Semiaquilegia guangxiensis Yan Liu & Y. S. Huang Y 2017, sp. nov.

TYPE:— CHINA. Guangxi Zhuang Autonomous Region: Yongfu County, Jiangyue Village, on limestone hillside, rare, elev. 191 m, 110°5 ʺ E, 24°57 ʺ N, 9 March 2013, Yu-Song Huang Y13030901 (holotype: IBK! Barcode number IBK00383980; isotypes: IBK, PE).

Diagnosis:— S. guangxiensis Yan Liu & Y.S.Huang is similar to S. adoxoides, but it differs by stamens 20–30; staminodes ca. 10 and half the length of the filaments; follicles ca. 1 cm long, ca. 3 mm wide; seeds 1.5–2.5 mm long; tuber 2–5 cm long, 0.5–2 cm in diam., usually thicker than S. adoxoides; leaf blade ovate to triangular ovate, 3–9.5 cm in length and width; pedicel up to 12 cm long; sepals broadly elliptic or obovate, and base of petals tubulose.

Description:— Perennial herbs. Tuber thick, blackish brown, 2–5 cm long, 0.5–2 cm in diam. Stem 3–10, 15–45 cm tall, 1–2 mm in diam., branches with spreading white hairs. Basal leaves numerous, ternately pinnate, rarely biternate; petiole 4–25 cm long, with spreading white hairs, basal petiole sheathed; leaf blade ovate to triangular ovate, both length and width 3–9.5 cm; leaflets flabellate-rhombic to obovate-rounded, 2–6 cm long, 2–5.5 cm wide, 3-parted; segments unequally lobed, adaxially green, and abaxially purple, both surfaces glabrous; petiole of the middle leaflets longer than lateral ones, 1–4.5 cm long. Cauline leaves shortly petiolate, similar to basal leaves but smaller. Inflorescences monochasial, 2- or 3-flowered, bracts oblanceolate to obovate, entire, 3-lobed. Flowers 1.5–2.5 cm in diam., Pedicel 2.5–12 cm long, covered by white pubescence; sepals white, broadly elliptic or obovate, 1–2 cm long, 0.5–1 cm wide, apex rounded or obtuse, usually purple tinged abaxially; petals spatulate, 4–6 mm long, over the middle yellow, apex subtruncate, retuse, reflexed along the lower edge, basally tubulose, glabrous. Stamens 20–30, anthers ca. 1 mm long, filaments 5–8 mm long; staminodes ca. 10, white, lanceolate, membranous, glabrous, 2.5–4 mm long. Pistils 4–5(–6), glabrous. Follicles ovate-oblong, ca. 1 cm long, ca. 3 mm in diam., striae transversely raised; persistent style incurve, 3–5 mm long, glabrous. Seeds elliptic, ca. 1.5 mm long, surface strumose.

Habitat and distribution:— Semiaquilegia guangxiensis grows in broad-leaved forests of limestone hillside, at elevations of 150– 300 m. The habitat is relatively dry and the associated species include Acer tonkinense (Sapindaceae), Bauhinia championii (Fabaceae), Derris fordii (Fabaceae), Alchornea trewioides (Euphorbiaceae), Pilea cavaleriei (Urticaceae), Diospyros saxatilis (Ebenaceae), Chrysanthemum indicum (Asteraceae), Impatiens macrovexilla (Balsaminaceae), etc. It is a pity that the localities of S. guangxiensis are not within protected areas and they are being affected by the local residents, through tree-cutting, clearance for cultivation, grazing, etc. However, S. adoxoides is widely distributed in the central and western regions of China, Japan and Korea, and usually grows in roadside or forest edge.

Phenology:— The new species was observed flowering in March and fruiting from April to May.

Etymology:— The specific epithet is derived from the type locality, Guangxi Zhuang Autonomous Region, China.

Additional specimens examined (Paratypes):— CHINA. Guangxi Zhuang Autonomous Region:Yongfu County, Jiangyue Village, in broad-leaved forests of limestone hillside, elev. ca, 190 m, 9 March 2013, Survey team of Yongfu County, 450326130309019LY (IBK), 14 April 2014, Yu-song Huang Y14041401 (IBK), elev. ca. 185 m, 21 April 2015, Yu-song Huang Y15042101 (IBK).

Conservation status:— Currently, the new species is only known from the type locality, and the population size is about 65 mature individuals. It seems that the new species can be accessed to be Endangered (EN) according to the IUCN Red List categories and criteria (IUCN 2001, 2012). However, it is possible that more populations could be found in similar habitats of limestone areas of northern Guangxi. With limited field works at present, we would temporarily consider this new species to be Data Deficient (DD).

Taxonomic Note:— Semiaquilegia dauciformis D.Q. Wang (1989: 51) was proposed by the following characteristics, i.e. tuber 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. And a variety, S. adoxoides (DC.) Makino var. grandis D.Q. Wang (1989: 53), was named based on the tuber 2–6 cm long, 0.7–2 cm in diameter, stem 20–40 cm tall, basal leaves ternate or biternate, and sepals 7–10 mm long. However, both of them have been regarded as conspecific to S. adoxoides in Flora of China (Fu & Orbélia 2001). Here S. guangxiensis is apparently a different member of Semiaquilegia as described above, which makes Semiaquilegia from a considered monotypic genus to including two species. The detailed morphological comparison between the two species of Semiaquilegia is summarized in Table 2.