The Identity of Aster Zayuensis Y. L. Chen (Asteraceae)

http://dx.doi.org/10.11646/phytotaxa.282.1.7

The identity of Aster zayuensis Y. L. Chen (Asteraceae)

ZHIXI FU1,2, GUOJIN ZHANG1,2, HONG YAN1,2, BAO NIE1,2, BOHAN JIAO1,2 & TIANGANG GAO1,* 1State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 10093, P.R. China 2University of the Chinese Academy of Sciences, Beijing 100049, P.R. China *Author for correspondence: e-mail: [email protected].

Abstract

Based on evidence from specimens and fieldwork, Aster zayuensis Y. L. Chen is shown to be conspecific with Duhaldea eupatorioides (DC.) Steetz.

Key words: Aster zayuensis, Aster, Asteraceae, Astereae, Duhaldea, identity, Inuleae

Introduction

The genus Aster Linnaeus (1753: 827) (Astereae, Asteraceae) consists of approximately 152 species mainly distributed in Eurasia (Nesom 1994; Chen et al. 2011). There are ca. 123 species of Aster in China. Within them, ca. 15 shrub or subshrub species are recorded (Chen et al. 2011). They are distributed in southwestern China and adjacent regions (Chen 1985a, 1985b, 1990). Our revision of the genus Aster, field investigation and examination of the type materials demonstrated that Aster zayuensis Y. L. Chen (1990: 485), a shrub species recognized as endemic to China, is conspecific with Duhaldea eupatorioides (Candolle 1836: 469) Steetz (1857: 309) (Inuleae, Asteraceae), a species widely distributed in China (Xizang), Bhutan, India, Laos, Myanmar, Nepal, Pakistan, Thailand and Vietnam. We hypothesized that A. zayuensis should be reduced as a synonym of D. eupatorioides.

Materials and methods

We conducted fieldwork in North India and Xizang (Tibet), China (including the type locality of Aster zayuensis), and checked specimens (including type specimens) from the following herbaria: PE and GDC. Our field collections (including FAA-fixed capitula) were deposited in the herbarium PE (Institute of Botany, Chinese Academy of Sciences). Floral micromorphological observations were conducted following the methods described in Zhang et al. (2015). The sources of these materials are listed in the legends of Figs. 1–3.

Results and discussion

Aster zayuensis was first described by Chen (1990) based on a single gathering (Z. C. Ni et al. 570) from Zayü county, Xizang (Tibet), China (Fig. 1). It was initially proposed as a new species based on the following morphological characters: shrub, oblong or oblong-lanceolate leaves, tomentose phyllaries, marginal florets carpellate, 7–8 in number, corolla yellow, style branch tips triangular. Our examination of the isotype specimen (Fig. 1, Z. C. Ni et al. 570, PE, barcode no. 00247923) made it obvious that this specimen was apparently different from Aster species in some key characters, i.e., the yellow ray florets (vs. non-yellow in Aster), long-tailed anther base (Fig. 2A; the anther base of the Aster is usually ecaudate or ecalcarate, as in A. amellus Linnaeus (1753: 873), the type species of the genus Aster, Fig. 2C), and apex of styles without sterile appendages (Fig. 2B; the species of Aster have sterile style branch appendages that are lanceolate to deltoid in shape, as in A. amellus, Fig. 2D). These were characteristics of the tribe Inuleae rather than of the tribe Astereae (Anderberg 1991; Nesom & Robinson 2007; Funk et al. 2009). Furthermore, supported by

Accepted by Alexander Sennikov: 1 Oct. 2016; published: 26 Oct. 2016 61 the project Flora of Pan-Himalaya, the first author revisited the type locality of A. zayuensis (alt. 1500 m, Zayü farm, Xizang) in 2012 and found numerous populations of D. eupatorioides (Z. X. Fu 1550, 1551, PE; Fig. 3A–B) but no shrubby species of Aster between 1500 and 1700 m.

FIGURE 1. Isotype of Aster zayuensis Y. L. Chen (Z. C. Ni et al. 570, barcode no. 00247923, PE). Image reproduced with permission from PE.

