Botanical Studies (2008) 49: 287-294.

*

Corresponding author: Email: qeyang@scib.ac.cn; Tel:

86-20-37094273.

INTRODUCTION

During field work in April 2007 for the second

author¡¦s Ph.D. project on systematics and evolution of the

genus Sinosenecio B. Nord. (Senecioneae-Compositae),

an unusual population was found in a valley in the

Dehang Geological Park, Jishou City, in northwestern

Hunan Province, China. Because of its broadly elliptic-

lanceolate and pinnately-veined leaves, at first glance the

plant appeared to be a member of the genus Senecio L.

Upon closer investigation, which included chromosome

counts and floral micromorphological observations,

the population was determined to represent a hitherto

undescribed species in the genus Sinosenecio. The site

was re-visited in November 2007 for the collection of

cytological material. Searches for more sites resulted in

the discovery of two additional populations in the park.

NEW SPECIES

Sinosenecio jishouensis D. G. Zhang, Y. Liu & Q. E.

Yang, sp. nov.¡XType: CHINA. Hunan, Jishou City,

Dehang Geological Park, moist soil on limestone rocks

in valley, ca. 250 m, 2 Apr 2007, Qin-er Yang, Qiong

Yuan & Ying Liu 544 (holotype, PE).

¦N­º»Z¨à®Ú

Figures 1, 2

Haec species caule foliato, foliis ambitu late elliptico-

lanceolatis, pinnatinerviis, acheniis pappo destitutis a

congeneribus diversa.

Rhizomatous herb with leafy stems, stolons absent.

Stems solitary or several, erect, up to 40 cm tall, ca.

5-10 mm in diameter at the base, simple, 3-6-angulate,

pubescent, sometimes more densely so along the angles.

Radical leaves long-petiolate; lamina elliptic-lanceolate,

4-14 cm long, 2-5 cm wide, pinnately 3-5-veined,

papyraceous or thinly papyraceous, green, sparsely

pubescent on both surfaces, more densely so along the

veins on abaxial surface, apex acuminate or acute, base

rounded or broadly cuneate, margin irregularly sinuate-

dentate; petioles 4-16 cm long, sparsely pubescent, slightly

winged, base expanded. Upper stem leaves smaller,

with shorter petioles. Capitula 5-¡Û in apical corymbs;

peduncles 1-2 cm long, pubescent, distally dilated.

Involucres campanulate, ecalyculate, 5-7 mm long, 6-8

mm wide. Phyllaries ca. 13, uniseriate, oblong-lanceolate,

6-7 mm long, 1.5-2 mm wide, apex acuminate or acutish,

pubescent, herbaceous, green. Ray florets ca. 13; corolla

tube 2 mm long, glabrous; rays yellow, oblong-elliptic,

8-10 mm long, 3-4 mm wide, apically 3-denticulate,

4-veined. Disc florets ¡Û; corolla 4 mm long; tube 2 mm

long; limb campanulate; lobes ovate-lanceolate. Anthers

1.5 mm long, base obtuse; appendages ovate-oblong. Style

arms ca. 1 mm long, apex truncate. Achenes cylindrical,

1.5 mm long, glabrous. Pappus absent.

Additional specimens examined. CHINA. Hunan,

Jishou City, Dehang Geological Park, stream side, 1 May

1990, Zhong-cun Gu 0208 (JIU); same locality, 2 Apr

2007, Dai-gui Zhang 070402001 (JIU).

Sinosenecio jishouensis (Compositae), a new species

from north-west Hunan, China

Dai-Gui ZHANG

1

, Ying LIU

2

, and Qin-Er YANG

3,

*

1

College of Biology and Environmental Science, Jishou University, Hunan 416000, China

2

State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing

100093, China

3

South China Botanical Garden, Chinese Academy of Sciences, Xingke Road, Tianhe District, Guangzhou 510650, China

(Received January 9, 2008; Accepted June 25, 2008)

ABSTRACT.

