Botanical Studies (2011) 52: 219-223.
SYSTEMATICS
Sinosenecio sichuanicus (Asteraceae), a new species from Sichuan, China
Ying LIU1 and Qin-Er YANG2'*
1State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing
100093, RR. China
2Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese
Academy of Sciences, Xingke Road, Tianhe District, Guangzhou 510650, P.R. China
(Received September 7, 2009; Accepted July 2, 2010)
ABSTRACT. Sinosenecio sichuanicus Y. Liu & Q. E. Yang, a new species from Sichuan, China, is described and illustrated. The new species is similar to S. chienii (Hand.-Mazz.) B. Nord. in the leaf shape and the ma­ture achenes usually epappose, but differs by having 2-3 cauline leaves, the leaf-lamina pubescent on both sur­faces, the petioles pubescent, and the rays larger, 18-20 x 4-5 mm. Its somatic chromosome number (2n = 60) is reported here. Photographs of both S. sichuanicus and S. chienii, line drawings, distribution map, and light microscope (LM) microphotographs of floral characters of S. sichuanicus are provided.
Keywords: Asteraceae; Chromosome number; Senecioneae; Sinosenecio sichuanicus.
INTRODUCTION
In the course of making a comprehensive survey of the specimens of the genus Sinosenecio B. Nord. (Senecione-ae-Asteraceae) deposited in Chinese herbaria for the first author's Ph.D. project on the systematics and evolution of this genus, a flowering collection, Wei-kai Bao et al. 2496 (CDBI) from Hongya County, Sichuan Province, China, caught our attention. The specimens in the collection had been previously identified as S. chienii (Hand.-Mazz.) B. Nord., possibly owing to similarities in the leaf shape and the mature achenes usually epappose, but they differed markedly from the latter in having 2-3 cauline leaves. In S. chienii, the leaves are always radical. Flowering and fruit­ing specimens of this plant were successfully collected during our field studies carried out in Hongya County in June 2007 and May 2009. Upon careful comparison, we found that the plant in question is different from S. chienii in a series of characters and thus represents a hitherto un-described species. Further herbarium work led to the dis­covery of more specimens of this new species.
NEW SPECIES
Sinosenecio sichuanicus Y Liu & Q. E. Yang, sp. nov.― TYPE: CHINA. Sichuan, Hongya County, Gao-miao: Qi-li-ping, Hua-jiao-gou, alt. 2,000 m, on rocks along streamside in deciduous broad-leaved forests, 20 May
2009, Ying Liu & Tao Deng 2009074 (holotype, IBSC; isotypes, HAST, PE).四川蒲兒根         Figures 1, 2
Haec species similis Sinosenecioni chienii (Hand.-Mazz.) B. Nord. foliorum laminis cordatis vel late cordatis et acheniis maturis plerumque pappo destitutis, sed caule 2-3-foliato, foliorum laminis utrinque pubescentibus, pe-tiolis pubescentibus, ligulis majoribus 18-20 x 4-5 mm facile distinguitur.
Description. Herb with leafy stem, stolons absent. Rhizomes 6-7 mm in diameter. Stems solitary or several, erect, 20-30 cm tall, simple, fulvous-sericeous, sparsely so in the upper part, densely so at the base. Leaves several, radical, and cauline. Radical leaves 1-2, long-petiolate; lamina broadly cordate to reniform in outline, 5-9 x 5-10 cm, palmately veined, submembranous, green above, pale-green beneath, pubescent on both surfaces, margin repand or sinuate-dentate with mucronulate teeth, apex acuminate or acute, apiculate, base deeply cordate to cordate; petioles 6-14 cm long, pubescent, densely sericeous at the base. Cauline leaves 2-3, smaller, with shorter petioles. Ca-pitula solitary or several; peduncles 4-8 cm long, sparsely fulvous-sericeous in the lower part, fulvous-sericeous in the upper part. Involucres obconic-campanulate, ecalycu-late, 5-8 x 8-12 mm. Phyllaries 13, uniseriate, oblong or oblong-lanceolate, 8 x 2-3 mm, apex acuminate or acute, fulvous-sericeous, apex fimbriate-ciliate, herbaceous, green. Ray florets 12-13; corolla tube ca. 2 mm long, glabrous; rays yellow, oblong-elliptic, 18-20 x 4-5 mm, apically 3-denticulate, 4-7 (-9)-veined. Disc florets many; corolla ca. 4 mm long, tube ca. 3 mm long, limb cam-panulate; lobes ovate-lanceolate. Anthers ca. 2 mm long,
*Corresponding author: E-mail: qeyang@scib.ac.cn; Tel: 86­20-37094273; Fax: 86-20-37094273.
