Bot. Bull. Acad. Sin. (2004) 45: 95-99

Li and Zhang — Aster shennongjiaensis, a new species

Aster shennongjiaensis (Asteraceae), a new species from central China

Wei-Ping Li* and Zhi-Guang Zhang

College of Life Sciences, Hunan Normal University, Changsha 410081, P. R. China

(Received April 25, 2003; Accepted September 1, 2003)

Abstract. A new species of Aster (Asteraceae) from China, Aster shennongjiaensis W. P. Li et Z. G. Zhang, is described and its morphology and karyotype illustrated. Aster shennongjiaensis is apparently endangered, presently known only from one small population in bamboo forests of Shennongjia Reserve in central China. On a morphological basis, the closest species to A. shennongjiaensis is A. lasiocladus Hayata, but they are quite different in many features. The morphological characteristics of the two species are compared. Karyotype of the new species is described and formulated as 2n = 2x = 18 = 16m + 2sm.

Keywords: Asteraceae; Aster shennongjiaensis; China; Diploid; Endangered species; Karyotype; New species.

Introduction

Shennongjia, a Biosphere Reserve of central China, is situated between longitude 109°56'-110°58' E and latitude 31°15'-31°57' N. This area has an archaic geological history, a complex and isolated topography, and complex climatic conditions. The mean elevation is 1,700 m, the annual mean temperature 10-12 °C, and the annual precipitation about 1,200 mm. An extremely diverse vascular flora inhabits this reserve with 2,638 species and infraspecific taxa belonging to 850 genera and 193 families (Zheng, 1993), making the reserve one of the three richest regions of plant diversity in China and a Biosphere Reserve.

During botanical exploration and conservation studies in Shennongjia Reserve in 1997, we collected an unknown taxon assignable to the genus Aster. After further field observations and collections and thorough consultation of Flora Reipublicae Popularis Sinicae (Ling and Chen, 1985), Plantae Sinenses (Handel-Mazzetti, 1938), Flora of Japan (Ito and Soejima, 1995), and Flora of Taiwan (Soejima and Peng, 1998a), and after comparisons with the herbarium specimens of Aster species in the PE, WUK, SZ, CDBI, HNNU, KUN, IBSC, IBK, NAS, HGAS, CCNU, HIB, HIMC, and FUS herbaria, we concluded that the taxon is a new species of the series Ageratoides (Asteraceae, Aster L., sect. Orthomeris A. Gray).

The series Ageratoides Kitam. is distributed mainly in East Asia (Ling and Chen, 1985). On the Chinese mainland, the series is represented by ten species (Ling and Chen,

1985; Soejima and Peng, 1998a), among which seven are endemic, that is, Aster homochlamydeus Hand.-Mazz., A. menelii Levl., A. alatipes Hemsl., A. dolichophyllus Ling, A. hunanensis Hand.-Mazz., A. limosus Hemsl., and A. moupinensis (Franch.) Hand.-Mazz.. The last five species are restricted to central China, and this is, therefore, one of centers of the series for speciation.

Materials and Methods

Field observations and collections were made four times respectively on 10 July 1997, 29-30 July 2000, 28-29 October 2000, and 14-15 September 2001 in Shennongjia Reserve, Hubei Province in central China. We collected 35 individuals of the new species, among which 25 were prepared for morphological analysis as specimens that were deposited in the Herbarium of Hunnan Normal University (HNNU), and 10 were cultivated at Hunan Normal University to be used for cytological investigations.

Actively growing root tips 5 mm long were cut and pretreated with 0.1% colchicine at about 20°C for 4 h before being fixed in Carnoy I (glacial acetic acid: 95% ethanol = 1:3) at 5°C for 12 h, then macerated in a 1:1 mixture of 1 mol/L hydrochloric acid and 45% acetic acid at 60°C for 2 min, and finally stained and squashed in 1% aceto-orcein.

The karyotype parameters came from the data of the chromosome characters of ten somatic metaphase cells from the ten plants. The symbols used to describe the karyotype followed Levan et al. (1964): m = median-centromeric chromosome (arm ratio: 1-1.70); sm = submedian-centromeric chromosome (arm radio: 1.71-3.00). The symmetry of karyotype was classified according to Stebbins (1971).

