Aster L. is one of the largest genera within the family Asteraceae, consisting of about 180 species, and is widely distributed in the temperate regions of the world (Ling et al., 1985; Nesom, 1994; Noyes and Rieseberg, 1999). Owing to the notoriously high propensity toward interspecific hybridization and polyploidy, limitations of species delimitation are often difficult to define (Jones, 1980). However, the species can be readily grouped into subgenera and sections characterized by the features of the habit, leaf, capitulum, receptacle, pappus, and achene (Chung and Kim, 1991a, 1991b, 1993; Ito 1995; Chen et al., 2011; Chung, 2018).

Aster altaicus var. uchiyamae Kitam., a Korean endemic plant, is found in limited area along the banks of the Namhan River in the Republic of Korea. It was described as a new variety based on a single gathering of T. Uchiyama s.n. made in 1902 from “Keisho, Suianpho” (currently Suanbo in Chungcheongbuk-do), one of several voucher specimens reported with the name A. altaicus Willd. in Flora Koreana (Nakai, 1911). However, this variety should be treated as a species rank because it is clearly distinguished from A. altaicus var. altaicus by the morphological characteristics of the plant habit (perennial for A. altaicus var. altaicus vs. biennial for A. altaicus var. uchiyamae), leaf width (ca. 7–15 mm vs. 3 mm), and head size (2.5–3.5 cm vs. 4.0–4.5 cm) (Chung and Kim, 1993; Chung and Jeong, 1999; Chen et al., 2011).

Nevertheless, when A. altaicus var. uchiyamae was treated as a species rank, the epithet uchiyamae was unavailable in Aster due to the earlier name A. uchiyamae Nakai, which was a replacement name for the illegitimate name A. depauperatus H. Lév. & Vaniot (Nakai, 1941). Aster uchiyamae Nakai was accepted as a legitimate name on some botanical websites, such as those of the Global Compositae Database (GCD; https://www.compositae.org), the International Plant Names Index (IPNI; http://www.ipni.org), and the Plant List (TPL; http://www.theplantlist.org). However, A. depauperatus was sometimes treated as synonym for A. meyendorffii (Regel & Maack) Voss (= A. ciliosus Kitam.) (Kitamura, 1937; Chang et al., 2014b). As a result of checking the holotype of A. depauperatus (Faurie 1074 (E00413387); an image of the holotype is available at https://data.rbge.org.uk/search/herbarium/?cfg=fulldetails.cfg&specimen_num=447093), it was identified as A. hispidus L. with a white crown pappus of ray florets. In conclusion, A. uchiyamae Nakai, a replacement name for A. depauperatus, is a different taxon name from that of A. altaicus var. uchiyamae Kitam. Therefore, we propose the new replacement name of A. altaicus var. uchiyamae under Articles 6.11 and 58.1 of the International Code of Nomenclature (ICN) (Turland et al., 2018).

Aster danyangensis J. Y. Kim & G. Y. Chung, nom. et stat. nov.

Replaced synonym: Aster altaicus var. uchiyamae Kitam., Mem. Coll. Sci. Kyoto Imp. Univ. Ser. B, 13: 367, 1937.— Type: KOREA. Chungcheongbuk-do: Chungju-si, Suanbomyeon, Suanbo, “Keisho (慶尙道), Suianpho (水安浦),” 2 Oct 1902, T. Uchiyama s.n. (lectotype, designated here: TI, Fig. 1; isolectotype: TI, Fig. 2)

Etymology: The specific epithet danyangensis refers to the geographic location of Danyang-gun, where the species was discovered.

Note: Regarding the typification of Aster altaicus var. uchiyamae, Kitamura mentioned a single collection (T. Uchiyama s.n.) in the protologue, which was gathered from Suianpho (水安浦), Keisho (慶尙道), in the Republic of Korea. Later, Chang et al. (2014a) reported the ‘holotype’ at Tokyo University (TI), though the label has been changed from 水安浦 to 水安堡 (error in Chinese characters). Nevertheless, the use of the term ‘holotype’ is not correct in this case and must be corrected to lectotype under Art. 9.9 of the ICN, as Kitamura only referred to a single gathering and not to a single specimen. There are currently two specimens at TI that could belong to the aforementioned type materials (Figs. 1, 2). Those duplicates are to be considered syntypes (Art. 9.5 of the ICN). Therefore, based on the information discussed above, we designated the sheet with a handwritten label of Uchiyama reading “Aster altaicus Willd.” as the lectotype of Aster danyangensis (Fig. 1). Its type information fits the protologue perfectly, which supports it being original material. The selected sheet bears a complete and well-preserved specimen that displays all of the diagnostic morphological features needed for the identification of the species, such as the plant habit, leaf width, and head size (Chung and Kim, 1993; Chung, 2018). Any other specimen from Uchiyama’s gathering in Suanbo must be considered as an isolectotype (Recommendation 9C of the ICN) (Fig. 2).