Vitisshizishanensis, a new species of the grape genus from Hubei province, China

Abstract Vitisshizishanensis (Vitaceae), a new species from Hubei, China, is described and illustrated. It is morphologically similar to V.flexuosa and V.bryoniifolia, but differs in leaf lobing and pubescence. It can be easily distinguished from the two species based on its glabrous or with very sparse arachnoid tomentum on the abaxial mature leaf surface, and its unlobed to 3–7 lobed leaves. A detailed description, along with photographs for the new species, and a table for morphological comparisons with similar Vitis species, are also provided.


Introduction
The grapes (Vitis vinifera L.) represent one of the earliest domesticated and the most widely cultivated economic fruits in the world, as the source for grapes, raisins, and wine (Myles et al. 2011;Gerrath et al. 2015;Wen et al. 2018b). The grape genus Vitis L. contains ca. 70 species with an intercontinental disjunct distribution in North America (to northern South America), East Asia and Europe to West Asia (Galet 1988;Chen et al. 2007; Moore and Wen 2016;Wen et al. 2018aWen et al. , 2018b. There are ca. 40 native species of Vitis in East Asia and most of them occur in China (Chen et al. 2007;Wan et al. 2008). Based on recent studies on molecular phylogeny and morphology of Vitis, a robust phylogenetic framework of Vitis has been reconstructed (Tröndle et al. 2010;Péros et al. 2011;Zecca et al. 2012;Aradhya et al. 2013;Wan et al. 2013;Liu et al. 2016;Ma et al. 2018a). However, due to rapid evolutionary radiations and extensive reticulate evolution of Vitis (Aradhya et al. 2013;Wan et al. 2013;Ma et al. 2018aMa et al. , 2018bWen et al. 2018a), the species delimitation of Vitis is still controversial and the number of species of Vitis needs to be further assessed (Chen et al. 2007;Wan et al. 2008;Wen et al. 2018b;Ma et al. 2016Ma et al. , 2018b. Taxonomic challenges of some Vitis species are caused by their morphological similarity and overlapping geographic distribution (Chen et al. 2007;Moore and Wen 2016). A very complex group of Vitis is the V. bryoniifolia clade and its close allies . The phylogenetic relationships of the V. bryoniifolia clade have been reconstructed recently with robust support, which indicated that some samples previously difficult to identify need to be treated as a different species distinct from V. bryoniifolia based on molecular phylogenetic evidence   (Fig. 1). The leaf shape of this species shows a high level of phenotypic plasticity, varying from unlobed to 3-7 lobed, which caused problems for species identifications . After consulting relevant literature (Li et al. 1996;Wang et al. 2000;Chen et al. 2007;Wan et al. 2008) and our extensive field studies in East Asia, we herein propose to describe the new species, Vitis shizishanensis Z.Y.Ma, J. Wen, Q. Fu & X-Q. Liu.

Material and methods
Descriptions and measurements of morphological characters of the new species were based on field observations of living plants at the type locality and specimens in the herbarium of Huazhong Agricultural University (CCAU) and the United States National Herbarium (US). We also examined herbarium specimens of Vitis comparatively from the following herbaria: CCNU, CSFI, HIB, HNNU, HUNST, HZU, JIU, JXCM, NYA, PE, and WH (abbreviations following Thiers 2020), and from images of type specimens and dried herbarium specimens on the Chinese Virtual Herbarium Website (http://www.cvh.ac.cn/), JSTOR Global Plants (http://plants.jstor.org), National Specimen Information Infrastructure (http://www.nsii.org.cn/), and Sharing Platform of IBK (http://www.gxib.cn/spIBK/).  Diagnosis. Vitis shizishanensis is morphologically similar to V. bryoniifolia Bunge, V. flexuosa Thunb, V. sinocinerea W. T. Wang, and V. bellula (Rehder) W. T. Wang, but differs from the V. bryoniifolia, V. sinocinerea, and V. bellula in its glabrous to hirtellously pubescent abaxial mature leaf surface (vs. abaxially densely arachnoid tomentose in V. bryoniifolia, V. sinocinerea, and V. bellula). It differs from Vitis flexuosa in its leaves varying from unlobed to 3-7 lobed (vs. unlobed to slightly 3-lobed leaves in V. flexuosa), tendrils unbranched or bifurcate from upper half (vs. tendrils bifurcate from approximately midway in V. flexuosa), lack of arachnoid tomentum (vs. with sparse arachnoid tomentum to glabrescent in V. flexuosa), and subcordate to cordate or sometimes truncate leaf base (vs. subtruncate or slightly subcordate leaf base in V. flexuosa).
Phenology. Flowering from March to May, fruiting from July to October. Etymology. The specific epithet is derived from the type locality, Shizishan, Wuhan, Hubei, China. The Chinese name is given as "狮子山葡萄".
Distribution and habitat. The new species is currently known from Wuhan and Tianmen in Hubei province, China (Fig. 7). It occurs on the scrubland and the roadside of farmland at an altitude of ca. 10-50 m.
Vitis shizishanensis is morphologically similar to V. bryoniifolia, V. flexuosa, V. sinocinerea, and V. bellula. Detailed morphological comparisons among the three species are provided in Table 1. These characters were based on field observations, and herbarium and literature studies (Li et al. 1996;Chen et al. 2007;Wan et al. 2008).