Cirsiumtaiwanense (Compositae, Cirsiumsect.Onotrophe, subsect. Australicirsium), a new species from Taiwan

Abstract A new species of Cirsium, C.taiwanense Y.H.Tseng & Chih Y.Chang from central-northern Taiwan is reported in this article. This species is similar to C.hosokawae Kitam. in having a densely cobwebby abaxial leaf surface, but differs in its yellow (vs. vivid purplish red) corolla and the angle between the midrib and the lateral veins of the leaf, which is acute as opposed to nearly at a right angle in C.hosokawae. Cirsiumtaiwanense has 2n = 32 chromosomes, which is different from the other species in the Taiwanese subsect. Australicirsium Kitam. (2n = 34). An identification key to the Cirsium taxa of Taiwan is presented.

For the morphological description, the terminology used by Peng et al. (1998) and Funk et al. (2009) was applied.

Herbarium resources
Herbarium acronyms follow Index Herbariorum (Thiers 2021, continuously updated). Voucher specimens collected for the current study were deposited in PPI, TCF, and TNM. Specimens of the following herbaria were also examined: CHIA, HAST, KYO, PPI, TAI, TAIF, TCF, TI, TNM and TNU. The holotypes of both C. arisanense and C. hosokawae were also studied.

Pollen morphology
Pollen grains were collected from fresh materials, and directly mounted on a stub. After air drying for 24 h at room temperature, the samples were sputter-coated with gold at 10-15 mA for 100 s (Quorum SC7620), and observed with a scanning electron microscope (Hitachi S-3400N). The shape, size and exine ornamentation were recorded using the methods of Erdtman (1952) and Halbritter et al. (2018). Information about voucher specimens is provided in Table 1.

Karyotype analysis
Karyotype analysis was performed using the procedures of Ozcan et al. (2011) and Yüksel et al. (2013). Root tips were collected on sunny mornings and pre-treated with 2 mM 8-hydroxyquinoline below 4 °C for 8 h, then fixed with Carnoy's solution (absolute ethanol:acetic acid, 3:1, v:v) for at least 24 h at 0 °C. The fixed roots were then stained with 2% aceto-orcein for 24 h at room temperature, squashed, and the slides were examined using an optical microscope (Accu-Scope 3025) equipped with a CCD camera (ProgRes C14 plus). Information about voucher materials is presented in Table 1.

Distribution map
A distribution map was generated using QGIS ver. 3.4 from the package developed by Lin (2018). Geographical climatic regions and altitudinal vegetation zones of Taiwan were indicated following Su (1984Su ( , 1985 (Fig. 4). The geographical range of each species was determined from information on herbarium specimens.

Data analysis
The values of the quantitative morphological and palynological traits were determined and their means and standard deviations were calculated (Table 2). Differences between taxa were analyzed using a one-way ANOVA, followed by Tukey's HSD multiple-range test (p ≤ 0.05) (Zar 1984). All analyses were performed using the PASW Statistics ver. 18 software (Sarma and Vardhan 2018).

