Semiaquilegia quelpaertensis (Ranunculaceae), a new species from the Republic of Korea

Abstract Semiaquilegia quelpaertensis sp. nov., a new species belonging to the family Ranunculaceae, from Hallasan National Park in Jeju-do, Republic of Korea, is described and illustrated. The new species is similar to Semiaquilegia adoxoides (DC.) Makino, but can be readily distinguished by a thick underground stem, shallowly lobed leaflets, larger flowers, (4–)6 staminodes and conspicuously rugose tuberculate seed surface.


Introduction
The genus Semiaquilegia Makino is well-known for tuberous-perennial herbaceous plants of the family Ranunculaceae and hitherto consisted of a sole species, S. adoxoides (DC.) Makino which is mainly found in China, Korea, Japan and Taiwan (Fu and Orbélia 2001, Hsu et al. 2004, Kadota 2006. Recently, Huang et al. (2017) described S. guangxiensis Yan Liu & Y.S. Huang, from the limestone areas of northern Guangxi, China, as a new species of Semiaquilegia, with its affinity to S. adoxoides and taxonomic implication confirmed by molecular evidence. Additionally, the morphological characteristics, such as the shape of underground stem, the length of pedicel, the shape of petals and the number of stamens and staminodes, have been recently confirmed as key characters in species delimitation within Semiaquilegia. As a traditional medicinal plant, S. adoxoides is often used against carbuncles, furuncles, swelling, breast carbuncles, scrofula and snakebite; the extract from the underground stem is also helpful for the prevention of cancer (Guang and Wang 2011).
Semiaquilegia is currently included in the tribe Isopyreae, subfamily Isopyroideae (Kadota, 2006), being widely recognised as closely related to Aquilegia L. based on petal evolution (Tucker andHodges 2005, Damerval andNadot 2007), geographical affinities (Munz 1946, Nold 2003 and molecular data (Yang et al. 2005). Recently, Wang and Chen (2007) showed that Semiaquilegia, Urophysa Ulbrich and Aquilegia form a monophyletic group, with Semiaquilegia as sister to Aquilegia. These three genera are characterised by the presence of membranous staminodes, most frequently 5 carpels and spurred petals, but can be distinguished from each other by their habitat, flowering season, flower size, floral structure with the petals divided into lamina and spur, the colour of sepals, the number of staminodia, the presence of spur, seed surface etc. (Munz 1946, Fu and Orbélia 2001, Kadota 2006, Zhao et al. 2016, Erst et al. 2017.
During a recent floristic survey, one species of Semiaquilegia which does not appear to be similar to previously reported species was collected at Hallasan National Park in Jejudo, Republic of Korea. After examination of the various flora and herbarium specimens of Korea and adjacent countries as well as relevant literature (De Candolle 1817, Makino 1902, Wang 1989, Fu and Orbélia 2001, Kadota 2006, it was concluded that the collected specimens represent undescribed species, formally described below as S. quelpaertensis.
Preliminary conservation status. Currently, the new species is only known at the type locality and the population size is about 200 mature individuals. It seems that the new species can be ascribed as Endangered (EN) according to the IUCN Red List categories and criteria (IUCN 2014). However, it is possible that further populations could be found in similar habitats of neighbouring areas of Jeju-do, Republic of Korea. Given the current limited field work, this new species could be temporarily considered as Data Deficient (DD).
Taxonomic notes. Semiaquilegia quelpaertensis shows morphological similarities with S. adoxoides concerning its narrowly elliptic sepals, shorter pedicel and petals subtruncate at apex. Despite these similarities, there are clear differences between these two species, such as the lobed shape of leaflets, the size of the flowers, the surface of seeds and the length and number of staminodes (Table 1), as well as the habitat (mountains for S. quelpaertensis vs. lowland for S. adoxoides). Semiaquilegia guangxiensis, which is endemic to China, also displays shallower lobed leaflets, larger flowers and seeds and more staminodes than S. adoxoides (Huang et al. 2017). However, S. guangxiensis greatly differs in the 2.5-12 cm long pedicel (vs. 0.8-2.5 cm in S. quelpaertensis), broadly elliptic or obovate sepals (vs. narrowly elliptic sepals in S. quelpaertensis) and apex retuse, reflexed along the lower edge, tubular petals (vs. apex subtruncate, cylindrical petals in S. quelpaertensis; Table 1). Meanwhile, the name Semiaquilegia dauciformis D.Q. Wang was proposed by the following characteristics, i.e. underground stem conical, ramose, basal leaves biternate, staminodes 0-6 and the length of style being about half of the ovary or as long as the ovary (Wang 1989). However, S. dauciformis have been regarded as a synonym of S. adoxoides in Flora of China (Fu and Orbélia 2001). According to the characteristics of the leaves dissection, S. dauciformis is similar to S. quelpaertensis, but the new species has ternate leaves, larger flowers and staminodes which are 1/2-2/3 of the length of the filaments.