Based on investigation of populations of Parnassia guilinensis and P. xinganensis, examination of herbarium specimens (including types), as well as consultation of protologues and distributions, P. guilinensis is hereby reduced to a synonym of P. xinganensis. P. xinganensis is endemic to northeastern Guangxi Province of China and characterized by having elliptic to ovate leaves and staminodes 3–5-branched with globose glands. Field photographs and an updated morphological description of P. xinganensis are provided.

Endemic species, morphology, staminode, synonymy, taxonomy

Parnassia L. consists of small, glabrous and rosulate perennial herbs, with several morphologically distinguishable traits, including a solitary, terminal, bisexual and pentamerous flower borne on an unbranched scape; five showy staminodes; and one-by-one stamen movement (Ku 1987; Ku and Hultgård 2001; Sandvik and Totland 2003; Ren 2010; Armbruster et al. 2014; Ren and Bu 2014). Species of Parnassia predominantly occur in arctic and alpine regions of Europe, Asia, and North America with a center of diversification in mountainous areas in Pan-Himalaya and southwest China (Phillips 1982; Ku 1987; Ku and Hultgård 2001; Wu et al. 2003; Simmons 2004; Wu 2005). According to the most updated checklist, Parnassia contains 61 species, 2 subspecies, 11 varieties and 1 form (Shu et al. 2017). However, results from several taxonomic investigations after Shu et al. (2017) have changed the number of species in the genus. These changes include: P. lanceolata var. oblongipetala T.C. Ku was reduced to a synonym of P. yunnanensis Franch. (Shu and Zhang 2017), P. venusta Z.P. Jien, P. degeensis T.C. Ku and P. kangdingensis T.C. Ku were reduced to synonyms of P. cacuminum Hand.-Mazz. (Shu and Zhang 2017), P. chengkouensis T.C. Ku and P. dilatata Hand.-Mazz. were reduced to synonyms of P. wightiana Wall. ex Wight et Arn. (Wang et al. 2018), P. brevistyla (Brieg.) Hand.-Mazz. and P. leptophylla Hand.-Mazz. were reduced to synonyms of P. delavayi Franch. (Yu et al. 2018), P. tibetana Z.P. Jien ex T.C. Ku, P. nubicola subsp. occidentalis Schönbeck-Temesy and P. nubicola var. nana T.C. Ku were reduced to synonyms of P. nubicola Wall. ex Royle (Ma et al. 2020). Meanwhile, some new species were described, including P. zhengyuana M.X. Ren et J. Zhang and P. simianshanensis M.X. Ren, J. Zhang et Z.Y. Liu (Zhang et al. 2019).

In the taxonomy of Parnassia, the shape of basal leaves, the characteristics of petals (entire or flat, divided into lobes or filiform rays, respectively), and the shape of staminodes (i.e., number and depth of staminode branches, shape of staminode lobes, with globose glands at apex or not) were considered to be of great significance in species delimitation (Ku 1987; Ku and Hultgård 2001; Wu 2005). P. guilinensis G.Z. Li et S.C. Tang (Tang and Li 1999) and P. xinganensis C.Z. Gao et G.Z. Li (Gao and Li 1983) were described based on specimens collected from the same mountain: Mao’er Mountain, Xing’an County, Guilin City, Guangxi Province, China. The type specimen of P. xinganensis (11 December 1978, G.Z.Li 62923) was collected at an altitude of 1200 m on the mountain while that of P. guilinensis (23 August 1998, G.Z.Li and S.C.Tang M93) was collected at 580 m. Tang and Li (1999) noted that P. guilinensis was morphologically similar to P. xinganensis but could be distinguished from the latter by the staminodes being 5-lobed and the apex of lobes with globose glands, whereas the staminodes of P. xinganensis are 3- or rarely 4-lobed without globose glands at the lobe apex. In both Flora Reipublicae Popularis Sinicae (Ku 1995) and Flora of China (Ku and Hultgård 2001), the staminodes of P. xinganensis were described as eglandular. However, when examining the type specimen of P. xinganensis (Fig. 1), we found that the apex of the staminode lobes obviously bear globose glands and the number of lobes range from three to five, strongly indicating that P. xinganensis and P. guilinensis are the same species. In order to clarify the relationship of the two sympatric taxa, we visited the Mao’er Mountain in September and October of 2020 and conducted population surveys of Parnassia species from low to high altitudes. Population observations clearly revealed that there are no differences among individuals at 580 m and 1200 m (Fig. 2), confirming that the later described species P. guilinensis is conspecific with the former one, P. xinganensis. We thus reduce P. guilinensis to a synonym of P. xinganensis, and provide an updated description of P. xinganensis based on population observations.

Figure 1. 

Type specimens of Parnassia xinganensis (A) and P. guilinensis (B).

Figure 2. 

Morphological comparisons between Parnassia xinganensis (A1–A5) and P. guilinensis (B1–B5) collected from their type localities of Mao’er Mountain at altitudes of 1200 m and 580 m, respectively A1, B1 habitat A2, B2 flower A3, B3 calyces, staminodes and ovary A4, B4 petals A5, B5 variation of staminodes.

Type specimens of P. guilinensis and P. xinganensis deposited at IBK, as well as other Parnassia specimens collected from Mao’er Mountain, Xing’an County, Guangxi Province, China, preserved in GXMG, IBK, IBSC, KUN and PE (acronyms according to Thiers 2020+) were carefully examined under a stereo dissecting microscope (Stereo Zoom Leica S8 APO, Leica Microsystems 2017). Morphological traits were measured using a ruler and a micrometer based on both herbaria and fresh materials. Field investigations were carried out during September to October of 2020 in Mao’er Mountain and some individuals of P. xinganensis collected from different altitudes were transplanted to the greenhouse at Jingdezhen University for further observation and to be photographed. Voucher specimens were deposited at the herbarium of Jingdezhen University.

We are grateful to the curators of GXMG, IBK, IBSC, KUN and PE for providing access to specimens; Dr. Li-Na Dong, Mr. Fang-Min Hu and Prof. Hui-Chun Du for their field assistance; Dr. Yu-Min Shu for sharing some Parnassia literature; and to Prof. Guang-Zhao Li for his comments on the manuscript. This work was supported by the National Natural Science Foundation of China (grants no. 41561014, 31900181).