62 • Phytotaxa 282 (1) © 2016 Magnolia Press FU ET AL. FIGURE 2. Micromorphology of Aster zayuensis and A. amellus. A, B. Aster zayuensis (voucher Z. C. Ni et al. 570, PE). A. Anther base. B. Style branches; C, D. Aster amellus (voucher, G. Kleopov s.n., barcode no. 00275044, PE). C. Anther base. D. Style branches. Scale bar: 500 μm.

Based on evidence from careful comparisons of morphological characters of the type specimens (Aster zayuensis, Z. C. Ni et al. 570, PE; Duhaldea eupatorioides, N. Wallich 2993, GDC) and fieldwork, we concluded that the vegetative and floral characters of A. zayuensis were identical to those reported for D. eupatorioides (Ling 1979; Chen & Anderberg 2011), i.e. leaves sessile or with short petiole up to 5 mm, oblong or oblong-lanceolate, 10–14 × 3–5 cm, apex acuminate, green and sparsely scabridulous adaxially, minor veins prominent abaxially (Fig. 3C), margin remotely serrulate; ray florets carpellate, yellow (Fig. 3D); involucre 4–5 mm long, tomentose (Fig. 3D); pappus whitish yellow (Fig. 3D); long-tailed anther base (Fig. 3E) and stigmatic bands apically confluent but separated below (Fig. 3F). Therefore, A. zayuensis should be reduced to a new synonym of D. eupatorioides.

Taxonomic treatment

Duhaldea eupatorioides (Candolle 1836: 469) Steetz (1857: 309)

Basionym:—Inula eupatorioides Candolle (1836: 469). Type:—BANGLADESH. Montes Sylhet, N. Wallich 2993A (G-DC, syntype [barcode no. 00453858], photo!); NEPAL. N. Wallich 2993B (G-DC, syntype [barcode no. 00453859], photo!). = Aster zayuensis Y. L. Chen (1990: 485), syn. nov. Type:—CHINA. Xizang (Tibet): Zayü county, Zayü farm, alt. 1500m, in thickets along riversides in valleys, 9 July 1980, Z. C. Ni et al. 570 (PE, holotype, not found; isotype PE! [barcode no. 00247923]).

THE IDENTITY OF ASTER ZAYUENSIS Y. L. CHEN Phytotaxa 282 (1) © 2016 Magnolia Press • 63 Distribution and habitat:—Bangladesh, Bhutan, China, India, Laos, Myanmar, Nepal, Pakistan, Thailand and Vietnam; in shade and moist places in pine forests; 1,400–1,800 m.

FIGURE 3. Duhaldea eupatorioides (DC.) Steetz (voucher, Z. X. Fu 1550, PE). A. Habit and habitat. B. Capitula, top view. C. Abaxial surface of the leaf blade. D. Capitulum, lateral view, showing the involucre. E. Anther base. F. Style apex. Scale bar: D, 1 mm; E–F, 500 μm.

Phenology:—Flowering and fruiting from July to December. Additional specimens examined:—CHINA. Xizang (Tibet): Mêdog county, B. S. Li and S. Z. Chen 2218 (PE). Zayü county, Z. X. Fu 1550, 1551 (PE); Qinghai-Tibet Exped. 660 (PE barcode no. 00571729, 00571730); J. W. Zhang 820 (PE). INDIA. Himachal: Dharmsala, T. G. Gao and B. Nie 8530 (PE). West Bengal: Darjeeling, T. N. Liou 6476 (PE). Note:—Ling (1979) once mentioned the superficial similarity between Duhaldea and some species of Aster. Duhaldea differs from Aster by the following key characters: corolla yellow or white (vs. not yellow in Aster), anther base with branched tails (vs. without branched tails in Aster), stigmatic bands apically confluent but separated below (vs. stigmatic bands apically separated by sterile appendages but confluent below in Aster) (Anderberg 1991; Nesom & Robinson 2007; Chen & Anderberg 2011).

We are indebted to the curators of the herbaria PE and GDC for access to specimens. This study was financed by the National Natural Science Foundation of China (No. 31270237, 31570204, J1310002), the Chinese Academy of Sciences External Cooperation Program of BIC (No. GJHZ201321) and S & T Basic Work (No. 2013FY112100, 2014FY210300).

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