*Corresponding author. Tel: 86-731-8871052; Fax: 86-731-888-3310; E-mail: lwp@hunnu.edu.cn

Botanical Bulletin of Academia Sinica, Vol. 45, 2004

Results and Discussion

Description

Aster shennongjiaensis W. P. Li et Z. G. Zhang, sp. nov.—TYPE: CHINA. Hubei Prov.: Shennongjia

Reserve, alt. 450 m, 14 Sep 2001, Wei-Ping Li 0776695 (holotype: HNNU; isotype: HNNU). ¯«¹A¬[µµÛ` (Fiugre 1)

Species Aster lasiocladus Hayata affinis, sed differt rhizomate horizontali absente, foliorum vaginis ad basin

Figure 1. Aster shennongjiaensis W. P. Li et Z. G. Zhang (drawn by Ya-Ling Hu). A, Habit; B, Middle portion of stem, showing villi; C, Hair from middle portion of stem; D, Middle cauline leaf; E, Disc floret (upper) and ray floret (lower). (A, B, C, and E from the holotype; D from the isotype)

Li and Zhang — Aster shennongjiaensis, a new species

Stapf ex Rendle. The herbaceous layer is dominated by a few shade-enduring grass species.

According to our field observations, there are no more than 300 plants of this species in Shennongjia Reserve. Furthermore, since the first discovery of the new species in the type locality in 1997, we have searched for it three times in areas surrounding the reserve, but no populations of A. shennongjiaensis have been found there. Therefore, this new species should be assigned to the Endangered (EN) category because of the single population and its small size.

Relationships

Aster shennongjiaensis belongs to ser. Ageratoides (Asteraceae, Aster L., sect. Orthomeris A. Gray) because of its triplinerved leaves, campanulate or hemispheric involucre, 4-seriate bracts with longer inner bracts, lanceolate-obovate achenes, and dirty-white pappus. On a morphological basis, the closest species to Aster shennongjiaensis is A. lasiocladus Hayata. Both are densely villous on stems and lower surface of leaves, glanduliferous on lower surface of leaves, slightly dimorphic in pappus, and heterostigmatic in the same ray floret. However, A. shennongjiaensis can be easily distinguished from A. lasiocladus. A morphological comparison between A. shennongjiaensis and A. lasiocladus is given in Table 1.

Karyotype

Observations of somatic mitosis at metaphase reveal that the chromosome number of A. shennongjiaensis is 2n = 18 (Figure 2) like A. lasiocladus (Soejima and Peng, 1998b). Since the basic chromosome number was reported to be x = 9 in the genus Aster (Huziwara, 1957; Soejima and Peng, 1998b; Li and Liu, 2002; Li, 2002; Li, 2003), A. shennongjiaensis is considered to be diploid. The chromosomes vary in length gradually from 7.92 to 4.89 µm, the ratio of the length of the longest and the shortest chro

caulium dense remanentibus, caulibus in medio villosis, calathidiis plerumque in racemo dispositis, involucri phyllariis interioribus dorsaliter glabris, ramentis alveolorum receptaculi brevioribus, et pappi breviore.

Herbs perennial with no horizontal rhizome. Stems erect, 40-75 cm tall, usually 3-6-branched above, villous (hairs usually 0.5-2 mm long). Leaves distinctly 3-nerved, yellow glandular punctate on low surface; radical leaves rosulate, base attenuate into a clearly winged petiole, withered before anthesis, and the persistent leaf sheath remains forming dense dark scales; lower cauline leaves oblong or obovate with a winged petiole, usually withering at anthesis; middle leaves obovate, oblong, or sometimes spathulate, 4.5-9 cm long, 2-3.6 cm wide, sessile or subsesile, margins entire or serrate with 1-8 pairs of teeth, densely hispidulous on upper surface, densely velutinous on lower surface; leaves on branches much smaller, 1-4.4 cm long, 0.5-2 cm wide, ovate or elliptic, margins entire or serrulate, sessile or subsessile. Heads few to many usually in racemes, sometimes in corymbs, peduncle 0.4-2.3 cm long with some scales. Involucre campanulate to hemispheric, bracts green at apex, 1-nerved, margins scarious and ciliolate, 4-seriate, inner ones glabrous on the dorsal surface, and the others lanuginous more or less. Chaffs of alveoli on clinanthium extremely short, 0.06-0.18 mm long. Ray florets 7-11 in one row, two stigmata different in length, ligules usually reddish purple, 6-9 mm long, 0.9-1.7 mm wide, 3-denticulate at apex, (3-)4(-5)-veined, tube 1.25-2 mm long. Disc florets 12-22, corolla yellow, tube 2.2 -2.8 mm long. Pappus dirty white in 1 series, 2-2.7 mm long in ray florets, 2.5-3.0 mm long in disc florets. Achenes lanceolate-obovate, slightly flattened, 2.0-3.3 mm long, 0.9- 1.2 mm wide, strigose. Flowering Jul-Sep; fruiting Sep-Nov.

