Semiaquilegia danxiashanensis L. Wu, J.J. Zhou, Q. Zhang & W.S. Deng, 2019

Zhou, Jian-Jun, Huang, Zhang-Ping, Li, Jia-Hui, Hodges, Scott, Deng, Wei-Sheng, Wu, Lei & Zhang, Qiang, 2019, Semiaquilegia danxiashanensis (Ranunculaceae), a new species from Danxia Shan in Guangdong, southern China, Phytotaxa 405 (1), pp. 1-14 : 9-11

Semiaquilegia danxiashanensis L. Wu, J.J. Zhou, Q. Zhang & W.S. Deng , sp. nov. ( Figs. 1–3 )

Type: — CHINA. Guangdong province: Renhua county, Danxiashan National Nature Reserve, alt. 122 m, wet cliffs, 25°1 ′ N, 113°44 ′ E, 17 March 2018, J. J. Zhou & W. S. Deng DXTK 001 (holotype CSFI 063660, isotypes CSFI, IBK).

Diagnosis: — Semiaquilegia danxiashanensis is distinguished in the genus by having clawed petals with golden-yellow suborbicular limbs and claws obviously longer than limbs.

Description: —Perennial herbs. Tuber thick, blackish brown, to 3 cm long, ca. 2 cm in diam. Stems 1–6, 10–30 cm in height, branches with spreading white hairs. Basal leaves numerous, ternately pinnate; petiole 2–11 cm long, sparsely spreading white pubescent, basal petiole sheathed; leaf blade broadly ovate to triangular-ovate, 3–5 × 3– 8.5 cm; leaflets flabellate-rhombic to obovate-rounded, 1.0–2.7 × 1.0– 3.5 cm, 3-parted; segments unequally lobed, adaxially green, abaxially pale green, both surfaces glabrous, or sometimes pubescent abaxially along nerves; petioles of the middle leaflets a little longer than those of the lateral ones, 1–3.5 cm long, sparsely pubescent. Cauline leaves subsessile, leaf blades similar to those of basal leaves but smaller. Inflorescences monochasial, 1- or 2-flowered; bracts oblanceolate to obovate, entire or 3-lobed. Flowers 7–9 mm in diam. Pedicel 2.0– 12 cm long, sparsely pubescent. Sepals white, rarely pink, elliptic or obovate, 5.2–8.3 × 2–2.5 mm, apex rounded or obtuse, usually emarginated. Petal limbs suborbicular, ca. 1 mm long, golden-yellow, retuse, glabrous; claw obviously longer than limb, ca. 3.5 mm long. Stamens 12–16; anthers ca. 0.6 mm long; filaments unequal in length, 3.5–4.5 mm long; staminodes ca. 5, linearlanceolate, white, membranous, glabrous, ca. 1.5 mm long. Pistils 2–4, sparsely pubescent. Follicles ovate-oblong, 6–7 mm long, ca. 2.5 mm in diam., striae transversely raised; style persistent, straight, filiform when drying, 3–4.5 mm long, glabrous. Seeds ellipsoid, ca. 1.5 mm long, surface rugose.

Phenology: —Flowers from February to April; fruits from March to May.

Etymology: —The specific epithet “ danxiashanensis ” is derived from the type locality of the new species, i.e. Danxia Shan in Renhua county, Guangdong, China.

Distribution and habitat: — Semiaquilegia danxiashanensis is currently known only from the type locality. The plants grow on wet cliffs. We have carried out several expeditions and investigations in the surrounding places with non-Danxia landform habitats but did not find this species there. Therefore, we presume that this new species may be endemic to Danxia Shan, as some other taxa, e.g. Firmiana danxiaensis ( Chen et al. 2015) .

Conservation status: —Four populations of Semiaquilegia danxiashanensis with approximately 300 mature individuals at each site are currently known, and all are from Danxiashan National Nature Reserve in northern Guangdong, southern China. Danxiashan National Nature Reserve was built in 1995 and the main purpose of the establishment is to protect its unique landform, so that the forests in the reserve and the habitats of this new species have been under continuous and effective protection as well. Taken together, the species is assigned to the status of ‘Near Threatened’ (NT) following the guidelines of IUCN (2016).

Additional specimen examined (paratypes): — China. Guangdong: Renhua county, Danxia Shan, 12 March 2018, J. J. Zhou & L. Wu DXTK031201 (CSFI), 17 March 2018, J. J. Zhou & W. S. Deng DXTK002 (CSFI, IBK), J. J. Zhou & W. S. Deng DXTK003 (CSFI), J. J. Zhou & W. S. Deng DXTK004 (CSFI), L. Wu 7011 (CSFI).

Notes: — Semiaquilegia danxiashanensis is a distinctive species in the genus by having clawed petals with suborbicular limbs, a character otherwise mainly occurring in the genus Dichocarpum . Indeed, the discovery of this new species has largely obscured the morphological distinction of Dichocarpum .

The genus Semiaquilegia consists of four species with the description of S. danxiashanensis ( Table 2). They can be keyed out as follows.

Figures

FIGURE 1. Semiaquilegia danxiashanensis. A. Habit; B. Flower; C. Pistils; D. Petal; E. Stamens; F. Staminodes; G. Follicles; H. Seeds. Drawn by X.Y. Zeng.

FIGURE 2. Holotype sheet of Semiaquilegia danxiashanensis.

FIGURE 3. Semiaquilegia danxiashanensis in the wild (Danxia Shan, Renhua, Guangdong, China).A, B. Habitat; C. Habit; D. Tuber; E. Flower; F. Flower with two sepals removed; G. Petals; H. Sepals; I. Stamens; J. Staminodes; K. Follicles; L. Seeds. Photos by J.J. Zhou and L. Wu.