Aster jiangkouensis X. L. Yu & X. Li, 2021

Li, Xiong, Wu, Lei & Yu, Xun-Lin, 2021, Aster jiangkouensis (Asteraceae), a new species from Guizhou, China, Phytotaxa 483 (1), pp. 75-79 : 77-79

Aster jiangkouensis X. L. Yu & X. Li , sp. nov. ( Figs. 1 & 2 )

Diagnosis: —The species is morphologically similar to the adjacently distributed A. huangpingensis W. P. Li & Z. Li ( Li et al. 2020: 242), but mainly differs in the following characters: leaves inconspicuously triplinerved (vs. conspicuously veined), leaf blades ovate to oblong-lanceolate (vs. narrowly oblanceolate or spatulate), involucre cylindric-campanulate (vs. campanulate), peduncle and pedicels glabrous (vs. sparsely strigillose), achenes 4-ribbed (vs. 2- or 3-ribbed).

Type: — CHINA. Guizhou Province: Tongren city, Jiangkou county, Zhenjiang village [27°42’N, 108°48’E], elevation ca. 490 m, on the moist rock of cliff near river of karst valley, 2 November 2019, X. Li 19110201 (holotype CSFI!; isotype CSFI!) .

FIGURE 3. Distribution map of Aster jiangkouensis (★).

Herbs perennial, 20–60 cm tall, rhizomes robust. Stem solitary, pendent or ascending, branched only in inflorescence, slender, glabrous. Leaves basal and cauline, lustrous, veins triplinerved, inconspicuous, thinly leathery, margins villous-ciliate, adaxially villous-strigose, abaxially glabrous or sparsely strigose, obviously when young. Basal leaf blades ovate, usually present at anthesis, 2–7 × 0.8–4 cm, base gradually narrowing, margin serrate with 3–5 pair of teeth, base attenuate, apex acute; lower cauline leaf blades ovate to lanceolate 3–7 × 2–4 cm, petiole 2–6 cm, base cuneate, apex acuminate; middle leaves lanceolate to oblong-lanceolate, 3–5 × 1–2 cm, shortly petiolate; upper leaves oblong-lanceolate, margin often entire, 2.5–3 × 0.5–1 cm, petiole nearly sessile, apex long acuminate. Capitula 3–7 (occasionally to 18) in terminal lax corymbiform to paniculate-corymbiform inflorescences, 2–2.5 cm in diameter; involucre cylindric-campanulate, 5.8–8 × ca. 3.8 mm; phyllaries 4–5-seriate, herbaceous, green, margins more or less scarious, fimbriate-ciliate, apex acute, receptacle slightly convex, abaxially sparsely puberulous; outermost phyllaries ovate-lanceolate, 0.6–0.9 × 2.4–2.8 mm; second-row phyllaries oblong-lanceolate, 0.7–1 × 3.5–4.2 mm; middle phyllaries oblong, 0.9–1.3 × 4.8–5.5 mm; fourth-row phyllaries narrowly oblong, 0.9–1.3 × 6–7 mm. Ray florets 9–13, female, glabrous, tube 3.4–4.2 mm long, ligules white, 9.5–11 × 1.3–1.7 mm, apex slightly 2–3-lobed. Disk florets hermaphrodite, many, tube base flared, limb campanulate, corolla yellow, 4.6–6 mm long, tube 3–3.7 mm long, sparsely strigillose at base, 5-lobed, lobes narrowly triangular; stigmatic appendage (style branch appendage) lanceolate, ca. 0.9 mm long. Anthers lanceolate, ca. 6.2 mm long (excluding collar), Achenes (mature) oblong, 2.5–2.8 × 0.6–0.8 mm, densely strigose, 4-ribbed. Pappus reddish-brown, short than disc corolla at anthesis, unequal, barbellate bristles (mature) 4.5–6 mm long.

Phenology: —Flowering from September to early November and fruiting from November.

Etymology: — Aster jiangkouensis is named after its type locality, Jiangkou county, which is situated in the southwestern Wuling Mountain. The Chinese name is given as “ 江口Ãẃ ”.

Distribution and habitat: —The new species is presently recorded from the karst area of Jiangkou county, Tongren city, Guizhou Province, China. All individuals are restricted to crevices of damp limestone cliffs and rocks near the edge of the river at the elevation range of 400– 500 m.

Preliminary conservation status: —So far, only three populations with a total of approximately 300 individuals were observed in a relatively narrow area (ca. 7.5 km 2). Moreover, Aster jiangkouensis appears to require undisturbed habitats. Two populations in narrow canyons, which are nearly inaccessible to the humans, are quite dense in both reproductive and immature individuals. On the contrary, only several weak individuals were found in disturbed habitats near roads and residential areas. Unfortunately, with the further local tourism development, these populations will be undoubtedly impacted. Therefore, based on its small population size, very limited distribution and threatening factors, A. jiangkouensis should be evaluated as Endangered (EN B2ab (iii) & D) ( IUCN 2016).

Notes: — Aster jiangkouensis is mainly characterized by inconspicuously triplinerved leaves, lax corymbiform to paniculate-corymbiform inflorescences, cylindric-campanulate involucre and reddish-brown pappus. In addition, the habitat of the new species also deserves attention; it grows in crevices of damp limestone cliffs and rocks near the edge of the river, especially favoring shady narrow canyons. The members of Aster occurring in such limestone habitats consist of only a few species in China, including A. jishouensis W. P. Li et S. X. Liu (2002: 455) , A. saxicola W. P. Li & Z. Li ( Xiong et al. 2019: 6), A. ageratoides var. pendulus W. P. Li & G. X. Chen and the new one. There are some morphological characters shared by these species, i.e. robust rhizome, lanceolate leaves, long and usually pendent stem, only basal leaves during the vegetative period.

Figures

FIGURE 1. Aster jiangkouensis X. L. Yu & X. Li. A. Habit B. Capitulum, in frontal view C. Opened capitulum, in side view D. Disc floret in side view E. Style of disc floret. F. Stamen G. Ray floret H. Ripe achene (mature) I. Phyllaries in frontal view. (Drawn by Jing Tian from the holotype).

FIGURE 2. Morphology of Aster jiangkouensis (A–H) and A. huangpingensis (I, J). A. Habitat B. Individual in fruit C. Individual in flower D. Capitulum in frontal (left) and lateral (right) views E. Ray and disc florets (left); ripe achenes attached to receptacle (right) F. Rhizomes (left); abaxial view of lower and middle cauline leaves (right) G. Abaxial surface of phyllaries H. Young individual showing basal leaves I. Capitulum J. Individual in flower.