220
Botanical Studies, Vol. 52, 2011
tion has suffered from habitat destruction due to intensive human activities such as medicinal plant cultivation.
Floral micromorphological characters. For observation of the anther endothecial cell wall thickenings and fila­ment collar of Sinosenecio sichuanicus, heads were boiled in distilled water for 3 min, and then fixed with Carnoy I (glacial acetic acid: absolute ethanol = 1 ： 3). Mature disc florets removed from the fixed heads were dehydrated in 70% ethanol for 30 min and then in 99% ethanol for 1 h
Figure 1. Sinosenecio sichuanicus Y. Liu & Q. E. Yang. A, Habit; B, Phyllary (right: abaxial side; left: adaxial side); C, Ray floret; D, Disc floret; E, Stamen; F, Style; G, Style-arms (All from Ying Liu & Tao Deng 2009074, HAST, IBSC, PE).
base obtuse, appendages ovate-oblong. Style arms ca. 1 mm long, apex truncate. Achenes obovoid-cylindrical, 1.5 mm long, smooth, glabrous. Pappus sometimes (in ca. 1/3 florets of a capitulum) of several 1.5-2 mm long hairs at anthesis, but often deciduous, and thus usually absent in mature achenes.
Additional specimens examined. CHINA. Sichuan, Hongya County, Hua-jiao-gou, alt. ca. 1,950 m, along stream, in woods, 27 Jun 1994, Wei-kai Bao et al. 2496 (CDBI); Hongya County, the same locality, 24 June 2007, Qin-er Yang, Qiong Yuan & Ying Liu 923 (IBSC); Hongya County, Luo-han-shan, Da-zhong-gang, alt. 2,400 m, 8
June 1994, Wei-kai Bao et al. 1981 (CDBI); Emei County,
Mt. Emei, San-dao-he, alt. 1,800 m, 19 May 1956, Shi-zhen Yu 49355 (SZ); Emei County, Mt. Emei, Hei-qiao, streamside, alt. 1,300 m, 17 May 1995, Hong-gui Xu
01830169 (PE).
Etymology. The specific epithet 'sichuanicus' is derived from Sichuan, a province in western China.
Phenology. Flowering May; fruiting June.
Distribution, habitat, and status. Sinosenecio sich-uanicus is currently known from four populations in Hongya County and Emei County, Sichuan Province, China (Figure 3), growing in grasses or on rocks along streamside in deciduous broad-leaved forests at altitudes of 1,300-2,400 m above the sea level. At least one popula-
Figure 2. Sinosenecio sichuanicus Y. Liu & Q. E. Yang. A, Hab­it; B, Florets (above) and capitulum (below); C, Leaf; D, Habitat (All from type locality and vouched by Ying Liu & Tao Deng
2009074, HAST, IBSC, PE).
Figure 3. Distribution of Sinosenecio sichuanicus (▲).
LIU and YANG ― Sinosenecio sichuanicus, a new species from China
221
before they were treated with 5% NaOH overnight. The anther tissue was isolated from the florets on the slide, flooded with 50% glycerol, and a cover slip was applied. Samples were then examined at 200x (filament collar) and 400x (endothecial cell wall thickenings) magnification by light microscopy and photographed.
The anther endothecial cell wall thickenings in Sino-senecio sichuanicus were strictly polar (Figure 4A), a character claimed by Jeffrey and Chen (1984) to occur in all the species of Sinosenecio sect. Sinosenecio. The thick­enings of its putative close relative, S. chienii, were also strictly polar (the results not shown here). In the members of Sinosenecio sect. Phyllocaulon C. Jeffrey & Y L. Chen, the endothecial cell wall thickenings are radial or radial and polar (Jeffrey and Chen, 1984; Zhang et al., 2008; Liu et al., 2009; Liu et al., 2010). As indicated in Figure 4B, its filament collar consisted of uniformly sized cells, con­forming to one of the diagnostic characters of this genus
(Nordenstam, 1978; Jeffrey and Chen, 1984; Chen, 1999).