Sinosenecio jishouensis D. G. Zhang, Y. Liu & Q. E. Yang, a new species from north-west

Hunan, China, is described and illustrated. This new species is easily distinguishable from all its congeners by

having leafy stems, broadly elliptic-lanceolate and pinnately-veined leaves, and achenes without a pappus. Its

somatic chromosomes were counted as 2n = 48 and 96. A color plate, line drawings, light microscope (LM)

photomicrographs of floral microcharacters, and a distribution map are given for the new species.

Keywords: Chromosome number; Endemism; Floral microcharacter; Senecioneae; Sinosenecio jishouensis;

Tephroseridinae.

TaxONOmy

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Botanical Studies, Vol. 49, 2008

Figure 1. Sinosenecio jishouensis D. G. Zhang, Y. Liu & Q. E. Yang. A, Habit; B, Inflorescence; C, Phyllary; D, Ray floret; E, Disc

floret; F, Stamen; G, Style-arms (All from Qin-er Yang et al. 544, PE).

ZHANG et al. ¡X

Sinosenecio jishouensis

, a new species from China

289

Figure 2. Sinosenecio jishouensis D. G. Zhang, Y. Liu & Q. E. Yang. A, Posture; B, Capitula; C, Florets; D, Leaf; E, Habitat. (All from

Qin-er Yang et al. 544, PE).

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Botanical Studies, Vol. 49, 2008

Etymology. The specific epithet ¡¥jishouensis¡¦ is derived

from the type locality, Jishou City, Hunan Province, China.

Phenology. Flowering March to April; fruiting May.

Distribution, habitat and status. Sinosenecio jishouensis

is only known from three small populations occurring

in three adjacent valleys in Jishou City, Hunan, China

(Figure 3), growing in moist soil on limestone rocks

along streams or under waterfalls at an altitude of about

250 m. According to the IUCN red list categories and

criteria, Version 3.1 (IUCN, 2001), this species should be

categorized as a critically endangered species (CR). The

most serious problem with the survival of the species is

that all its populations thus far known are situated within

a geological park which aims not to conserve biodiversity

but mainly to attract tourists, and hence the sites of the

populations are very easily accessible. In particular, a

beautiful waterfall in the park, under which the biggest

population of S. jishouensis was discovered, is the most

frequent destination of tourists visiting the park.

Floral microcharacters. Floral micromorphological

characters of Sinosenecio jishouensis and Senecio

scandens Buch.-Ham. ex D. Don were comparatively

investigated. It should be noted that S. scandens does

not belong in Senecio s. str. as circumscribed by Pelser

et al. (2007). However, it remains a typical member of

the subtribe Senecioninae, so the comparison is still

justified. For observation of their anther endothetical cell

thickenings and filament collar, heads from specimens

were boiled and then fixed with Carnoy¡¦s solution. Mature

disc florets removed from the fixed heads were transferred

to 70% ethanol for 30 min and then to 99% ethanol for 1

h before they were immersed in 5% NaOH for 24 h. 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 200¡Ñ

(filament collar) and

40

0

¡Ñ (endothetical cell thickenings) by light microscopy

and photographed.

Although a few cells near the connective tissue

exhibited a somewhat radial pattern, the anther

endothetical cell thickenings of Sinosenecio jishouensis

were predominantly polar (Figure 4A), conforming to

previous reports that endothetical cell thickenings are

strictly polar, polar and radial or radial in other species of

the genus (Jeffrey and Chen, 1984). The cell thickenings

of Senecio scandens, like those of other Senecio species

reported by Nordenstam (1978) and Jeffrey and Chen

(1984), were radial (Figure 4C). Cells of the filament

collar of S. jishouensis were of uniform size (Figure 4B),

an important diagnostic feature of Sinosenecio, while the

filament collar of Senecio scandens was dilated towards

the base, with the basal lateral cells enlarged (Figure 4D),

one of the distinguishing features of Senecio (Nordenstam,

1978; Jeffrey and Chen, 1984).

Chromosome cytology. For chromosome counts, root

tips were pretreated with 0.1% colchicine for 3 h before

they were fixed in Carnoy I, then macerated in a 1:1

mixture of 45% acetic and 1 N HCl at 60¢XC for 4 min,

stained and squashed in Carbol fuchsin.

