Liparis tianchiensis (Orchidaceae, Epidendroideae), a new species from Wenxian County, Gansu Province, China, is described and illustrated, based on morphological characters. Liparis tianchiensis is morphologically similar to L. damingshanensis, L. pauliana and L. mengziensis with erect, lax flowered-inflorescences, small persistent floral bracts, small greenish-purple flowers, spreading sepals, free reflexed and linear petals, a lip with 2 calli near the base and an arcuate column. Liparis tianchiensis differs from L. pauliana by the single and much smaller leaf, shorter sepals and petals, smaller and reflexed oblong lip. It differs from L. mengziensis by having fewer and larger flowers and not connate lip apex. The novelty mostly resembles L. damingshanensis, but can be readily identified by having longer sepals and a reflexed oblong lip. Liparis tianchiensis only occurs in evergreen broad-leaved forest around a mountain lake in Wenxian County, Gansu Province, China.

Malaxideae, morphology, new species, Wenxian County

The genus Liparis Richard (1817: 21) belongs to tribe Malaxideae (subtribe Malaxidinae) of the subfamily Epidendroideae (Chase et al. 2015) and comprises approximately 424 species (Plants of the World Online (https://powo.science.kew.org/)) with cosmopolitan distribution from the tropics and subtropics to the temperate and alpine regions. Most species in this genus occur in Southeast Asia as well as in Africa, Australia and the Americas (Pridgeon et al. 2005). Liparis is easily distinguished from its allies, Malaxis Sol. ex Sw. (Swartz 1788: 119), Oberonia Lindley (1830: 15) and Hippeophyllum Schltr. in Schumann and Lauterbach (1905: 107), based on its floral morphology (viz. resupinate flowers with narrow linear petals and a curved, slightly winged column lacking a foot) (Pearce and Cribb 2002; Chen et al. 2009). The taxonomy of the genus is very confused and inconsistent (Margońska and Szlachetko 2001, 2004; Pridgeon et al. 2005; Liu et al. 2008) and some research indicated that Liparis were polyphyletic. Tang et al. (2015) performed molecular and morphological analyses to establish the phylogenetic relationships within Malaxideae, the results supporting the division of Liparis into 11 genera, but the intergeneric relationships remain unclear and the genus definition is considerably controversial. Therefore, we tentatively opted to maintain Liparis as a broad concept for the present taxonomic treatment. There are approximately 70 species of Liparis in China, including many recently described taxa (see Chen et al. (2009); Feng and Jin (2010); Jin (2010, 2011); Wu et al. (2012); Hsu (2013); Li and Yan (2013); Su et al. (2014); Su et al. (2015); Tang et al. (2015); Li et al. (2019); Ya et al. (2021)).

Wenxian County, Gansu Province, is situated in the northwest of China, in a transitional zone between the north subtropical and warm temperate regions. The altitudes vary from 595 to 4072 m. Variations in climate combined with complex topography have resulted in high plant diversity (Li 2014). Although being a biodiversity hotspot in China, the flora of this area is still unknown despite many years of directed fieldwork and research. Several new species have been described in the last decades, such as Cardamine tianqingiae Al-Shehbaz & Boufford in Ihsan (2008: 89) (Brassicaceae), Spiranthes sunii Boufford & Wen H.Zhang (2008: 261) (Orchidaceae), Vitis wenxianensis W.T.Wang (2010: 288) (Vitaceae), Clematis austrogansuensis W.T.Wang & L.Q.Li (2011: 285) (Ranunculaceae) and, more recently, Oreocharis wenxianensis XiaoJ.Liu & X.G.Sun (2021: 182) (Gesneriaceae) and Saxifraga sunhangiana T.Deng, X.J.Zhang & J.T.Chen in Zhang et al. (2022: 197) (Saxifragaceae).

Tianchi Lake in Wenxian County is a famous mountain lake in China, covering an area of nearly 1 km², surrounded by mountains, rich in plant diversity. During our field trip around Tianchi Lake in 2021, we collected nearly 20 orchid species, including an unknown Liparis. Further examination by means of morphological comparison indicated that it represented a new species, which is described and illustrated here.

Specimens from the single known subpopulation of the putative new species were collected during field expeditions in 2021. Morphological characters of five living plants, including three flowering and two non-flowering individuals, were observed, measured and photographed under an Olympus stereozoom microscope. Specimens were deposited in the Forestry Herbarium of Gansu Agricultural University (GAUF), located in Lanzhou City, Gansu Province, China.

After consulting relevant literature (Pearce and Cribb 2002; Pridgeon et al. 2005; Liu et al. 2008; Chen et al. 2009; Yang et al. 2009; Feng and Jin 2010; Jin 2010, 2011; Wu et al. 2012; Hsu 2013; Li and Yan 2013; Su et al. 2014; Su et al. 2015; Tang et al. 2015; Li et al. 2019; Ya et al. 2021) and examining scans of type specimens and other relevant herbarium specimens of Liparis available online from AMES, BM, E, L, K, P and PE (acronyms following Thiers, continuously updated), JSTOR Global Plants (http://plants.jstor.org), China National Specimen Information Infrastructure NSII (http://www.nsii.org.cn/2017/home-en.php) and The Chinese Virtual Herbarium NPSRC (http://www.cvh.ac.cn), the taxonomic status of the putative new species and morphologically similar species were investigated.

We sincerely thank Prof. Xiao-Hua Jin (Institute of Botany, Chinese Academy of Sciences) for his useful suggestions and comments of a previous version of the manuscript and Hui Lin for the illustration. This work was supported by a grant from the Special Survey Project of Wild Orchid Resources of the National Forestry and Grassland Administration (202007).