Macro-morphological differences
The abaxial leaf surface of the members of subsect. Australicirsium in Taiwan displays two types of indumentum. Both C. hosokawae and C. taiwanense are densely covered with cobwebby hairs, whereas C. arisanense is without cobwebby indumentum. The angle between the midrib and the lateral veins of the leaves of C. hosokawae is often almost 90°, (60-)82-90°, which differs significantly (p ≤ 0.05) from that of C. arisanense, (49-)57-78° and C. taiwanense (44-)52-73° (Fig. 1, Table 2). In addition, the mature capitula of C. arisanense are erect and rarely nodding, whereas those of C. hosokawae and C. taiwanense are usually nodding. Cirsium taiwanense has significantly (p ≤ 0.05) more florets in a capitulum (101-135(-194)) than C. arisanense (78-137) and C. hosokawae (54-111), and a larger number of phyllaries: 90-127 vs. 66-100 for C. arisanense and 68-109 for C. hosokawae. (Fig. 1, Table 2). Further, • the corolla of C. taiwanense and C. arisanense is yellow, but that of C. hosokawae is vivid purplish red. Although the color of the corolla of C. hosokawae could not be determined from its type specimen, it is described as red in the protologue (Kitamura 1932). The populations described here have yellow corollas and are therefore regarded as C. taiwanense. Moreover, the corolla lobes of C. arisanense are revolute, whereas the two other species have erect corolla lobes ( Fig. 1, Table 2). Finally, the pappus of the  (Fig. 1, Table 2). In general, the leaves of C. taiwanense and C. hosokawae are similar, as the abaxial leaf surfaces of both species are covered with dense cobwebby hairs. Therefore, herbarium specimens are often misidentified. Our field observations however suggest that the color of the corolla and the angle between the midrib and the lateral veins of the leaves are reliable characters for distinguishing the two species.
Although the chromosomes of the three taxa were too short to determine their karyotypic formula, satellites and secondary constrictions could be observed in longer chromosomes. Satellites were observed in C. arisanense for the 3 rd , 6 th and 7 th pairs (Fig. 3A), in C. hosokawae for the 1 st , 2 nd and 5 th pairs (Fig. 3B), and in C. taiwanense for the 5 th and 7 th pairs (Fig. 3C). In addition, only the 1 st and 2 nd pairs of C. taiwanense have secondary constrictions (arrows in Fig. 3C). Our results show that each taxon of subsect. Australicirsium in Taiwan has a clearly different karyotype (Fig. 3).

Distribution
Cirsium arisanense is the most common Cirsium species in high altitude regions in Taiwan (see distribution map in ). In comparison, C. hosokawae and C. taiwanense are less common and widespread. Both C. hosokawae and C. taiwanense occupy similar habitats and altitudes, often occurring in open areas such as in wide roadsides and forest margins at 1400-3600 m a.s.l. However, the latitudinal distributions of the two species are different. Cirsium hosokawae and C. taiwanense are mainly found in the northwest inland region (Su 1985). However, C. hosokawae is absent from the central west inland region, whereas C. taiwanense is found less frequently near the western boundary of the north section of the east region. In general, the distribution of C. taiwanense is concentrated in the southwest and C. hosokawae is in the northeast of their combined distribution area (Fig. 4). The climate of the C. hosokawae habitat is usually more humid than that of C. taiwanense.

Discussion
The differences and the taxonomic status of the unknown Cirsium Cirsium taiwanense has a unique combination of morphological characteristics: its corolla lobes are erect and yellow, and the abaxial surface of the leaves is densely covered with cobwebby hairs (Fig. 1C). Additionally, C. taiwanense has the largest pollen grains and shortest pollen spines of the three species of subsect. Australicirsium in Taiwan (Fig. 2, Table 2). The chromosome number of C. taiwanense is 2n = 32 (Fig. 3C), which is different from the other known Cirsium species in Taiwan (Hsu 1970;Peng and Hsu 1978;Chen andYeh 2010a, 2010b;. Also, the 1 st and 2 nd pairs of chromosomes in its karyotype have secondary constrictions, which is different from other subsect. Australicirsium species (Fig. 3). Based on the above comparison, C. taiwanense is clearly different from other known congeners. We therefore here describe C. taiwanense as a new species.   Su (1985), and the blue dotted lines indicate sections within each climate region. The right part of the figures shows a side view of Taiwan and the vertical lines indicate altitudinal vegetation zones as per Su (1984 Description. Perennial herbs, stems 0.5-1.0 m tall, internodes terete. Leaves pinnatipartite or pinnatisect, space between pinnae V-shaped, adaxial surface puberulent or cobwebby, abaxial surface densely cobwebby, margin spinose; rosette leaves narrowly elliptic to oblanceolate, base cuneate to attenuate, apex narrowly acute, 19.5-34.1 × 4.1-7.4 cm, angle between the midrib and the lateral veins (40-)55-76°; pinnae 7-11 pairs, 0.9-2.6 ×1.2-2.1 mm, space between pinnae 0.4-1.2 cm, petiole 1.5-4.0 cm; cauline leaves narrowly elliptic to narrowly triangular, base cordate, apex narrowly acute, 9.0-25.5 × 2.2-6.9 cm, angle between the midrib and the lateral veins (44-)52-73°; pinnae 5-8 pairs, 1.3-2.1 × 0.8-1.9 cm, space between pinnae 0.6-1.5 cm, sessile. Capitula