Thirteen individuals of Sinosenecio jishouensis were

studied, nine from one population (Qin-er Yang, Qiong

Yuan & Ying Liu 544) and four from a second (Qin-er

Yang, Qiong Yuan & Ying Liu 1500). 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, D). The prophase chromosomes displayed a

distinctly continuous condensation pattern (Figure 5B, E).

The metaphase chromosomes were counted to be 2n = 48

(Figure 5C) in twelve individuals, but 2n = 96 (Figure 5F)

in one individual from the first population.

Discussion. Sinosenecio was segregated as an

independent genus from the quite heterogeneous Senecio

L. by Nordenstam (1978), on the basis of its petiolate

leaves with the lamina distinct from the petiole, ecalyculate

involucres, campanulate limb of the disc florets, polarized

or radial pattern of anther endothetical cell thickenings

and uniformly sized cells of the filament collar. Jeffrey

and Chen (1984), and Chen (1999) accepted Nordenstam¡¦s

concept of the genus Sinosenecio. Thirty-seven species

have been recognized in the genus heretofore (Janovec and

Barkley, 1996; Chen, 1999; Liu, 2000). All are restricted to

China, Korea, and Indo-China (Nordenstam, 1978; Jeffrey

and Chen, 1984; Chen, 1999) except one, S. newcombei

(Greene) J. P. Janovec & T. M. Barkley, a species endemic

to the Queen Charlotte Islands, British Columbia, Canada

(Janovec and Barkley, 1996). As such, Sinosenecio is an

East Asian-North American disjunctive genus, with its

center of species diversity in central and south China.

Jeffrey and Chen (1984) pointed out that because of the

narrow endemism of many of its species, the discovery of

further new species was to be expected as the botanical

exploration of China proceeded.

Molecular sequence data from the ITS region of

nuclear ribosomal DNA and micromorphological data

from anther endothetical cells indicate that S. newcombei

is closely related to North American species of the genus

Figure 3. Distribution of Sinosenecio jishouensis

(¡¶)

in Hunan

Province, China.

ZHANG et al. ¡X

Sinosenecio jishouensis

, a new species from China

291

Figure 4. Endothetical cell thickenings (A, C) and filament collars (B, D) of Sinosenecio and Senecio. A, Sinosenecio jishouensis

with predominantly polarized thickenings; B, Sinosenecio jishouensis with uniformly sized cells; C, Senecio scandens with radial

thickenings; D, Senecio scandens with enlarged basal lateral cells. (A, B from Qin-er Yang et al. 544; C, D from Qin-er Yang et al. 633.

All vouchers at PE).

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Botanical Studies, Vol. 49, 2008

Figure 5. Interphase nuclei (A, D), mitotic prophase (B, E) and metaphase (C, 2n = 48, F, 2n = 96) chromosomes of Sinosenecio

jishouensis. (All from Qin-er Yang et al. 544, PE).

ZHANG et al. ¡X

Sinosenecio jishouensis

, a new species from China

293

Tephroseris (Golden et al., 2001; Pelser et al., 2007).

This genus, together with Sinosenecio and Nemosenecio,

constitutes the subtribe Tephroseridinae C. Jeffrey &

Y. L. Chen within tribe Senecioneae Cass. (Jeffrey and

Chen, 1984), which was recently found to nest within the

subtribe Tussilagininae (Pelser et al., 2007). These three

very closely related genera are more or less distinguishable

on the basis of morphological characters. Nemosenecio

has pinnately divided leaves, Tephroseris is often

arachnoid-tomentose and has pinnately-veined subentire

or dentate leaves with the lamina sometimes not distinct

from the petiole, and achenes with a pappus, Sinosenecio

has usually palmately-veined, sinuate-dentate, sinuate-

denticulate or lobulate leaves with the lamina distinct

from the petiole, and achenes sometimes without a pappus

(Jeffrey and Chen, 1984).

