(2807) Proposal to conserve the name Acalypha wilkesiana against A. tricolor (Euphorbiaceae)

Abstract

(2807) Acalypha wilkesiana Müll. Arg. in Candolle, Prodr. 15(2): 817. Aug (sero) 1866 [Angiosp.: Euphorb.], nom. cons. prop. Typus: Fiji, [Viti Levu], Rewa, “Unit. Stat. explor. exped. under Capt. Wilkes” (G-DC barcodes G00324021 & G00324022; isotypi: GH barcode GH00045512, K barcode K000959008, US Nos. 1944717 & 1944718 [barcodes 00096423 & 00096424]). (=) Acalypha tricolor Veitch ex Mast. in Gard. Chron. 1866: 483. 26 Mai 1866, nom rej. prop. Neotypus (hic designatus): “Hort. Veitch, New Hebrides [Vanuatu]”, Jul 1844 (K barcode K001235482). In late August 1866, Johannes [Jean] Müller [“Argoviensis”] described Acalypha wilkesiana Müll. Arg. (in Candolle, Prodr. 15(2): 817. 1866) from material collected in Fiji during the United States Exploring Expedition commanded by Captain Charles Wilkes, 1838–1842. This species is not known from the wild, but has long been cultivated as an ornamental in Melanesia (Pax & Hoffmann in Engler, Pflanzenr. IV. 147 XVI (Heft 65): 153. 1924; Fosberg & Sachet in Smithsonian Contr. Bot. 45: 10. 1980); by 1866 it was being grown in Europe (Nicholson, Ill. Dict. Gard. 1: 7. 1885). It is now popular throughout the world, being grown for its showy, usually multicolored leaves that sometimes have unusual shapes. It has escaped from cultivation and become naturalized in tropical and subtropical parts of Africa, the Americas, and Asia (Govaerts & al., World Checkl. Euphorb., https://wcsp.science.kew.org, accessed 20 Jan 2021; Levin in FNA Ed. Comm., Fl. N. Amer. N. Mexico 12: 165. 2016). Among the synonyms of Acalypha wilkesiana listed by Seemann (Fl. Vit.: 225. 1867) and some later authors (e.g., Pax & Hoffmann, l.c.) is A. tricolor Hort., with no reference to a place of publication. However, as shown by Mabberley (in Feddes Repert. 101: 275. 1990), this name was published in The Gardeners’ Chronicle (Gard. Chron. 1866: 483. 1866) in reference to a plant given that name by the nurseryman and plant collector John Gould Veitch. The article was not signed, but appears to have been written by the newspaper's editor, Maxwell Tylden Masters, to which the International Plant Names Index (https://www.ipni.org/n/337889-1, accessed 19 Jan 2021) attributes the name. Although the description is brief (an Acalypha “with ovate acuminate leaves of a brownish-green cast, and some of the portions as if they had been stained with red lead”), it is diagnostic of A. wilkesiana. The description of A. tricolor presumably was based on a living plant as it was in a report of new plants at the “Exhibition of Flowers […] on Tuesday last at South Kensington”, and no type has been designated previously. However, there is a specimen of A. wilkesiana with variegated leaves (faded, but apparently green and red) in K (stamped “Herbarium Hookerianum 1867”) that bears a handwritten label saying “‘Acalypha tricolor’ Hort. […] Hort. Veitch”, apparently indicating it was grown by Veitch; the label also suggests that the specimen is from a plant collected by Veitch in the New Hebrides (now Vanuatu) in July 1844. There apparently being no original material for the name, the K specimen is here designated as the neotype. Because that issue of The Gardeners’ Chronicle was published on 26 May 1866, about three months before Müller's work appeared, A. tricolor Veitch ex Mast. is a validly published, older name for A. wilkesiana. The name Acalypha wilkesiana or its synonym A. amentacea Roxb. subsp. wilkesiana (Müll. Arg.) Fosberg (in Smithsonian Contr. Bot. 45: 10. 1980) have been consistently used for this well-known and horticulturally important species since 1866 (cf. publication lists at Govaerts & al., l.c.; Plants of the World Online, http://powo.science.kew.org), whereas A. tricolor has never been accepted, although ‘tricolor’ is sometimes used as a cultivar name. In the interest of nomenclatural stability, we propose conserving the name Acalypha wilkesiana Müll. Arg. against A. tricolor Veitch ex Mast. GAL, https://orcid.org/0000-0003-1514-1570 VGS, https://orcid.org/0000-0002-5348-0648 We thank David Mabberley for calling our attention to his paper, cited above. We are grateful to John McNeill and John Wiersema for their editorial comments. Lynn Gillespie provided valuable comments on an early version of the paper.