Habitat

The vegetation type of this new species' habitat is bamboo forests at 450-500 m elevation in Shennongjia Reserve, dominated by Phyllostachys nigra var. henonis (Mitf.)

Botanical Bulletin of Academia Sinica, Vol. 45, 2004

Figure 2. Micrographs of somatic chromosomes of Aster shennongjiaensis at metaphase (bar = 4 µm). A, Metaphae chromosomes; B, Karyotype.

Literature Cited

Handel-Mazzetti, H. 1938. Plantae Sinenses. Acta Horti Gothoburgensis 12: 203-226.

Huziwara, Y. 1957. Karyotype analysis in some genera of Compositae. II. The karyotype of Japanese Aster species. Cytologia 22: 96-112.

Ito, M. and A. Soejima. 1995. Aster. In K. Iwatsuki, T. Yamazaki, D. E. Boufford, and H. Ohba (eds.), Flora of Japan, Angiospermae, Dicotyledoneae, Sympetalae (b). Kodansha, Vol IIIb, Tokyo, pp. 59-73.

Levan, A., K. Fredga, and A.A. Sandberg. 1964. Nomenclature for centromeric position on chromosomes. Hereditas 52: 201-220.

Li, W.-P. 2002. The biosystematic studies on Aster ageratoides (Asteraceae) polyploid complex. Unpublished Ph. D. Thesis, The Hunan Agricultural University, China.

Li, W.-P. 2003. Morphology and Cytology of Aster moupinensis (Asteraceae) native to the Three Gorge Reservoir Area. Life Sci. Res. 7: 68-71.

Li, W.-P. and S.-X. Liu. 2002. Aster jishouensis (Asteraceae), a new species from Hunan, China. Acta Phytotaxonomica Sin. 41: 455-457.

Ling, Y. and Y.-L. Chen (eds.). 1985. Flora Reipublicae Popularis Sinicae, Vol. 74. Science Press, Beijing, pp. 70-284.

Soejima, A. and C.-I Peng. 1998a. Aster. In Editorial Commottee of the Flora of Taiwan (ed.), Flora of Taiwan, Second edition, vol. 4. Taipei, pp. 848-868.

Soejima, A. and C.-I Peng. 1998b. Cytological features of the Aster ageratoides complex (Asteraceae) in Taiwan. Bot. Bull. Acad. Sin. 39: 299-302.

Stebbins, G. L. (ed.). 1971. Chromosomal evolution in higher plants. Edward Arnold, London, pp. 85-128.

Zheng, Z. 1993. A preliminary study on the flora of vascular plants in Shennongjia, China. J. Wuhan Bot. Res. 11: 137-148.

mosome is 1.62, and there is no chromosome with an arm ratio of more than 1.70 except the fourth longest pair (Table 2), indicating that the species has a relatively low interchromosomal and intrachromosomal asymmetry. We found no secondary constriction in this new species while the longest chromosome pair of A. lasiocladus has that on its short arm (Soejima and Peng, 1998b). The karyotype of A. shennongjiaensis is formulated as 2n = 2x = 16m + 2sm and belongs to Stebbins' 1A type because the ratio of the length of the longest chromosome to the shortest is below 2, and no arm ratio is more than 2 (Table 2).

Acknowledgments. We are grateful to Prof. De-Yuan Hong, Prof. Liang-Bi Chen, Prof. Sheng-Xiang Liu and Prof. Ke-Ming Liu for their generous concern and help. Our thanks also to Prof. Ging-I Pen for sending us some necessary literature. Many thanks also to Prof. Yi-Ling Chen, a Chinese botanist and Aster expert, for his valuable discussion, and to Prof. Thomas G. Lammers and an anonymous reviewer for critically reading the manuscript and suggesting improvements.

Li and Zhang — Aster shennongjiaensis, a new species