(080) Proposal to amend Article H.5.2 concerning a nothotaxon with parent taxa at unequal ranks

Abstract

Article H.5.2 of the Shenzhen Code (Turland & al. in Regnum Veg. 159. 2018) currently states that “If the postulated or known parent taxa are at unequal ranks, the appropriate rank of the nothotaxon is the lowest of these ranks.” This wording, perhaps unintentionally, creates a problem in certain cases. If the nothotaxon is the only one known for hybrids between the species to which its unequally ranked parent taxa belong, the rule could be interpreted as the author being instructed to publish an autonym at the lower rank, without valid publication of the name of an infraspecific nothotaxon that does not include the type of the nothospecies to which it is subordinate. This would be contrary to Art. 22.3. To clarify this situation, it is proposed that an explanatory clause and a further Example be added to Art. H.5.2. “H.5.2. If the postulated or known parent taxa are at unequal ranks, the appropriate rank of the nothotaxon is the lowest of these ranks, unless the nothotaxon is the only one known for hybrids between the species to which the parent taxa of the nothotaxon belong.” “Ex. 3. Smith & Figueiredo published the name Aloe ×engelbrechtii Gideon F. Sm. & Figueiredo (in Phytotaxa 464: 253. 2020) for the nothospecies with parents A. arborescens Mill. var. arborescens and A. hardyi Glen. If a nothotaxon is described between A. arborescens var. mzimnyati van Jaarsv. & A. E. van Wyk and A. hardyi, it will be at the rank of nothovariety and valid publication of its name will establish an autonym that will apply to A. arborescens var. arborescens × A. hardyi.” Nicholas Turland, Botanischer Garten und Botanisches Museum Berlin, and John H. Wiersema, Department of Botany, Smithsonian Institution, Washington, D.C., are thanked for helpful suggestions and refining the manuscript.