As shown in Figure 2, Sinosenecio jishouensis has

ecalyculate involucres, campanulate limb of the disc

florets, leaves with distinct lamina and petiole, achenes

without a pappus, and is only pubescent on leaves

and stem but never arachnoid-tomentose. Its anther

endothetical cell thickenings are predominantly polar

(Figure 4A) and the filament collar cells are uniform in

size (Figure 4B), which are two important diagnostic

characters of Sinosenecio (Nordenstam, 1978; Jeffrey and

Chen, 1984). Both external morphological characters and

floral micromorphological characters, therefore, justify our

treatment of the new species as a member of Sinosenecio.

Sinosenecio is very poorly known cytologically. Liu

(1999) checked the chromosomes of six taxa in the genus

and reported the chromosome numbers of 2n = 24 in S.

homogyniphyllus (Cumm.) B. Nord. and S. oldhamianus

(Maxim.) B. Nord., 48 in S. bodinieri (Vant.) B. Nord.

and S. septilobus (Chang) B. Nord., 60 in S. subcoriaceus

C. Jeffrey & Y. L. Chen, and 72 in S. globigerus (Chang)

B. Nord. var. adenophyllus C. Jeffrey & Y. L. Chen,

indicating a remarkable variation in the chromosome

number of this genus. The lowest basic number thus far

known in the genus, n = 12, has also been reported in

Nemosenecio and Tephroseris (Koyama, 1965; Patrik,

2006), two genera very closely related to Sinosenecio as

mentioned above, whereas the basic chromosome number

of Senecio s. str. is x = 10 (Jeffrey, 1992; Robinson et al.,

1997). This study has shown that Sinosenecio jishouensis

has the chromosome numbers 2n = 48 and 96 (Figure 5), a

tetraploid or octoploid based on x = 12. The chromosome

number of Senecio scandens was reported as 2n = 2x =

20 (Li, 2004). Having broadly elliptic-lanceolate and

pinnately-veined leaves, S. jishouensis is reminiscent of

some Senecio members. Cytological data indicate that the

similarity of this new species with some Senecio species

in leaf shape and venation is totally superficial, and lend

strong support to its placement in the genus Sinosenecio.

Sinosenecio jishouensis is easily distinguished from

all its congeners by having leafy stems, broadly elliptic-

lanceolate and pinnately-veined leaves, and achenes

without a pappus. Prior to the discovery of our new

species, S. hainanensis (Chang & Tseng) C. Jeffrey & Y.

L. Chen was the sole species in the genus with pinnately-

veined leaves; all other Sinosenecio species typically have

rounded or reniform to ovate or deltoid and palmately-

veined leaves (Jeffrey and Chen, 1984; Chen, 1999).

Sinosenecio jishouensis is the second species with

pinnately-veined leaves in this genus, but it is distinct

from S. hainanensis in habit and leaf shape. Unlike S.

jishouensis in which the leaves are both radical and

cauline, broadly elliptic-lanceolate in outline, the leaves

of S. hainanensis are only radical and rosulate, and ovate-

oblong or obovate in outline (Jeffrey and Chen, 1984).

These two species also differ in habitat preference and

geographical distribution, with S. hainanensis occurring in

tropical forests at altitudes from 900 to 1,200 m on Hainan

Island, southern China, whereas S. jishouensis occurs in a

very open habitat at an altitude of about 250 m in central

China¡¦s northwestern Hunan.

Although in general facies Sinosenecio jishouensis is

rather distinctive within the genus, it seems somewhat

related to S. globigerus (Chang) B. Nord. and its allied

species in habit (the presence of both radical and cauline

leaves), flower structure (achenes without a pappus) as

well as chromosome number (2n = 48) (this study and

unpublished data), and thus may be referred to series

Elati C. Jeffrey & Y. L. Chen, subsection Phalacrocarpa,

section Sinosenecio. More work is needed to determine the

systematic position of S. jishouensis in the genus.

Acknowledgments. We are very grateful to Dr. Bertil

Nordenstam for his invaluable comments on the

manuscript. We thank Mr. Sun Ying-bao for making the

drawing. This work was supported by National Natural

Science of Foundation of China (Grant no. 30770157),

and the Knowledge Innovation Project of the Chinese

Academy of Sciences (KZCX2-YW-415).

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