Chromosome cytology. As we failed to harvest actively growing roots both in field and greenhouse for chromo­somal observation, leaf buds were used. They were pre-treated with 0.1% colchicine for 1.5-2 h before being fixed in Carnoy I (glacial acetic acid: absolute ethanol = 1 ： 3).
They were then macerated in a 1:1 mixture of 45% acetic acid and 1 M HCl at 60°C for 3 min, stained, and squashed in Carbol fuchsin.
In the interphase nuclei, a few darkly stained condensed bodies were observed, but their boundaries were not clear, because the other part was also stained fairly well but un­evenly (Figure 5A). The prophase chromosomes displayed a distinctly continuous condensation pattern (Figure 5B). Its metaphase chromosomes were counted to be 2n = 60 (Figure 5C). Sinosenecio chienii, the putative close relative of S. sichuanicus, has also the same chromosome number (Ying Liu & Qin-er Yang, unpublished data).
Notes. Sinosenecio sichuanicus is similar to S. chienii (Figure 6) in the leaf shape and the mature achenes usually epappose, but differs by having radical and 2-3 cauline leaves (vs. radical), the leaf-lamina pubescent on both sur­faces (vs. sparsely fulvous-pilose or subglabrescent above, sparsely villous or glabrescent beneath), the petioles pu­bescent (vs. fulvous-villous, more or less glabrescent), and the rays larger, 18-20 x 4-5 mm (vs. 8-10 x 2.5-3.5 mm) (also see Table 1).
Although Sinosenecio sichuanicus and S. chienii are overlapping in their geographical distribution and occupy basically the same altitudinal range (Table 1), they have
Figure 4. Anther endothecial cell wall thickenings (A) and fila­ment collar (B) of Sinosenecio sichuanicus. A, Strictly polar thickenings; B, Uniformly sized cells (All from Ying Liu & Tao Deng 2009074, HAST, IBSC, PE).
Figure 6. Sinosenecio chienii (Hand.-Mazz.) B. Nord. A, Habit; B, Inflorescence; C, Florets (left) and capitulum (right); D, Leaf; E, Habitat (All from Wawushan, Hongya County, Sichuan Province, China and vouched by Ying Liu & Tao Deng 2009078,
IBSC, PE).
Figure 5. Interphase nuclei (A), mitotic prophase (B), metaphase (C, 2n = 60) chromosomes of Sinosenecio sichuanicus (All from Ying Liu & Tao Deng 2009074, IBSC, PE).
222
Botanical Studies, Vol. 52, 2011
Table 1. Comparison of Sinosenecio sichuanicus and S. chienii.
S. sichuanicus
S. chienii
Height (cm)
20-30
20-30
Posture
Herb with radical and 2-3 cauline leaves
Herb with radical leaves
Leaf shape
Lamina broadly cordate to reniform in outline, repand or sinuate-dentate
Lamina cordate to broadly cordate in outline, repand or sinuate-dentate
Leaf size (cm)
7-9 x 7.5-10
4-9 x 4.5-9.5
Petiole
Pubescent
Fulvous-villous, more or less glabrescent
Leaf-lamina pubescence
Pubescent on both surfaces
Sparsely fulvous-pilose or glabrescent above, sparsely villous or glabrescent beneath
Anther endothecial cell wall thickenings
Strictly polar
Strictly polar
Ray-floret number
12-13
10-12
Ray size (mm)
18-20 x 4-5
8-10 x 2.5-3.5
Veining of rays
4-7 (-9)-veined
4-veined
Epidermis of achene
Smooth, glabrous
Smooth, glabrous
Pappus
Absent usually in mature achenes or of several hairs at anthesis
Absent usually in mature achenes or of several hairs at anthesis
Florescence
May
Late March-April
Chromosome number (2n)
60
60
Habitat
On rocks in forests along streamside, 1,300-2,400 m a.s.l
Moist shady places in forests, 950-2,200 m a.s.l
Geographical distribution
Restricted to Hongya and Emei counties, W Sichuan
Widely distributed in W Sichuan
not as yet been found to co-occur in a same community. The two species have different flowering periods and habitat preferences. According to our field observations, S. sichuanicus prefers to grow in moist places on rocks or in grasses along streamside in woods, and flowers in May while S. chienii often grows in drier places in the woods or on hillsides and flowers from late March to April. In view of these facts, the two closely related species seem to be well isolated from each other reproductively, and it is thus not surprising that we did not observe any putative hybrids in the field.
