(2732) Senecio palmatisectus Jeffrey in Notes Roy. Bot. Gard. Edinburgh 9: 128. Mar 1916 [Angiosp.: Comp.], nom. cons. prop.

Typus: China, N.W. Yunnan, 1907, Monbeig 151 (E barcode E00417081).

(=) Senecio pelleifolius King ex J.R. Drumm. in Bull. Misc. Inform. Kew 1911: 271. 25 Jul 1911, nom. rej. prop.

Lectotypus (hic designatus): China, Tibet, Chumbi valley, Do Tho, 30 Jul 1877, King 4683 (CAL barcode CAL0000033487; isolectotypi: CAL barcodes CAL0000033489 & CAL0000033491).

This work clarifies the identity of Senecio pelleifolius King ex J.R. Drumm. (in Bull. Misc. Inform. Kew 1911: 271. 1911), a mysterious species ever since its description, and proposes conserving its later synonym, S. palmatisectus Jeffrey (in Notes Roy. Bot. Gard. Edinburgh 9: 128. 1916), the basionym of the widely accepted Parasenecio palmatisectus (Jeffrey) Y.L. Chen (Fl. Reipubl. Popularis Sin. 77(1): 82. 1999). This name applies to a species widely distributed in SW China and also reported from Bhutan; its basionym, S. palmatisectus, was lectotypified by Koyama (in Acta Phytotax. Geobot. 29: 175. 1978).

Senecio pelleifolius was described based on two collections from Chumbi valley in southeastern Tibet, China, i.e., Dungboo s.n. and King 4683. After its description, it was absent from any taxonomic study until, in their serial revisions of Senecioneae, Robinson & Brettell (in Phytologia 27: 270. 1973) established a new genus Koyamacalia H. Rob. & Brettell for a group of Asian cacalioid species, and S. pelleifolius was included as K. pelleifolia (King ex J.R. Drumm.) H. Rob. & Brettell (l.c.: 273) based on its description. Later, Jeffrey & Chen (in Kew Bull. 39: 209. 1984) reduced Koyamacalia to synonymy under the earlier name Parasenecio W.W. Sm. & J. Small (in Trans. & Proc. Bot. Soc. Edinburgh 28: 93. 1922). Also based on its description, Jeffrey & Chen (l.c.: 432) agreed with the position of S. pelleifolius in Parasenecio, but did not propose a new combination. Grierson & Springate (in Grierson & Long, Fl. Bhutan 2: 1571. 2001) located a syntype of S. pelleifolius, Dungboo s.n., in BM (BM000035561), and found it identical to P. palmatisectus. Although S. pelleifolius has priority over the basionym of P. palmatisectus, Grierson & Springate (l.c.) refrained from making any change in name because they noticed that the BM sheet of Dungboo s.n. differed from the original description of S. pelleifolius in capitulum length, which was described as “1.7 cm” and “quite exceptional” for P. palmatisectus. In addition, Grierson & Springate (l.c.) suggested rejecting S. pelleifolius, if it was finally confirmed to be conspecific with P. palmatisectus.

Apart from the BM sheet of Dungboo s.n., we failed to locate any other original materials of Senecio pelleifolius in BM, E, or K, but three sheets of King 4683 and two of Dungboo s.n. have been successfully located in CAL. One sheet of King 4683 (CAL0000033487) also bears King's detailed notes. Since King was once the superintendent of Calcutta Botanical Gardens (1871–1898) and the director of Botanical Survey of India (1891–1898) (Stafleu & Cowan in Regnum Veg. 98: 545. 1979), and Drummond also lived and worked in India for several decades (1874–1904) (Stafleu & Cowan, l.c. 94: 684. 1976), these specimens should be the exact materials that King and Drummond studied. We examined the specimens and conclude that they are all clearly P. palmatisectus. As to the capitulum length, the “1.7 cm” in the description of S. pelleifolius must be based on Dungboo s.n., because the capitula of King 4683 are not fully in bloom. Among the three sheets of Dungboo s.n., the capitula are 1.5–1.6 cm long in both BM000035561 and CAL0000033490, and 1.6–1.7 cm in CAL0000033488. These are indeed slightly longer than the average capitula of P. palmatisectus, but still fall within its variation range, which is normally 1.2–1.5 cm, but can reach 1.8 cm in some large individuals with the anthers entirely outstretching the corolla tubes at full flowering stage.

Since Senecio pelleifolius predates S. palmatisectus, if the Shenzhen Code (Turland & al. in Regnum Veg. 159. 2018) is strictly followed, S. pelleifolius should be adopted with a new combination in Parasenecio, while P. palmatisectus would need to be synonymized. However, S. pelleifolius is a name almost unknown to the taxonomic community, while P. palmatisectus or its homotypic synonym Cacalia palmatisecta (Jeffrey) Hand.‐Mazz. (in Vegetationsbilder 22(8): 9. 1932) has been consistently used for the taxon (e.g., Handel‐Mazzetti, Symb. Sin. 7: 1128. 1936, in Notizbl. Bot. Gard. Berlin 13: 635. 1937; Hu in Quart. J. Taiwan Mus. 19: 7. 1966; Koyama in Mem. Fac. Sci. Kyoto Univ. Ser. Biol. 2: 174. 1969, l.c. 1978), and now accepted in all the national and regional Floras (Anonymous in Iconogr. Cormophyt. Sin. 4: 557. 1975; Pan in Wu, Fl. Xizang. 4: 805. 1985; Chen, l.c.; Li & al., Fl. Gaoligong Mts.: 910. 2000; Grierson & Springate, l.c.; Liu in Zhuang, Fl. Yunnan. 13: 382. 2004; Chen & Jin in Fu & al., Higher Pl. China 11: 502. 2005; Chen & al. in Wu & Raven, Fl. China 20–21: 458. 2011).

Following the suggestion of Grierson & Springate (l.c.), we here propose conserving S. palmatisectus against S. pelleifolius. It will allow the consistent use of the epithet of P. palmatisectus for the taxon and avoid the potential confusions introduced by the unhelpful nomenclatural change, and thus best serve the nomenclatural stability. No disadvantages would be expected from this conservation.