Cirsiumtatakaense (Compositae), a new species from Taiwan

Abstract A new species of Cirsium, Cirsiumtatakaense Y.H.Tseng & C.Y.Chang, from central-southern Taiwan is described and illustrated. This species is similar to C.kawakamii Hayata in leaf shape, achene and chromosome number (2n = 64), but can be readily distinguished from C.kawakamii by the narrower leaf lobes, usually higher number of florets and phyllaries, the purplish-red corolla (vs. white) and larger pollen grains. A key to the species of Cirsium in Taiwan is also presented.

Recently, we discovered a rare Cirsium growing in the high mountain areas of centralsouthern Taiwan. Based on the systems of Kitamura (1937) and Iwatsuki et al. (1995), this taxon belonged to section Onotrophe subsection Nipponocirsium and appeared to be similar to Cirsium kawakamii Hayata, sharing the longer leaf lobes, nodding bowlshaped mature capitula and corolla lobes as long as the inflated part of the corolla tube.

Materials and methods
We compared the new species to the other two species of Cirsium sect. Onotrophe in Taiwan.

Herbarium examination
Materials primarily comprised fresh and dried specimens; voucher specimens were deposited in TCF, PPI and TNM. The herbaria referenced included HAST, KYO, PPI, TAI, TAIF, TCF, TI and TNM.

Pollen morphology
Pollen grains, all from fresh material, were directly mounted on a stub without any pretreatment and sputter coated with gold (Quorum SC7620) for observation with a scanning electron microscope (Hitachi S-3400N). The shape, size and exine ornamentation were studied following Erdtman (1952) and Hesse et al. (2009). Vouchers for the pollen material studied are provided in Table 1.

Karyotype analysis
Karyotype analysis was performed by following the same procedure applied by Ozcan et al. (2011) and Yüksel et al. (2013). Root tips were collected on sunny mornings and preserved in 0.002 M 8-hydroxyquinoline solution below 10 °C for eight hours. This material was then fixed with Carnoy's solution (1 part acetic acid: 3 parts EtOH) for at least 24 hours at 4 °C. The fixed roots were then stained with acetic-orcein for 24 hours at room temperature, squashed and the slides examined using an stereo microscope (ACCU-ScoPE 3025). Voucher material is presented in Table 2.

Morphological comparison
Following Kitamura (1937) and Iwatsuki et al. (1995), Cirsium tatakaense is placed in section Onotrophe together with C. kawakamii and C. arisanense. Amongst them, C. arisanense belongs to subsection Australicirsium, which is characterised by having rosette leaves, pot-shaped capitula which are erect or nodding when mature, corolla lobes equal in length to the inflated part of corolla tube and corona-like achene beaks. Both C. tatakaense and C. kawakamii belong to subsection Nipponocirsium, which is characterized by not having rosette leaves, larger bowl-shaped capitula which are nodding when mature, corolla lobes equal in length to the inflated corolla tube and tube-like achene beaks. In comparison with C. kawakamii (Table 3)

Chromosome number
The basic number of chromosomes amongst Cirsium species is often 2n = 34 (Hsu 1970;Funk et al. 2009;Chen and Yeh 2010a;Chen and Yeh 2010b), including in C. arisanense (Peng and Hsu 1978). However, the chromosome number of C. tatakaense is 2n = 64 (Fig. 6A), which is the same as that of C. kawakamii (Fig. 6B), indicating that  the two species are similar in this respect. Notably, other taxa of the same subsection in Japan are 2n = 68 (Iwatsuki et al. 1995). These findings imply that subsect. Nipponocirsium are tetraploids with aneuploid cells.
Phenology. Flowering between September and October and fruiting between October and November.
Phenology. Flowering between August and October and fruiting between September and November.
Distribution. Endemic species of Taiwan. Cirsium tatakaense is located in open areas of cloud forests of vegetation zones from the Quercus to Abies forest zone at alt. 2000−3000 m in central-southern Taiwan (Fig. 3). Based on the geographical climatic regions and vegetation zones (Su 1984(Su , 1985, C. tatakaense is distributed mainly in the central-west inland regions. Cirsium tatakaense has been discovered in sunny environments, such as roadsides and forest margins, concentrated on the upper portions of hills along Provincial Highway no. 18. Miscanthus transmorrisonensis Andersson (Poaceae), Rubus taitoensis Hayata (Rosaceae) and Senecio nemorensis L. var. dentatus (Kitam.) H. Koyama (Compositae) are often discovered with C. tatakaense. Sometimes, C. arisanense Kitam. and C. ferum Kitam. are found near to C. tatakaense; however, no hybrid individual between these species has been observed.
Conservation status. Cirsium tatakaense is distributed in central-southern Taiwan, with a population of more than 1000 mature individuals. Its habitats are mainly located in high and sunny mountain areas and many of them are difficult to locate. Therefore, following the International Union for Conservation of Nature (IUCN) Categories and Criteria (IUCN 2014), we regard this species as Least Concern. However, long-term monitoring of its population is still required.