Sinosenecio sichuanicus can be readily referred to subsection Phalacrocarpa C. Jeffrey & Y. L. Chen, sec­tion Sinosenecio, based on its strictly polar anther endoth-ecial cell wall thickenings and mature achenes usually epappose. Jeffrey and Chen (1984), in their infrageneric division of the genus Sinosenecio, used the presence or ab­sence of cauline leaves as the only character to distinguish series Elati C. Jeffrey & Y. L. Chen from series Scaposi C. Jeffrey & Y. L. Chen under subsection Phalacrocarpa, with the former series regarded as being characterized by the presence of cauline leaves and the latter by the absence of cauline leaves. We have pointed out that the discovery of S. yilingii, a species also from Sichuan, results in the collapse of this character at the series level (Liu et al., 2010). This view is further corroborated by discovery of the present new species. These two species, albeit with cauline leaves, seem to be much more closely related to S. chienii and S. homogyniphyllus (Cumm.) B. Nord. within
series Scaposi than to the members within series Elati. The chromosome number 2n = 60 and the strictly polar pat­tern of anther endothecial cell wall thickenings of the four species also lend strong support to their placement in the former series (Liu & Yang, 2010; Ying Liu & Qin-er Yang, unpublished data).
Acknowledgments. We are very grateful to Dr. B. Nor-denstam for his invaluable comments on the manuscript. We thank Ms. Liu Yun-xiao for making the drawing, and Mr. Deng Tao for his help in the field work. This work was supported by the Knowledge Innovation Project of the Chinese Academy of Sciences (KZCX2-YW-415, KSCX2-YW-Z-0918) and the National Natural Science Foundation of China (Grant No. 30970183).
LITERATURE CITED
Chen, Y.L. 1999. Sinosenecio B. Nord. In Anonymous (ed.), Flora Reipublicae Popularis Sinicae 77(1). Science Press, Beijing, pp. 101-141.
Jeffrey, C. and Y.L. Chen. 1984. Taxonomic studies on the tribe Senecioneae (Compositae) of Eastern Asia. Kew Bull. 39: 205-446.
Liu, Y. and Q.E. Yang. 2010. Sinosenecio yilingii (Asteraceae), a new species from Sichuan, China. Bot. Stud. 51: 269-275.
Liu, Y, G.X. Chen, and Q.E. Yang. 2009. Sinosenecio baojin-gensis (Asteraceae), a new species from Hunan, China. Bot.
LIU and YANG ― Sinosenecio sichuanicus, a new species from China
223
Stud. 50: 107-113.
Liu, Y., D.G. Zhang, and Q.E. Yang. 2010. Sinosenecio hup-ingshanensis (Asteraceae), a new species from Hunan and
Hubei, China. Bot. Stud. 51: 387-394.
Nordenstam, B. 1978. Taxonomic studies on the tribe Sene­cioneae (Compositae). Opera Bot. 44: 1-84.
Zhang, D.G., Y. Liu, and Q.E. Yang. 2008. Sinosenecio jishouensis (Compositae), a new species from north-west
Hunan, China. Bot. Stud. 49: 287-294.
中國四川產蒲兒根屬一新種：四川蒲兒根
劉 瑩 1楊親二2
1中國科學院植物研究所系統與進化植物學國家重點實驗室
2中國科學院植物資源保護與可持續利用重點實驗室（華南植物園）
本文描述了中國四川產蒲兒根屬一新種：四川蒲兒根(^Sinosenecio sichuanicus Y. Liu & Q. E.
Yang)。本新種在葉片形狀，成熟瘦果通常無冠毛方面與雨農蒲兒根(：Sinosenecio chienii (Hand.-Mazz.)
B. Nord.)相似，但以具2-3莖生葉，葉片兩面及葉柄被柔毛，舌片較大（18-20 x 4-5 mm)而與後者相
區別。其體細胞染色體數目為2n = 60 。本文提供了四川蒲兒根以及雨農蒲兒根的彩色圖版、四川蒲兒
根的線繪圖、花部微觀性狀的光鏡照片以及地理分佈圖。
關鍵詞：菊科；染色體數目；千里光族；四川蒲兒根。