What is <i>Cactus opuntia</i> today? Epitypification of the Linnaean name, originally based on highly heterogeneous original elements: An alternative to a proposal to conserve another name in use

Abstract The original material of the Linnaean name Cactus opuntia (currently Opuntia vulgaris , syn. subst./replacement name) represents more than one taxon. The name was lectotypified in 1981 with the illustration “Opuntia vulgo herbariorum” published by Bauhin and Cherler in 1650. However, the lectotype is demonstrably ambiguous, and the name cannot be applied to a single currently recognized taxon with certainty. This had previously led to consider the application of this name doubtful, and even led some to propose that O. vulgaris should be treated as a nomen ambiguum. Several subsequent proposals attempted to change the type of this name to an unambiguous element. However, these changes are contrary to the International Code of Nomenclature , because the illustration cited by Linnaeus in the protologue and selected as the lectotype is part of the protologue and therefore cannot be in serious conflict with it or be superseded. Depending on the interpretation of the lectotype, some authors have considered this name conspecific with O. monacantha , or even with O. humifusa (for both, the Linnaean name would take precedence), while in other cases, it has been interpreted as a synonym of O. ficus‐indica . Here, we discuss the name Cactus opuntia and propose a solution to conclusively fix the use of the Linnaean name and its concept. Accordingly, for the purpose of nomenclatural stability and to support the continued and well‐established use of the name O. vulgaris as a heterotypic synonym of O. ficus‐indica , we propose an epitype to fix the application of the name to an element that unambiguously represents the current concept and use of the name O. vulgaris . The epitype selected is a modern and well‐preserved specimen in the herbarium of the University of Florida (FLAS), with available molecular data. Finally, the type of the Linnaean name Cactus ficus‐indica (currently Opuntia ficus‐indica ) is also discussed.