Ainsliaea daheishanensis (Asteraceae): a new species from China

Abstract In this work, we describe a new species, Ainsliaea daheishanensis Y.L.Peng, C.X.Yang & Y.Luo, based on morphological traits. The new species was discovered in the mountains of Yunnan, near the border between Myanmar and China. The new species differs from the phenotypically closely-related Ainsliaea foliosa Handel-Mazzetti in the morphology of the leaf veins and phyllaries, those having a protruding abaxial reticulate pattern in the lower and median part of stem with white hairs and narrow inner phyllaries. A key to the three closed Ainsliaea species occurring in China is provided.


Introduction
Ainsliaea DC., first described by de Candolle (1838), belongs to the subfamily Mutisioideae, tribe Mutisieae. The genus Ainsliaea is a monophyletic group as supported by molecular data (Mitsu et al. 2008) and it includes 50 estimated species distributed in Afghanistan, Bangladesh, Bhutan, China, India, Indonesia, Japan, Korea, Myanmar, Nepal, Pakistan, Philippines, Thailand and Vietnam (Freire 2007, Gao et al. 2011). In addition, in recent years, new species have been reported in China and Vietnam (Qian 2000, Freire 2002, Wang et al. 2010. China is the centre of diversity for Ainsliaea. Forty of them are distributed in China, including 28 endemic species (Wang et al. 2010, Gao et al. 2011). However, some species are restricted only to a very narrow area of Sichuan and Yunnan.
During our fieldwork on the border between China and Myanmar, we found a novel and undescribed species of Ainsliaea in the Dahei Mountain in Menglian County. This new species is easily distinguishable from other taxa in the Ainsliaea genus by the protruding white hairy reticulate veins on the lower surface of leaves and narrow inner phyllaries. Here, we name it as A. daheishanensis Y.L.Peng, C.X.Yang & Y.Luo, sp. nov. and we describe its morphology, based on the living plants in the field and several collections in the herbarium. Description. Plants perennial, herbaceous, 60-80 cm tall. Stems erect, unbranched, villous. Leaves alternated in lower to median part of the stem. Petiole 4-6 cm long, large winged, gradually reducing, villous, leaf blades papery, palmatepinnate veined, ovate to elliptic, 8-10 × 2-4 cm, apex acute, base abruptly constricted into winged petiole, margin obscurely callose-denticulate, slightly discoloured, upper surface green, sparsely strigose, subglabrous palmate-pinnate veined, lower surface pale with evident reticular veins densely covered by thick white hairs, the remaining part of the lower surface light green and subglabrous. Upper leaves ovate to elliptic, 1-3 × 0.5-1.5 cm, upper surface green-olivaceous, subglabrous palmate-pinnate veined, lower surface densely covered in thick white hairs. Capitula sessile and distantly spaced upwards to the inflorescence axis; disposed in spikes, involucre 6-seriate, cylindrical, ca. 15 × 5 mm; phyllaries papyraceous, glabrous, or sparsely pilose, outer phyllaries ovate, acute, ca. 2 × 1 mm; inner phyllaries linear-oblong to lanceolate, acute, mid-vein dark green, margin pale to pale green. ca. 15 × 0.3 mm. Florets ca. 3-4, flowers not present. Achenes ca. 2-3 mm, densely pilose, pappus reddish-brown, ca. 7 mm long.

Ainsliaea daheishanensis
Etymology. The new specific epithet "daheishanensis" refers to the name of the Dahei Mountain, located at the border between China and Myanmar, where the novel species was discovered.
Phenology. Flowering was not observed, fruiting in November-March. Distribution and habitat. Ainsliaea daheishanensis is only known from the type collection cited above, at 2100-2300 metres altitude, under evergreen forests ( Discussion. This new species is mostly similar to Ainsliaea foliosa in the broadly winged leaves that are loosely aggregated near the median part of the stem and having an ovate blade. Ainsliaea daheishanensis can be distinguished from A. foliosa by its protruding white reticulate veins on the abaxial surface of the lower part of cauline leaves, which is covered with thick white hairs and by the innermost phyllaries that are narrow and slightly shorter than the crown hairs (Table 1) (Fig. 1A, B, E, H). Ainsliaea daheishanensis resembles A. latifolia by its leaves and inflorescences. Both species have ovate to elliptic leaf    Loosely aggregated or occasionally alternated in median part of stem.

Leaf morphology
Lower surface with obvious reticular veins, which are covered with thick white hairs.
Lower surface with sparse trichomes and obscure reticular veins Lower surface densely covered with white fluff, mixed with long, slightly stiff hair of the same colour. Petioles 4-6 cm, obviously shorter than leaf blade.
2.5-5 cm, almost equal or shorter than leaf blade.
Subsessile or shortly pedunculate, (1 or) 2-4 clustered, arranged in spikes or panicles, 3-flowered. blades, with long and winged petioles and the capitula are arranged in spikes. These similarities between the two species led some researchers to wrongly identify the specimens of Ainsliaea daheishanensis as A. latifolia. Morphologically, Ainsliaea daheishanensis differs from A. latifolia in the position of the leaves appearing above the base of the stem (vs. a basal rosette in A. latifolia), and in the evident reticulate veins of the abaxial surface of leaves with thick white hairs, mainly occurring in the reticulate veins. The abaxial surface of A. latifolia leaves is densely covered with white fluff, mixed with long stiff hairs of the same colour. A key to the three closely related Ainsliaea species in China is provided below.