4-6 cm) with fewer pairs of secondary veins (3-4 vs. 6-7), shorter inflorescence (1-1.5 cm vs. 1.5-3.5 cm), non-glandular tomentellate or densely pubescent (vs.glandular pubescent) inflorescence rachis and pedicel, shorter pedicel (0.7-1 mm vs. ca. 2 mm), densely white-pubescent (vs.glabrous) hypanthium and pilose (vs.glabrous) filament.A detailed morphological comparison between the two species is presented in Table 1.
Etymology.The species epithet is derived from the genus of beard lichen "Usnea" and the suffix "-oides", which means the habit of this new species looks very much like beard lichen on trees from a distance.Chinese name is given as 松萝越橘 (Pinyin: sōng luó yuè jú).
Distribution and habitat.This species is currently known only from the type locality, i.e. the part of the Gaoligong Mountain in Fugong County.It grows on trees in mountainous evergreen and deciduous broad-leaved mixed forests at elevations of 2400-2800 m a.s.l.Fang and Wu (1987), Fang and Stevens (2005) and its type specimens.

Figure 1 .
Figure 1.Vaccinium usneoides sp.nov.A habitat, the red ovals indicating this species B habit C leafy branches, the arrow showing the indumentum on young branchlets and leaf blades D flowering branchlets with young inflorescences E flowering branchlet F fruiting branchlet.A, B taken by Yi-Hua Tong C, F taken by Yong-jie Guo D taken by Ji-Dong Ya E taken by Ting Zhang.

Figure 2 .
Figure 2. Vaccinium usneoides sp.nov.A flowering branchlet B trichomes on abaxial surface of leaf blades C fruiting branchlet D flower E flower with corolla and calyx limb removed, showing androecium and gynoecium F stamens, adaxial (left), abaxial (middle) and lateral (right) view G seeds.Illustrated by Ding-Han Cui.

Table 1 .
A morphological comparison of Vaccinium usneoides and V. brachyandrum.The character information of the latter species is taken from